The A to Z of Effective & Less Effective Immuno-Nutrients to Prevent and Combat Respiratory Tract & Other Infections

Teddy bears are like vitamin C and zinc. They can help you when you are already sick, but what are supplements athletes and gymrats take in advance to survive the flu season without getting sick at all?

Specifically during the winter time, hard working athlete and manic gymrats can be particularly susceptible to all sorts of infections. To help you having to work out with a handkerchief in your hand all winter long, I have compiled a non-comprehensive list of supplements that may help you to maintain and even improve your immune defenses and thus to survive the cold and dark winter times without catching a cold or even the flu.

In their recent review in the Journal of the International Society of Sports Nutrition Vinicius Fernandes Cruzat, Maurício Krause and Philip Newsholme reviewed the extensive literature on nutritional supplements that act as immuno-nutrients, may to reduce immunosuppression and excessive inflammation in hard-training athletes and gymrats like yourself (or yourself in 2015 ;-)

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In said paper, the researchers from the CHIRI Biosciences Research Precinct at the Curtin University in Perth and the Laboratory of Cellular Physiology at the Federal University of Rio Grande do Sul in Porto Alegre focus what they call the "key immuno-nutrients" L-glutamine, L-arginine, branched chain amino acids (BCAA) and whey protein. Now this would not be the SuppVersity if I didn't go beyond this list and added a few more or less promising extra supplements to the list. Before we get to any of those extras, let's briefly recap what Cruzat et al. (2014) found:

"Although a balanced diet with high quality and sufficient quantity of nutrients is essential, there is growing evidence that some non-synthetic supplements can assist optimal nutrition. In fact, the use of nutritional supplements especially the provision of amino acids, has grown year-on-year. [...]

The use of proteins and amino acids for supplementation deserves special attention, since these molecules are critical for anti-oxidant and fuel provision, participating in the whole-body energy homeostasis, growth, development, recovery and immune responses.

As Cruzat et al. point out, the key targets for immunonutrition may include provision of key metabolites for immune cells per se. In other words: Immuno-nutrients feed the immune system and don't suppress but optimize the multi-layered immunte response consisting of

• the inflammatory response and cytokine release, 
• the production of chaperone proteins such as the heat shock proteins (HSPs), 
• changes in the redox balance (including glutathione, GSH metabolism), and 
• the protection of skeletal muscle mass (see Figure 1). 

Thus your reasons to consume immuno-nutrients go well beyond warding off the common cold and encompass (a) performance improvements, (b) the general strengthening of the immune system and (c) the shortening of the exercise recovery period (Nieper. 2005).

Figure 1: Biphasic immuno-inflammatory response to severe exercise and the possible immunonutrition role. Immuno-inflammatory response induced by severe exercise or heavy periods of training and the proposed role of specific nutrients with immune benefits, also called immunonutrition (Cruzat. 2014).

In that, the most widely used supplements are vitamins and minerals. Reliable evidence for their immuno-protective effects, however is scarce and the results are ambigious:

• Vitamin C: South African ultramarathon runners did demonstrate that vitamin C (but not E or beta-carotene) supplementation (about 600 mg day7 1 for 3 weeks) was related to fewer reports of upper respiratory tract infections (URTI) symptoms (Peters 1983, 1990, 1993, 1996; Peters-Futre, 1997).
  
  

  

  Classic ROS-scavengers like vitamin C are not just ineffective, when it comes to countering the increased susceptibility to infection they have also been shown to hamper the adaptational response to exercise | read more.

  These beneficial effects have yet not been replicated by other research teams. Himmelstein, Robergs, Koehler, Lewis and Qualls (1998), for example, reported no alteration in URTI incidence among 44 marathon runners and 48 sedentary individuals randomly assigned to a 2 month regimen of 1000 mg /day of vitamin C or placebo. And in view of the fact that most randomized, placebo-controlled studies have been unable to demonstrate that vitamin C supplements modulate immune responses following heavy exertion (Nieman et al., 1997b, 2002b; Nieman, Peters, Henson, Nevines, & Thompson, 2000b), it should be clear that vitamin C must not be counted among the highly effective immune nutrients. 

Zinc + C, not protetive, but effective? While the evidence supplementing with a combination of vitamin C and zinc would protect you from upper respiratory tract infections (URTIs) is scarce, there are studies like Maggini et al. (2012) which indicate that the provision of a combination of 1000 mg vitamin C plus 10 mg zinc in patients with the common cold will lead to a nonsignificant reductionof rhinorrhoea duration (range 9 – 27%) was seen. Moreover, a pooled analyses of the two studies Maggini et al. conducted shows that "vitamin C plus zinc was significantly more efficient than placebo at reducing rhinorrhoea over 5 days of treatment" (Maggini. 2012). Furthermore, symptom relief was quicker and the product was well tolerated. Despite the fact that the subjects in these experiments were ordinary people, upping your zinc and vitamin C intake, when you've already caught a cold may help you to recover faster and thus get back to the grind earlier.

• Vitamin E: As Niemann et al. point out in their review of the efficacy of various immuno-nutrients, vitamin E functions primarily as a non-specific, chain-breaking antioxidant that prevents the propagation of lipid peroxidation. The vitamin is a peroxyl radical scavenger and protects polyunsaturated fatty acids within membrane phospholipids and in plasma lipoproteins.
  
  The effect of vitamin E supplementation on the inflammatory and immune response to intensive and prolonged exercise is largely unstudied and equivocal. Cannon et al. (1991) found that vitamin E supplementation of 800 IU/day for 48 days attenuated endotoxin-induced IL-6 secretion from mononuclear cells for 12 days after running downhill on an inclined treadmill. Singh et al. (1999) showed no effect of vitamin E supplementation (4 days, 800 IU/day) on the increase in plasma IL-6 following a 98 min treadmill run at 65 – 70% V_ O2max to exhaustion. Petersen et al. (2002) reported no influence of vitamin E and C supplementation (500 mg and 400 mg, respectively, for 14 days before and 7 days after) on the plasma cytokine response to a 5% downhill 90 min treadmill run at 75% VO2max.
  
  

  

  Figure 2: Chronic supplementation with 800 IU of vitamin E (as alpha-tocopherol) has significant negative effects on markers of lipid oxidation and inflammation in triathletes (Nieman. 2004).

  A 2004 study in the course of which triathletes competing in the Kona Triathlon World Championship race event received 800 IU/day of a-tocopherol for two months does even indicate that vitamin E can increase the degree of exercise induced lipid peroxidation and the amount of several cytokines in the blood following a triathlon.Against that background and in view of the previously cited ambiguous results, Niemann et al. (2006) rightly conclude that "vitamin E supplementation to counter immune suppression and oxidative stress in endurance athletes cannot be recommended" (Niemann. 2006).
• Vitamin D: For vitamin D a slightly different image emerges. It appears to be indisputable that athletes with low vitamin D levels are at higher risk of upper-respiratory tract infections - specifically during winter times (He. 2013).
  
  The results of clinical trials investigating the benefits of vitamin D supplementation, however, are less unambiguous. In non-athletes, the monthly administration of 100 000 IU of vitamin D did not reduce the incidence or severity of URTIs; and that despite the fact that the supplement brought the 25OHD levels of the healthy subjects up, significantly (Murdoch. 2012). A meta analysis by Bergman et al. (2013), however indicates that "vitamin D has a protective effect against RTI, and dosing once-daily seems most effective".
  
  

  

  Figure 3: Length of time to viral infection related to initial serum concentration of 25-hydroxyvitamin D.
  Shown are the results of the pharmacodynamic model relating 25-hydroxyvitamin D to length of time before a viral respiratory tract infection (Bergman. 2013)

  Bergamn et al. do yet also point out that "[d]ue to heterogeneity of included studies and possible publication bias in the field, these results should be interpreted with caution" (Bergman. 2013). Against that background it may be a good idea to at least make sure that you are in the "normal range" for vitamin D - irrespective of the fact that low levels may rather be a marker than a trigger of an increased susceptibility to infections that results from uncontrolled inflammation (vitamin D as a negative acute phase reactant | cf. Waldron. 2013).

Next to vitamins, many studies have described the use of proteins, such as whey for supplements or isolated amino acids like glutamine (Kreider. 2008; Cury-Boaventura. 2008).

