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

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

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

"What exactly is a leaky gut?"

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

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

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

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

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

HIIT veterans or weight lifters are not off the hook

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

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

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

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

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

• 

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

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

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

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

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

• Colostrum supplementation to cell cultures has been shown to increase the expression of HSP-70 in human epithelial cells; studies with human subjects are rare and ambiguous:  While Marchbank et al., have been able to show that bovine colostrum truncates the increase in gut permeability caused by heavy exercise in athletes (Marchbank. 2011), Buckley et al. actually observed detrimental effects of 8 weeks of bovine colostrum supplementation on the exercise induced gut permeability in runners (Buckley. 2009).The explanation for these discrepencies is not clear, but may be related to the longer duration / different intensity of the exercise protocols, or differences in the immunoglobolin, peptide or amino acid composition of the supplements.
• Zinc in general and specifically polaprezinc, a zinc based anti-ulcer drug, which has primarily been used in Japan as a means to seal leaky Japanese guts, show some promises, as in the treatment and prevention of increased intestinal permeabilty (Zhang. 2009). It is thought that zinc is critical for tight junction assembly and has been shown to be critical in the protection of the gut lining from the chronic toxic assault of alcohol (Zhong. 2010). That being said, you should keep in mind that alcohol will deplete your bodies zinc stores, so that it cannot be said, if someone with an adequate zinc intake would benefit to the same degree as a zinc deficient alcoholic. Moreover, as "natural" as they may be, even essential minerals like zinc don't come without potential side effects (cf. "After 120 Days Rodents on Diets Containing 2xRDA of Zinc Develop Metabolic Syndrome", read more).
• Glutamine has been used as treatment for patients suffering from irritable bowel syndrome and Crohn’s disease and has been shown to actively increase the expression of HSP70 in critically ill patients (Jonas. 1999; Ziegler. 2005).  
• Berberine could be an ideal addition to glutamine (thx to Maxim Okhrimenko for pointing that out in the comments); berberine does not only modulate the TNF-alpha response in the intestines and increases AKT, but has also been shown to maintain / rescue intestinal glutamine transport and glutaminase activity (Gu. 2009; Amasheh. 2010; Li. 2010; Niu. 2011)
• Probiotics are still an 'under-researched' newcomer and though there is some preliminary evidence pointing to the efficacy of probiotic therapy as a means of improving gut function and enhancing the integrity of the intestinal tight junctions, the ideal supplement regimen, as well as its long-term effects will still have to be elucidated in human studies. Studies by Ewaschuk et al. have yet already shown that the impact factors released from Bifidobacteria infantis can offer a certain degree of protection against experimentally induced colitis in rodents (Ewaschuk. 2008). As far as exercise specific studies are concerned, a recently published paper by Lamprecht et al. is probably the first peer reviewed human study to report allegedly "borderline significant" beneficial effects on gut permeability (measured only indirectly by quantifiying the zonolin conent of the feces) and TNFalpha expression in response to a multi-species probiotics (1010 CFU/day, Ecologic®Performance orOMNi-BiOTiC®POWER) in 23 trained men (Lamprecht. 2013; the study was partially funded with a grant from Winclov, the manufacturer of the respective supplements).
• Butyrate, yet not all short chain fatty acids, have recently been found to decrease gut permeability (Ferreira. 2013). Both data from human studies, as well as exercise specific data is yet still absent.
• Hydroxypropyl methylcellulose (HPMC), which is a non-fermentable fiber, has been shown to protect rodent guts from a high fat diet induced increase in gut permeability (Kim. 2013), as in the case of butyrate its efficacy (and when you think about athletes, tolerability) will yet still have to be confirmed in human trials.
• L-Arginine (and AAKG) as a source of nitric oxide, which is necessary to protect the gut barrier from invaders could have a protective effect, as well (Quirino. 2013); and though this effect is not exercise specific, we know that arginine requirements increase in states of chronic stress, it would therefore be logical that supplementation with l-arginine, or even better AAKG, which comes with a precursor to glutamine will have beneficial effects on the tightness of the guts of intensely training athletes, as well (suggested read: BCAAs, glutamine and ammonia detox) .
• Oats, maybe due to their beta glucan content and their ability to increase the production of short-chain fatty acids in the large intestine, oats offer protection against alcohol induced increases in tight junction permeability (Tang. 2009); exercise specific studies have yet to be conducted, though.Personally I would yet not be surprised if this would turn out to be very effective (note: as long as they are not cross-contaminated, oats are 100% gluten-free)
• Goats milk (powder) has been shown to be equally effective as colostrum in reducing heat and thus most likely exercise induced gut permeability (Prosser. 2004)
• Lactoferrin, a multifunctional protein of the transferrin family that is present in milk may have protective effects against LPS-mediated intestinal mucosal damage and impairments of the barrier function in intestinal epithelial cells (Hirotani. 2008)
• Vitamin A in adequate amounts is necessary to maintain gut integrity; it is likely that this is all the more true if gut integrity and immune function are additionally challenged by strenuous exercise (Quadro. 2000)

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

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

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

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

References:

• Amasheh M, Fromm A, Krug SM, Amasheh S, Andres S, Zeitz M, Fromm M, Schulzke JD. TNFalpha-induced and berberine-antagonized tight junction barrier impairment via tyrosine kinase, Akt and NFkappaB signaling. J Cell Sci. 2010 Dec 1;123(Pt 23):4145-55.
• Banan A,Zhang LJ, Shaikh M,et al. theta Isoform of protein kinase C alters barrier function in intestinal epithelium through modulation of distinct claudin isotypes: a novel mechanism for regulation of permeability. J Pharmacol Exp Ther. 2005; 313:962–82.
• Buckley JD, Butler RN, Southcott E, Brinkworth GD. Bovine colostrum supplementation during running training increases intestinal permeability. Nutrients. 2009 Feb;1(2):224-34.
• Dokladny K, Lobb R, Wharton W, Ma TY, Moseley PL. LPS-induced cytokine levels are repressed by elevated expression of HSP70 in rats: possible role of NF-kappaB. Cell Stress Chaperones. 2010 Mar;15(2):153-63. Epub 2009 Jun 24. 
• Ewaschuk JB, Diaz H, Meddings L, Diederichs B, Dmytrash A, Backer J, Looijer-van Langen M, Madsen KL. Secreted bioactive factors from Bifidobacterium infantis enhance epithelial cell barrier function. Am J Physiol Gastrointest Liver Physiol. 2008 Nov;295(5):G1025-34. 
• Ferruzza S, Scacchi M, Scarino ML, Sambuy Y. Iron and copper alter tight junction permeability in human intestinal Caco-2 cells by distinct mechanisms. Toxicol In Vitro. 2002 Aug;16(4):399-404. 
• Gu L, Li N, Li Q, Zhang Q, Wang C, Zhu W, Li J. The effect of berberine in vitro on tight junctions in human Caco-2 intestinal epithelial cells. Fitoterapia. 2009 Jun;80(4):241-8.
• Heyman M, Abed J, Lebreton C, Cerf-Bensussan N. Intestinal permeability in coeliac disease: insight into mechanisms and relevance to pathogenesis. Gut. 2013 Sep;61(9):1355-64.
• Hirotani Y, Ikeda K, Kato R, Myotoku M, Umeda T, Ijiri Y, Tanaka K. Protective effects of lactoferrin against intestinal mucosal damage induced by lipopolysaccharide in human intestinal Caco-2 cells. Yakugaku Zasshi. 2008 Sep;128(9):1363-8.
• Jeukendrup AE,Vet-Joop K, Sturk A,et al. Relationship between gastrointestinal complaints and endotoxaemia, cytokine release and the acute-phase reaction during and after a long-distance triathlon in highly trained men.Clin Sci (Lond). 2000;98:47–55. 
• Jonas CR, Ziegler TR. Potential role of glutamine administration in inflammatory bowel disease. Nestle Nutr Workshop Ser Clin Perform Programme. 1999;2:217-30.
• Johri RK, Thusu N, Khajuria A, Zutshi U. Piperine-mediated changes in the permeability of rat intestinal epithelial cells. The status of gamma-glutamyl transpeptidase activity, uptake of amino acids and lipid peroxidation. Biochem Pharmacol. 1992 Apr 1;43(7):1401-7.
• Kim H, Bartley GE, Young SA, Davis PA, Yokoyama W. HPMC supplementation reduces abdominal fat content, intestinal permeability, inflammation, and insulin resistance in diet-induced obese mice. Mol Nutr Food Res. 2013 Sep;56(9):1464-76. 
• Kuennen M, Gillum T, Dokladny K, Bedrick E, Schneider S, Moseley P. Thermotolerance and heat acclimation may share a common mechanism in humans. Am J Physiol Regul Integr Comp Physiol. 2011 Aug;301(2):R524-33.
• Lambert GP, Gisolfi CV, Berg DJ, Moseley PL, Oberley LW, Kregel KC. Selected contribution: Hyperthermia-induced intestinal permeability and the role of oxidative and nitrosative stress. J Appl Physiol. 2002 Apr;92(4):1750-61; discussion 1749. PubMed PMID: 11896046.
• Lambert GP, Boylan M, Laventure JP, Bull A, Lanspa S. Effect of aspirin and ibuprofen on GI permeability during exercise. Int J Sports Med. 2007 Sep;28(9):722-6.
• Lambert GP, Lang J, Bull A, Pfeifer PC, Eckerson J, Moore G, Lanspa S, O'Brien J. Fluid restriction during running increases GI permeability. Int J Sports Med. 2008 Mar;29(3):194-8.
• Lamprecht M, Bogner S, Schippinger G, Steinbauer K, Fankhauser F, Hallstroem S, Schuetz B, Greilberger JF. Probiotic supplementation affects markers of intestinal barrier, oxidation, and inflammation in trained men; a randomized, double-blinded, placebo-controlled trial. J Int Soc Sports Nutr. 2013 Sep 20;9(1):45. 
• Li N, Gu L, Qu L, Gong J, Li Q, Zhu W, Li J. Berberine attenuates pro-inflammatory cytokine-induced tight junction disruption in an in vitro model of intestinal epithelial cells. Eur J Pharm Sci. 2010 Apr 16;40(1):1-8.
• Marchbank T, Davison G, Oakes JR, Ghatei MA, Patterson M, Moyer MP, Playford RJ. The nutriceutical bovine colostrum truncates the increase in gut permeability caused by heavy exercise in athletes. Am J Physiol Gastrointest Liver Physiol. 2011 Mar;300(3):G477-84.
• Musch MW, Sugi K, Straus D, Chang EB. Heat-shock protein 72 protects against oxidant-induced injury of barrier function of human colonic epithelial Caco2/bbe cells. Gastroenterology. 1999 Jul;117(1):115-22. 
• Niu L, Qiao W, Hu Z, Li N, Huang Q, Gong J, Li Q, Zhu W, Li J. Berberine attenuates lipopolysaccharide-induced impairments of intestinal glutamine transport and glutaminase activity in rat. Fitoterapia. 2011 Apr;82(3):323-30.
• Peters HP, Bos M, Seebregts L,et al. Gastrointestinal symptoms in long-distance runners, cyclists, and triathletes: prevalence, medication, and etiology. Am J Gastroenterol. 1999; 94:1570–81. 
• Prosser C, Stelwagen K, Cummins R, Guerin P, Gill N, Milne C. Reduction in heat-induced gastrointestinal hyperpermeability in rats by bovine colostrum and goat milk powders. J Appl Physiol. 2004 Feb;96(2):650-4.
• Quadro L, Gamble MV, Vogel S, Lima AA, Piantedosi R, Moore SR, Colantuoni V, Gottesman ME, Guerrant RL, Blaner WS. Retinol and retinol-binding protein: gut integrity and circulating immunoglobulins. J Infect Dis. 2000 Sep;182 Suppl 1:S97-S102.
• Roig-Pérez S, Cortadellas N, Moretó M, Ferrer R. Intracellular mechanisms involved in docosahexaenoic acid-induced increases in tight junction permeability in Caco-2 cell monolayers. J Nutr. 2010 Sep;140(9):1557-63.
• Ruiz M. Wikipedia contributors, 'Tight junction', Wikipedia, The Free Encyclopedia, 10 November 2013, 07:58 UTC, <http://en.wikipedia.org/w/index.php?title=Tight_junction&oldid=522300074> accessed 25 November 2013
• Tang Y, Forsyth CB, Banan A, Fields JZ, Keshavarzian A. Oats supplementation prevents alcohol-induced gut leakiness in rats by preventing alcohol-induced oxidative tissue damage. J Pharmacol Exp Ther. 2009 Jun;329(3):952-8.
• Tsukura Y, Mori M, Hirotani Y, Ikeda K, Amano F, Kato R, Ijiri Y, Tanaka K. Effects of capsaicin on cellular damage and monolayer permeability in human intestinal Caco-2 cells. Biol Pharm Bull. 2007 Oct;30(10):1982-6.
• Usami M, Muraki K, Iwamoto M, Ohata A, Matsushita E, Miki A. Effect of eicosapentaenoic acid (EPA) on tight junction permeability in intestinal monolayer cells. Clin Nutr. 2001 Aug;20(4):351-9.
• van Wijck K, Lenaerts K, van Loon LJ,et al. Exercise-induced splanchnic hypoperfusion results in gut dysfunction in healthy men.PloS One. 2011; 6.
• Worobetz LJ,Gerrard DF. Gastrointestinal symptoms during exercise in Enduro athletes: prevalence and speculations on the aetiology.N Z Med J 1985; 98:644–6.
• Zhang B, Guo Y. Supplemental zinc reduced intestinal permeability by enhancing occludin and zonula occludens protein-1 (ZO-1) expression in weaning piglets. Br J Nutr. 2009 Sep;102(5):687-93.
• Zhong W, McClain CJ, Cave M, Kang YJ, Zhou Z. The role of zinc deficiency in alcohol-induced intestinal barrier dysfunction. Am J Physiol Gastrointest Liver Physiol. 2010 May;298(5):G625-33. 
• Ziegler TR, Ogden LG, Singleton KD, Luo M, Fernandez-Estivariz C, Griffith DP, Galloway JR, Wischmeyer PE. Parenteral glutamine increases serum heat shock protein 70 in critically ill patients. Intensive Care Med. 2005 Aug;31(8):1079-86

