Low Sodium Intake for Athletes? Good for Your Health, or Ergolytic Bogus & Hazardous Bullshit? 30g/Day Sodium Loss in "Hard Sweating" Athletes Speak for Themselves

Salt reduction is for "hard-sweating" athletes not.

Whenever I am browsing the latest studies, I see at least one of those hilarious "salt kills" papers citing official recommendations to reduce sodium intake, in order to lower your risk for hypertension, diabetes, stroke and what not. So, if everyone recommends it and scientists write about, it must be true, right? Well, I guess after reading today's SuppVersity article, you may question the way the average Westerner thinks: What the government suggests you should do is not always good for you.

You, a decently lean & insulin sensitive individual who works out at least thrice a week, and someone who takes the stairs instead of the elevator at least every other day, may in fact put himself / herself at risk of hampering your workout performance and eventually even your health if you reduce your salt intake too much.

Normal salt and sodium bicarbonate are not bad for athletes:

The Hazards of Acidosis

Build Bigger Legs W/ Bicarbonate

HIIT it Hard W/ NaCHO3

BA + Bicarb are Synergists

Bicarb Buffers Creatine

Creatine + Baking Soda = 2x Win!

And even if you weren't lean and athletic, it's questionable, whether you'd benefit. The latest Cochraine Review of the effects of reductions in dietary salt intake on the prevention of cardiovascular disease, for example says:

"Despite collating more event data than previous systematic reviews of RCTs (665 deaths in some 6,250 participants) there is still insufficient power to exclude clinically important effects of reduced dietary salt on mortality or CVD morbidity. Our estimates of benefits from dietary salt restriction are consistent with the predicted small effects on clinical events attributable to the small BP reduction achieved." (Taylor. 2011)

And there is more, as I've previously reported the low chloride intake that comes hand in hand with a reduction in dietary salt intake has been associated with +21% increased mortality risk.

Figure 1: Associations of serum chloride, natrium, potassium and HCO2 with systolic and diastolic blood pressure as well as risk of all-cause, cardiovascular disease, ischemic heart disease, stroke and non-CVD mortality risk (McCallum. 2013)

Scientists from the Incorporated Administrative Agency of Health and Nutrition a Japanese government institution that claims to have made "numerous contributions to improve nutrition and dietary habit and to advance the knowledge of health and nutrition science for the public," (Institute Website), say: "Low dietary Na may [...] be a risk factor for maintaining positive balances of Ca and Mg" (Nishimuta. 2005).

Figure 2: If exercising individuals follow the WHO recommendation for salt intakes, they will put themselves at risk of having negative magnesium and calcium balances (based on data from Nishimuta. 2005)

Nishimuta et al. base their assessment on analyses of the content of calcium (Ca) and magnesium (Mg) in sweat during exercise, which is considerably higher during a relatively low intake of sodium (Na) of 100 mmol/d than with an intake of 170 mmol/d. As the scientists point out in their 2005 paper, this is the reason that their subjects developed a negative calcium and magnesium balance, when their sodium intakes were below 61mg and 63mg per day, respectively.

Salt Reduction Kills! New Studies Suggest Cutting Back Below 3-5g Could Do More Harm Than Good! Scientists Say: Minimum Intake is Physiologically Set (King. 2014) -- Too much sodium remains a valid concern, but are current targets too low for optimal health?

Healthy salt intake physiologically determined - don't restrict, if you crave.

New research moves beyond sodium’s effect on the surrogate marker of blood pressure to examine the relation between sodium intake and cardiovascular morbidity and mortality. Results show that sodium intakes both less than and greater than ~3000–5000 mg/d increase the risk of negative health outcomes. Additionally, newly compiled sodium intake data across populations show a uniformity that suggests that intake is physiologically set. Perhaps not coincidentally, the observed intakes fall within the range related to lowest risk.

These findings are highly relevant to current efforts to achieve low sodium intakes across populations, because the data suggest that the efforts will be unsuccessful for healthy people and may cause harm to vulnerable populations. Remaining mindful of risks associated with both excessive and inadequate intakes is imperative with all nutrients, and sodium is no exception. Avoiding too much, and too little, sodium may be the best advice for Americans.

