Arginine increases muscle, decreases fat, and may be . . .
A New Treatment for Obesity
Surprising findings in a new study using oral arginine for
skeletal-muscle gain over fat gain
By Will Block
I guess I don’t so much mind being
old, as I mind being fat and old.
— Benjamin Franklin
. . . [T]he chocolate tax looks about
as unlikely as the sex tax . . .
The Hidden Side of Everything
he time has come to tax obesity—urgently, some have argued—in order to save the planet! Or, at least they say, it is time to tax foods that make people fat. Did you know that a Scottish doctor has called for a tax on chocolate? Chocolate, for Heaven’s sake! What next? Chocolate is a beloved food, and while taxing it might work in Scotland (aka heart attack central) yet (it was narrowly defeated by 2 votes!), it’ll never work here. Americans are too smart for food tyranny, you would think.
Yet “food morality” legislation is proposed somewhere in the U.S. nearly every week, and indeed there are 24 pieces of legislation currently working their way through Congress, and hundreds at the State level. Here’s an ominous example: Mississippi actually proposed a law that would force restaurants to ban obese customers. “No service for fat people.” But alas, this law was ahead of its time, and has been defeated—at least for the meanwhile. Also foreboding: In an article published last year in the Lancet (a medical journal by reputation), the authors asserted that legislation promoting cycling and walking are good for the planet. Why? Because they reduce obesity which helps cause global warming! In visions-of-things-to-come Japan, the government regularly checks the waistlines of citizens over 40, who if found to be overweight are compelled to endure diet counseling. If they fail to lose weight, they are mandated to undergo further “education” and their communities are hit with hefty fines. This is a consequence of the “fairness” of Japan’s universal health care, and is certainly one of the dangers of such legislation if passed in the U.S.
More Taxes on Junk Food
Like it or not, “fat taxes” are on the way. Known variously as the “Twinkie tax,” the obesity tax, the snack tax, and the junk-food tax, these schemes are created by politicians to enlarge their larder by appealing to what they presume to be commonly held beliefs: that certain foods are bad for your health. But not all agree about which foods are unhealthy—as certainly is the case with chocolate, which offers significant health benefits provided that sugar and fat levels are reduced. And any attempt to legislate behavior is bound to find significant opposition and, if passed, may result in unintended consequences. For example, the demonization of dietary fat resulted in a massive switch to high-carbohydrate foods, which has increased obesity and proven that the “cure” is worse than the “disease.”
Fighting with Ideas Instead of Taxes
Coming at this from another angle—one partial to ideas instead of force—new research published recently in the Journal of Nutrition has found that the amino acid
arginine can reduce obesity in rats and that it could very well have the same effect for humans. Obesity is caused by an imbalance in energy metabolism, when energy
intake chronically exceeds energy expenditure, for whatever reason. It is intimately associated with a wide variety of conditions and diseases, including insulin resistance, type II diabetes, atherosclerosis, stroke, hypertension, and some types of cancer—for which it is a major risk factor. The prevalence of obesity, not to mention its enormous costs, is a substantial burden on health and productivity. “Given the current epidemic of obesity in the U.S. and worldwide, our finding is very important,” said lead author of the arginine study, Dr. Guoyao Wu, an animal nutritionist at Texas A&M University.
While earlier studies have shown that arginine can reduce white fat mass in genetically obese rats, (as well as increase expression of the genes for the master regulator of mitochondrial oxidation PGC-1α*), this is the first time fat reduction has been shown in rats with diet-induced obesity. Diet-induced obesity is the principal problem with humans. While genes may play a role in obesity with humans—and in certain rats—most of it is diet-induced, and there’s the hope. If only the diet could be altered in such a way as to provide adequate energy intake, without increasing fat. This is the angle that the researchers investigated.
In the study, the researchers fed rats a high-fat (HF) diet (40% of total energy as lipids) beginning at 4 weeks of age. Controls were fed a low-fat (LF) diet (10% of total energy as lipids), and at the end of 15 weeks, there were significant differences, as one would expect. Those on the high-fat diet were found to gain more than 18% in body weight and a 74% increase in the weights of their major white fat pad tissues.
Arginine for Fat Loss
Then, at 19 weeks of age, the rats in each dietary group were fed either L-arginine or L-alanine (as a control) in their drinking water. Thus, there were four groups: HF diet + arginine, LF diet + arginine, HF diet + alanine, and LF diet + alanine. The HF-fed rats consumed the same amount of dietary energy as the LF-fed rats per kg body weight during the 12-week period of arginine supplementation. Yet at the end of this period, the arginine-fed rats (HF diet + arginine and LF diet + arginine) were found to have significantly less fat compared to controls (HF diet + alanine and LF diet + alanine), despite similar energy intake. The absolute weights of white fat pad tissue increased by 98% in control rats over a 12-wk period but only by 35% in arginine-supplemented rats. The arginine treatment reduced the relative weights of white fat pads by 30%. This is amazing.
The researchers found that arginine supplementation for 12 weeks decreased the body fat gains of LF fed rats by 65% and HF fed rats by 63%, respectively. At the same time, arginine supplementation decreased the body weight gains of LF- and HF-fed rats by 60 and 40%, respectively, compared with the controls. Moreover, this long-term (for rats) arginine treatment did not have any adverse effects on either group.
