The Potato Manifesto - Part 2/2: The Sweet Potato, Is It More Than Just the "En Vogue Tuber of the Year"?

Image 1: A mixer like this would be one of the best choices to turn your healthy low-GI sweet (or regular) potato into a high GI "nightmare".

If you've read yesterday's first part of the Potato Manifesto, you should by now be aware that the common notion of the pro-diabetic high-glycemic regular potato is another of the numerous black-or-white nutrition myths that do not become right, no matter how many bloggers and forum posters reiterate them. In today's second part of the series I will try to elucidate, whether the sweet potato, of which I would venture to say that she is the "en vogue tuber of the year", is not still the "safer starch alternative". So bear with me while I am using my scientific peeling knife to check whether there is a bitter truth hidden beneath skin of the sweet potatoes ;-)

Come on sweety, show me what's beneath your skin!

Now, if we take a look at the literature, a review of the glycemic index of 33 commonly available foodstuffs from the 1990s lists sweet potatoes with a glycemic index of 49 as #17 (with #1 peanuts and a GI of 11 and #32 cornflakes and a GI of 83 as the "extremes"; Nishimune. 1991). It is "outperformed by spaghetti (GI 47) and closely followed by Buckwheat, Yam (both GI 51) and you guessed it the good old "regular" potato, to which Takahiro Nishirnune and his colleagues assign a GI of 54, which - as you should know from yesterday's installment of the Potato Manifesto is nothing but an average on a scale that ranges from 10 to 110!

Figure 1: Difference in plasma glucose concentrations (expressed as the increase due to the "high GI" normal potato vs. the "low GI" sweet potato) in response to the ingestion of 50g of carbohydrates in form of bush potato or regular potato in 7 Aborigines and 7 Caucasians (data adapted Thorburn. 1986)

A brief note on the fallacy of common arguments for "traditional diets" (=sweet potato diets): I recently started listening to archived episodes of Jimmy Moore's Living La Vida Low Carb show and encountered time and again the 99% nonsensical argumentation that the XYZ thrived on whatever diet and that by just mimicking their diet(s), we would thrive, as well. To me this is like saying: "Look, the Panda bears thrive on a 100% bamboo diet! So, the ice-bears in our zoo should get along pretty well, if we stopped feeding them meat." Now, this is obviously a provocative comparison, but if I look at myself and then look at an Aborigine, the difference may not be as significant as the one between panda and ice-bear and yet, according to the results of a 1986 study by Anne W. Thorburn et al. (Thorburn. 1986) our glucose responses to the ingestion of 50g of carbohydrates from either the sweet-potato'esque bush potato and a "normal" western potato would be completely different (cf. figure 1). While the poor Aborigine would encounter the typical blood sugar ups and downs that are so characteristic for the ingestion of "high GI" carbs, my body would probably not care whether I eat the 100% paleo bush potato or its readily available, cheap cousin. The futility of common "neo-paleolithic" reasoning aside, this example also shows that genetic individualities are another major determinant of the glycemic index.

Three yeas later, in 1994, Thomas Wolever and his colleagues from the University of Toronto tested the glucose response of diabetic patient to 102 complex carbohydrate foods (Wolever. 1994). "Complex", in this case, indicates that they tested combinations of foods like they could appear on someone's dinner table and lo and behold, the "low GI" sweet potato took a close second to the "high GI" boiled white potato, when the both were boiled and served to 16 diabetic patients along with tomatoes. The 1 GI point difference between sweet and white potato (60 vs. 59) is yet well within the statistical margin.

Identical glycemic index, but differing free sugar compositions

Although, I hope that I should by now have convinced you that the glucose response is no convincing argument in favor of the sweet potato. I am even convinced that, if people abused their sweet potatoes in similar ways as their "regular" potatoes, i.e. mashed, fried, pureed, powdered and instantized it, we would soon see the (contemporarily) sexier sister of the regular potato on the list of "foods to avoid if you want to lose wait or just live a long and healthy life". Nevertheless, taste and name of the sweet potato, leave no doubt that there must be a sugary difference between her and her white brethren.

Figure 2: Free sugar composition (in mg/g) of 16 "regular" and 3 sweet potatoes cultivars (comparison based on data from Zhu. 2011 and Dincer. 2011)

And in fact, as my juxtaposition of data from a 2010 study on the relation between amino acid and sugar content of commercially available regular potatoes and its effect on the formation of acrylamite during heating (Zhu. 2011) and data from the previously mentioned (cf. Part 1) study by Cuneyt Dincer and his (or her) colleagues from the Akdeniz University in Ankara, Turkey (Dincer. 2011) shows (cf. figure 2), there is a non-negligable difference in the amount and composition of "free sugars" (vs. sugars in the form of starch). Although I am not 100% about the exact nature of the exotic Chinese potatoes, it is quite obvious that, despite large varieties in the absolute and relative sugar content of "regular" potatoes, the "classic" potato has a lower absolute free sugar content and contains more fructose and glucose than her sweet sister, 90% of the free sugar content of which is plain table sugar (=sucrose = glucose + fructose).

Figure 3: Mean free sugar composition (in mg/g) of fresh "regular" and sweet potatoes (comparison based on data from Zhu. 2011 and Dincer. 2011)

This "sugary" pattern does yet broaden, when you expose the sweet potato to heat in the form of either boiling or baking (cf. figure 4). In that, the cultivar-dependent slight reductions in glucose and fructose carry little weight compared to the sudden appearance of significant amounts of maltose, which had been beyond the detection before the sweet potatoes were boiled or baked (cf. figure 4).

Figure 4: Free sugar content (mg/g dry weight) of fresh and cooked sweet potatoes (data adapted from Dincer. 2011)

From a chemical perspective, the latter is not really surprising and its formation in response to heat treatment has been reported as early as 1923, when H.C. Gore published a paper in the Journal of Industrial and Engineering Chemistry (Gore. 1923), in which he makes the important observation that the formation of sugars from starch takes place within the first minutes of heating:

The  raw  potatoes  contained  0.34  per cent of  reducing  sugar calculated as maltose, the  cubes  cooked for  5  minutes in boiling water contained 8.32 per cent, and the cubes cooked for 1  hour,  7.82 per  cent.  Thus,  no sugar formation  occurred  at the  boiling point.

In view of this immediate heat-induced increase in the high GI free sugars, maltose (maltose has a ~10% higher GI than glucose), it should not surprise you that a study that was conducted by Jamaican scientists (Bahado-Singh. 2011), only a few months ago, found statistically significant increases in glycemic index and the area under the incremental glucose curve after boiling, frying, baking or roasting 10 sweet potato cultivars, which are commonly consumed in Jamaica (cf. figure 5):

Figure 5: Glycemic indices and glucose AUC of 10 common Jamaican sweet potato cultivars after boiling, frying, baking and roasting (data adapted from Bahado-Singh. 2011)

If we disregard the differences between the 10 cultivars and focus on the overall pattern, it is quite obvious that on the "less to worst thing you can do with your sweet potatoes if you are concerned about GI"-scale boiling is at the most benign end of the continuum, while baking and roasting compete for the position at the other end - a pattern, those of you who have already read Part 1 of the Potato Manifesto should be familiar with: Contrary to common believe new boiled (regular / sweet) potatoes are in fact a low GI food. In our kitchen (and even more so in the industrial processing machinery of the food industry), where the harmless tubers are mashed, pureed, dried, instantized, fried, baked, roasted etc., both, regular, as well as sweet potatoes do yet acquire at least some resemblance to the "pro-diabetic frankenfood", as which they have gotten labeled within the blogosphere, all along.