At first it may sound strange that a reduced salt intake would increase the calcium and magnesium loss during exercise, but when you look at it from a biochemical point of view you will realize that in the absence of sodium, other cations (like magnesium or calcium) will have to bind to the lactic acid molecule to form lactate and postpone the development of subchronic metabolic acidosis (Robergs. 2004).

Cramps could be a sign of severe sodium deficiency

The role of sodium during exercise takes us to another thing you should consider before you start restricting your sodium intake. If there is any mineral that is associated with exercise related cramping, it's not, as many people believe, magnesium or potassium, it's sodium! In his 2007 paper in Sports Medicine, Eichner points out that (Eichner. 2007)...

• heat cramping in industrial workers is alleviated by saline, and in a self-experiment, salt depletion provoked muscle cramping
• in tennis and football alike, heat-crampers tend to be salty sweaters
• triathletes who cramp may lose more salt during the race than peers who do not cramp
• practical experience with therapy and prevention indicates that untravenous saline can reverse heat cramping, and
• lastly, more salt in the diet and in sports drinks can help prevent heat cramping

All this evidence clearly indicates that the most prevalent reason for cramping is a lack / loss of sodium, not magnesium of which you've just learned that it's excreted in your sweet in significant amounts only if you don't consume enough salt.

Salt is essential and covering your needs will reduce, not increase water retention: Salt is 40% sodium and 60% chloride and both are important for athletes. Sodium is the major cation of the extracellular fluidandone of its primary functions is to maintain fluid equilibrium in the body. Sodium is a criticalnutrient in the maintenance of normal physiologic function and optimal exercise performance (Valentine. 2007). Although the typical American diet often contains more sodium than is needed, this may not be true for the athlete. Significant sodium and water losses can occur during exercise, exceeding the dietary intake and adversely affecting the fluid balance.

Very low sodium can impair glucose uptake (learn more)

In that, sodium is particularly important because sodium is needed in the rehydration process. The ingestion of plain water causes a rapid fallin plasma sodium concentration and osmolarity, leading to decreased aldosterone and vasopressin production; this increases urine output.... in the short run. Chronic low salt and high water intakes will yet have the opposite effects. As previously discussed, studies by Luther et al. (2011) even suggest that reducing sodium too much will not just increase water retention, the consequent increase in aldosterone may even impair your glucose sensitivity (see Figure on the left).

Acute high sodium intakes, on the other hand, have no effect on the water retention in healthy individuals, where an increase in serum renin (increases sodium excretion) and urinary aldosterone excretion (lowers water retention) nullified the effects of high salt intakes on body water - without the need to increase the potassium intake, by the way (Kirkendall. 1976).

In 2005 Stofan et al. published a paper that investigated the correlation between sodium loss during exercise and the occurrence of heat cramps in NCAA football players. What they found was that sweat potassium was similar between groups, but the sodium loss in the sweat of those NCAA players who had cramps was two times higher than it was in the controls (54.6 ± 16.2 vs. 25.3 ± 10.0 mmol/L). As Stofan et al. point out, "[l]arge acute sodium and fluid losses (in sweat) may thus be a characteristic of football players with a history of heat cramping." (Stofan. 2005)

Figure 3: Football players may be the best studies, but they are certainly not the only athletes who lose tons of salt during an intense training session (data in the figure based on (Fowkes Godek. 2010)

Only recently, E. Randy Eichner, who has long been arguing that "salt is simplest, most effective antidote" against heat cramps in athletes (Eichner. 1999), highlighted in an article in Current Sports Medicine Reports that the current momentum of those who argue that we all need to drastically reduce our sodium intake could hurt those who would do better if they even increased their intakes: Athletes (Eichner. 2014).

I am not giving a one size fits it all recipe, but what I can do is to cite the following considerations from Valentine (2007): "An athlete exercising 4 hours a day who has a sweat rate of 3.0L/h with a sweat sodium concentration of 80mmol/L will lose 12 L of fluid and 960 mmol of sodium in 1 day. This equates to over 22 g of sodium or over 55 g of salt." I guess that's impressive enough to make you reconsider any efforts to reduce sodium - specifically in view of the fact that chronic low sodium can cause, not prevent water retentions in athletes due to its effects on aldosterone. And as I have pointed out previously, this will even worsen whole body glucose uptake.