Simply eating enough: It may sound funny, but in the end it's not surprising that a lack of readily usable energy makes you more susceptible to infections. Firstly, a general calorie restriction is often related to an insufficient intake of important micronutrients (Pendergast. 2002). And even if the intake of all micronutrients is adequate. Important immune factors such as glutamine are (ab-)used as a substrate to produce glucose in the liver and are thus no longer available to "feed" your immune cells. Accordingly it should not surprise you that Niemann and Bishop highlight in their review of "nutritional strategies to counter stress on the immune system in athletes" that the existing data indicates that "physiological stress to some aspects of the immune system is reduced when athletes use carbohydrate during intense exertion lasting 90 min or more" and their own experiments suggest that this means "that athletes using carbohydrate beverages during competitive events will lower their risk of sickness afterwards" (Nieman. 2006).

Figure 4: Mechanisms involving whey proteins as a source of different immunonutrients. (Cruzat. 2014).

In their previously cited review, Cruzat et al. included a nice graphical overview (Figure 4) of the mechanisms by which complete proteins and peptides and their individual amino acids effect the immune system of hard training athletes.

As you can see in Figure 4, Cruzat et al. put a particular emphasis on whey protein - for good reasons.

Firstly, whey contains all the "good" amino acids of which previous studies indicate that they may have direct beneficial effects on the immune system:

• Glutamine: As Cruzat et al. point out, "L-glutamine is probably the most widely recognized immuno-nutrient since it can be used as an oxidizable fuel, a substrate for nucleotide synthesis, a modulator of intermediary metabolism of amino acids, HSP expression and a component of GSH-mediated antioxidant defense" (see Figure 5 | Cruzat. 2014).
  
  Put simply glutamine is the food your immune cells thrive on. Accordingly scientists, athletes and coaches have speculated ever since the early 1990s that supplemental glutamine should be able to prevent the exercise induced immune impairments.
  
  

  

  Figure 6: 5g of glutamine per day led to significant reductions in the occurrance of infections in marathon, ultra-marathon, mid distance runners and rowers (Castell. 1996a).

  Why? Well, exercise depletes the amount of circulating glutamine and will thus "steal" the fodder your immune cells need to survive and function (Wernerman. 2008).
  
  And in fact, there are studies that support the logical conclusion that the repletion of the glutamine that has been burned as alternative fuel during a workout with 0.1 g/kg body weight ameliorates the exercise induced reduction of lymphocytes, and could thus eventually reduce the risk of URTI’s (Castell. 1997).
  
  In that, I deliberately used the conditional, because subsequent studies with fixed (20–30 g/day) or variable (0.3 - 0.5 g/kg body wt) doses of glutamine did not report similar outcomes (Castell. 1996b; Krzywkowski. 2001; Hiscock. 2002). Accordingly, Castell et al. write in their contribution to the BMJ A-Z Supplement review (ed. Newsholme. 2011):
  

  "Overall, there is no consensus or unifying concept to explain the efficacy of exogenous provision of glutamine alone on performance in athletes, although in combination with carbohydrate or other amino acids, significant improvements have been reported." (Newsholme. 2011)

  In other words: Benefits can't be guaranteed, but specifically when glutamine is ingested in amounts of at least 20g/day in addition to carbohydrates and protein supplements it appears as if it could be a useful dietary supplement for hard-training athletes.

Where are all the other supplements gone? As I wrote in the introduction, this list is not supposed to be comprehensive. Furthermore, agents like quercetin, beta-glucan, curcumin or astragalus may be backed by animal studies, their efficacy in human beings does yet warrant further testing - specifically in athletes (Nieman. 2006). Other supplements such as the often-used herb Echinacea purpurea have been shown to fail to stimulate the nonspecific immune response and may be useful only when you are already sick or if the preperations are administered intravenously (Schwarz. 2002).

• Arginine: No, this is not a mistake. L-arginine is in fact the #2 on the list of supplemental immune modulators for hard-training athletes. Needless to say that it's not arginine itself, but rather Nitric Oxide (NO) which acts as a mediator of inflammation and immune system activation in the human body (Krause. 2011 & 2012).
  
  As a SuppVersity reader, you know that arginine has little ergogenic effect. It has beneficial effects in diabetics and may offer benefits for people who want to control their blood pressure. As a immuno-modulator, however it is similarly ineffective as it is as an ergogenic. Benefits can only be expected if the blood levels of arginine are depleted and that is - even with heavy exercise - usually not the case.

Whey protein, however, is more than the sum of its amino acid parts. Yes, whey can contain up to 26% of BCAA, plus L-arginine, L-lysine, L-glutamine.

Figure 7: Effect of maltodextrin (filled square) and maltodextrin plus hydrolyzed whey protein enriched with glutamine dipeptide (filled triangle) supplementation on exercise-induced loss of membrane integrity and depolarized mitochondria in lymphocytes and neutrophils, which are essential for the response against viral infections, such as upper respiratory tract infections (URTI), in athletes after intense training (Cury-Boaventura. 2008).

Whey does yet also contain a range of powerful proteins / peptides, namely betalactoglobulin, alpha-lactalbumin, bovine serum albumin, lactoferrin, immunoglobulins (e.g. IgA), lactoperoxidase enzymes, glycomacropeptides, as well as vitamins such as vitamin D, and minerals such as Ca2+, of these...

• lactoferrin and lactoferricin, demonstrate direct anti-microbial activity and may thus protect you from infections,
• lysosome, lactoperoxidase and diverse globulins and peptides in whey provide a synergistic protective “cocktail” activity against viral and bacterial organisms (Ha. 2003), and
• sulphur-containing amino acids, such cysteine and taurine attenuate the reduction of intracellular GSH concentration induced by intensive exercise (Lands. 1999). 

For all three of them, it is yet not fully established to which extend they contribute to the proven immune-modulating effects of whey (note: the levels of these agents will be higher in concentrates compared to isolates, due to the increased number of processing steps). It is in fact likely that Cruzat et al. (2014) are right, when they say that its the cocktail of amino acids, proteins, peptides and other micro- and macronutrients, vitamins and minerals in whey protein that acts via direct and indirect pathways (e.g. via optimizing the redox status / GSH) on the immune function of athletes.

Bottom line: While there is good evidence for vitamin D supplementation (1,000-2,000IU/day in individuals with low levels and / or hard-working athletes during the winter months) and high doses of glutamine in hard working athletes. There is little doubt that the amino acid + protein + peptide coctail in whey proteins is the "goto supplement" you would choose if you wanted to use only one of the supplements discussed in this article.

Whey Beyond Brawn: 10+ Things You Probably Didn't Know Whey & Peptides That Form During its Digestion Can Do | learn more.

In that, a reasonable dosage suggestion would be similar to that for maximal muscle hypetrophy and range from 20-60g per day - with the higher dosage being consumed in 2-3 servings evenly spread accross the day. Furthermore, studies like the one by Cury-Boaventura et al. (2008) indicate that, during periods of intense training, it may be useful to add glutamine. Either in large amounts of 10-20g per day (5-10g on top of each serving of whey) or, as it was the case in said study, as a dipeptide which has a higher chance of making it past the splachnic bed and not ending up as "fuel" for your organs and or glyconeogenic substrate in the liver.

And yes, if you've already caught a cold, 1 gram (in divided doses) of the the good old vitamin C (if you want to along with 5-15mg of zinc) is useful, as well - along with plenty of rest and sleep, of course ;-) Comment on Facebook!