Figure 5: Comparison of regular and sweet potato glycemic indices after boiling, frying, baking and roasting.

If we now take a final look at the comparison of the average GI (figure 6 is based on data from both installments of the Potato Manifesto) of regular and sweet potatoes after boiling, frying, baking and roasting, it seems as if the main differences were that on average the regular potato has a slightly higher baseline GI (I do not need to remind you that according to Soh. 1999 boiled Desiree potatoes have a GI of 10!, do I?) and tends to be more resistant to heat-induced deteriorations in her starch / free sugar composition.

So, are boiled sweet and baked and roasted regular potatoes the way to go?

In view of the fact that probably 99% of the average and maybe 70% of the health conscious consumers don't even know the name of the potato cultivar they are using, let alone their age, storage temperature, the amount of phosphate in the soil on which it was grown, and all the other countless variables that have an impact on the "basal" GI of a potato, I honestly doubt that switching from one of the waxier, new regular potatoes (low basal GI) to a random (I mean, how many sweet potato cultivars are available at your grocery store?) sweet potato cultivar, would make you healthier, help you lose weight or offer any other GI-related benefits.

Image 2: Tapioca, another purpoted "health food" with a surprisingly high glycemic index GI of 84

Just as an aside, the Wolever study also examined the glucose response to another of the funky foods that are resurfacing on the Internet as "health foods", these days: Tapioca - also known as cassava, manioc, aipim, bitter-cassava, boba, mandioca, macaxeira, manioca, tapioca plant, yuca. With a GI of 84 it easily outperforms, corn chips (GI 76) and even waffles (GI 79).

Note: Wherever this was necessary I converted GIs that were given with white bread as a reference to the glucose as a reference.

Whether you could benefit from the (again, on average and in this case specifically referring to the white variety of the regular potato) higher beta-carotene and vitamin C content of sweet potatoes would depend on the rest of your diet. If the latter is "99% paleo" ;-), the likelihood that you would not get enough of these antioxidants is close to zero and it should thusly not really make a difference whether you go for the "paleo-" or the "neolithic" potato, as long as you don't (over-)process her into another of the innumerable frankenfoods the average member of the neolithic convenience society is so fond of.

Seabuckthorn Leaves Increase PPAR-Alpha & PPAR-Gamma Expression, Keep the Liver Fat Free and Fatty Oxidation Up. Plus: PPARs - High or Low? How Are They Supposed to Be?

This time, the magic is in the leaves, not the fruits or kernels. And it's dose dependent. With an almost linear increase from 500-1,000mg/kg

Honestly, I don't think that it is coincidence that many of the most promising medical plants are shrubs that live on barren soil, like sand dunes and cliffs and are full of thorns as well as innate polyphenolic defense mechanisms. Whatever the "evolutionary" basis may be, if we go by the beneficial metabolic effects, researchers from the Department of Food Science and Human Nutrition at the Chonbuk National University in the Republic of Korea, it appears worth going through all the traditional used folk medicine across the world and identify which of them work, how they work and whether they may already have what it takes to get rid of one or the other of the typical Western diseases.

In the case of the ethanolic extract of seabuckthorn (Hippophae rhamnoides L) Pichiah et al. used in their most recent experiment, this would be ameliorative effects on weight gain through down-regulation of adipogenic and lipogenic gene expression.

Less weight gain more fatty acid turnover, better glucose management and leptin sensitivity

The ameliorative effects on the detoriation of glucose metabolism, the reduced but still significant weight gain of the 60% fat diet (additional fat 100% from lard) and the profound overexpression of leptin, which is indicative of the fact that the mice developed full-blown leptin resistance within the 13-weeks of HFD administration, were all ameliorated to a greater degree in the high dose seabuckthorn leaf extract group (human equivalent  ~6.5g/day).

Figure 1: Effect of the different diets on weight gain, visceral fat weight, feed intake and energy intake (left; data expressed relative to control diet); effects on blood sugar (AUC in glucose tolerance test) and leptin (Pichiah. 2012)

The differences between high and low dose supplementation of the extract which had been prepared by

"[...] by soaking the dried, powdered leaves in 70% ethanol for 7 days at room temperature. Then the extract was concentrated by evaporating ethanol using a rotary vacuum evaporator (N-N Series, EYELA, Tokyo, JAPAN) set at 60°C and 100 hPa" (Pichiah. 2012)

were even more pronounced, when we compare the effects on fatty acid oxidation (CPT-1), the PPAR-alpha and -gamma values.

Figure 2: Carnitine palmitoyltransferase I (CPT1), PPAR-alpha & -gamma activity and triglyceride & cholesterol content in the liver (left; expressed relative to rodents on normal chow). Histology of liver sections at 200x magnification for the different diets (Pichiah. 2012)

What's yet most striking is however that the liver - the organ that's so heavily involved in the etiology of insulin resistance - was virtually "fat-free" in the rodents who received the 1,000mg/day dose. The total triglyceride and cholesterol content was even lower than in the mice on the normal diet and the overall darker staining in the slices on the right of figure 2 is only further evidence of the beneficial effects the seabuckthorn extract had on the liver histology.

The effects of a 5% conjugated linoleic acid diet do actually resemble that of lipodystrophy, i.e. pathological fat loss and inability to store body fat. Strange, no? Well that's PPAR-gamma (read more).

PPAR-gamma? Wasn't that what you actually wanted to avoid? In a way this is right, since PPAR-gamma and even alpha are somewhat Janus-faced molecules (overview for PPAR-alpha). As beneficial as their expression in the liver may be, both inhibit the oxidation of glucose. PPAR-gamma is also involved in the maturation process from pre-adipocytes to mature adipocytes, increases lipogenesis in white adipose tissues, decreases the cell surface fatty acid transporter on muscle cells and increases glucose uptake in adipocytes (exclusively). All that is healthier than fat clogging your liver, but it's not exactly something that will make you leaner if you are work out and consume a junk-free diet.

In fact, the PPAR-gamma suppressing effects of the trans-10, cis-12 isomer of conjugated linoleic acid (CLA; cf. Kennedy. 2008) are actually what what produces such profound effects, as they were observed in the study I discussed on July 22, 2012 (see link beneath the image of the mice).

TTA and fish oil are potent antagonists of liver PPAR expression. With the uncoupling and anti-inflammatory effects of TTA being the key to unleash & maintain fat-burning (read more).

Bottom line: It appears as if the liver is - once again - emerging as a central player in "sick obesity", meaning being fat and sick and not just fat. Which reminds me of yesterday's post on Gluten and the development of metabolic disease, where fatness is no criteria, at all. The expression of the "liver cleansing" PPAR-gamma enzymes on the other hand was.