Bottom line: I am not sure if you consider the previously presented evidence convincing, but if you want to give salt a try, I'd suggest you simply follow your appetite. Studies like the one Wald & Lesham conducted in 2003 clearly suggest that your appetite for salty foods after a workout will increase, if your salt stores are depleted (Wald. 2003). In view of the fact that Walt & Lesham found that this increase is astonishingly proportional to the amount of salt their subjects lost during a 90 minute workout, the average gymrat (not the ultramarthoner, though) will just have to follow his appetite for salt to make sure that a lack of sodium won't impair his performance and / or overall health.

Against that background and in view of the large inter-individual differences (Bergeron. 2003), the differences between different types of sports, exercise intensities and, of course, the environmental conditions, I am not stupid enough to try and make a general recommendation other than the aforementioned advise to simply follow your bodies lead - trust it, it knows it, when he needs salt | Comment on Facebook!

References:

• Bergeron, M. F. "Heat cramps: fluid and electrolyte challenges during tennis in the heat." Journal of science and medicine in sport 6.1 (2003): 19-27.
• Eichner, E. R. "Heat cramps: salt is simplest, most effective antidote." Sports Med Digest 21.8 (1999): 88. 
• Eichner, E. Randy. "The role of sodium in ‘heat cramping’." Sports Medicine 37.4-5 (2007): 368-370.
• Eichner, E. Randy. "The Salt Paradox for Athletes." Current sports medicine reports 13.4 (2014): 197-198.
• Fowkes Godek, Sandra, et al. "Sweat rates, sweat sodium concentrations, and sodium losses in 3 groups of professional football players." Journal of athletic training 45.4 (2010): 364. 
• King, Janet C., and Kristin J. Reimers. "Beyond Blood Pressure: New Paradigms in Sodium Intake Reduction and Health Outcomes." Advances in Nutrition: An International Review Journal 5.5 (2014): 550-552.
• Kirkendall, Walter M., et al. "The effect of dietary sodium chloride on blood pressure, body fluids, electrolytes, renal function, and serum lipids of normotensive man." J Lab Clin Med 87.3 (1976): 411-434.
• Luther JM, Brown NJ. The renin-angiotensin-aldosterone system and glucose homeostasis. Trends Pharmacol Sci. 2011 Dec;32(12):734-9.
• McCallum L, Jeemon P, Hastie CE, Patel RK, Williamson C, Redzuan AM, Dawson J, Sloan W, Muir S, Morrison D, McInnes GT, Freel EM, Walters M, Dominiczak AF, Sattar N, Padmanabhan S. Serum Chloride Is an Independent Predictor of Mortality in Hypertensive Patients. Hypertension. 2013 Aug 26.
• Nishimuta, Mamoru, et al. "Positive correlation between dietary intake of sodium and balances of calcium and magnesium in young Japanese adults--low sodium intake is a risk factor for loss of calcium and magnesium--." Journal of nutritional science and vitaminology 51.4 (2005): 265-270.
• Palacios, C., et al. "Sweat mineral loss from whole body, patch and arm bag in white and black girls." Nutrition Research 23.3 (2003): 401-411.
• Stofan, John R., et al. "Sweat and sodium losses in NCAA football players: a precursor to heat cramps?." International journal of sport nutrition and exercise metabolism 15.6 (2005): 641.
• Taylor, Rod S., et al. "Reduced dietary salt for the prevention of cardiovascular disease: a meta-analysis of randomized controlled trials (Cochrane review)." American journal of hypertension 24.8 (2011): 843-853. 
• Valentine, Verle. "The importance of salt in the athlete’s diet." Current sports medicine reports 6.4 (2007): 237-240.
• Wald, N., and M. Leshem. "Salt conditions a flavor preference or aversion after exercise depending on NaCl dose and sweat loss." Appetite 40.3 (2003): 277-284.

Deep Mineral Water Maximizes Recovery After Dehydrating Exercise: Significant Effects Within the First 4h, Measurable Effects Even 24h Post - Mechanism Not Clear

Thirsty? Drink mineral water and recover faster!

