With Beetroot Juice to the SuperBowl XLVIII: 490ml Beetroot Juice Will do the Ergogenic Trick in Team Sports. Plus: Brief Research Overview to Identify Who Else Will Benefit

There are a couple of important confounding factors which will determine whether or not you or anyone else can benefit from nitrate supplementation. Sex is yet - as far as I know know - not one of them... ah, by the way, there may be other benefits to nitrates that are "sex-specific", but in this case the semantics are somewhat different ;-)

You know that the SuppVersity is all about self-education (hence "-versity" as in University), so what would be better than using the publication of the latest paper on the purported ergogonic effects of nitrates as an incentive to "inform" you about the current state of the research? Sounds good? I would think so. Let's take a look, then. What's this nitrate business all about? Contrary to the argument many supplement vendors have been bringing forward to make muscleheads buy their products, the idea is not to use the vasodilating effects for cosmetic pumps that will make you feel - as Arnold said it - better than you felt last night with your significant other (or whom ever else you may have picked up). It's rather their purported effect on the VO2max, which is the maximal oxygen consumption during a workout and the downstream performance effects that puts scientists on -- scientists like Lee J. Wylie and colleagues from the department of Sport and Health Sciences at the University of Exeter, for example (Wylie. 2013).

The latest on dietary nitrate supplementation: Focus on team sport athletes

The paper we are taking a closer look at today has just been published ahead of print in the European Journal of Applied Physiology and investigated the acute effects 490 mL of concentrated, nitrate-rich beetroot juice (BR) and nitrate-depleted placebo juice (PL) had on the performance of fourteen male recreational team-sport players during a Yo–Yo intermittent recovery level 1 test (Yo–Yo IR1) that was performed ~30h after the ingestion of the purported ergogenic (the Yo-Yo IR1 test has been found to mirror the physical demands encountered during team sports, like soccer, football, basketball, rugby etc petty accurately.; cf. Atkins. 2006; Veale. 2010; Vernillo. 2013).

Would dosages as high as in the study at hand (or even higher) provide similar muscle gains, as they were observed with "real" nitrate in rodents (read more).

A note on the "optimal" dosage: The dosage that was used in the study at hand is equal to  ~29 mmol of nitrate, which is 4x more than the current recommended daily allowance in the UK and 6x more than what was most in the majority of previous. Aside from the subjects' training status, which has emerged as a possible confounding factor determining whether athletes will benefit from the consumption of beet-root juice / dietary nitrates, the dosage, as well as the plasma nitrate response (+400% vs. 50-150% in other trials), which was likewise much higher in the Wiley study than in most previous studies, could thus be another important, if not the most important confounding factor. Whether the "more helps more principle" actually holds, whether athletes need more than normalos and if / at which dosages negative side effects occur will yet still have to be elucidated in future trials.

As it was to be expected, the resting plasma nitrite concentration NO2(-) was ~400 % greater in the active compared to the passive trial of this double-blind, randomized cross-over trial (remember: Cross-over means, all participants completed two tests sessions on seperate occasions, one w/ the active, one with the placebo supplement).

Figure 1: Effects of 490ml beetroot juice on serum NO2/3(-) levels, performance and mean glucose concentration during the Yo-Yo R1 test (Wylie. 2013)

As you will learn from the comprehensive research overview further down, the fact that this increase in plasma NO2(-) did also translate into performance increases, on the other hand, was not really to be expected:

Betaine (TMG) increses IGF-1 & lowers cortisol (read more)

"Plasma [NO2 -] declined by 20 % in PL (P\0.05) and by 54 % in BR (P<0.05) from pre-exercise to end-exercise. Performance in the Yo–Yo IR1 was 4.2 % greater (P<0.05) with BR (1,704±304 m) compared to PL (1,636 ±288 m). Blood [lactate] was not different between BR and PL, but the mean blood [glucose] was lower (3.8 ±0.8 vs. 4.2±1.1 mM,P\0.05) and the rise in plasma [K+] tended to be reduced in BR compared to PL (P=0.08)." (Wylie. 2013)

That being said the study at hand confirms that the consumption of a significant bolus of nitrate with all the natural co-factors in beetroot, i.e. >20 betacyanins + derivatives, 11 betaxanthins, highly bioavailable folate, various carotenoids, and, of course betaine has beneficial ergogenic effects on the performance of recreationally active men (Nemzer. 2011). As we are about to see both, the training status of the subjects, as well as the nutrient combination (or absence of the latter) may be a confounding factor due to which this trial was a success whereas ostensibly similar ones were failures.