This in turn reminds me of the effects of fish oil and TTA (a pan PPAR-activator), which - despite their questionable use as a long-term intervention can in fact stimulate intra-hepatic fatty acid oxidation to levels which are so high that oxidation rates in and out of itself could bring about some problems.

Other nutritional factors you should take into account are choline (a deficiency will actually cause fatty liver disease; read more about choline) or taurine. And on the endocrine side of things you want to keep an eye on optimal DHEA levels (read more about its effects on PPAR-gamma), thyroid hormones, testosterone and estrogen (Nemoto. 2000).

References

• Kennedy A, Chung S, LaPoint K, Fabiyi O, McIntosh MK. Trans-10, cis-12 conjugated linoleic acid antagonizes ligand-dependent PPARgamma activity in primary cultures of human adipocytes. J Nutr. 2008 Mar;138(3):455-61.
• Nemoto Y, Toda K, Ono M, Fujikawa-Adachi K, Saibara T, Onishi S, Enzan H, Okada T, Shizuta Y. Altered expression of fatty acid-metabolizing enzymes in aromatase-deficient mice. J Clin Invest. 2000 Jun;105(12):1819-25.
• Pichiah PB, Moon HJ, Park JE, Moon YJ, Cha YS. Ethanolic extract of seabuckthorn (Hippophae rhamnoides L) prevents high-fat diet-induced obesity in mice through down-regulation of adipogenic and lipogenic gene expression. Nutr Res. 2012 Nov;32(11):856-64.

The Potato Manifesto - Part 1/2: A (Re-)Evaluation of the Contemporary Discrimination of "the" Ordinary Potato

Image 1: The grunty regular (left) and the cute sweet potato (left), which one would you commit your health to? (img. menshealth.co.uk)

This is a blogpost, which eventually turned out to be the first part of a series, is a post with a history, a rather complex one, to be precise. It is rooted (not tubered ;-) in my amazement over the contemporary craving for sweet potatoes within the ever-growing neo-paleolithic community on the Internet and was sparked by the recent publication of a study on sweet potatoes, I stumbled upon on my daily tours of the most recent scientific literature. To make long story short, instead of immediately summarizing the data, drawing some graphs and commenting on the real-world implications of this study, I decided to use the holiday to descend into the archives and take a closer look at what science has to say on the bitter truth about the grunty regular and the starchy promises of cute sweet potato (cf. image 1 ;-)...

When wheat was devils excrement, would regular potatoes then be his horns?

According to the official obesity statistics of the European Union, British women are the fattest in Europe (Eurostat. 2011): 23.9% were classified as being obese (BMI > 30) in the year 2008 to 2009. This certainly raises the not altogether serious question, whether the British obesity problem (the obesity rate among the men was 22.1% and thusly topped only be the Maltese with 24.7%) is due to the fried fish or the fried (regular) potatoes in the unofficial British national dish, fish & chips.

Image 2: Obese British woman's rear view (img. BBC.co.uk)

A note to my dear American friends: Don't crow too soon, the obesity rate in the US tops the one in the UK by more than just a margin. According to a 2010 paper by Flegal et al. that was published in the Journal of the American Medical Association, the estimated obesity rate in the US amounts to 35.5% among the women and 32.2% among the men (Flegal. 2010). And a constantly increasing percantage (currently 4.7%) of the American population is already "extremely obese" and has a BMI > 40! Just to put that into perspective. A man or woman with a BMI beyond 40 and a height of 5 foot and 7 inches (170cm) would weigh at least (!) 254.85lbs (115.6kg) - this is already "Kig-Size Homer"-territory (cf. Intermittent Thoughts).

If we follow the current dietary paradigms and ignore the frying procedure, the answer to this question does not appear to be very difficult. I mean, when wheat was devil's excrement, then regular potatoes would be his horns or even nastier body parts, I do not want to mention here... and though a reasonable explanation for the widespread vilification of potatoes still escapes me, the contemporary nutritional paradigm within the health and nutrition blogosphere suggests that regular white potatoes have an awfully high glycemic index, will spike your blood sugar levels and have your neolithic body pump out tons of insulin - even if the rest of your diet is 99% paleo, as many of the listeners of Robb Wolf's podcast like to describe the way they are eating after having read his (widely read, yet controversial - esp. wrt to starches / carbs, fish oil and a few other topics) book ;-)

Figure 1: Names and characteristics of eight common potato cultivars in the British diet (left) and experimentally evaluated area under the glucose curve and glycemic indices (right; data based on Henry. 2005)

If we take a look at the data in figure 1, which shows both the incremental area under the glucose curve (AUC) and the GI of eight commercially available and commonly consumed British potato cultivars, it should however be quite obvious that the concept of the bad high-GI regular potato is about as misguided as the racist or religious prejudices some of our fellow human beings are still harboring against other members of the human race. With glycemic indices that range from 56 for the "waxy" Marfona to 94 for the "firm" Maris Peer, the "bad" regular potatoes cover the exact same GI range as their "healthy" sweet cousins (come back tomorrow for Part II of this series with more information on sweet potatoes).

Cultivar, processing, serving temperature and more have profound influences on the GI

The type  (=cultivar) of the (classic) potato, is yet neither the only, nor the most important determinant of the glycemic index of a potato meal. The processing method and, to my own surprise, even the food temperature have considerable influence on the glucose response to otherwise identical test meals, as well:

Figure 2: Incremental areas under the curve (AUC) and glycemic index values for 50 g available carbohydrate portions of white bread and seven potato meals tested in a cohort of 12 healthy subjects (data adapted from Fernandes. 2005)

On the left = "better than white bread"-side of figure 2, we have cold, boiled red potatoes (GI 56.2) and, surprise, frensh fries (GI 63.6) and roasted Californian white potatoes  (GI 72.3, but lower AUC than white bread). On the right = "worse than white bread"-side, instant mashed potatoes (GI 87.7) and the hot variety of the "low GI" red potatoes (GI 89.4) are competing for the red lantern.

With regard to the unexpected differences between cold and hot red potatoes, it is important to note that the results of a 2011 study by Kinnear et al. confirm that the latter is not an artifact of the Fernandes study. In their trial, the scientists from the University of Toronto found an average GI reduction of -37% (mean GI for the tested cultivars ~47), when the freshly boiled potatoes were refrigerated at 4°C for 24–28h before they were served to the 10 healthy study participants (Kinnear. 2011). As far as the reasons for this temperature-dependence of the glycemic index is concerned, Kinnear et al. speculate that it is an effect "due to starch retrogradation", which is a process that takes place in gelatinized starch, when the amylose and amylopectin chains realign themselves and thusly causes the liquid to gel. This is quite interesting, as it stands in line with the low GI of the Marfona potato (cf. figure 1), the texture of which is described as "waxy". The long-established relation of the phosphate content and the degree of starch gelatinization (and thusly digestibility and GI), on the other hand, could explain difference between crops and differences between identical crops grown on soil with different phosphate contents.