If you have seen the FIFA World Cup quarter finals, France vs. Germany, you will be aware that the Germans could use a supplement that speeds up regeneration after dehydrating physical activity in the heat. Interestingly enough, a "supplement" like that has been identified only recently by Loreta Stasiule and her colleagues from the Lithuanian Sports University (Stasiule. 2014).

In the corresponding paper, which has been published in the Journal of the International Society of Sports Nutrition roughly a week ago, the researchers report the results of a randomized, double-blind, placebo-controlled crossover human study to evaluate the effect of ingestion of natural mineral water extracted from a depth of 689 m on recovery from prolonged fatiguing aerobic running conducted at 30°C.

You can still drink your protein shake just add the water on top!

Are You Protein Wheysting?

Blends over Isolates!

Protein requ. of athletes

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Fast vs. slow protein

5x More Than FDA Allows

"689 m?" - if that's what you're thinking right now, just forget this hilarious detail and think of it as mineral water - I seriously doubt that the exact depth is relevant by any means. What really counts, is the mineral composition of the mineral and regular waters the subjects consumed after running on a motorized treadmill at 40% of their VO2max at a room temperature  of 30°C until a 3% decline in body mass was observed. The total amount of water the subjects had to consume was standardized and amounted to 1.5 times their body mass loss.

Table 1: Concentrations of the minerals and trace elements in drinks used inthe study (Stasiule. 2014)

The water supplements were evenly divided into five equal parts and were ingested at 30 min intervals. To compare their effects, measures of physical performance (aerobic power and lower-body muscle power) and blood CK activity were assessed at 4, 24, and 48 h during the recovery period. To control for possible confounding effects of individual variation, a randomized, double-blind crossover design was used with trials spaced 7 days apart.

Figure 1: VO2max and VO2Max Pulse changes (%) during the post-exercise period (Stasiule. 2014).

If you take a look at the outcome of these trials (Figure 1), its hard to deny that the effects are significant, but irrelevant for the German national soccer team. The next match, the semi finals, is on Tuesday, next week and that's way beyond those 48h where the advantage of mineral over regular water vanishes. The same is true for the accelerated recovery of muscle strength (not shown in Figure 1), which would be particularly useful in dead-ball situations ;-)

You can also use whey while rehydrating: A recent study in the peer-reviewed scientific journal Amino Acids shows that the provision of extra protein "neither enhances nor inhibits post-exercise rehy- dration, when a volume equivalent to 150 % of sweat losses is ingested in 1 h" (James. 2014). In other words: You don't have to drink only mineral water, you can add some whey protein on top of it - and if you're supersmart, you use mineral water to prepare that shake.

Bottom line: Ok, deep mineral water works but why is that the case? Honestly, I don't have a definite answer. One possible explanation the authors have to offer is "that stroke volume recovered better in the DMW trial and that this led to a faster and better recovery of VO2max." As they point out, the expansion of the plasma volume is a well-recognized early response to endurance training and is observed even as an acute response to a single bout of intense exercise. The onset of the phenomenon is extremely rapid and the consequent hypervolemia can improve performance by inducing better muscle perfusion and by increasing stroke volume and maximal cardiac output.

In view of the beneficial effects of the sulfur amino acid taurine, the sulfur and, via a totally different mechanism, the total electrolyte and trace mineral content could and certainly do figure as well. In fact, the latter, i.e. the high comparatively high amount of electrolytes may eventually facilitate the aforementioned maintenance / recovery of an optimal plasma volume and the observed improvements in muscle power recovery which depend on optimal electrolyte levels as well.

Reference:

• James, Lewis J., et al. "Effect of whey protein isolate on rehydration after exercise." Amino acids 46.5 (2014): 1217-1224. 
• Stasiule, Loreta, et al. "Deep mineral water accelerates recovery after dehydrating aerobic exercise: a randomized, double-blind, placebo-controlled crossover study." Journal of the International Society of Sports Nutrition 11.1 (2014): 34.