References:

• Cury-Boaventura, Maria Fernanda, et al. "Effects of exercise on leukocyte death: prevention by hydrolyzed whey protein enriched with glutamine dipeptide." European journal of applied physiology 103.3 (2008): 289-294.
• Bergman, Peter, et al. "Vitamin D and respiratory tract infections: a systematic review and meta-analysis of randomized controlled trials." PloS one 8.6 (2013): e65835. 
• Castell, L. M., E. A. Newsholme, and J. R. Poortmans. "Does glutamine have a role in reducing infections in athletes?." European journal of applied physiology and occupational physiology 73.5 (1996a): 488-490.
• Castell, L. M., et al. "Some aspects of the acute phase response after a marathon race, and the effects of glutamine supplementation." European journal of applied physiology and occupational physiology 75.1 (1996b): 47-53.
• Castell, Linda M., and Eric A. Newsholme. "The effects of oral glutamine supplementation on athletes after prolonged, exhaustive exercise." Nutrition 13.7 (1997): 738-742. 
• Cruzat, Vinicius F., et al. "Amino acid supplementation and impact on immune function in the context of exercise." Journal of the International Society of Sports Nutrition 201.4 (2014): 11:61.
• Cury-Boaventura, Maria Fernanda, et al. "Effects of exercise on leukocyte death: prevention by hydrolyzed whey protein enriched with glutamine dipeptide." European journal of applied physiology 103.3 (2008): 289-294.
• Ha, Ewan, and Michael B. Zemel. "Functional properties of whey, whey components, and essential amino acids: mechanisms underlying health benefits for active people (review)." The Journal of nutritional biochemistry 14.5 (2003): 251-258.
• He, Cheng-Shiun, et al. "Influence of vitamin D status on respiratory infection incidence and immune function during 4 months of winter training in endurance sport athletes." Exerc Immunol Rev 19 (2013): 86-101. 
• Hiscock, Natalie, and Bente Klarlund Pedersen. "Exercise-induced immunodepression–plasma glutamine is not the link." Journal of Applied Physiology 93.3 (2002): 813-822. 
• Lands, L. C., V. L. Grey, and A. A. Smountas. "Effect of supplementation with a cysteine donor on muscular performance." Journal of Applied Physiology 87.4 (1999): 1381-1385.
• Krause, Mauricio S., et al. "L-arginine is essential for pancreatic β-cell functional integrity, metabolism and defense from inflammatory challenge." Journal of endocrinology 211.1 (2011): 87-97.
• Krause, Mauricio, et al. "Differential nitric oxide levels in the blood and skeletal muscle of type 2 diabetic subjects may be consequence of adiposity: a preliminary study." Metabolism 61.11 (2012): 1528-1537.
• Kreider, Richard B., et al. "Effects of ingesting protein with various forms of carbohydrate following resistance-exercise on substrate availability and markers of anabolism, catabolism, and immunity." Journal of the International Society of Sports Nutrition 4.1 (2007): 1-11.
• Maggini, S., S. Beveridge, and M. Suter. "A combination of high-dose vitamin C plus zinc for the common cold." Journal of International Medical Research 40.1 (2012): 28-42.
• Murdoch, David R., et al. "Effect of Vitamin D3 Supplementation on Upper Respiratory Tract Infections in Healthy AdultsThe VIDARIS Randomized Controlled TrialVitamin D3 and Upper Respiratory Tract Infections." Jama 308.13 (2012): 1333-1339.
• Newsholme, Philip, et al. "BJSM reviews: A to Z of nutritional supplements: dietary supplements, sports nutrition foods and ergogenic aids for health and performance—Part 18." British journal of sports medicine 45.3 (2011): 230-232.
• Nieman, David C., et al. "Vitamin E and immunity after the Kona triathlon world championship." Medicine and science in sports and exercise 36 (2004): 1328-1335.
• Nieman, David C., and Nicolette C. Bishop. "Nutritional strategies to counter stress to the immune system in athletes, with special reference to football." Journal of sports sciences 24.07 (2006): 763-772.
• Nieper, A. "Nutritional supplement practices in UK junior national track and field athletes." British journal of sports medicine 39.9 (2005): 645-649. 
• Pendergast, David R. "Effect of dietary intake on immune function in athletes." Sports medicine 32.5 (2002): 323-337.
• Schwarz, Eveline, et al. "Oral administration of freshly expressed juice of Echinacea purpurea herbs fail to stimulate the nonspecific immune response in healthy young men: results of a double-blind, placebo-controlled crossover study." Journal of Immunotherapy 25.5 (2002): 413-420.
• Waldron, Jenna Louise, et al. "Vitamin D: a negative acute phase reactant." Journal of clinical pathology (2013): jclinpath-2012. 
• Wernerman, Jan. "Clinical use of glutamine supplementation." The Journal of nutrition 138.10 (2008): 2040S-2044S.

Shedding Some Light on the Leaky Gut <> Exercise Connection. Plus: 20+ Things You Should or Shouldn't Do to Protect and Restore the Integrity of Your Intestinal Wall

Have you ever felt nauseated after a workout? Or does your protein supplement gives you diarrhea only if you take it right after a workout? Both can be related to the toll  exercise can take on the integrity of your intestinal tract.

To be honest, I was quite surprised that I did not get a hell lot of hatemail in response to the the 'MSG heals the gut study' I posted last Sunday... Be that as it may, I feel sort of awkward to have opened Pandora's box without proving you with some betters tools than mono-sodium glutamate (MSG) to seal the box, or rather your leaky gut, again. Therefore I decided to post this mini-feature on a particular issue all of us will be dealing with: An exercise induced increase in gut permeability. As you are going to see, there are a lot of similarities to the 'classic' leaky gut, which is often implicated in the etiology of chronic inflammatory bowel diseases. In order to understand these similarities, but also the few, yet important differences, we will have to lay some theoretical groundwork.

"What exactly is a leaky gut?"

The easiest way to answer this question would be to say: "That's what everybody and his mama is talking about these days". This definition as concise (and precise) as it may be, is yet about as productive as the talk that's at its heart. So, instead of relying on hearsay, let's rather briefly recap how intestinal wall actually works.

Since the intestines are meant to let nutrients and fluid pass, a certain degree of leakiness is absolutely natural. Problems arise only, when the self-regulatory system is broken and/or the permeability exceeds a normal / healthy threshold (img. by Mariana Ruiz).

The mucosal layer of the intestinal tract is made up of epithelial cells, so-called enterocytes which are connected to one another by specialized proteins. These proteins form the tight junctions (TJ) - a term, you will probably have encountered numerous times before. The main constituents of this kit in between the enterocytes are proteins such as occludin, zona-occludens and claudins. Together, the array of enterocytes and the tight junction form the the intestinal barrier, which allows the absorption of nutrients and water, while preventing the translocation of harmful substances from the gut into the bloodstream.

The integrity of this barrier is influenced by the phosphorylation state of the proteins within the tight junctions.The exact interactions are compilcated and can be looked up elsewhere (Banan. 2005). What's important for you to realize is that during prolonged exercise which is necessarily accompanied by an increase in core temperature, cardiovascular and thermoregulatory responses compromise intestinal blood flow.

With the core temperature usually being lower than the temperature in your intestines, the temperature of your gut can easily approach 41°C during a workout.That's more than your epithelial cells can handle and can lead to structural damage of the 'patches' in the tight junctions + epithelial cell layer (Lambert. 1985).

HIIT veterans or weight lifters are not off the hook

Now, the last paragraph may have sounded as if only long endurance workouts like 10k-runs or marathons could entail damage to the intestinal cells. That's however not the case, since the redirection of the blood away from the splanchnic arteries and to the working muscle that's even more pronounced in high(er) intensity exercise, will initiate an ischaemia reperfusion cycle which can entail oxidative damage not during, but interestingly after the the workout, when the blood rushes back into the intestines (Wijck. 2011).

Take home message: There are two distinct pathways that contribute to the leaky gut during and after a workout (a) heat and (b) ischaemic/reperfusion stress. Both influcne the phosphorylation state of the proteins in the tight junctions and will thus increase the permeability of the gut lining.

It stands to reason that the combination of high intensity and long durations, as you will find it in an ultra-marathon runner, for example, is particularly detrimental to the integrity of the intestinal wall, so that it is not exactly surprising that (ultra-)endurance athletes have the highest prevalence (60-90%) of gastrointestinal distress that which manifests in the form of diarrhoea, nausea, stomach problems, bloating and intestinal cramps (Worobetz.1985; Peters.1999; Jeukendrup.2000)

There is more than one thing you can to to protect, heal and restore your gut integrity

The fact that a "leaky gut" is like an open door not just for exogenous toxins or live bacteria, but also for their 'endotoxic poop' is probably no news for you. In fact, it is also the reason why you want to either prevent the pathological increases in gut permeability, in the first place, and/or (re-)seal the gut as soon as possible after your workouts. In this regards, there are three fundamental and easily implementable strategies that should always be employed before you even think about using specific supplements:

• 

  Figure 1: HSP 70 offers protection against endotoxins (LPS) in vivo (top) and in vitro (bottom; Dokladny. 2010)

  Despite the possible ischaemic / reperfusion stress short high intensity exercise bouts like sprinting are generally less taxing on the integrity of the tight junctions than longer duration medium intensity aerobic workouts. Avoiding these particularly gut-stressing workouts and/or taking special precautions before and after marathons and other endurance events would thus be strategy #1 to keep the epithelial cell layer intact and pathogens and toxins from entering the circulation.
• The natural intracellular expression of heat shock proteins (HSPs) can protect the tight gut junctions during and/or help their restoration after a workout. Just like all our endogenous protection systems the production of HSPs can be trained. Giving your body the time it needs to accommodate by making small, but consistent steps towards longer and/or more intense workouts would therefore be strategy #2.
• That leaves us with strategy #3, of which I hope all of you will be using anyway - even if you have not been aware of its gut protective effect, yet: The provision of adequate fluid supply before, during and after a workout (Lambert. 2008).