Figure 3: Areas under the glucose curves (AUC) in 32 healthy volunteers to 50g carbohydrates from mashed potatoes with or without 10g fructose administered 0, 30 or 60min before the meal. Measure by Accu Check finger-prick glucometer and YSI glucose oxidase analyzer (data adapted from Heacock. 2002)

Did you know that fructose, of all, is able to reduce the postprandial increase in serum glucose in nondiabetic adults (mean age: 26)? In their 2002 study, Patricia M. Heacock and her colleagues were able to show that pre-ingestion of 10g of fructose 60min and 30min before the ingestion of a 50g carbohydrate meal (from potatoes) reduced the area under the glucose curve (glucose AUC; cf. figure 3) by 25% and 27%, respectively (Heacock. 2002). The immediate co-administration of 10g of fructose with the potato meal (figure 3, 0 min), on the other, did not induce any statistically significant changes in the glucose AUC of the 13 male and 19 female study participants whose blood glucose levels were measured by finger-prick capillary blood (Accu Check) and glucose oxidase analyzers (YSI).

Furthermore, a 1999 study by Soh and Brand-Miller from the University of Sidney (Soh. 1999) shows that the real-world glucose responses of different individuals to differently processed and stored potato cultivars cover an even broader spectrum (especially on the low GI side) than the results of the previously cited studies suggested. The GI values, the Australian scientists calculated based on the glucose response to a 50g carbohydrate portion of eight different potato meals (three varieties, four cooking methods, two states of maturity) differed by as much as +/- 55pts, with canned new potatoes (GI 65) at the upper and boiled Desiree potatoes (GI 10) at the very lower end of the spectrum. And as if things were not complicated enough, already, Soh and Brand-Miller also introduce yet another variable into the equation - the size of the tuber, which showed a statistically significant correlation with the glucose response of the study 10 healthy participants (correlation between GI and tuber size: r=0.83, p < 0.05).

Black-and-white thinking and ineradicable prejudices

If we base our argumentation solely on the glycemic index, which is in fact the main argument that is brought forward against "regular" potatoes in the public debate, it is quite clear that the poor (regular) potato is another victim of the human propensity to black-and-white thinking and the public's stubborn adherence to convential nutritional wisdom. With reference to the "unjustified generalization" that "all potatoes have a high glycemic index", Anette E. Buyken and Anja Kroke, two researchers from the Research Institute of Child Nutrition in Dortmund, Germany, write in their letter to the editor of the British Journal of Nutrition (Buyken. 2005):

Figure 4: GI values (glucose reference) for potatoes by different cooking methods; the horizontal bars indicate the minimal and maximal glycemic index; the dotted vertical lines mark the conventionally accepted  "low GI" <55 (left) and "high GI" >70 (right) cut-off points (the figure was taken directly from Buyken. 2005)

[...] as with all GI data, the GI values of potatoes may depend on cooking method, processing, variety and the composition of the meal. This fact deserves attention since mashed potatoes, French fries, baked potatoes and potatoes cooked in a microwave are characterised by GI values mostly exceeding the upper limit for a high GI value of 70; whereas conventionally boiled potatoes appear to have a GI value on average below 70. The values of conventionally boiled potatoes do vary considerably though, so it may also be that some potato varieties have an inherently low GI what-ever the cooking method (Najjar. 2004; Fernandes. 2005). In this context, it should be considered that most currently available GI values are based on mature potato varieties (Ontario, Prince Edward Island, Desiree, Pontiac, Sebago). The starch of more mature potatoes is, however, easier to digest, presumably due to increased amylopectin branching and hence lower resistance to gelatinisation, which in turn results in a higher GI (Soh. 1999).

Buyken and Kroke support their argument by the means of an illustration of the broad range of the glycemic responses (and respective GI) of study participants to 46 different potato meals (cf. figure 4) and emphasize that there are significant differences in both the preferred potato cultivars, as well as the respective cooking / processing methods between European and US customers. While the former "prefer potato varieties characterised by a lower GI", the prevailing potato varieties in the US are mature and exhibit significantly higher glycemic indices. This trend toward higher glycemic indices in US potato meals is reinforced by the average American's preference to fry, bake, mash, roast or microwave his potatoes, so that it would  be "thoughtless" for any European, or American who selects less mature, low GI cultivars and refrains from frying, baking, mashing, roasting or microwaving his potatoes to follow the grossly over-generalized recommendation to eat less potatoes.

Ok, not all regular potatoes are made equal, but sweet potatoes are still king, right?

Against the background that my grand father who lived a 100% healthy, diabetes-free life into his late 90s, competed in track and fields and swam laps until about 6 months before he died, had regular potatoes with every dinner, I may be somewhat biased as far as the "bad potatoes" are concerned. This does yet not compromise the value of the rational arguments and scientific evidence against the unjust and, above all, over-generalized vilification of regular potatoes I have brought forward in this first installment of the Potato Manifesto. If you are interested in how the "holy" sweet potato which is currently hailed as the savior of the neo-paleolithic race compares, come back tomorrow for Part II of the Potato Manifesto ;-)

Beyond Celiac: Study Sheds New Light on Obesogenic Effects of Gluten - Are PPARs & Bacteria Both Involved?

Cornflakes peanut butter cookies - guaranteed not gluten free ;-)

With Christmas Eve being over, and grandma's cookies, Christmas stollen, and all sorts of other stuff from the bakery in front of you (literally), Christmas Day may actually prove to be a way more "dangerous" than Christmas Eve - not just because of the total amount of calories, but also because of the low satiety effect of these sweet treats.

A recent paper by scientists from the Universidade Federal de Minas Gerais in Belo Horizonte in Brazil does now point to another reason you better give those bakery products a wide berth - not just, but especially with the energy overshoot on Christmas day: Gluten!

Study confirms for the first time what scientists and laymen alike have been speculating about

In what the scientists claim is the first well-controlled study of the effects of gluten intake on metabolic health in a non-celiac, but Western-style diet scenario, Fabíola Lacerda Pires Soares and her colleagues put two groups of C57BL/6 mice on identical, iso-caloric high fat (hypercaloric) diets that differed only in terms of the amount of gluten that was added to the chow (0% gluten vs. 4.5% gluten).

Interestingly, the gluten diet did not influence any of the usual suspects, like food intake, total fat-free mass, fecal lipids excretion, blood lipid profile, blood total protein and ectopic (liver and muscle) lipid concentration (if you look closely you will realize that the gluten-free group actually had higher TRIGs, although the difference did not reach statistical significance).

Figure 1: Usual suspects and closer look at the effects 8 weeks gluten supplemented vs. gluten-free diets had on serum markers of metabolic syndrome and visceral fat parameters (Soares. 2012)

The data in figure 1 (right) does yet also show that the gluten content of the diet did nevertheless have a significant impact on the total body mass, visceral fat mass, lipid content and most importantly the adipocyte size.

Figure 2: Absolute adipokine levels (left) and fasting glucose and insulin levels, as well as Homa-IR (Soares. 2012)

Add to that the blunted expression of the anti-inflammatory and anti-diabetic fat hormone adiponectin and the increased the >5x higher expression of leptin (figure 2). And mix that with the reduced expression of PPAR-alpha and gamma of which Soares et al. argue that they may well be the key factor in the detrimental modulatory effect the addition of gluten had on the visceral fat structure and the lowered expression of the fat liberating enzymes LPL and and HSL, as well as reduced levels of the fat burning proteins ACC and CPT-1 (figure 3).