Milk & Exercise a Perfect Match? A Summary of the Latest Scientific Studies on Its Ability to Sustain Muscle Growth, Protect from Muscle Damage, Binges and Dehydration

Is milk the perfect fluid replacement + anti-post-workout binge + muscle protector for gymrats, fitness junkies and professional athletes? 

It stands out of question. Compared to Coke and many of the so-called "sports-" or "energy drinks" that are in fact no much more than over-caffeinated liquid sugar bars, milk is a healthy beverage. Whether it's also a potent ergogenic though, is still intensely debated.

A recent study from the McMaster University in Hamilton, Ontaria, for example, indicates that the initial surge in post-workout protein synthesis cannot be sustained solely by the low amount of protein in regular milk (Volterman. 2015). Its inability to trigger longlasting increases in protein synthesis and thus to promote a positive whole body protein balance does yet not negate the already proven benefits milk and some of its less-known constituent (I am not talking about whey or casein!) may have for athletes and gymrats.

You can learn more about dairy at the SuppVersity

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Is There Sth. Like a Dairy Weight Loss Miracle?

There is Good A2 and Bad A1 Dairy, True or False?

Lactulose For Your Gut & Overall Health

Is There a "Fat Advantage" for Dairy Lovers

Dairy, Diabetes, Estrogen, IGF-1, Cancer & More

You want to know what kind of advantages this may be? Well, here is a brief overview of the latest scientific evidence that is either directly or indirectly related to potential beneficial effects of milk:

• Consumption of 500 ml of milk post-exercise-induced muscle damage can limit decrements in muscle function in females, and limit increases in soreness and serum markers of muscle damage in females and males.
  
  That's not something I say, but something, scientists from the Institute of Technology in Carlow, Ireland, conclude based on their observations in 32 team sport players (male n = 16; female n = 16) who were randomly, but equally divided into four groups: male milk, male carbohydrate, female milk, and female carbohydrate. Immediately following muscle damaging exercise, participants consumed either 500 ml of milk or 500 ml of an energy-matched carbohydrate solution. Skeletal troponin I (sTnI), creatine kinase (CK), peak torque, counter movement jump height, 20 m sprint performance and passive and active soreness were recorded prior to and 24, 48 and 72 h post-exercise-induced muscle damage (EIMD).
  

  

  Figure 1: Brief overview of the most important facts (Rankin. 2015).

  What the scientists found was that the women experienced likely to very likely beneficial effect on attenuating losses in peak torque at 60°/s from baseline to 24, 48 and 72 h, and a likely beneficial effect in minimizing decrements in sprint performance and soreness over 72 h. Furthermore, the milk consumption was unlikely to have a negative effect on serum markers of damage from baseline to 48 and 72 h.
  
  For males, on the other hand, milk had an unclear effect on muscle function variables. Milk had a most likely/likely beneficial effect on limiting muscle soreness from baseline to 72 h, and a possible beneficial effect on attenuating increases in CK. The effect on sTnI was unlikely to be negative from baseline-72 h. In that, the female participants demonstrated smaller increases in sprint time, passive soreness, active soreness (non-dominant leg) and sTnI values and did thus benefit to a greater yet not significantly greater extent from the 500 ml of milk - that's a difference that could be both sex- and/or protein-specific; I mean, for a man, 500 ml of milk yield significantly less protein on a per kg body weight basis than the same 500 ml do for a woman. That's a difference that could well partly explain why women benefit more from milk vs. carbohydrates only compared to men.
• The consumption of skimmed milk following 30 min of moderate-vigorous cycling exercise reduces subsequent energy intake in female recreational exercisers.
  
  Obviously, working out will only help you shed body fat if the increased energy expenditure during the workout is not (over-)compensated by increased food intake after your workouts. Against that background the results from a recent study from the Northumbria University (Rumbold. 2015) are significant, because they indicate that 600 mL of skimmed milk have a significantly more pronounced "anti-binging" effect than 600 mL of an isocaloric orange drink when they are ingested immediately after a workout.
  

  

  Figure 2: Absolute and relative energy intake during the milk vs. orange juice trials (Rumbold. 2015).