As the workout durations become longer and longer and/or the respective intensities higher and higher, solely relying on your bodies self-healing capacity and adequate hydration may seize to work, though. Despite the fact that our bodies accommodate to the ever increasing demand for intracellular protection against heat stress by upregulating the HSP expression (athletes have higher HSP expression to a standardized endurance training protocol than normal individiuals; cf. Fehrenbach. 2000), there is - just as with about every adaptive response - a certain threshold, when hormesis, i.e. the beneficial adaptation to a manageable amount of stress, is no longer an option.

From "A" as in arginine to "Z" as in zinc - a list of things to keep the gut lining intact

While there has been quite a lot of research as of late into which dietary supplements and even regular foodstuff would be able to modulate the heat shock proteins in order to prefer the desired downstream benefits on gut integrity, the number of compounds of which it is reasonable to assume that they can actually make a difference is still very small:

• Colostrum supplementation to cell cultures has been shown to increase the expression of HSP-70 in human epithelial cells; studies with human subjects are rare and ambiguous:  While Marchbank et al., have been able to show that bovine colostrum truncates the increase in gut permeability caused by heavy exercise in athletes (Marchbank. 2011), Buckley et al. actually observed detrimental effects of 8 weeks of bovine colostrum supplementation on the exercise induced gut permeability in runners (Buckley. 2009).The explanation for these discrepencies is not clear, but may be related to the longer duration / different intensity of the exercise protocols, or differences in the immunoglobolin, peptide or amino acid composition of the supplements.
• Zinc in general and specifically polaprezinc, a zinc based anti-ulcer drug, which has primarily been used in Japan as a means to seal leaky Japanese guts, show some promises, as in the treatment and prevention of increased intestinal permeabilty (Zhang. 2009). It is thought that zinc is critical for tight junction assembly and has been shown to be critical in the protection of the gut lining from the chronic toxic assault of alcohol (Zhong. 2010). That being said, you should keep in mind that alcohol will deplete your bodies zinc stores, so that it cannot be said, if someone with an adequate zinc intake would benefit to the same degree as a zinc deficient alcoholic. Moreover, as "natural" as they may be, even essential minerals like zinc don't come without potential side effects (cf. "After 120 Days Rodents on Diets Containing 2xRDA of Zinc Develop Metabolic Syndrome", read more).
• Glutamine has been used as treatment for patients suffering from irritable bowel syndrome and Crohn’s disease and has been shown to actively increase the expression of HSP70 in critically ill patients (Jonas. 1999; Ziegler. 2005).  
• Berberine could be an ideal addition to glutamine (thx to Maxim Okhrimenko for pointing that out in the comments); berberine does not only modulate the TNF-alpha response in the intestines and increases AKT, but has also been shown to maintain / rescue intestinal glutamine transport and glutaminase activity (Gu. 2009; Amasheh. 2010; Li. 2010; Niu. 2011)
• Probiotics are still an 'under-researched' newcomer and though there is some preliminary evidence pointing to the efficacy of probiotic therapy as a means of improving gut function and enhancing the integrity of the intestinal tight junctions, the ideal supplement regimen, as well as its long-term effects will still have to be elucidated in human studies. Studies by Ewaschuk et al. have yet already shown that the impact factors released from Bifidobacteria infantis can offer a certain degree of protection against experimentally induced colitis in rodents (Ewaschuk. 2008). As far as exercise specific studies are concerned, a recently published paper by Lamprecht et al. is probably the first peer reviewed human study to report allegedly "borderline significant" beneficial effects on gut permeability (measured only indirectly by quantifiying the zonolin conent of the feces) and TNFalpha expression in response to a multi-species probiotics (1010 CFU/day, Ecologic®Performance orOMNi-BiOTiC®POWER) in 23 trained men (Lamprecht. 2012; the study was partially funded with a grant from Winclov, the manufacturer of the respective supplements).
• Butyrate, yet not all short chain fatty acids, have recently been found to decrease gut permeability (Ferreira. 2012). Both data from human studies, as well as exercise specific data is yet still absent.
• Hydroxypropyl methylcellulose (HPMC), which is a non-fermentable fiber, has been shown to protect rodent guts from a high fat diet induced increase in gut permeability (Kim. 2012), as in the case of butyrate its efficacy (and when you think about athletes, tolerability) will yet still have to be confirmed in human trials.
• L-Arginine (and AAKG) as a source of nitric oxide, which is necessary to protect the gut barrier from invaders could have a protective effect, as well (Quirino. 2012); and though this effect is not exercise specific, we know that arginine requirements increase in states of chronic stress, it would therefore be logical that supplementation with l-arginine, or even better AAKG, which comes with a precursor to glutamine will have beneficial effects on the tightness of the guts of intensely training athletes, as well (suggested read: BCAAs, glutamine and ammonia detox) .
• Oats, maybe due to their beta glucan content and their ability to increase the production of short-chain fatty acids in the large intestine, oats offer protection against alcohol induced increases in tight junction permeability (Tang. 2009); exercise specific studies have yet to be conducted, though.Personally I would yet not be surprised if this would turn out to be very effective (note: as long as they are not cross-contaminated, oats are 100% gluten-free)
• Goats milk (powder) has been shown to be equally effective as colostrum in reducing heat and thus most likely exercise induced gut permeability (Prosser. 2004)
• Lactoferrin, a multifunctional protein of the transferrin family that is present in milk may have protective effects against LPS-mediated intestinal mucosal damage and impairments of the barrier function in intestinal epithelial cells (Hirotani. 2008)
• Vitamin A in adequate amounts is necessary to maintain gut integrity; it is likely that this is all the more true if gut integrity and immune function are additionally challenged by strenuous exercise (Quadro. 2000)

I guess, I could find even more supplements (and foods) that may help you protect or restore your gut lining, but let's be honest: As important and beneficial eating and supplementing the right things may be, all your efforts would be foiled if you eat foods and supplements that will have the opposite effect on your gut lining. So here is the complementary and likewise non-exhaustive list of stuff you'd better avoid (at least in high doses) if you want to keep your tight junctions intact and your gut from becoming leaky:

Figure 2: Gliadin peptides induce the release of zonulin which in turn interacts with the tight junctions and increases the diffusion of small molecules (∼350 Da) across the cell membrane. Whether the tight junctions open up wide enough to allow for free diffusion of whole gliadin peptides, whose molecular weight is at least 2000 Da, remains to be determined, though (Heyman. 2011)

• Alcohol will wreak havoc on the permeability of your intestines; probably in consequence of its depleting effect on ileal zinc concentration (Zhong. 2010).
• Gliadin (in wheat/gluten) does actively promote the release of zonolin and the widening of the tight junctions (see figure 2); whether you will notice that or not, depends on the occurrence and extent of an immune response as it is characteristic for Celiac patients. I guess, it's actually not necessary to say that all sorts of other allergens, respectively the ensuing inflammatory response to being exposed to them will have detrimental effects on the integrity of your gut, as well, right?
• ALA, EPA and DHA the dietary omega-3 fatty which may help sooth tight junction permeability in states of chronic inflammation will actually increase it, when the baseline inflammation is already low or they are consumed in excess (Usami. 2001; Roig-Pérez. 2010)
• Copper and iron increase tight junction permeability of caco-2 cells via distinct mechanisms (Ferruzza. 2002)
• Capsaicin, piperine and other hot spices do not only cause a burning sensation in your mouth, it literally burns your intestinal cell lining, as well (Johri. 1992; Tsakura.2007)
• Quercitin by blocking the increase in HSP-70 will increase the suceptibility of your gut to exercise induced increases in permeablity (Kuennen. 2011)
• NSAIDs like aspirin and ibuprofen increase the permeability of the gut ad amplify the potentially detrimental effects of exercise (Lambert. 2007)

Obviously, only few of the last mentioned offenders are exercise specific, but if you start working out with already compromised gut integrity, you can hardly complain if a couple of grams of glutamine, or whatever else you may have picked from the previous list, don't effectively protect your intestinal wall from damage. What's even more important though is that you understand the Janus-faced nature of anti-oxidants and anti-inflammatory compounds. As beneficial as they may be in situations of chronic or acute pathologic inflammation, NSAIDs, quercitin and even your beloved omega-3 can eventually extinguish the 'controlled fire' your body needs to keep all immune and metabolic functions simmering along nicely (suggest reads: "Are you stressed enough for a longer life?" and "Inflammation is a True Fat Burner").