How does that stuff actually work?

Before we go over to the comparison phase, let's yet briefly check out what the scientists have to say about the underlying mechanism(s) of the ergogenic effects they observed:

• reduction of NO3(-) to NO2(-) and in (sub-)hypoxic or acidic conditions to NO (nitric oxide) - Based on their data, the researchers speculate that this it is likely that this reduction took place during the Yo-Yo  IR1 test (it''s about as likely in most similar high intensity exercise protocols). Base on previous data from Dreissigacker et al. who found signficantly higher baseline NO3(-) and NO2(-) levels in trained vs. untrained subjects an the results of Totzeck et al., who found that baseline NO2(-) correlates with lactate threshold and predicts exercise capacity during an incremental cycle test in highly trained athletes, Wiley and his colleagues argue that it is more than likely that the ability to produce more NO quasi 'on demand' is the underlying cause of the performance increases (Dreissigacker. 2010, Totzeck. 2013).
• dietary nitrate supplementation can protect the phosphocreatine (PCr) stores from being depleted - With PCr being the most readily available energy source for short burst activities like sprinting the preservation of the PCr stores (similar to their "supercharging" via supplemental creatine; click here to learn all about creatine supplementation) would certainly explain why the nitrate supplement delay, what the scientists label as "the attainment of a ‘critical’ intramuscular environment"  and would thus "extend the tolerable duration of high-intensity constant-work-rate exercise". This hyptothesis woul be supporte by the fact that NO increases skeletal muscle glucose uptake, the correspondingly lower blood glucose levels the researchers observed in the active arm of the study and the fact that readily available glucose will spare the PCr stores.
• decreased leakage of K+ (potassium) from the muscle - As the post hoc analysis revealed significantly lover plasma K+ levels during the beetroot juice condition of this double-blind ranomized cross-over study after 600 m of the test, a third mechanism by which the supplementation protocol could have postponed fatigue would thus be the preservation of the electrical potential which is established by the distribution of K and Na ions inside, respectively outside of the muscle cell.
• increased oxidative capacity and consequent glucose sparing - Previous rodent studies have shown that nitrate supplementation increases blood flow and oxygenation of the muscle, the latter could translate into faster recovery of the glycogen content of the muscles in the short recovery phase.
• increased force production due to increased sarcoplasmic reticulum calcium release and force production - The increase in force would likewise have an energy sparing effect as it would mean that at a given exercise intensity (in watts) a lower number of muscle fibers would have to be recruited to get the job done. As with the previous information on the oxygenation of the muscle, this is yet based on observations in rodents and warrants verification in human studies.

Irrespective of the underlying mechanisms, it's likewise necessary to put them into perspective before we freak out and start raving about a new "superstar supplement" being born. After all, the effect size was significant, but comparably modest. A 2011 study by Mohr et al. for example observed a +16% performance increase after the ingestion of 6mg/kg caffeine in a subsequent Yo–Yo IR2 test (Mohr. 2011) and the effect simple training (i.e. +29% for sprint-endurance training; cf. Mohr. 2007) has on the perfomance in the same test, is likewise nothing to sneeze at.

So what did previous studies show?

As I have already hinted at in the red infobox a couple of paragraphs above, the dosage alone may explain why Wiley et al. did observe beneficial effects of nitrate / beetroot juice supplementation, while previous studies have shown very mixed results. Two other factors, I have highlighted in the following mini-overview (in bold and w/ an underline) that are probably relevant, are the training status of the study participants and the duration of the supplementation:

The combination of beta-alanine an baking soda (esp. the latter) may serve as a viable alternative for those trainees who are "too advanced" for nitrates to do the trick (read more)

You should by now be aware that orally ingested arginine does not induce significant NO boosts or performance increases, but did you know that it could help you get shredded? (read more)

• recreationally active and trained but sub-elite subjects, short-term dietary nitrate supplementation: 
• increased exercise tolerance at a fixed sub-maximal work rate (Bailey. 2009, 2010; Lansley. 2011b)
• increased power output during self-paced endurance exercise leading to improved cycle time-trial performance (Cermak.2013a; Lansley. 2011a).
• well-trained subjects (details in brackets) short-term dietary nitrate supplementation:
• higher mean power output in HIIT 6 x 500m rowing trial (rowers, Bond. 2013)
• little / no effect in endurance trained athletes in their respective disciplines (Besco. 2013; Cermak. 2013b; Christensen. 2013; Peacock. 2013; Wilkerson. 2013) 
•  recreationally active no regular, planned exercise, regimen chronic nitrate supplementation:
• reduced BP and the O₂ cost of submaximal exercise are maintained over 15d supplementation period (Vanhatalo. 2010)

The number of studies investigating the long-term effects of nitrate supplementation is to low to make a definite statement about whether or not it may be likely that short-term supplementation studies, in the course of which the researchers did not observe any ergogenic benefits of supplemental nitrate, would have yielded different results, if the supplementation had lasted for a couple of days or weeks.