  As the data in Figure 2 indicates the 9 female recreational exercisers (19.7 ± 1.3 years) who completed a standardized exercise regimen consisting of an VO2 peak test and 30 min of moderate-vigorous exercise (65% V̇O2peak) consumed 25.2% ± 16.6% less energy on an ad-libitum pasta meal that was served 60 minutes after the workout.
  
  If we assume that they women didn't compensate for the "missing" 25% of the energy later during the day and assuming that they did the workout 2x per week, the 169kcal per workout would yield a total fat loss of 1.9kg per 6 months - well, if the 7,000kcal deficit per 1kg of fat equation actually held ;-)
• Milk-based drinks are more effective rehydration options compared with traditional sports drinks. The additional energy, protein, and sodium in a milk-based liquid meal supplement facilitate superior fluid recovery following exercise.
  
  The aim of a recent study from the Griffith University study was to compare the rehydration potential of a carbohydrate-electrolyte beverage with several varieties of milk following exercise-induced fluid losses. Fifteen male participants (age 24.9 ± 5.5 years, height 179.3 ± 4.9 cm, body mass 75.8 ± 6.6 kg (mean ± SD)) lost 2.0% ± 0.2% body mass through intermittent cycling before consuming a different beverage on 4 separate occasions.
  
  The drinks that were tested included cow's milk (286 kJ·100 mL(-1)), soy milk (273 kJ·100 mL(-1)), a milk-based liquid meal supplement (Sustagen Sport (Nestle); 417 kJ·100 mL(-1)), and a sports drink (Powerade (Coca Cola Ltd); 129 kJ·100 mL(-1)). Beverages were consumed over 1 h in volumes equivalent to 150% of body mass loss. Body mass, blood and urine samples, and measures of gastrointestinal tolerance were obtained before and hourly for 4 h after beverage consumption.
  

  

  Figure 3: Overview of the most important study results (Desbrow. 2014).

  The results show that the net body mass at the conclusion of each trial was significantly less with Powerade (-1.37 ± 0.3 kg) than with cow's milk (-0.92 ± 0.48 kg), soy milk (-0.78 ± 0.37 kg), and Sustagen Sport (-0.48 ± 0.39 kg). Net body mass was also significantly greater for Sustagen Sport compared with cow's milk trials, but not soy milk. Upon completion of trials, the percentage of beverage retained was Sustagen Sport 65.1% ± 14.7%, soy milk 46.9% ± 19.9%, cow's milk 40.0% ± 24.9%, and Powerade 16.6% ± 16.5%.
  
  If it were not for the fact that some of the subjects were complaining over increased bloating and fullnessduring all milk trials compared with Powerade, there would thus be no reason to go for the "classic" high carb + electrolyte solutions.

Are the hormonal side effects of dairy and its cancerous consequences even worse than they're painted by the steadily growing anti-dairy lobby? Find the answer to this and related questions in a previous SuppVersity article from January 2014 | read more.

Not all that glitters white like milk is gold, though. Only recently scientists from the Tokyo Metropolitan Institute of Gerontology had to realize that milk fat globule membranes, of which previous studies have shown that they may help avoiding metabolic syndrome (Pfeuffer. 2007), do not boost the already beneficial effects of exercise on the frailty status of elderly men and women (Kim. 2015).

Just like the previously discussed disappointing results of the Volterman (2014) study, the results Kim et al. present in their latest study do not negate the existing beneficial effects on satiety / anti-binging, muscle damage and function in response to muscle damaging exercise and rehydration discussed in this article | Comment on Facebook!

References:

• Desbrow, Ben, et al. "Comparing the rehydration potential of different milk-based drinks to a carbohydrate–electrolyte beverage." Applied Physiology, Nutrition, and Metabolism 39.12 (2014): 1366-1372.
• Kim H, Suzuki T, Kim M, Kojima N, Ota N, Shimotoyodome A, Hase T, Hosoi E, Yoshida H. "Effects of Exercise and Milk Fat Globule Membrane (MFGM) Supplementation on Body Composition, Physical Function, and Hematological Parameters in Community-Dwelling Frail Japanese Women: A Randomized Double Blind, Placebo-Controlled, Follow-Up Trial." PLoS One 6;10.2 (2015):e0116256.
• Pfeuffer, M., and J. Schrezenmeir. "Milk and the metabolic syndrome." Obesity reviews 8.2 (2007): 109-118.
• Rankin P, Stevenson E, Cockburn E. "The effect of milk on the attenuation of exercise-induced muscle damage in males and females. Eur J Appl Physiol. (2015): Feb 12. [Epub ahead of print] 
• Rumbold, Penny, et al. "Milk Consumption Following Exercise Reduces Subsequent Energy Intake in Female Recreational Exercisers." Nutrients 7.1 (2015): 293-305.
• Volterman, Kimberly A., et al. "Effects of postexercise milk consumption on whole body protein balance in youth." Journal of Applied Physiology 117.10 (2014): 1165-1169.