References:

• Amasheh M, Fromm A, Krug SM, Amasheh S, Andres S, Zeitz M, Fromm M, Schulzke JD. TNFalpha-induced and berberine-antagonized tight junction barrier impairment via tyrosine kinase, Akt and NFkappaB signaling. J Cell Sci. 2010 Dec 1;123(Pt 23):4145-55.
• Banan A,Zhang LJ, Shaikh M,et al. theta Isoform of protein kinase C alters barrier function in intestinal epithelium through modulation of distinct claudin isotypes: a novel mechanism for regulation of permeability. J Pharmacol Exp Ther. 2005; 313:962–82.
• Buckley JD, Butler RN, Southcott E, Brinkworth GD. Bovine colostrum supplementation during running training increases intestinal permeability. Nutrients. 2009 Feb;1(2):224-34.
• Dokladny K, Lobb R, Wharton W, Ma TY, Moseley PL. LPS-induced cytokine levels are repressed by elevated expression of HSP70 in rats: possible role of NF-kappaB. Cell Stress Chaperones. 2010 Mar;15(2):153-63. Epub 2009 Jun 24. 
• Ewaschuk JB, Diaz H, Meddings L, Diederichs B, Dmytrash A, Backer J, Looijer-van Langen M, Madsen KL. Secreted bioactive factors from Bifidobacterium infantis enhance epithelial cell barrier function. Am J Physiol Gastrointest Liver Physiol. 2008 Nov;295(5):G1025-34. 
• Ferruzza S, Scacchi M, Scarino ML, Sambuy Y. Iron and copper alter tight junction permeability in human intestinal Caco-2 cells by distinct mechanisms. Toxicol In Vitro. 2002 Aug;16(4):399-404. 
• Gu L, Li N, Li Q, Zhang Q, Wang C, Zhu W, Li J. The effect of berberine in vitro on tight junctions in human Caco-2 intestinal epithelial cells. Fitoterapia. 2009 Jun;80(4):241-8.
• Heyman M, Abed J, Lebreton C, Cerf-Bensussan N. Intestinal permeability in coeliac disease: insight into mechanisms and relevance to pathogenesis. Gut. 2012 Sep;61(9):1355-64.
• Hirotani Y, Ikeda K, Kato R, Myotoku M, Umeda T, Ijiri Y, Tanaka K. Protective effects of lactoferrin against intestinal mucosal damage induced by lipopolysaccharide in human intestinal Caco-2 cells. Yakugaku Zasshi. 2008 Sep;128(9):1363-8.
• Jeukendrup AE,Vet-Joop K, Sturk A,et al. Relationship between gastrointestinal complaints and endotoxaemia, cytokine release and the acute-phase reaction during and after a long-distance triathlon in highly trained men.Clin Sci (Lond). 2000;98:47–55. 
• Jonas CR, Ziegler TR. Potential role of glutamine administration in inflammatory bowel disease. Nestle Nutr Workshop Ser Clin Perform Programme. 1999;2:217-30.
• Johri RK, Thusu N, Khajuria A, Zutshi U. Piperine-mediated changes in the permeability of rat intestinal epithelial cells. The status of gamma-glutamyl transpeptidase activity, uptake of amino acids and lipid peroxidation. Biochem Pharmacol. 1992 Apr 1;43(7):1401-7.
• Kim H, Bartley GE, Young SA, Davis PA, Yokoyama W. HPMC supplementation reduces abdominal fat content, intestinal permeability, inflammation, and insulin resistance in diet-induced obese mice. Mol Nutr Food Res. 2012 Sep;56(9):1464-76. 
• Kuennen M, Gillum T, Dokladny K, Bedrick E, Schneider S, Moseley P. Thermotolerance and heat acclimation may share a common mechanism in humans. Am J Physiol Regul Integr Comp Physiol. 2011 Aug;301(2):R524-33.
• Lambert GP, Gisolfi CV, Berg DJ, Moseley PL, Oberley LW, Kregel KC. Selected contribution: Hyperthermia-induced intestinal permeability and the role of oxidative and nitrosative stress. J Appl Physiol. 2002 Apr;92(4):1750-61; discussion 1749. PubMed PMID: 11896046.
• Lambert GP, Boylan M, Laventure JP, Bull A, Lanspa S. Effect of aspirin and ibuprofen on GI permeability during exercise. Int J Sports Med. 2007 Sep;28(9):722-6.
• Lambert GP, Lang J, Bull A, Pfeifer PC, Eckerson J, Moore G, Lanspa S, O'Brien J. Fluid restriction during running increases GI permeability. Int J Sports Med. 2008 Mar;29(3):194-8.
• Lamprecht M, Bogner S, Schippinger G, Steinbauer K, Fankhauser F, Hallstroem S, Schuetz B, Greilberger JF. Probiotic supplementation affects markers of intestinal barrier, oxidation, and inflammation in trained men; a randomized, double-blinded, placebo-controlled trial. J Int Soc Sports Nutr. 2012 Sep 20;9(1):45. 
• Li N, Gu L, Qu L, Gong J, Li Q, Zhu W, Li J. Berberine attenuates pro-inflammatory cytokine-induced tight junction disruption in an in vitro model of intestinal epithelial cells. Eur J Pharm Sci. 2010 Apr 16;40(1):1-8.
• Marchbank T, Davison G, Oakes JR, Ghatei MA, Patterson M, Moyer MP, Playford RJ. The nutriceutical bovine colostrum truncates the increase in gut permeability caused by heavy exercise in athletes. Am J Physiol Gastrointest Liver Physiol. 2011 Mar;300(3):G477-84.
• Musch MW, Sugi K, Straus D, Chang EB. Heat-shock protein 72 protects against oxidant-induced injury of barrier function of human colonic epithelial Caco2/bbe cells. Gastroenterology. 1999 Jul;117(1):115-22. 
• Niu L, Qiao W, Hu Z, Li N, Huang Q, Gong J, Li Q, Zhu W, Li J. Berberine attenuates lipopolysaccharide-induced impairments of intestinal glutamine transport and glutaminase activity in rat. Fitoterapia. 2011 Apr;82(3):323-30.
• Peters HP, Bos M, Seebregts L,et al. Gastrointestinal symptoms in long-distance runners, cyclists, and triathletes: prevalence, medication, and etiology. Am J Gastroenterol. 1999; 94:1570–81. 
• Prosser C, Stelwagen K, Cummins R, Guerin P, Gill N, Milne C. Reduction in heat-induced gastrointestinal hyperpermeability in rats by bovine colostrum and goat milk powders. J Appl Physiol. 2004 Feb;96(2):650-4.
• Quadro L, Gamble MV, Vogel S, Lima AA, Piantedosi R, Moore SR, Colantuoni V, Gottesman ME, Guerrant RL, Blaner WS. Retinol and retinol-binding protein: gut integrity and circulating immunoglobulins. J Infect Dis. 2000 Sep;182 Suppl 1:S97-S102.
• Roig-Pérez S, Cortadellas N, Moretó M, Ferrer R. Intracellular mechanisms involved in docosahexaenoic acid-induced increases in tight junction permeability in Caco-2 cell monolayers. J Nutr. 2010 Sep;140(9):1557-63.
• Ruiz M. Wikipedia contributors, 'Tight junction', Wikipedia, The Free Encyclopedia, 10 November 2012, 07:58 UTC, <http://en.wikipedia.org/w/index.php?title=Tight_junction&oldid=522300074> accessed 25 November 2012
• Tang Y, Forsyth CB, Banan A, Fields JZ, Keshavarzian A. Oats supplementation prevents alcohol-induced gut leakiness in rats by preventing alcohol-induced oxidative tissue damage. J Pharmacol Exp Ther. 2009 Jun;329(3):952-8.
• Tsukura Y, Mori M, Hirotani Y, Ikeda K, Amano F, Kato R, Ijiri Y, Tanaka K. Effects of capsaicin on cellular damage and monolayer permeability in human intestinal Caco-2 cells. Biol Pharm Bull. 2007 Oct;30(10):1982-6.
• Usami M, Muraki K, Iwamoto M, Ohata A, Matsushita E, Miki A. Effect of eicosapentaenoic acid (EPA) on tight junction permeability in intestinal monolayer cells. Clin Nutr. 2001 Aug;20(4):351-9.
• van Wijck K, Lenaerts K, van Loon LJ,et al. Exercise-induced splanchnic hypoperfusion results in gut dysfunction in healthy men.PloS One. 2011; 6.
• Worobetz LJ,Gerrard DF. Gastrointestinal symptoms during exercise in Enduro athletes: prevalence and speculations on the aetiology.N Z Med J 1985; 98:644–6.
• Zhang B, Guo Y. Supplemental zinc reduced intestinal permeability by enhancing occludin and zonula occludens protein-1 (ZO-1) expression in weaning piglets. Br J Nutr. 2009 Sep;102(5):687-93.
• Zhong W, McClain CJ, Cave M, Kang YJ, Zhou Z. The role of zinc deficiency in alcohol-induced intestinal barrier dysfunction. Am J Physiol Gastrointest Liver Physiol. 2010 May;298(5):G625-33. 
• Ziegler TR, Ogden LG, Singleton KD, Luo M, Fernandez-Estivariz C, Griffith DP, Galloway JR, Wischmeyer PE. Parenteral glutamine increases serum heat shock protein 70 in critically ill patients. Intensive Care Med. 2005 Aug;31(8):1079-86