Did you know that the scientists adjusted the comparatively high dosage of dietary nitrate the subjects received in the study at hand to the levels you would get, if you followed the anti-hypertensive DASH (Dietary Approaches to Stop Hypertension) diet? Obviously not an there is a good reason I am telling you that, 'cause this means that a paleo-ish high greens diet could in fact bring your nitrate levels into the same range as those of the subjects in the active trial of the study at hand - without having to spend a single buck on extra supplements, of course.

Nevertheless, the results Vanhatalo et al. present, namely that the effects persist in recreationally active subjects over 15 days of continuous supplementation, do actually stand in line with the hypothesis that the low / non-existent response in highly trained athletes could be due to their higher baseline NO3(-) and NO2(-) levels. I have invoked the latter in the discussion of the possible beneficial effects of NO generation in the previous discussion of the underlying mechanisms, already. If we assume that there is some sort of a saturation level and/or at least a logarithmic response to nitrate supplementation, where high baseline levels require even higher amounts of supplemental NO3(-) in order to bump the levels further up, we would have to conclude that

• highly trained athletes won't benefit from nitrate supplementation at all, because their blood NO3(-) levels are "saturated" and don't respond to supplementation
• highly trained athletes need way more nitrate to see a minimal increase in their NO3(-) levels

If the former was the case, nitrate supplementation would not make sense at all for highly trained athletes, if the latter was the case, it could produce benefits, but those would be much less pronounced than those observed in the study at hand or similar studies with recreationally active or even previously sedentary individuals.

Bottom line: I seriously can't tell you whether you will see significant performance increases from dietary nitrate supplementation. Unfortunately, especially those of you for whom even small increases in performance count, namely people with years of training under their belt, are probably the ones who benefit least. That being said, nitrates are probably not going to make it into the SuppVersity "must have" supplement list (read more about those in Part II of my recent interview w/ Sean Casey). The fact that they can have ergogenic effects, especially for HIIT and other "endurance-like" exercises with non-aerobic elements in themm is yet obviously indisputable. Whether they are worth the money effective dosages would cost you is yet highly questionable.... When I think about all the rest of purported ergogenics you can buy all over the Internet, a nitrate supplement or a 6-pack of beetroot juice are yet probably still better investments than 90% of the other "auxiliary" revenue,... ah pardon me, I mean "performance enhancers" the supplement market has to offer  ;-)


References:

• Atkins SJ. Performance of the Yo–Yo intermittent recovery test by elite professional and semiprofessional rugby league players. J Strength Cond Res. 2006; 20:222–225
• Bailey SJ, Winyard P, Vanhatalo A, Blackwell JR, DiMenna FJ, Wilkerson DP, Tarr J, Benjamin N, Jones AM. Dietary nitrate supplementation reduces the O2 cost of low-intensity exercise and enhances tolerance to high-intensity exercise in humans. J Appl Physiol. 2009; 107:1144–1155.
• Besco´s R, Ferrer-Roca V, Galilea PA, Roig A, Drobnic F, Sureda A, Martorell M, Cordova A, Tur JA, Pons A. Sodium nitrate supplementation does not enhance performance of endurance athletes. Med Sci Sports Exerc. 2013; 44:2400–2409. 
• Bailey SJ, Fulford J, Vanhatalo A, Winyard PG, Blackwell JR, DiMenna FJ, Wilkerson DP, Benjamin N, Jones AM. Dietary nitrate supplementation enhances muscle contractile efficiency during knee-extensor exercise in humans. J Appl Physiol. 2010; 109:135–148.
• Bond H, Morton L, Braakhuis AJ. Dietary nitrate supplementation improves rowing performance in well-trained rowers. Int J Sport Nutr Exerc Metab. 2013; 22:251–256.
• Christensen PM, Nyberg M, Bangsbo J. Influence of nitrate supplementation on VO(2) kinetics and endurance of elite Cyclists. Scand J Med Sci Sports. 2013. 23:e21–e31
• Cermak NM, Gibala MJ, van Loon LJ. Nitrate supplemen-tation’s improvement of 10-km time-trial performance in trained cyclists. Int J Sport Nutr Exerc Metab. 2013a; 22:64–71.
• Cermak NM, Res P, Stinkens R, Lundberg JO, Gibala MJ, van Loon L JC. No improvement in endurance performance following a single dose of beetroot juice. Int J Sport Nutr Exerc Metab. 2013b; 22:470–478.
• Dreissigacker U, Wendt M, Wittke T, Tsikas D, Maassen N. Positive correlation between plasma nitrite and performance during high-intensive exercise but not oxidative stress in healthy men. Nitric Oxide; 2010; 23:128–135
• Iaia FM, Thomassen M, Kolding H, Gunnarsson T, Wendell J, Rostgaard T, Nordsborg N, Krustrup P, Nybo L, Hellsten Y, Bangsbo J. Reduced volume but increased training intensity elevates muscle Na(-)–K(+) pump alpha1-subunit and NHE1 expression as well as short-term work capacity in humans. Am J Physiol Regul Integr Comp Physiol  2008; 294:R966–R974.
• Lansley KE, Winyard PG, Bailey SJ, Vanhatalo A, Wilkerson DP, Blackwell JR, Gilchrist M, Benjamin N, Jones AM. Acute dietary nitrate supplementation improves cycling time trial performance. Med Sci Sports Exerc. 2011a; 43:1125–1131
• Lansley KE, Winyard PG, Fulford J, Vanhatalo A, Bailey SJ, Blackwell JR, DiMenna FJ, Gilchrist M, Benjamin N, Jones AM. Dietary nitrate supplementation reduces the O2 cost of walking and running: a placebo-controlled study. J Appl Physiol. 2011b; 110:591–600.
• Mohr M, Krustrup P, Nielsen JJ, Nybo L, Rasmussen MK, Juel C, Bangsbo J. Effect of two different intense training regimens on skeletal muscle ion transport proteins and fatigue development. Am J Physiol Regul Integr Comp Physiol. 2007; 292:R1594–R1602
• Mohr M, Nielsen JJ, Bangsbo J. Caffeine intake improves intense intermittent exercise performance and reduces muscle interstitial potassium accumulation. J Appl Physiol. 2011; 111:1372– 1379.
• Nemzer B, Pietrzkowski C, Spórna A, Stalica P, Thresher W, Michałowski T, Wybraniee, S. Betalainic and nutritional profiles of pigment-enriched red beet root (Beta vulgaris L.) dried extracts. Food Chemistry. 2011; 127:42–53. 
• Peacock O, Tjønna AE, James P, Wisløff U, Welde B, Bo¨hlke N, Smith A, Stokes K, Cook C, Sandbakk O. Dietary nitrate does not enhance running performance in elite cross-country skiers. Med Sci Sports Exerc. 2013; 44:2213–2219. 
• Totzeck M, Hendgen-Cotta UB, Rammos C, Frommke LM, Knack-stedt C, Predel HG, Kelm M, Rassaf T. Higher endog-enous nitrite levels are associated with superior exercise capacity in highly trained athletes. Nitric Oxide. 2013; 27:75–81
• Vanhatalo A, Bailey SJ, Blackwell JR, DiMenna FJ, Pavey TG, Wilkerson DP, Benjamin N, Winyard PG, Jones AM. Acute and chronic effects of dietary nitrate supplementation on blood pressure and the physiological responses to moderate-intensity and incremental exercise. Am J Physiol Regul Integr Comp Physiol. 2010; 299:R1121–R1131
• Veale JP, Pearce AJ, Carlson JS. The Yo–Yo intermittent recovery test (level 1) to discriminate elite junior Australian football players. J Sci Med Sport. 2010;  13:329–331.  
• Vernillo G, Silvestri A, Torre AL. The Yo–Yo intermittent recovery test in junior basketball players according to performance level and age group. J Strength Cond Res. 2013; 26:2490–2494.
• Wilkerson DP, Hayward GM, Bailey SJ, Vanhatalo A, Blackwell JR, Jones AM. Influence of acute dietary nitrate supplemen-tation on 50 mile time trial performance in well-trained cyclists. Eur J Appl Physiol. 2013; 112:4127–4134. 
• Wylie LJ, Mohr M, Krustrup P, Jackman SR, Ermιdis G, Kelly J, Black MI, Bailey SJ, Vanhatalo A, Jones AM. Dietary nitrate supplementation improves team sport-specific intense intermittent exercise performance. Eur J Appl Physiol. 2013 Feb 1.

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:

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