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

19 Billion Euro that's the estimated 2011 financial burden due to lung cancer, alone, here in Europe and the On Short Notice figure of the week (information based on ESMO2013 press release)

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

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Problems thinking straight? Guess what: 3-4 cups of coffee could help :-) According to a soon-to-be-published paper by scientists from the Jordan University of Science and Technology in Irbid, Jordan, the ingestion of the human equivalent of approximately 3.8mg caffeine per kg body weight or 3-4 cups of coffee per day, can inhibit both, the stress, related as well as diet induced (we are talking of the "typical" Western diet (WD), that's both high in carbohydrates and fat) cognitive impairments (Alzoubi. 2013)... well, at least in the researchers 3-months rodent study it worked like a charm

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

With respect to the underlying mechanisms the scientists speculate that caffeine may "act mainly by inhibiting adenosine receptors" (Alroubi. 2013), which has in turn been shown to to inhibit long term potentiation (LTP) in rat hippocampal slices and disrupt the process of learning and memory at the synaptic level by blocking release of glutamate (de Mendonca. 1994).

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

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Figure 1: While the Hedonic tone and alertness reduced to baseline on day 5 of caffeine withdrawal, the habitual caffeine consumers had >15% higher anxiety scores on day 7 after giving up on their daily dose of methylxanthine (data calculated based on Smith. 2013).

Don't worry, caffeine will also work for humans. And what's best, upon short-term withdrawl (8 days) your cognitive performance is not going to suck - at least not as much as when you are stressed or living on pizza and French fries, only. All that and a couple of interesting other results have been published ahead of print in the online version of the Journal of Pharmacology (Smith. 2013).