Arginine Blunts Growth Hormone Response to Resistance Training: Will the -41% Reduction in Post-Workout Growth Hormone Release Hamper Your Strength & Size Gains?

Arginine-based pre-workout products are more popular with guys than with girls. Could this be the reason that only women complain about unlovedly rapid muscle gains? ;-)

No, this is not a typo! The verb in the headline of today's SuppVersity article really is "to blunt", as in "to neutralize partially" (OED Online 2013). I have to admit that I was also surprised, when I spotted the study over in the "ahead of print" section of the International Journal of Sports Nutrition and Exercise Metabolism. Unless Forbes, Harber and Bell, of whom you will learn later that they've already conducted another 'arginine study', messed up, the results of their most recent experiment do yet leave little doubt: Arginine, an amino acid that is used to test the function of the GH-releasing somatotropic cells within the lateral wings of the anterior pituitary, does - when it is administered at a dosage of 0.075 g·kg-1 body mass right before an acute bout of resistance exercise (3 sets of 8 exercises, 10 repetitions at ~75% 1RM) attenuate the post-workout growth hormone surge in strength trained individuals (Forbes. Nov 2013).

You want more details? Here you go...

With ~5-6g of arginine being taken before a workout that consists of 3 sets of 8 classic strength training exercises that are performed for 10 repetitions and at an intensity ~75% of the personal 1RM of the 14 strength trained men [age: 25±4 y; body mass: 81.4±9.0 kg; height: 179.4±6.9 cm; and training experience: 6.3±3.4 y], the researchers from the Faculty of Physical Education & Recreation at the University of Alberta in Edmonton, Alberta, Canada designed an experimental setup which comes "shockingly" close to what the average and extraordinaire gymrat is doing, when he or she is hitting the grind.

Figure 1: Level of arginine, GHRH and IGF-1 at T = 0, 15, 30, 60 min of rest-recovery + integrated area under the curve for growth hormone (iAUC GH); all values expressed relative to placebo control (Forbes. Nov 2013)

Against that background the question whether you and the rest of the millions of hobby athletes who spend hundreds of bucks on pre-workout products every year have been hampering their own progress is, as hilarious as it may sound, not a totally unwarranted one. I mean, we can hardly ignore the statistically highly significant -41% reduction in total growth hormone secretion in the one hour "anabolic window" after the workout, Forbes and his colleagues measured - can we?

What do we make of these results?

Most of you will probably remember the often referenced results of West & Phillips, whose 12-week resistance training intervention in the course of which the researchers from the Exercise Metabolism Research Group at the Department of Kinesiology of the McMaster University in Hamilton, Ontario,  made the following observations (West. 2012):

• 

  Suggested Read: "Anabolic Workouts Revisited!" | more

  No correlations between GH, testosterone or IGF-1 and the lean mass gains of their 56 recreationally active young men, who were not actively participating in any weightlifting
  activities <8 months before the study.
• Significant correlations between GH and the increase in type I (slow twitch, oxidative) muscle fibers, but no correlation between testosterone, IGF-1 and cortisol.
• Significant correlations between GH, as well as cortisol and the increase in type II (fast twitch, gylcolytic) muscle fibers, but no correlation between testosterone and IGF-1.

Unlike Forbes, Harber and Bell in the study at hand, West and Phillips measured the hormone levels for up to 2h after the workout. It is thus possible, but in view of the progression of the GH levels in the Forbes study relatively unlikely, that we'd see a rapid increase in the 2nd hour of the rest period and thus an increase in the total amount of GH that's released in response to the combination protocol (arginine + exercise).

Is the decrease the result of a previous GH "overload"?

With respect to the possible involvement of an auto-negative feedback, which is another, previously suggested explanation for this phenomenon, of which I had to realize during my research for this article that it has been covered in the literature before (Kanalay. 2008), Forbes et al. remark that their data would basically exclude the possibility that "the GH suppression was not due to a GH or IGF-1 induced autonegative feedback loop." (Forbes. Nov 2013)

It may not be the perfect muscle builder and maybe not even something you want to take in the vicinity of a workout, but there is still promising data on the metabolic effects of arginine esp. for (pre-)diabetics | more

In other words, Forbes et al. exclude the possibility that the subjects experienced a rapid increase in growth hormone as we would see it in response to the intravenous injection of arginine (10x increase with 20g/m² surface area of the 12 normal men in a 1996 study by Rahim et al.) that would then have shut down the GH production just as the exogenous administration of steroids would shut down your natural testosterone production.

If we focus on the available data, the conclusion of the researchers from the University of Alberta is certainly right. If we do take into account that we are talking about post workout supplementation and remind outselves that "the somatotrope is also known to have a refractory period" (Kanaley. 2008), it should be obvious that post-workout measurements, alone, cannot exclude the possibility that the GH spike that's responsible for the auto-negative feedback occurred during, not after the workout.

In other words: Instead of focusing exclusively on the post-workout GH levels, Forbes, Harber and Bell would actually have had to measure the pre & intra-workout GH response, as well. The GH spike that would cause the auto-negative feedback could after all have been caused by a sudden drop in blood glucose in response to the insulin sensitizing effects of arginine and the 'glucose hungry' strength training session.

Auto-negative feedback is still possible, but isn't there something else?

An alternative explanation for the lowered growth hormone response may come from a closer reading of the 'prequel' to this study. In January, Forbes et al. published a paper with the same supplement, but a different exercise protocol. Instead of hitting the weights, their 15 aerobically trained male subjects cycled for 60 min at 80% of their personal VO2_max - again, immediately after ingesting 5-6g of l-arginine (0.075g/kg body weight).

Is there anything arginine is good for, if it's not a muscle builder and it's effects on nitric oxide are overblown? There is a previous SuppVersity article that would suggest so: "Arginine a BAT Building WAT Killer & Repartitioning Agent?" | more

Contrary to the strength training routine, the (relatively) high intensity cycling had identical effects on the hormonal, metabolic and cardio-respiratory markers of the subjects, the two things that differed, though, were

• the rate of fatty acid oxidation at the onset of the workout, which was reduced in the l-arginine group, and
• the levels of the sugar alcohol glycerol at the 45-min time point, which were slightly, but significantly increased

These observations stand in line with the effects McConell et al.  observed in a 2006 study in response to the infusion of l-arginine.

The arginine infusion increased the glucose uptake and blunted the increase in nonesterified fatty acid and glycerol concentrations during 120min of cycling at 72% of the VO2max which were followed immediately by a 15-min "all-out" cycling performance bout (McConell. 2013). Whether it also changed the GH response is however something I can't tell you, because reseachers from the The University of Melbourne did not measure the effect the arginine infusion had on the growth hormone levels of their study participants. I would yet guess that it will have been similar to the one on the cycling study Forbes did. This, in turn, would suggest that the effect depends on (a) duration and energy expenditure, or (b) the substrate utilization during the workout (lifting weights = glycolytic; cycling = rather oxidative). In the end both of these are related to the reliance on fat, not glucose / glycogen to fuel the energetic demands of your workout and as you all know the acute provision of  glucose is the prerogative of glucocorticoids (i.e. cortisol), not GH.