Hydrated or Dumb: Dehydration Affects Brain, Muscle and Other Vital Organs - Plus: 15+ Causes of Dehydration + Can the Color of Your Urine Tell You if You Drink Enough?

If you want to stay smart, you should join hands w/ water!

Those of you who are following the 10+ SuppVersity Facebook news on a daily basis, will remember my post about the recent paper - co-authored by Brad Schoenfeld (Ribeiro. 2014) - about the significant "water gain" after workouts. I wrote about that myself, a couple of weeks before in "Cell Swelling Keeps Muscles "Pumped" For More Than 52h. Size Increases of Up to 16% After a Single Leg Workout!" | read more, and mentioned that the intra-muscular swelling is probably a necessary prerequisite, if not driver of skeletal muscle growth.

In today's SuppVersity article, I will now take a step back, away from the musclehead's only interest and peek at other health aspects that are influenced by the hydration status not just of your muscles, but of your whole body.

Hydration Tip of the Century: Many of you will accidentally (or because they read it here, at the SuppVersity, before) already follow this advice, but I still would like to emphasize that the dairy protein you're probably consuming after your workout is not only going to boost your muscle, but also your "water" (=positive hydration) gains. In 2010 James et al. were able to show just that: A post-workout beverage with 40 g/l carbohydrate + 25 g/l milk protein are more effective at augmenting fluid retention than 65g of pure carbs carbohydrate (James, 2010).

In one of the most recent papers on this issue, Natalie A. Masento and her colleagues from the University of Reading reviewed the surprisingly profound effect of dehydration on cognition and mood, of which Masento et al. write that it is "particularly relevant for those with poor fluid regulation, such as the elderly and children" (Masento. 2014).

"With evidence to suggest that individuals are routinely at a risk of mild dehydration day to day (Greenleaf. 1965), particularly vulnerable populations such as children and older adults, there has been an increased interest in studying whether additional water consumption might benefit cognitive performance. The small collection of published water intervention studies involving either young adults or school children report consistent positive effects of water intervention on particular cognitive abilities" (Masento. 2014)

If you take a look at the overview, the researchers compiled (it's too long and eventually repetitive to post it here), you will find studies everything from self-reported fatigue, tiredness and headaches to objectively measured declines in cognitive performance, eye-hand coordination, word recognition, visual attention and - as mentioned in the previously cited article physical performance markers, such as grip strength.

How come? I mean, why does dehydration have such a profound impact?

The above, probably is the question that's preying on your mind right now and I have to admit, I have - just like the researchers from the University of Reading - no conclusive, water-tight *pun intended* answer to that question.

"Despite the expansion of this research area, we still do not have a clear understanding as to how acute water intervention may influence mental performance and its associated neural activity. Researchers have suggested psychological mechanisms related to limited attentional resources during thirst. However, evidence has also highlighted the  importance of physiological mechanisms, with findings that the expectancy of water alone does not influence cognitive performance." (Masento. 2014)

Hitherto proposed mechanisms include references to the Global Workspace Model (Baars. 1993) and being distracted by the often subconscious thought "Where do I find water".

Gray matter activation clusters in dehydration (Streibürger. 2012).

Of potentially greater interest (at least to me) are theories that involve physiological mechanisms, such as the already confirmed...

• shrinkage of total brain volume shrinkage (Streitbürger. 2012; Kempton. 2011) and 
• over-recruitment of specific brain areas during cognitively demanding tasks,

as well as other significant changes at the neural level which contribute to the previously mentioned decline in cognitive performance and awareness (Kempton. 2011).