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

Anxious, but smart: Caffeine gives you the edge

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

"The results confirmed previous findings, with ingestion of caffeine being associated with a faster simple reaction time, fewer long responses, more targets detected and faster encoding of new information. There were no main effects of consumer status, nor were there any significant interactions between caffeine and consumer status." (Smith. 2013)

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

Figure 2: Performance on day 2 of withdrawal phase (w/out caffeine) and on day 8 before (w/out caffeine) and after (w/ caffeine)the ingestion of decaffeinated tea or coffee with 2mg/kg caffeine in it (data based on Smith. 2013)

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

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

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

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Figure 3: W/out arginine (Arg-) intestinal epithelial cells can't proliferate (graph based on Stadelmann. 2013)

Giardia eats away your guts arginine supply and makes itself at home within an increasingly morbid digestive tract! As a group of scientists from Sweden and Argentina reports in their latest paper, the protozoan parasite, Giardia intestinalis, feasts on the arginine your gut cells need to proliferate (Stadelmann. 2013). This will lead to reduced polyamine levels and upregulated cell cycle inhibitory genes, which will eventually disrupt the the cell cycle of the intestinal epithelial cells. The reduced intestinal epithelial cell proliferation, on the other hand, allows the gut pathogen to thrive and will, in the long run, disrupt the intestinal tissue homeostasis and thus initiate the decay of the intestinal epithelium  - a central feature of so many of the wide-spread gut pathologies.

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

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

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

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

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

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

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

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

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

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

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

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

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

---

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

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

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

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


References:

• Aleisa AM, Alzoubi KH, Gerges NZ, Alkadhi KA. Chronic psychosocial stress-induced impairment of hippocampal LTP: possible role of BDNF. Neurobiology of Disease 2006;22:453–62. 
• Alzoubi KH, Abdul-Razzak KK, Khabour OF, Al-Tuweiq GM, Alzubi MA, Alkadhi KA. Caffeine prevents cognitive impairment induced by chronic psychosocial stress and/or high fat-high carbohydrate diet. Behav Brain Res. 2013 Sep 20.
• ESMO. Press releases related to the ESMO 2013 Congress of the European Society for Medical Oncology in Vienna.
• Forbes GB, Porta CR, Herr BE, Griggs RC. Sequence of changes in body composition induced by testosterone and reversal of changes after drug is stopped. JAMA. 1992 Jan 15;267(3):397-9.
• de Mendonca A, Ribeiro JA. Endogenous adenosine modulates long-term potentiation in the hippocampus. Neuroscience 1994;62:385–90.
• Molteni R, Wu A, Vaynman S, Ying Z, Barnard RJ, Gomez-Pinilla F. Exercise reverses the harmful effects of consumption of a high-fat diet on synaptic and behavioral plasticity associated to the action of brain-derived neurotrophic factor. Neuroscience 2004;123:429–40.
• Smith AP, Christopher G, Sutherland D. Acute effects of caffeine on attention: a comparison of non-consumers and withdrawn consumers. J Psychopharmacol. 2013 Sep 19.
• Stadelmann B, Merino MC, Persson L, Svaerd SG. Arginine Consumption by the Intestinal Parasite Giardia intestinalis Reduces Proliferation of Intestinal Epithelial Cells. PLoS ONE. 2013; 7(9): e45325. 
• Tejman-Yarden N, Eckmann L. New approaches to the treatment of giardiasis. Curr Opin Infect Dis. 2011 Oct;24(5):451-6.

Fishing for Better Wheys to Improve Your Physique and Overall Health? 6g/d Cod Protein Could Help You Cut Body Fat & Build Muscle Without Having to Change Your Diet

Image 1: This can of tuna (140g) would contains exactly 7 servings of muscle building fat burning fish protein... well, sort of. At least it contains as much protein as the subjects in the Vikøren study consumed in the form of capped cod protein isolate in the 2nd half, the "high-dose" phase of the 8-week intervention (Vikøren. 2013)

Protein days at the SuppVersity! Well, sort of... after yesterday's news on the pro-insulinogenic effects of whey protein and its not so significant negative impacts on your body composition in the absence of profoundly increased energy consumption (i.e. whey, ah... I mean "way" beyond the ~20% max. increase I suggest for a clean bulk). We will take a look at another, hitherto largely overlooked protein source: Fish! Yeah, I know, you all eat your serving of fish once or twice a week - fatty fish to be precise to derive the alleged health benefits of the latter, but did you ever remotely consider supplementing with fish protein? As a regular you may in fact have done that after reading about the superiority of cod over casein and pea as far as muscle repair are concerned, here at the SuppVersity, and if you have not the data from a recently published study from the Institute of Medicine and the Department of Heart Disease at the University of Bergen in Norway (Vikøren. 2013) could not just be an incentive for you to do so, it could in fact promote the production of fish protein isolates, which has not really kicked off before the 2011 when a Peruvian company hit the market with fat-free, membrane-refined fish protein and fish peptide products at prices of $5/kg and thus at least 38% cheaper than whey or egg protein isolates (Daniells. 2011).

Fish protein supplementation: A little goes a long way

What is so particularly stunning about the data from the 8-week double-blinded cod protein supplementation trial Linn A. Vikøren and her colleagues conducted were not so much the results,

• a decrease in postprandial blood glucose AUC,
• more pronounced, yet less sustained insulin responses (sign of increases insulin sensitivity),
• a decrease in C-reactive peptide (CRP) levels, and
• reduced LDL cholesterol, as well as
• increases in lean muscle mass, and
• decreases in fat mass,

but rather the amount of supplemental fish protein which elicited those changes: 3g/day for the first 4 weeks and 6g/day for the last 4 weeks - not much, if you relate that to the average protein intake (70-90g) of the overweight, yet healthy middle-aged study participants, right?