There may be another reason arginine does not make you "big": It's one out of three amino acids that have an especially pronounced satiety effect | learn about the others!

I can't exactly tell you why, but I can tell you that... I openly admit that I was surprised by the results of the study at hand. I  surprised that I missed this (side) effect of arginine, before, but I am not worried that the arginine supplements you may be or may have been taking are / were  hampering your training success.

 If that was the case one of the many "real-world" arginine supplementation studies, where the study outcome wasn't some funky hormonal marker of which we still don't know whether / to which extent it actually affects skeletal muscle hypertrophy, would have shown a trend for decreasing performance, lean mass and strength gains with arginine supplementation - this, I can assure you was not the case.

In fact, those of you who remember one of my posts on the 'arginine powered' VPX preworkout products (learn more), will remember that the scientists observed, if anything, opposing, i.e. beneficial effects from complex preworkout products as most of you will be using. A somewhat different picture emerges for the 'arginine only studies' where "only" three out of five acute supplementation and four out of eight chronic supplementation studies showed measurable, but in many cases negligible performance gains (Alvares. 2011). And the null-effect the authors of the other papers observed is no reason to be concerned, either.

References:

• Álvares TS, Meirelles CM, Bhambhani YN, Paschoalin VM, Gomes PS. L-Arginine as a potential ergogenic aid in healthy subjects. Sports Med. 2011 Mar 1;41(3):233-48.
• "blunt, v.". OED Online. September 2013. Oxford University Press. http://www.oed.com/view/Entry/20664?rskey=iZQVcA&result=3&isAdvanced=false (accessed November 19, 2013).
• Forbes SC, Harber V, Bell GJ. The acute effects of L-arginine on hormonal and metabolic responses during submaximal exercise in trained cyclists. Int J Sport Nutr Exerc Metab. 2013 Aug;23(4):369-77. Epub 2013 Jan 8.
• Forbes SC, Harber V, Bell GJ. Oral L-Arginine Prior To Resistance Exercise Blunts Growth Hormone in Strength Trained Males. Int J Sport Nutr Exerc Metab. 2013 Nov 13. [Epub ahead of print]
• Kanaley JA. Growth hormone, arginine and exercise. Curr Opin Clin Nutr Metab Care. 2008 Jan;11(1):50-4. Review.
• McConell GK, Huynh NN, Lee-Young RS, Canny BJ, Wadley GD. L-Arginine infusion increases glucose clearance during prolonged exercise in humans. Am J Physiol Endocrinol Metab. 2006
• Rahim A, Toogood AA, Shalet SM. The assessment of growth hormone status in normal young adult males using a variety of provocative agents. Clin Endocrinol (Oxf). 1996 Nov;45(5):557-62.
• West DW, Phillips SM. Associations of exercise-induced hormone profiles and gains in strength and hypertrophy in a large cohort after weight training. Eur J Appl Physiol. 2012 Jul;112(7):2693-702.

Caffeine Protects Brain Function Against Stress & SAD Diet; Coffee Withdrawal, Anxiety & More; Giardia, Messy Subtenant W/ Gusto For Arginine; Vit B6 & n6:n3 PUFA Ratio

19 Billion Euro that's the estimated 2011 financial burden due to lung cancer, alone, here in Europe and the On Short Notice figure of the week (information based on ESMO2012 press release)

Those of you who are also following the SuppVersity facebook news, will probably recognize the figure on the right: 16,000,000,000€ or $24,419,000,000, that's the estimated economical burden due to lung cancer, alone, here in Europe (cf. "Who cares if people are dying as long as the economy is thriving?"). An enormous financial loss, and still not the reason that this is my figure of the week. Rather than the financial damage, itself, it is the tragic fact that only the latter, yet not the fate of the patients and their families, would make a valid argument, when policy makers were debating a long overdue, total and all-encompassing public smoking ban... but now for a couple of more sciency, yet not less intriguing news from the past week.

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Problems thinking straight? Guess what: 3-4 cups of coffee could help :-) According to a soon-to-be-published paper by scientists from the Jordan University of Science and Technology in Irbid, Jordan, the ingestion of the human equivalent of approximately 3.8mg caffeine per kg body weight or 3-4 cups of coffee per day, can inhibit both, the stress, related as well as diet induced (we are talking of the "typical" Western diet (WD), that's both high in carbohydrates and fat) cognitive impairments (Alzoubi. 2012)... well, at least in the researchers 3-months rodent study it worked like a charm

• learning trial: animals in the caffeine/stress, caffeine/WD, and caffeine/stress/WD groups made fewer errors, than non-supplemented stressed or WD animals; overall their performance was comparable to those of the control
• memory tests: treatment reduced the number of error and restored short-term memory and long-term memory during chronic stress and/or WD (P < 0.05) to normal levels

With respect to the underlying mechanisms the scientists speculate that caffeine may "act mainly by inhibiting adenosine receptors" (Alroubi. 2012), which has in turn been shown to to inhibit long term potentiation (LTP) in rat hippocampal slices and disrupt the process of learning and memory at the synaptic level by blocking release of glutamate (de Mendonca. 1994).

Additionally, caffeine has also been shown to increases the expression of hippocampal brain-derived neurotrophic factor (BDNF) and its receptor, which is impaired in response to chronic stress and a hypercaloric Western diet (Aleisa. 2006; Molteni. 2004) and leads to deteriorations in cognitive performance. In the long run those effects could also contribute to the anti-dementia and anti-Parkinson's effects, I mentioned in the recent SuppVersity post on the insulin sensitizing effects of coffee.

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Figure 1: While the Hedonic tone and alertness reduced to baseline on day 5 of caffeine withdrawal, the habitual caffeine consumers had >15% higher anxiety scores on day 7 after giving up on their daily dose of methylxanthine (data calculated based on Smith. 2012).

Don't worry, caffeine will also work for humans. And what's best, upon short-term withdrawl (8 days) your cognitive performance is not going to suck - at least not as much as when you are stressed or living on pizza and French fries, only. All that and a couple of interesting other results have been published ahead of print in the online version of the Journal of Pharmacology (Smith. 2012).

To probe the effects of acute caffeine ingestion on cognitive performance and the influence of previous caffeine consumption and withdrawal, Andrew P Smith, Gary Christopher and David Sutherland recruited 70 volunteers (25 male, 45 female; mean age 22.8 years). The 35 consumers (>100mg caffeine /day, mean 300mg; range 110–600 mg) were put on withdrawal and tested on day 2, alone and without caffeine, and day 8 together with the non-consumers in a double-blind placebo-controlled fashion. During the caffeine challenge, the cognitive performance was tested twice, once before and once 30min after the provision of the caffeinated beverages.

Anxious, but smart: Caffeine gives you the edge

The results of the trial clearly indicate that the ingestion of 2 mg/kg of caffeine, which were served in decaffeinated coffee or tea 30min before the testing procedures, were associated with faster simple reaction times, fewer long responses, greater detection of targets in the cognitive vigilance task, and faster encoding of new information.

"The results confirmed previous findings, with ingestion of caffeine being associated with a faster simple reaction time, fewer long responses, more targets detected and faster encoding of new information. There were no main effects of consumer status, nor were there any significant interactions between caffeine and consumer status." (Smith. 2012)

Notwithstanding, I believe that many of you will probably be more interested in the effects of caffeine withdrawal on overall withdrawal symptoms (figure 1, top), as well as the alertness, hedonic tone and anxiety (figure 1, bottom) and the cognitive performance on day 2 of the withdrawal period (figure 2, left), than in any of the well-established performance cognitive performance boost, right?

Figure 2: Performance on day 2 of withdrawal phase (w/out caffeine) and on day 8 before (w/out caffeine) and after (w/ caffeine)the ingestion of decaffeinated tea or coffee with 2mg/kg caffeine in it (data based on Smith. 2012)

As you can see on the left-hand side of figure 2 there was a minimal performance decline on day 2 of the withdrawal phase, but the latter was statistically not significant and all measured markers of cognitive function had returned to normal on day 8 (remember longer response times = worse performance!), when the resumption or first time provision of caffeine spiked the reaction times and lowered the mistakes in all tests, irrespective of whether the subjects were former habitual consumers on withdrawal, or not.