Figure 3: PPAR-alpha, -gamma, LPL, HSL, ACC and CPT-1 expression compared to rodents on regular chow (left); crown like structures in stained slices from visceral fat, inflammatory markers TNF-alpha and IL-6 (Soares. 2012)

So, even if the initially mentioned blood markers (aka the usual suspects) would suggest that both the gluten-consuming and gluten-free rodents were similarly bad off, the profound difference in inflammatory markers within the adipose tissue and the presence of comparatively many necrotic and inflammatory adipocytes in the crown like structures stand in line with increases in HOMA-IR, fasting glucose and insulin and an already compromised glucose clearance which are well-known harbingers of the metabolic syndrome.

These observations do not simply shed a whole new light on a hitherto largely ignored contributer to the etiology of the metabolic syndrome, they do also show that one of the reasons it has not been identified before is an over-reliance on BMI, total fat mass and serum lipids in the early stages of diabesity.

Reardless of whether the gut microbiome is part of the mechanism by which gluten predisposes the development of metabolic syndrome. Eating more inulin- and beta-glucan rich foods like Jerusalem artichokes, agave, bananas, onion, steel cut oats, wild yams, yacon, etc. certainly won't hurt your efforts to get lean, stay lean and leave the role of the obese diabetic to the other (read more)

Bottom line: The study at hand provides a good reason to limit your intake of "healthy whole grains" and other gluten containing foods, regardless of whether you suffer from celiac or not. Whether the established detrimental effects of gluten on the integrity of the intestinal wall and the increased leakage of bacterially produced endotoxins from the highly unfavorably changes in the gut microbiome in response to the high fat diets (Hildebrandt. 2009) are part of, or even the primary cause of these observations still has to be elucidated. The same goes for strategies to counter the translocation of the endotoxins across the gut lining (cf. "Shedding some light on the leaky gut") and the dose response relationship between the total amount of gluten in your diet and its effects on your metabolism. With 7% of pure gluten, it goes without saying that you would basically have to live of wheat in order to get to anywhere similar amounts of gluten in the diet... that said: Is it possible that the effects occur only in the presence of the high fat diet? After all, this alone has been shown to favor a pro-inflammatory gut microbiome.

You see there are enough questions to be answered in 2013 and the SuppVersity is going to be the place you will read the respective answers first ;-)

References:

• Hildebrandt MA, Hoffmann C, Sherrill-Mix SA, Keilbaugh SA, Hamady M, Chen YY, Knight R, Ahima RS, Bushman F, Wu GD. High-fat diet determines the composition of the murine gut microbiome independently of obesity. Gastroenterology. 2009 Nov;137(5):1716-24.e1-2.
• Soares FL, de Oliveira Matoso R, Teixeira LG, Menezes Z, Pereira SS, Alves AC, Batista NV, de Faria AM, Cara DC, Ferreira AV, Alvarez-Leite JI. Gluten-free diet reduces adiposity, inflammation and insulin resistance associated with the induction of PPAR-alpha and PPAR-gamma expression. J Nutr Biochem. 2012 Dec 17.

Complete Meals & GI (Non-)Sense, Glutamine & GLP-1, Low Thyroid & High Trigs, N-3 vs. N-6 Interactions, Optimal DHA Dosage in Kids W/ NAFLD, Selenium vs. Aluminum Toxicity

While this is not the exact combination of chicken breast, mashed potatoes and salad in the first one of today's news items, it's more than likely that the predicted GI (and thus probably what you would find if you looked it up in a table) overestimates the postprandial glucose response to this meal by ~50% and says absolutely nothing about the insulin response. It looks like complex meals and over-simplified theories, don't mix well, at all ;-)

78% that's the SuppVersity Figure of the Week and actually part of the additional information I provided on one of today's On Short Notice items. It's the increase in coronary heart disease risk women with subclinical hypothyroidism have compared to their peers with spot on TSH levels of 0.5-1.5mU/L (Asvold. 2012). In conjunction with other more or less recent studies, such as Mitchel's, Hsu's and Sahai's paper confirming the previously often talked about but not well-established 2-fold increase in congenital hypothyroidism from the early 1990s to the first years of the new millennium (Mitchel 2011), the predictive value of high TSH levels in the first trimester (early pregnancy hypothyroidism) for adverse pregnancy outcomes (Schneuer. 2012), the 30% risk increase in all-cause mortality in both women and men with subclinical hypothyroidism Tseng et al. reported in their paper earlier this year or the impairment of spatial working memory (Yin. 2012), Asvold's results only add to the evidence that the potential pitfalls of an increasingly prevalent metabolic dysfunction may have been ignored way too long.

• More GI lovin' - On the menu today: Mashed potaoes with chicken, rapeseed oil or both (Hätönen. 2011) - I thought a mini-follow-up on Friday's post on the GI would be nice, 'cause some of you have not without reason been complaining that not everyone would eat pure white bread, like my students do.
  
  

  

  Figure 1: The real (=measured) GI of a meal does differ significantly from the theoretical prediction. So, even if the concept was worth bothering, the GIs of complete meals simply wrong, if they are not measured (Hötönen. 2011).

  Moreover, the mere fact that the scientists from the Department of Lifestyles and Participation at the National Institute for Health and Welfare in Helsinki, Finland, found that the addition of chicken breast, rapeseed oil and a salad, individually and in combination, had the GI of a meal containing six mashed potatoes (this was the parameter that was held constant) induced more than twofold changes in GI, with the addition of chicken breast having the greatest deviation from the predicted value in this group of 11 (initially 12) healthy subjects, three men and nine women, aged 36.2 (SD 14.1) years with a BMI of 21.3 (SD 1.7) kg/m² and normal glucose tolerance (see figure 1).
  
  Now given the fact that most data on the GI of complete meals has never been measured, but is actually based on the same predictions the scientists used, it stands to reason that...
  

  [...] this highlights the problems encountered when predicting the GI values of mixed meals. The protein com-ponent of the mixed meal evoked the largest insulinaemic responses and markedly increased the II of the mixed meal containing protein. However, introducing fat into the meal decreased the effect of protein on the insulinaemic responses (Hätönen. 2011)

  So, this does not simply bust the idea that you could calculate the GI, it does likewise show you that people who are still overtly scared of insulin (which is hillarious as long as you are insulin sensitive) are doing he exact wrong thing, when they make food-choices based on GI: Whey protein would in that case be in as much a no-go as simply eating a chicken breast with your mashed potatoes would be, because other than what most people believe, it does increase the insulin spike and thus reduce the glycemic index by allowing your body to clear the glucose more efficiently from the circulation.
  
  Suggested reads: The red box in the "Whey is More Insulinogenic than White Bread" post on the partitioning effects of BCAAs and yesterday's Facebook post on the anti-Alzheimer's effects of insulin.