The whole is mostly way more than just the sum of its parts

If we go simply by the protein content that previous studies, such as , even the large dose, i.e. the 6g of cod protein isolate per day, the subjects received in the 2nd month of the intervention period, equals no more than

*Please keep in mind that Pilon et al. observed differences with respect to the physiological effects of fish proteins from different sources. In their rodent study, only salmon, yet not bonito, herring or mackerel protein had ameliorative effects on body weight and visceral body fat gain in rodents on a high-fat diet (Pilon. 2011)

• 20g of tuna
• 21g anchovies
• 22g salmon or halibut
• 23g snapper or tilapia

Now, feeding them fish, was however not a viable option. After all, it is pretty easy to distinguish a can of tuna such as the one in image 1 from a similar can with chicken, let alone "fillers and sweeteners", the sole ingredients of the placebo tablets. So in as much as you may decry the use of supplemental, instead of real fish protein, it is hardly debatable that the use of 500mg fish protein (cod) caps was necessary to effectively double-blind the study.

Figure 1: Comparison of amino acid concentration  (g/kg) of fish and whey protein (data for fish and whey from Vikøren. 2013 and Engelen. 2013, respectively)

If we take a look at the actual amino acid content (which is yet, as you should know, only one of the potential reasons we would see differences to other protein sources), it is evident that cod has a similarly high essential amino acids content as whey, but contains significantly less proline, much more arginine, glutamine and taurine.

Reminder: Just in case you have forgotten about the SuppVersity news from Friday, May 4th, 2013, I suggest you briefly go back and read up on how "Cod Protein Promotes Muscle Repair After Injury More than Casein or Peanut Protein"

What is it about fish protein that makes it so potent - arginine, taurine, or synergistic effects?

As a regular, here at the SuppVersity, you will also know that there exists a fairly decent amount of research on potential and scientifically established health effects of arginine and taurine. Whether those two individual amino acids or rather synergistic effects due to the specific protein / peptide structure of cod proteins are able to explain any of the observed health benefits (see bullet points 1-4) or the changes in body composition (see bullet points 5-6 and figure 2, below) remains yet to be elucidated.

Figure 2: Macronutrient composition of the diets at baseline, after 4 weeks and 8 weeks and changes in body composition compared to baseline (Vikøre. 2013)

Whatever the exact reasons may be, the -1.6% drop in body fat percentage (this is different from body fat mass!) is certainly astonishing given the fact that it occurred in the absence of significant changes in either the macronutrient composition or total energy content of the subjects' diets.

So what? Are fish protein isolates, the better whey?

Now without knowing the exact physiological mechanism behind the the observed effects on glucose and lipid metabolism and body composition of the 16 male and 19 female study participants, which could, as Vikoren et al. rightly point be a result of either the

• specific amino acid profile,
• the presence or formation of specific peptides (protein bonds), or 
• as of yet unknown bioactive components of fish/cod protein,

it would certainly be premature for most of you to make a switch from whey to cod, before scientific data from human trials confirms not just the efficacy, but also the supremacy of high(er) dose cod supplements over whey and other dairy proteins as the go-to muscle builders for physical culturists.

In view of the results of previous studies by by Zhang etl al. (1993), Shukla et al. (2006), and specifically van Post-Skagagard et al. (2006) on the health effects of supplemental cod protein, it may yet be prudent to make another switch in your dietary / supplement regimen, namely one from fish oils to whole fish, which has already been shown to produce superior weight-loss and health effects than supplemental fish oil (e.g. Gunnarsdotti. 2008) - results of which we know by know that they well be mediated by the synergistic effects of oil and protein from whole fish.

References

1. Daniells S. Low-cost, fat-free fish protein facility gets go ahead. Nutraingredients-usa.com. May, 27 2011. < http://www.nutraingredients-usa.com/Industry/Low-cost-fat-free-fish-protein-facility-gets-go-ahead >
2. Engelen MP, Rutten EP, De Castro CL, Wouters EF, Schols AM, Deutz NE. Casein protein results in higher prandial and exercise induced whole body protein anabolism than whey protein in Chronic Obstructive Pulmonary Disease. Metabolism. 2013 Apr 16.  
3. Gunnarsdottir I, Tomasson H, Kiely M, Martinéz JA, Bandarra NM, Morais MG, Thorsdottir I. Inclusion of fish or fish oil in weight-loss diets for young adults: effects on blood lipids. Int J Obes (Lond). 2008 Jul;32(7):1105-12. Epub 2008 May 20.
4. Lavigne C, Tremblay F, Asselin G, Jacques H, Marette A. Prevention of skeletal muscle insulin resistance by dietary cod protein in high fat-fed rats. Am J Physiol Endocrinol Metab. 2001 Jul;281(1):E62-71.
5. Pilon G, Ruzzin J, Rioux LE, Lavigne C, White PJ, Frøyland L, Jacques H, Bryl P, Beaulieu L, Marette A. Differential effects of various fish proteins in altering body weight, adiposity, inflammatory status, and insulin sensitivity in high-fat-fed rats. Metabolism. 2011 Aug;60(8):1122-30.
6. von Post-Skagegård M, Vessby B, Karlström B. Glucose and insulin responses in healthy women after intake of composite meals containing cod-, milk-, and soy protein. Eur J Clin Nutr. 2006 Aug;60(8):949-54.
7. Shukla A, Bettzieche A, Hirche F, Brandsch C, Stangl GI, Eder K. Dietary fish  protein alters blood lipid concentrations and hepatic genes involved in cholesterol homeostasis in the rat model. Br J Nutr. 2006 Oct;96(4):674-82.
8. Vikøren LA, Nygård OK, Lied E, Rostrup E, Gudbrandsen OA. A randomised study on the effects of fish protein supplement on glucose tolerance, lipids and body composition in overweight adults. Br J Nutr. 2013 May 31:1-10.