Outside of controlled experiments "real" coffee and tea do at least as well

Since a large cup of coffee contains about the same amount of caffeine the scientists simply added to decaffeinated beverages, to ensure that the drinks could not be distinguished (by their smell for example), you can simply stick to your regular coffee and if you want to enjoy similar benefits. And to be honest, in view of the plethora of benefits of chronic low dose coffee consumption, I would not even think for a second about whether or not you may be missing out on the occasional boost, when you are not "going on withdrawal" from time to time...

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Figure 3: W/out arginine (Arg-) intestinal epithelial cells can't proliferate (graph based on Stadelmann. 2012)

Giardia eats away your guts arginine supply and makes itself at home within an increasingly morbid digestive tract! As a group of scientists from Sweden and Argentina reports in their latest paper, the protozoan parasite, Giardia intestinalis, feasts on the arginine your gut cells need to proliferate (Stadelmann. 2012). This will lead to reduced polyamine levels and upregulated cell cycle inhibitory genes, which will eventually disrupt the the cell cycle of the intestinal epithelial cells. The reduced intestinal epithelial cell proliferation, on the other hand, allows the gut pathogen to thrive and will, in the long run, disrupt the intestinal tissue homeostasis and thus initiate the decay of the intestinal epithelium  - a central feature of so many of the wide-spread gut pathologies.

Provision of additional arginine + citrulline can help ... in the short run

Now, the good news about all that is that the in-vitro data in figure 3 clearly suggests and anecdotal, as well as the effective therapy of diarrhea patients with arginine/citrulline actually confirm that the provision of supplemental arginine (or citrulline) constitutes a cheap and readily available way to ameliorate the decay, until the bugs have been eradicated by antimicrobial drugs.

A pros pos, antimocrobial drugs, with regard to latter, Noa Tejman-Yarden and Lars Eckmann write in a recent review of the latest drug innovations, that despite the fact that metronidazole and other antimicrobials are usually effective, "treatment failures are common and antimicrobia resistance occurs" (Tejman-Yarden. 2011), so that it would appear as if complex derivatives of 5-nitroimidazole and benzimidazole, which form the core structure of the most widely used antigiardial drugs, will replace them in the short-run. At least for so long, until several new classes of antigiardial drug candidates that have already been identity by high-throughput screening of large compound libraries, will eventually hit the market (Tejman.Yarden. 2011)

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More about vitamin B6: Helps with neurotransmitters synthesis; is involved in nerve function and necessary for normal brain development & function; influences mood, and melatonin production; effects circadian clock; is needed for B12 absorption and thus red blood cell production

When low: "Pins and needles" in extremities, mental disorders, seborrheic dermatitis, estrogenic PMS, dizziness, irritability, kidney stones, abnormal EEG, anemia, convulsions, edema (water retention), hypothyroidism, migraine-headaches, glossitis, lymphopenia

When high: Depression, suicidal tendencies, severe fatigue, mood swings, low blood sugar, migraine-headaches, heart palpitations, thyroid abnormalities (hyper- in the short, hypo in the long term), numbness in hands and/or feet, spinal / nerve degeneration, muscle spasms / cramps, osteoporosis, arthritis, higher blood pressure (short-term suppl.), lower blood pressure (long-term suppl.), mineral imbalances (high phosphor & magnesium vs. low sodium & calcium), restlessness, insomnia, vivid dreams, decreased estrogen & prolactin, depressive PMS.

RDA (adults): 1.3 mg*
*higher for pregnant women & >50y

Upper tolerable limit: 30-100mg*
*depending on the source of information

Food sources: chicken, turkey, tuna, salmon, shrimp, beef liver, milk, cheese, lentils, beans, spinach, carrots, brown rice, bran, sunflower seeds, wheat germ, and whole-grain flour

n6:n3 ratio does not depend on dietary intake alone: A marginal deficiency in vitamin B6 will skew your serum PUFA levels towards the N6-side That's the long and short of the results of a study that's going to be published in the October issue of the Journal of Nutrition.

Mei Zhao and her colleagues analyzed the fatty acid profiles in plasma, erythrocytes, and peripheral blood mononuclear cells (PBMC) of healthy men and women who had been fed a low-vitamin B-6 (pyridoxine) diet for 28 days and observed that contrary to the plasma HDL and LDL cholesterol concentrations, the amount of free fatty acids (FFA) in the blood and the erythrocyte and PBMC membrane fatty acid compositions, neither of which showed any statistically significant changes, the amount of all long-chain polyunsaturated fatty acids, i.e. arachidonic acid (n6) and EPA and DHA (n3) decreased from 548 ± 96 to 490 ± 94 μmol/L, 37 ± 13 to 32 ± 13 μmol/L, and 121 ± 28 to 109 ± 28 μmol/L, respectively.

The subsequent 8% increase in the total n6:n3 PUFA ratio from 15.4 to 16.6 is not alarming, but if this trend would continue linearly, it would certainly become problematic, in the long run. Moreover, the decrease in both n6 and n3 long-chain PUFAs (of which people tend to forget that the "inflammatory" arachidonic acid is as vitally important as its "anti-inflammatory" omega-3 counterparts) could provide an alternative / complementary mechanistic explanation for the increased cardiovascular disease risk that has been associated with vitamin B-6 deficiency.

In view of the fact that the RDA is not exactly high and can easily be achieved from dietary sources, along (as long as you follow a diversified whole foods diet), and considering the fact that high levels of B6 have been associated with more negative side-effects than B6 deficiency (see infobox on the right; please note that I collected the information on a couple of trustworthy websites on RDAs & co and did not verify the research on each of them!), I would however caution against the typical Western "more helps more" supplementation mentality.

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Figure 4: Easy come, easy go - the mass you gain and the fat you lose by doing nothing than simply injecting testosterone is lost / regained within 6 months after discontinuation of the "testosterone therapy" (Forbes. 1992); read more about the role of testosterone in skeletal muscle hypertrophy in the Intermittent Thoughts on Building Muscle

In view of the fact that (a) today's short news items are pretty long(ish) and you still got a couple of interesting facebook news to check out, such as...

• health related: "Vitamin D: We probably won't know before 2017, whether supplementation is advisable", "Aromatase inhibitors to treat endometriosis", or 
• muscle related: "The muscle sparing effects of CLA + Omega-3" and a true classic "Muscle mass gained on injectable testosterone is lost, when injections are seized", 

... and a plethora of additional gems from the realms of health, exercise, nutrition & supplementation, I will call it a day for today and save the exercise and a couple of other exciting On Short Notice items for later next week.


References:

• Aleisa AM, Alzoubi KH, Gerges NZ, Alkadhi KA. Chronic psychosocial stress-induced impairment of hippocampal LTP: possible role of BDNF. Neurobiology of Disease 2006;22:453–62. 
• Alzoubi KH, Abdul-Razzak KK, Khabour OF, Al-Tuweiq GM, Alzubi MA, Alkadhi KA. Caffeine prevents cognitive impairment induced by chronic psychosocial stress and/or high fat-high carbohydrate diet. Behav Brain Res. 2012 Sep 20.
• ESMO. Press releases related to the ESMO 2012 Congress of the European Society for Medical Oncology in Vienna.
• Forbes GB, Porta CR, Herr BE, Griggs RC. Sequence of changes in body composition induced by testosterone and reversal of changes after drug is stopped. JAMA. 1992 Jan 15;267(3):397-9.
• de Mendonca A, Ribeiro JA. Endogenous adenosine modulates long-term potentiation in the hippocampus. Neuroscience 1994;62:385–90.
• Molteni R, Wu A, Vaynman S, Ying Z, Barnard RJ, Gomez-Pinilla F. Exercise reverses the harmful effects of consumption of a high-fat diet on synaptic and behavioral plasticity associated to the action of brain-derived neurotrophic factor. Neuroscience 2004;123:429–40.
• Smith AP, Christopher G, Sutherland D. Acute effects of caffeine on attention: a comparison of non-consumers and withdrawn consumers. J Psychopharmacol. 2012 Sep 19.
• Stadelmann B, Merino MC, Persson L, Svaerd SG. Arginine Consumption by the Intestinal Parasite Giardia intestinalis Reduces Proliferation of Intestinal Epithelial Cells. PLoS ONE. 2012; 7(9): e45325. 
• Tejman-Yarden N, Eckmann L. New approaches to the treatment of giardiasis. Curr Opin Infect Dis. 2011 Oct;24(5):451-6.