• 

  Suggested read: Amino Acids for Super Humans the purported ergogenic effects of l-glutamine

  30g of oral glutamine have similar effects on GLP-1 as 75g of glucose (Greenfield. 2008) - Still a follow up on the GI discussion, I think you may be interested in. If you are someone who follows the questionable practice of ingesting large boluses of glutamine in the futile believe that this would increase your gains or speed up recovery, you may be pleased to hear that only 30g of oral l-glutamine produced an increase in the "Fat Burning Satiety Hormone GLP-1" (read more on GLP-1) that's on a gram to gram basis more pronounced than in response to insulin (0.41pmol/L per gram glucose vs. 0.75pmol/L per gram of glutamine; in 8 healthy subjects).
  
  Before you go and buy tons of glutamine, you should however consider that GIP, the pro-insulinogenic peptide and glucagon (ramps up gluconeogenesis in the liver) were likewise increased by the ingestion of this bolus of glutamine. It is therefore no wonder that glutamine has never been shown to be a "fat burner". Nonetheless, a 1999 study by Bowtell et al. would suggest that it may come handy to replenish liver and muscle glycogen after a workout (8g alone did increase glucose storage after a workout to a similar degree as a 18.5% glucose polymer solution and additional 25% glucose storage mostly in the liver, when both were coingested; cf. Bowtell. 1999). And if you don't care about that - your gut integrity could also be a reason to consider supplementation in the vicinity of particular strenuous or length workouts (see "Shedding Some Light on the Leaky Gut <> Exercise Connection") 

• Practical relevance? Based on data from a 12-year longitudinal study, even women with subclinical hypothyroidism have 76% risk for coronary heart disease (p = 0.005), than women with spot on TSH levels of 0.5-1.5mU/L (Asvold. 2012). And even women well within in the "normal range" (TSH of 1.5-2.4mU/l) have a 41% higher risk of heart disease, although this is only borderline significant (p = 0.08). For men the TSH level alone had not predictive value. Spec. w/ regards to T3, there are also reports of increased incidence of ventricular disfuntion (Cassetti. 2009), increased cardiac death in CVD patients (Iervasi. 2003) and impaired recovery after a stroke (Alevizaki. 2007). We do yet have to be cautious, here as "low T3" syndrome could as well be the consequence of overall inflammation and the association does not tell us anything about what's the chicken and the egg.
  Low thyroid, high triglyceride (Hashimoto. 2012) -- If you are wondering why on earth your trigs won't come down, it may well be that it's the absence of sufficient amounts of thyroid hormone. I a soon-to-be-published paper in Endocrinology scientists from the Gunma University in Maebashi, Gunma, Japan, report that thyroid hormone regulates the expression of a Stearoyl-CoA desaturase-1 (SCD-1) which controls the production of trigs from carbohydrates.
  
  Surprisingly the 75% increase due to hypothyroidism and the 75% decrease in SCD-1 mRNA expression (both compared to a euthyroid state) the scientists observed in rodents in response to the administration of T3 were not mediated by receptor binding, but simply as a down-stream effect of direct modifications of the SCD-1 gene promoter between -124 and -92 bp by T3.
  
  On a related side note: It is actually the last mentioned mechanism which is the major new finding in the study at hand and not the fact that T3 can reduce the conversion of carbohydrates to triglicerides that is the actual news here. After all, the latter is something scientist should know, but obviously like to forget about ever since the late 1999s (Waters. 1997)

• Omega-6 intake and not low omega-3 intake is the problem (Liou. 2007) -- Another older study, but one I am posting in response to a discussion some of you are having about omega-3 (ALA) intake in the post about safflower oil and DHT, because I simply feel that it's necessary to shed some light  on the erroneous assumption that by simply upping your intake of omega-3s or fish oil intake you could get away without decreasing your omega-6 intake, which in and out of itself will already increase the amount of anti-inflammatory omega-3 fatty acids (supplementation of DHA can still be advisable, specifically if you are a vegetarian).
  
  

  

  Figure 2: Effect of 4 weeks of high (red) vs. 4 weeks of low (green) linoleic acid (n-6) intake on short and long-chain omega-3 plasma phospholipid content in healthy men (Liou. 2007)

  In 2007, already Liu et al. conducted a very interesting experiment in the course of which they fed healthy men diets with identical amounts of omega-3 fatty acids (1% of the total energy intake), but two different amounts of linoleic acid (omega-6) and found that the high omega-6 intake (10.1% vs. 3.8% of the total energy intake) alone decreased the total amount of EPA among the plasma phospholipids (the major long-chain omega-3 fatty acid in fish oil), not just the ratio of omega-3 to omega-6, in the blood of their 29-45 year-old subjects by more than 25% (see figure 2). The paradoxical effect on DHA, on the other hand, would warrant further investigation, and underlines how reliant we are - if anything on the intake of pure DHA, which dropped in consequence to the test diet, which was devoid of fatty fish, while the original diet of the non-vegetarian subjects had fish in it.
  
  In this context, I would also like to point out that DHA is exactly where real fish is far superior to fish oil caps, because it has a way more favorable EPA:DHA ratio than fish oil caps. Salmon fillets for example have - depending on the fatty acid source in the diet 8.5g : 13.8g, 4.4g : 7.8g and 1.5g : 2.9g (all values per 100g) when the feed contains fish oil, fish and rapeseed and fish + rapeseed and rapeseed, only.
  
  And while the ratios are similar regardless of the chow, the data from the Seierstad et al. clearly shows that the fatty acid content of the diets can induce almost 5-fold differences in terms of the total DHA content and the omega-3 to omega 6 ratio (fish oil diet: 6.5, fish oil + rapeseed: 1.7, rapeseed: 0.6) of salmon fillets (Seierstad. 2003). 

• It does not take much: 500mg DHA not more effective than 250mg  (Nobili. 2012) -- At least if it comes to its beneficial effects against liver steatosis in children  (mean age 11 years; BMI 26.6kg/m² and 24.4kg/m², in the low and high dose groups respectively with with NAFLD, the amount of DHA does not appear to be so important. According to the results of their 2-year registered controlled trial, both 250mg and 500mg of Docosahexaenoic acid lead to identical and profound reductions in the odds ratio of developing more severe steatosis during the study period.
  
  

  

  Figure 3: Odds ratio (comparing DHA supplement vs. placebo) of more severe vs. less severe liver steatosis determined every 6 months during the 24-month study period (Nobili. 2012)

  If you take a closer look at the data in figure 3, you will even have to concede that the lower dosage did a better job - while the mean odds ratios were only marginally lower in the 250mg DHA group, the extremely high standard deviations in the 500mg DHA would suggest that the 250mg dose appears to be more reliable. In this regard it may be interesting that the increase in serum DHA did mirror the dosages. With a 0.65% and 1.15% increase in DHA those were about 2x higher in the 20 boys and girls in the high dose group compared to the 20 kids in the control group who received a 290 mg linoleic acid germ oil supplement "placebo" (by the way, a monosaturated fatty acid placebo would have been more of a placebo than 290mg of omega-6)
  
  In view of the fact that the changes in triglycerides, ALT, HOMA-IR and BMI (which was not even different from the placebo group) were likewise identical, it does not appear as if anything that goes beyond the amount you will find in 2x cheap fish oil caps, or 10g even of the cheapest salmon fillet (see last paragraph of previous item) would be necessary to ellicit the anti-steatosis effect of fish oil - since those kids weight on average 55kg, an adult may want to add in another fish oil cap to get up to 360mg DHA per day or simply eat his fatty fish once or twice a week.