Arginine a BAT Building WAT Killer & Repartitioning Agent? Plus: The Arginine Enriched Biscuits Diet ;-)

Whenever the word "vascularity" appears on one of the boards, this image pops up. Now we know that arginine alone won't make your veins pop, but could it be that we have hitherto overlooked that it could help you meet another more important criteria to look like that - namely to drop body fat?

In a 2013 paper Mohammad Alizadeh and his colleagues published a paper in the Annals of Nutrition & Metbabolism. The paper deals with the effects of the addition of 5g/day l-arginine to hypocaloric diets in a group of 84 premenopausal women, where the supplement regimen led to significantly greater reductions in visceral obesity (8cm vs. just 4cm reduction in waist circumference within 6 weeks; cf. Alizadeh. 2013). I filed the paper in my "candidates" folder and forgot about it - simply too much interesting news to cover everything.

Now, almost a year later, Lucilla D. Monti et al. have published yet another paper on l-arginine in the latest issue of the scientific journal Metabolism (Monti. 2013). "A pilot study in healthy subjects and a cross-over study in subjects with impaired glucose tolerance and metabolic syndrome" as the title tells us and reason enough for me to take another look at an amino acid that has gotten sort of a bad rep as a supplemental non-starter, because the marketing machinery of the bodybuilding supplement producer has been pimping it as an "nitric oxide (NO) booster" (which is similar to saying that bricks were 'house builders' by the way).

Arginine cookies the saviors of the human race!?

Just so there is no misunderstanding here, while arginine may be more useful as a weight loss tool (esp. for the insulin resistant), it is neither an NO booster, nor a fat burner in the sense that it would "actively" do anything to elicit the named effects. The additional 4cm the arginine stripped off the waists of the initially mentioned ~28-44year-old women, for example, occurred in the context of a diet containing 500kcal less than the baseline diet (that's about -20% and the average subject ended up eating ~2000kcal/day).

Figure 1: As this illustration goes to show you, nitric oxide (NO) play and important role in the activation of PPAR-alpha and will thus determine (among other factors) if your immature fat cells become ugly passive and potentially health threatening stores or metabolically active brown adipose tissue (based on Wu. 2013).

Nevertheless, it is unquestionably interesting that Zhenlong Wu et al. remark in one of the more recent reviews on the fat loss effects of l-arginine that the inconspicuous nitric oxide precursor has the hardly known ability to

"increases mammalian BAT growth and development via mechanisms involving gene expression, nitric oxide signaling, and protein synthesis [, so that t]his enhances the oxidation of energy substrates and, thus, reduces white fat accretion in the body." (Wu. 2013)

Usually I would discard these effects as "most likely irrelevant for virtually BAT free mammals" like humans (even those among us with a "high" amount of brown adipose tissue have way less of it than the average "mammal" does; this is particularly true if you compare us to our small hairy mammalian brethren that are living in lab cages ;-).

With the positive effects that have already been observed in past human studies and the "growth promoting effect" arginine is supposed to have on mammalian brown adipose tissue (cf. figure 1), the potential weight loss and ensuing health benefits of the "conditionally essential" (meaning you must consume it in significant amounts under certain circumstances, like bein very sick, burned, hurt, etc. though your body can theoretically produce it on its own) amino acid appear to be well-worth being mentioned in a SuppVersity article again (again, because I already mentioned these effects as an aside in Part II of the Amino Acids for Super Humans Series back in 2011.

Back to the cookies then

After this lengthy general introduction, let's now finally have a look at the Monti study (Monti. 2013). Now, despite the auspicious term "pilot study" in the title of the Italian researcher latest paper, the idea to add some l-arginine to cookies, biscuits and other stuff is actually not really new. In 2011, already, he same research group has published a paper on this concept with initial data on the acute response to the ingestion of arginine enriched biscuits (see previous SuppVersity post). So, the "pilot trial" is actually nothing but a slightly revamped version of the initial test in 7 healthy subjects, plus a 2-week extension in which the scientists probed the effects of the chronic ingestion of their biscuits on 15 obese subjects (8 men, 7 women, aged 62.5±3.5years; BMI ~30kg/m²; 36% body fat) with impaired glucose tolerance (IGT) and metabolic syndrome (MS).

Figure 2: Weight loss, fat loss and insulin sensitivity (*I divided the actual values on the Matsuda index by 10 so that they would fit into the same graph), as well as glucose response during an OGGT (Monti. 2013)

While the results of the former trial were very similar to those in the pilot of the pilot study (see previous SuppVersity post), the data in figure 1 goes to show you that the "long-term" (14-days, with a wash out period of another 14 days and a cross-over afterwards, so that every subject was tested both for the effects of the placebo and the acuve treatment), were promising and statistically significant, but far from representing a solution to the diabesity epidemic.