Luckily, these changes can be reversed by the provision of water in minutes, as long as the subjects are only mildly dehydrated. In view of the

"lack of data related to baseline hydration states of individuals and no further published work using imaging techniques to examine hydration state" (Masento. 2014) 

We do yet once more have to acknowledge that "we know that we know nothing" or, put differently, that these proposed mechanisms are merely speculative.

Potential causes of dehydration: It's not just working out in the heat or simply forgetting to drink (very common in the elderly), there is a multitude of other things that promote dehydration and here are a couple of examples: ✋Low sodium + chloride (can't store water), ✋high calcium, magnesium, zinc, chromium intake, ✋ extreme high sodium or potassium intake, ✋low phosphor intake; ✋high vitamin D, pantothenic acid (B5), pyridoxine (B6) intake; ✋low adrenal output; ✋high protein intakes (esp. when protein is abused as energy source); ✋laxatives, diuretics or other meds or supps -- One thing, however, does not cause dehydration: ☕ Coffee!

Another physiological mechanism that has been suggested is the albeit age-dependent reaction of the central nervous system in response to the ingestion of significant (500ml) amounts of water, of wich May & Jordan found that it causes

• a significant drop in heart rate and an increase in vasodilation in young adults (May. 2011), and the opposite effects, i.e.
• a significant increase in blood pressure in the healthy old subjects in a 2002 study by Schroeder et al. (Schroeder. 2002)

- whether this difference may be brought about by different baseline hydration status, is not clear. What is obvious, though, is that the cardiovascular reactivity promotes cerebral blood flow, which, in turn, will encourage the circulation of substances such as oxygen and glucose that are known to stimulate neural activity and associated behavioural performance (Gold. .1995) in healthy, non-diabetic individuals.

If you think about this hypothesis, i.e. the beneficial effects of water-induced increases, and the detrimental effects of reductions in glucose and oxygen availability in the brain and other organs that would occur, even upon mild dehydration, it seems perfectly logical, a mechanism similar to that has after all been proposed to account for the improved cognitive function due to physical exercise (Kashihara. 2009).

The urine color chart is a valuable tool to judge your hydration status (Wakefield. 2002)

"So how much water to I need?" -- I know. I am mean... the question that's been preying on your mind ever since the introduction. I still did not answer it - right?

Well, you can find the answer in your toilet bowel (see color chart on the right for a guide). You just have to check the color of your urine to know if you're drinking enough... well, at least if you didn't have beets, which will turn it red-brown or red, blackberries, which will give it a red tinge, carrots, which will produce a rusty yellow, paprika, which will make it look orange, rhubarb, which turns it re-brown, then orange, sometimes even yellow-pink, rusty or yellow-brown... and of course the nasty neon-green that's caused by the tons of useless riboflavin (aka vitamin B2) in your urine.

References:

• Baars, Bernard J. "How does a serial, integrated and very limited stream of consciousness emerge from a nervous system that is mostly unconscious, distributed, parallel and of." Experimental and theoretical studies of consciousness 174 (1993): 282.
• Greenleaf, John E., and Frederick Sargent. "Voluntary dehydration in man." Journal of Applied Physiology 20.4 (1965): 719-724.
• Kempton, Matthew J., et al. "Dehydration affects brain structure and function in healthy adolescents." Human brain mapping 32.1 (2011): 71-79. 
• Masento et al. "Effects of hydration status on cognitive performance and mood". British Journal of Nutrition (2014) [ahead of print].
• Ribeiro, Alex S., et al. "Resistance training promotes increase in intracellular hydration in men and women." European Journal of Sport Science ahead-of-print (2014): 1-8.
• Schroeder, Christoph, et al. "Water drinking acutely improves orthostatic tolerance in healthy subjects." Circulation 106.22 (2002): 2806-2811.
• Streitbürger, Daniel-Paolo, et al. "Investigating structural brain changes of dehydration using voxel-based morphometry." PloS one 7.8 (2012): e44195.
• Wakefield, Bonnie, et al. "Monitoring hydration status in elderly veterans." Western Journal of Nursing Research 24.2 (2002): 132-142.