• Selenium ameliorates aluminum toxicity (Viezeliene. 2012) -- With the whole upheaval about the potential negative side effects of the aluminum in vaccines, the formerly overlooked yet well-known neurotoxic (Exley. 1992; Gupta. 2005), hepatotoxic (Abubakar. 2003; Perez. 2005) and nephrotoxic metal (Geyikoglu. 2012) has all of a sudden returned to the center of public interest.
  
  Therefore I thought that you will be interested in the results of a study that's going to be published in the next issue of the Journal of Trace Elements in Medicine and Biology - irrespective of whether you believe, like Tomljenovic and Shaw that
  

  "the possibility that vaccine benefits may have been overrated and the risk of potential adverse effects underestimated, has not been rigorously evaluated in the medical and scientific community"(Tomljenovic. 2011)

  After all, vaccines are not the only potential source of aluminum in our environment, so that the ameliorative effects (all values remained normal in the aluminum exposed group, while there were 30%, 55% and 42% increases in GSH in the animals who received only the selenium injection) the co-administration of supplemental selenium had on the GSH reductions in liver, kidney and brain of Balb/c mice weighing 20–25g who were exposed (by i.p. injection)to AlCl3 (25 mg Al(3+)/kg body mass) for 16h could be important, regardless of whether you do or don't intend to get vaccinated.
  
  

  

  There is more about selenium at the SuppVersity, for example on its pro-fertility effects, and its anti-corrosive effects in the brain.

  That said, the dosage requirements necessary to maintain healthy GSH levels are probably much lower than the hillarious (for a healthy individual) in the study at hand 1,250µg/kg body weight of sodium selenite (Na2SeO3). Considering the elemental selenium content in Na2SeO3, the latter would equal to ~3,650µg - unquestionably WAY too much (remember this was a one-time dosage that was specifically co-administered w/ the aluminum). Even the 'no observed adverse effect' level for a 70kg man of intake which is ~1000µg/d (Whanger. 1999) appears unnecessarily high, so that the consumption of a handful of brazil nuts once or twice a week and/or other high selenium foods such as tuna, cod, oysters, shrimp, but also eggs, meats, poultry, mushroom and onions on a regular should suffice to get what you need, to fortify yourself against the constant assault of heavy metals.
  
  What would be interesting, though, is a study into the effects of adding selenium to the "safe" aluminum in vaccines. I mean, you cannot seriously tell me that we could not afford doing that and if it reduced any toxicity issues, why not?

That's about it for today, I did not post all too many new facebook news as of yet (I mean, come on, it's Saturday ;-), but if you are into medicinal horror-stories, you will certainly like the story about the flesh eating killer fungus. If you prefer microbes over fungi, you are probably better off with the latest insights into the associations of certain gutbacteria with the incidence of stroke. And if you are more into other aspects of the digestive tract you may be interested in the effects of gastric emptying time on postprandial gylcemia and insulin release.

If none of those news is to your liking, I suggest you either wait for me to post something else (could be happening within the next hours at www.facebook.com/SuppVersity), or simply enjoy the weekend and come back tomorrow when you are rested for another (hopefully) enlightening SuppVersity post.

References:

• Abubakar  MG,  Taylor  A,  Ferns  GA.  Aluminium  administration  is  associated  with enhanced  hepatic  oxidant  stress  that  may  be  offset  by  dietary  vitamin  E  in  the rat. Int J Exp Pathol 2003;84:49–54.
• Asvold BO, Bjøro T, Platou C, Vatten LJ. Thyroid function and the risk of coronary heart disease: 12-year follow-up of the HUNT Study in Norway. Clin Endocrinol (Oxf). 2012 Dec;77(6):911-7.
• Bowtell JL, Gelly K, Jackman ML, Patel A, Simeoni M, Rennie MJ. Effect of oral glutamine on whole body carbohydrate storage during recovery from exhaustive exercise. J Appl Physiol. 1999 Jun;86(6):1770-7.
• Cassetti G, Pinelli M, Bindi M, Bianchi M, Castiglioni M. [Low T3 syndrome and left ventricular diastolic function]. G Ital Cardiol (Rome). 2009 Aug;10(8):553-7. 
• Exley  C,  Birchall  JD.  The  cellular  toxicity  of  aluminium.  J  Theor  Biol 1992;159:83–98.
• Geyikoglu  F,  Turkez  H,  Ozhan  Bakir  T,  Cicek  M.  The  genotoxic,  hepa- totoxic,  nephrotoxic,  haematotoxic  and  histopathological  effects  in  rats after aluminium chronic intoxication. Toxicol Ind Health 2012;15.
• Greenfield JR, Farooqi IS, Keogh JM, Henning E, Habib AM, Blackwood A, Reimann F, Holst JJ, Gribble FM. Oral glutamine increases circulating glucagon-like peptide 1, glucagon, and insulin concentrations in lean, obese, and type 2 diabetic subjects. Am J Clin Nutr. 2009 Jan;89(1):106-13.
• Gupta  VB,  Anitha  S,  Hegde  ML,  Zecca  L,  Garruto  RM,  Ravid  R,  et  al.  Alu- minium  in  Alzheimer’s  disease:  are  we  still  at  a  crossroad?  Cell  Mol  Life  Sci 2005;62:143–58.
• Hashimoto K, Ishida E, Miura A, Ozawa A, Shibusawa N, Satoh T, Okada S, Yamada M, Mori M. Human Stearoyl-CoA Desaturase 1 (SCD-1) Gene Expression Is Negatively Regulated by Thyroid Hormone without Direct Binding of Thyroid Hormone Receptor to the Gene Promoter. Endocrinology. 2012 Dec 7.
• Hätönen KA, Virtamo J, Eriksson JG, Sinkko HK, Sundvall JE, Valsta LM. Protein and fat modify the glycaemic and insulinaemic responses to a mashed potato-based meal. Br J Nutr. 2011 Jul;106(2):248-53. 
• Iervasi G, Pingitore A, Landi P, Raciti M, Ripoli A, Scarlattini M, L'Abbate A, Donato L. Low-T3 syndrome: a strong prognostic predictor of death in patients with heart disease. Circulation. 2003 Feb 11;107(5):708-13.
• Liou YA, King DJ, Zibrik D, Innis SM. Decreasing linoleic acid with constant alpha-linolenic acid in dietary fats increases (n-3) eicosapentaenoic acid in plasma phospholipids in healthy men. J Nutr. 2007 Apr;137(4):945-52. 
• Mitchell ML, Hsu HW, Sahai I; Massachusetts Pediatric Endocrine Work Group. The increased incidence of congenital hypothyroidism: fact or fancy? Clin Endocrinol (Oxf). 2011 Dec;75(6):806-10.
• Perez  G,  Pregi  N,  Vittori  D,  Di  Risio  C,  Garbossa  G,  Nesse  A.  Aluminium  expo- sure  affects  transferrin-dependent  and  -independent  iron  uptake  by  K562  cells. Biochim  Biophys  Acta  2005;1745:124–30. 
• Schneuer FJ, Nassar N, Tasevski V, Morris JM, Roberts CL. Association and predictive accuracy of high TSH serum levels in first trimester and adverse pregnancy outcomes. J Clin Endocrinol Metab. 2012 Sep;97(9):3115-22.
• Seierstad SL, Seljeflot I, Johansen O, Hansen R, Haugen M, Rosenlund G, Frøyland L, Arnesen H. Dietary intake of differently fed salmon; the influence on markers of human atherosclerosis. Eur J Clin Invest. 2005 Jan;35(1):52-9.
• Waters KM, Miller CW, Ntambi JM. Localization of a negative thyroid hormone-response region in hepatic stearoyl-CoA desaturase gene 1. Biochem Biophys Res Commun. 1997 Apr 28;233(3):838-43. 
• Whanger P, Vendeland S, Park Y-C & Xia Y. Metabolism of sub-toxic levels of selenium in animals and humans. Annals of Clinical Laboratory Science. 1996;26, 99-113.