During each of the two 14-day intervention periods, the obese volunteers had consumed identically packaged L-arginine-enriched biscuits containing 6.6g l-arginine, 21.9g carbohydrates (15g available
carbohydrates and 6.9g resistant starch), 3.6g protein, 7.5g fat or an isoenergetic biscuit without the 6.6g of l-arginine as morning and afternoon snack . The additional 171kcal provided by the biscuits were included in the daily allowance of the subjects who followed a 55% carbohydrate, 25%–30% fat and 15%–20% protein diet that contained a total of 1,600kcal during the whole 6-week study period (the study used a randomized cross over design with a 2-week washout in-between).

Let's get back to a more general perspective

Not just because I'd hope that most of you don't have just as much weight to lose as the participants of the Monti study, but also in view of statements like "[a]nother added value of the biscuit is the low protein content (6.1% vs. 20%–50%)" (Monti. 2013) in the discussion of the paper, I don't want to go into more details on this particular study, but rather return to a more general analysis of the metabolic effects of l-arginine in these last paragraphs. I mean, it should be obvious that the important most important question here is: "Is there any metabolic benefit of arginine supplementation, or not?

The results of the Monti study clearly show that there is (and that despite the fact that its authors' don't appear to have a grasp of the latest research results). Monti's paper does yet not describe the only experiment, the results of which would suggest that there is more to arginine than nitric oxide - or, if we go by the overview in figure 1, that there is more to nitric oxide than the pump.

• In June 2013, researchers from the Poznan University of Medical Sciences in Poland, for example, published a paper in which they report that the provision of 9g/day of the nitric oxide precursor l-arginine for 3-months lead to statistically highly significant improvements in insulin sensitivity and a non-significant 1% reduction in body fat in the absence of any changes in dietary or activity patterns in patients with visceral obesity (BMI 39kg/m²). It did yet not, as the scientists had speculated reduce the expression of tumor necrosis factor alpha (TNF-alpha), so that we have to assume that the beneficial effects on glucose management were not mediated by any hitherto largely ignored direct anti-inflammatory effects of the amino acid the Swiss chemist Ernst Schultze discovered in 1886 (Bogdanski. 2013). 
• In the American Journal of Physiology. Endocrinology and Metabolism Lucotti et al. reported in 2006 that the addition of l-arginine (8.3g/day) to a combined diet plus exercise program for 21 days had highly beneficial effects on the study outcome, promoted the loss in fat mass (3kg vs. 2kg) and waist circumference (10cm vs. 3cm; no typo!), helped preserve lean mass (0kg vs. 2kg muscle loss) and improved the mean daily glucose profiles and the amount of fructosamine, a glycated serum protein and marker of poor glucose control, in the blood (Lucotti. 2006). Moreover, the supplementaion protocol increased the nitric oxide production, the andioxidant capacity and the adiponectin levels and improved the adiponectin-to-leptin ratio of the 25 women and 8 men (all obese, BMI ~39kg/m²) who participated in the study. 
• In addition, studies on rodents and pigs have conclusively shown that arginine supplementation can increase the use and decrease the storage of fatty acids in different dietary scenarios (Fu. 2005; Jobgen. 2009; Tan. 2011).

One thing we should not forget, though is that there may in fact be something like an "arginine timing" effect, which could play a role in it's effect on body composition. In the scientific journal Amino Acids Smajilovic et al. report only recently that the l-arginine induced release of insulin is not mediated by a direct interaction of the alpha-amino acid with the amino acid receptors on the pancreas. Now, despite the fact that we do not know how, the mere fact that arginine will produce an immediate release of insulin tells us that it's use before / with a meal, would be more beneficial than during periods of fasting. This is particularly true for people who are either developing or at risk of developing insulin resistance and type II diabetes. After all, the decline in the early insulin response to the meal has been implicated as one of the first and most important steps in the etiology of type II diabetes (Pratley. 2001; Del Prato. 2002).

Is timing crucial and what about the arginine induced insulin release?

Maybe it's even it's effect on the health of your intestines (read more about that) that helps weight loss, who knows?

Unfortunately, few studies report whether the arginine was ingested before or with a meal. What we do know from the Monti study, however,  is that it's presence in the meal (which would be equal to the co-ingestion of supplemental l-arginine) tripled the amount of body fat the dieting subjects lost in the course of the two week intervention (2.02kg vs. 0.70kg). In conjunction with the previously mentioned ability to boos pancreatic insulin production, this observation would invalidate the still widely heralded assumption that a robust, appropriate early insulin response (critics would call it a "spike") would be something to be avoided at all costs - if it were, the l-arginine should have decreased the efficacy of the diet, right?

What we should however keep in mind, though is that a robust initial insulin response will lead to a faster reduction of blood glucose in into the normal range. That it turn will (ideally) render the release of even more insulin obsolete so that the initial spike will actually allow you to avoid the far more detrimental chronically (or in a "healthy" individual "long-term") elevation of insulin and can thus have the bring about the exact opposite of what most people believe it will do: weight loss, or a reduction in weight gain!

"So does it work and if so how? Can't be insulin, alone, can it?"

It is nevertheless unlikely that the increased acute response of the pancreas is the only mechanism (I would bet probably not even the most important one) by which increases in the amount of arginine in the diet facilitate and as examples like the study by Bogdanski et al. (Bogdanski. 2013) even trigger weight loss (remember: the obese subjects in this study did not do anything but take 9g/day of supplemental l-arginine three times a day).

Effects by which arginine could promote fat loss and body recompositioning: Stimulation of lypolysis (release fat from adipose tissue); activation of genes that are responsible for the oxidation of fatty acids; interaction with PGC-1 alpha and triggers mitochondrial biogenesis and the "browning" of fat; regulation of adipocyte-muscle crosstalk resulting in an energy repartitioning effect away from the adipose and towards the muscle tissue; activation of the AMPK pathway, resulting in improvements in both lipid and glucose metabolism.

According to a review by Tan et al., both the additive (dieting + arginine = better fat loss), as well as the "stand alone" (simply adding arginine on top of whatever diet you are following) effects of the nitric oxide precursor could be brought about by a combination of various factors (Tan. 2013). We have already seen in figure one that the nitric oxide exerts direct agonistic effects on PPAR-alpha. We also know that other substances such as fish oil and TTA (see "TTA + Fish Oil - Fat Burning Super Fats?"), which are likewise PPAR-alpha agonists will also promote the oxidation of fatty acids (specifically in the liver). Now, if you add the list of metabolic benefits, the scientists from the Institute of Subtropical Agriculture at the Chinese Academy of Sciences in Changsha and their colleagues from the Texas A&M University have compiled (see infobox on the right), you will have to concede that your pre-workout nitric oxide booster would - at least on paper - make a pretty decent "fat burner", if all these effects, most of which have been observed in either rodents or pigs could be replicated in human beings.

Bottom line: For the metabolically deranged, the evidence is there. For followers of physical culture, on the other hand, there is as of yet no clear cut proof for the fat burning or repartitioning effects of l-arginine. Ah, and just in case you consider your little N=1 experiment with whatever pre-workout supplement evidence that it does not work - forget about that. With the minuscule amounts of l-arginine most of these products contain you can hardly make a difference when your basal diet does deliver tons of arginine, already (plus: you were probably taking it at the wrong time, namely on empty before a workout).

So do I suggest you buy a 5kg pouch of bulk l-arginine and go through it within 2 weeks? No, certainly not. You better wait until more data becomes available. For now, it would suffice if you don't fall for the anti-hype that's at least in part instigated by the same supplement companies that have been pimping l-arginine a couple of years ago as the ueber-supplement and an absolute must have for any serious trainee. I mean if you had the choice between six pack abs lasting 24/7 and a pump, what would you pick? I thought so... therefore this new area of application, could turn out to be way more exciting than the never-established, but highly marketed NO-boosting effects of l-arginine.

References:

• Alizadeh M, Safaeiyan A, Ostadrahimi A, Estakhri R, Daneghian S, Ghaffari A, Gargari BP. Effect of L-arginine and selenium added to a hypocaloric diet enriched with legumes on cardiovascular disease risk factors in women with central obesity: a randomized, double-blind, placebo-controlled trial. Ann Nutr Metab. 2013;60(2):157-68.
• Bogdanski P, Suliburska J, Grabanska K, Musialik K, Cieslewicz A, Skoluda A, Jablecka A. Effect of 3-month L-arginine supplementation on insulin resistance and tumor necrosis factor activity in patients with visceral obesity. Eur Rev Med Pharmacol Sci. 2013 Jun;16(6):816-23.
• Del Prato S, Marchetti P, Bonadonna RC. Phasic insulin release and metabolic regulation in type 2 diabetes. Diabetes. 2002 Feb;51 Suppl 1:S109-16.
• Fu WJ, Haynes TE, Kohli R, Hu J, Shi W, Spencer TE, Carroll RJ, Meininger CJ, Wu G. Dietary L-arginine supplementation reduces fat mass in Zucker diabetic fatty rats. J Nutr. 2005 Apr;135(4):714-21.
• Jobgen W, Fu WJ, Gao H, Li P, Meininger CJ, Smith SB, Spencer TE, Wu G. High fat feeding and dietary L-arginine supplementation differentially regulate gene expression in rat white adipose tissue. Amino Acids. 2009 May;37(1):187-98.
• Lucotti P, Setola E, Monti LD, Galluccio E, Costa S, Sandoli EP, Fermo I, Rabaiotti G, Gatti R, Piatti P. Beneficial effects of a long-term oral L-arginine treatment added to a hypocaloric diet and exercise training program in obese, insulin-resistant type 2 diabetic patients. Am J Physiol Endocrinol Metab. 2006 Nov;291(5):E906-12.
• Monti LD, Casiraghi MC, Setola E, Galluccio E, Pagani MA, Quaglia L, Bosi E, Piatti P. l-Arginine enriched biscuits improve endothelial function and glucose metabolism: A pilot study in healthy subjects and a cross-over study in subjects with impaired glucose tolerance and metabolic syndrome. Metabolism. 2013; 62:255–26.
• Pratley RE, Weyer C. The role of impaired early insulin secretion in the pathogenesis of Type II diabetes mellitus. Diabetologia. 2001 Aug;44(8):929-45.
• Tan B, Yin Y, Liu Z, Tang W, Xu H, Kong X, Li X, Yao K, Gu W, Smith SB, Wu G. Dietary L-arginine supplementation differentially regulates expression of lipid-metabolic genes in porcine adipose tissue and skeletal muscle. J Nutr Biochem. 2011 May;22(5):441-5.
• Tan B, Li X, Yin Y, Wu Z, Liu C, Tekwe CD, Wu G. Regulatory roles for L-arginine in reducing white adipose tissue. Front Biosci. 2013 Jun 1;17:2237-46.