Warding Off Holiday Weight Gain 2.0: The Anti-Diabesity Effect of Coffee Goes Beyond its Caffeine Content.

Image 1: If they are not laden with pesticides and anti-fungals, the small brown beans from the coffee pant can easily compete with green, black oolong and pu-erh teas, when it comes to countering the unwanted side-effects of the "holiday diet"

Back in the days, both, tea and coffee were luxury goods and people felt privileged if they could have any of them. Today, they have become another of the endless commodities of our convenience society, where coffee, the former drink of the kings (and popes), has gotten a bad rep lately as being the underlying cause of the "adrenal burnout" that has befallen 90% of the visitors of pertinent Internet bulletin boards. I was thusly not surprised that SuppVersity student Fat Free commented yesterday's blogpost on the anti-obesity effects of tea rather sheepishly. As if his wish for "a coffee" on the list of the anti-holiday-weight-gain items was some atrocious act in the sense that "a coffee" could never be as healthy as a hip green tea. I mean wasn't it bad enough that the "holy" green tea was outperformed by its primitive black brother?

Well, guess what, dear green tea connoisseurs, it may well be that (organic) coffee beans are in no way inferior to the unquestionably healthy, yet recently slightly over-hyped unoxidized camellia sinensis leaves. At least this is what a soon to be published study by Yuji Matsuda and his colleagues from the Nagoja University in Japan would suggest (Matsuda. 2011).

Tea or coffee during the holiday season - only a matter taste?

Matsuda et al. put a group of 8-week old mice on a pro-diabetic high-fat diet (this is the type of "high fat diet" that is high both in fat and in carbs and thusly is a perfect image of what 75% of the people are "eating" in the holiday season ;-). In the course of the 17-week study period the mice received either regular drinking water, or 2.5x diluted coffee, or water that was laced with 200mg of caffeine per liter (with a water intake of 13-14g/100g BW this would translate to a daily dose of 2.8mg/100mg and a human equivalent of 2.3mg/kg, or 182mg of caffeine per day for an 80kg human being). The intention was to investigate whether the results of epidemiological studies by van Dam (2002; 2005), Huxley (2009) and Goto (2011), which suggest that regular coffee consumption is associated with a profoundly reduced risk of developing metabolic syndrome or type II diabetes, could be replicated in a laboratory setting.

Figure 1: Body weight at the beginning and end of the study period in the control group and the mice receiving 2.5x dilluted coffee or 200mg/L caffeine in their drinking water; food intake in g per 100g of  body weight (data adapted from Matsuda. 2011).

If you look at the weight changes of the animals in figure 1, it becomes evident that despite a (non significantly) greater food intake esp. in the "real coffee" group, the mice on the coffee or caffeine supplemented high-fat diets gained approx. 8% less body weight than their water guzzling peers.

Figure 2: Fat weight in mice after 17 weeks on high fat diet with either water, 2.5x diluted coffee or water + 200mg caffeine per L (data adapted from Matsuda. 2011).

Now while the intrinsically flawed concept of a "body mass index" that is still propagated by mainstream media would suggest that there is something like an "ideal body weight", the numbers on your scale, alone, have no predictive value in terms of future health risk. The reductions in visceral (epididymal fat) and subcatenous fat accumulation in the mice of the coffee and caffeine arm is thusly a considerably more important finding of this study than the slightly reduced weight gain. After all, the amount of visceral (=inter-organ) fat you are carrying around is one of the few relatively reliable indicators of whether you are going to see your grand-children graduate, or not.

Time and again: Whole foods, or drinks, outperform extracts

If you take a closer look you will notice that despite a general tendency towards lower body fat levels in the coffee and caffeine group, the "whole food", or I should say, "whole beverage" has a much more pronounced effect on the "bad" visceral (epididymal) fat depots. So, just in case you still like your pills, caps and powders: This is only the latest in a long line of foods (this is the stuff that is not sold in caps or powder form) with verified health benefits, where one isolated compound, of which we believe that it is the "active ingredient" turns less potent than the whole food - so, could it possibly be that Nature knows best?

Figure 3: Reductions in inflammatory cytokine (MCP-1, TNF-alpha, IL-6) and adipokine expression in the epididymal fat pads of mice receiving 2.5x diluted coffee or water laced with 200mg/L caffeine in addition to their high fat diet (data calculated based on Matsuda. 2011).

The "whole foods" vs. "extract" difference is also evident in the differential effects coffee and caffeine had the expression of the inflammatory cytokines MCP-1, TNF-Alpha and IL-6 and the adipokines adiponectin and leptin. With a more pronounced expression of the latter (leptin) and an almost identical expression of the former (adiponectin) indicating an improved visceral fat metabolism in the epididymal fat pads of the "coffee-drinking" mice.

Figure 4: Insulin response (area under the curve in mg * min / dl) during glucose tolerance at different time-points during the 17-week study period (data calculated based on Matsuda. 2011).

As the areas under the insulin response curve in the glucose tolerance test go to show. Coffee (=whole food!) consumption does also reduce the transient caffeine induced decrease in insulin sensitivity that has been touted as one of the reasons why coffee would be "bad" for you. As the data from the study goes to show, this effect is only temporary, even for plain caffeine and should not be an issue for the habitual coffee drinker. Moreover, the long term benefits totally outweigh any short term increases in fasting blood glucose (approx. +8% in the first weeks of the study) - or, getting back to the initial research hypothesis: Coffee consumption is a possible way to reduce the risk of developing type II diabetes (at least  for mice ;-)

Coffee or tea? The choice is up to thee!

Since a direct comparison of the data from yesterday's tea study on teas would not be valid, anyways, and because I do not want to disturb the pre-Chrismas harmony and provoke a war between coffee and tea drinkers in the comment area of this blogpost, I would just advice everyone to just decline the soda your relatives may be offering you over the holidays and stick to either tea or coffee... whatever you like better - and by the way, dehydration is neither an issue for the habitual tea nor the habitual coffee drinker (Grandjean. 2000)!