Also worth noting, the rats fed arginine had lower serum concentrations of triglycerides, leptin, urea, glutamine, branched-chain amino acids, and glucose. What’s more, the rats fed arginine had high serum concentrations of nitric-oxide (NO) metabolites, and improvement in glucose tolerance. According to the researchers, this meant that dietary arginine supplementation shifts nutrient partitioning to promote muscle over fat gain and may provide a useful treatment for improving the metabolic profile and reducing body white fat in diet-induced obese rats.
Arginine for Muscle Gain
And indeed, the arginine-fed rats had increases in muscle mass, 13% in the soleus (a powerful muscle located in the back part of the lower leg), and 11% in the extensor digitorum longus muscle (located in the lateral part of the front of the leg). There was no muscle gain for the control groups taking alanine, whether on the LF or the HF diets. This is not the first time this has been shown. Other research has found that arginine can increase lean tissue growth. In pigs, for example, dietary arginine supplementation reduced fat buildup while increasing muscle gain in growing/finishing pigs without affecting body weight.
Back to the current study, the rats fed arginine had an increase in brown fat by 34% compared with control rats. Brown fat cells are rich in mitochondria, which determine their color. Mitochondria may be thought of as “cellular power plants” because they produce most cellular adenosine triphosphate (ATP), the universal energy molecule which is used for chemical energy. Arginine has previously been found to increase the mass of brown adipose tissue due to nitric oxide-induced mitochondrial biogenesis. (See also
“Can Nitric Oxide Increase Lifespan?” in the January 2006 issue.) Remember that the researchers found that serum concentrations of nitrite and nitrate (an indicator of systemic NO synthesis) were higher in the arginine- rather than the alanine-supplemented rats in either case, HF or LF feeding.
In view of these discoveries, arginine dietary supplementation shifts nutrient partitioning to promote skeletal-muscle gain over fat gain. Thus, the results offer strong evidence that arginine may provide a way to improve the metabolic profile while reducing body white fat obese rats. In the words of Dr. Wu, “This metabolic change is likely beneficial because elevated concentrations of branched-chain amino acids may lead to insulin resistance in obesity. Additionally, arginine can stimulate muscle protein synthesis, a biochemical process that requires large amounts of energy. . . . Thus, dietary energy would be utilized for lean tissue rather than fat gain.”
The Future of Arginine Supplementation
“[Our findings] could be directly translated into fighting human obesity,” Wu said. “At this time, arginine has not been incorporated into our food (but could in the future).” But where will the arginine come from? There are a lot of arginine-rich foods, including certain dairy products such as ricotta and cottage cheese, seafood such as salmon and swordfish, various nuts and seeds, meats and especially game, and rice protein concentrate and soy protein isolate. But even so, it would be difficult to get the human equivalent of the arginine given the rats from normal foods. So dietary supplements appear to provide the only logical answer.
“Follow-up research will include clinical studies with obese children and adults,” Wu said. Fortunately, arginine supplementation is safe, having been in use for several generations, and also at the equivalent levels used in the study. For those who want to use the human equivalent dose used to reduce obesity, increase muscle mass, and more in the Jobgen et al. study, taking about 13 grams of arginine per day will suffice. (see the sidebar, “Human Equivalent Doses of Arginine.”
Human Equivalent Doses of Arginine
In the Jobgen et al study, the rats on the LF diet consumed 969 (±23) mg of arginine/kg of body weight/day: those on the HF diet consumed 922 (±24) mg of arginine/kg of body weight/day. Using the scaling factor for a rat of 0.162 (see the
“Human Equivalent Doses of Resveratrol” table from “The Universal Cause of Aging” in the February issue for the methodology) results in an equivalent human dose of either 157 (±3.7) mg of arginine/kg of human weight/day for the LF diet, and 149 (±3.9) mg of arginine/kg of human weight/day for the HF diet. Assuming that an average American weighs 85 kg (about 187 lbs), the amount of arginine per/day would range from 13.3 (±0.3) g/day for the LF group and 12.67 (±0.3) g/day for the HF-fed equivalency.
While arginine has been shown to have a significant success rate in helping those with a wide variety of conditions—from hypertension, to arthritis, to liver disorders, to wound healing, to fertility problems, and even to cancer—and despite its already proclaimed use by bodybuilders to gain muscle, this is the first study identifying its possibilities in fighting obesity. So despite the dubious fat tax, the future is hopeful indeed.
- GPs vote against “chocolate tax.” BBC, March 12, 2009.
- Tierney J. Obesity Promotes Global Warming? New York Times, March 16, 2008.
- Basham P, Luik J. Fat risks? Sumo, some less. Washington Post, July 11, 2008.
- Jobgen W, Meininger CJ, Jobgen SC, Li P, Lee MJ, Smith SB, Spencer TE, Fried SK, Wu G. Dietary L-arginine supplementation reduces white fat gain and enhances skeletal muscle and brown fat masses in diet-induced obese rats. J Nutr 2009 Feb;139(2):230-7.
- Texas A&M (2009, February 12). Arginine Discovery Could Help Fight Human Obesity. ScienceDaily. Retrieved March 8, 2009, from http://www.sciencedaily.com/releases/2009/02/090204161848.htm
- 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;135:714–21.
- Tan BE, Yin YL, Liu ZQ, Li XG, Xu HJ, Kong XF, Huang RL, Tang WJ, Shinzato I, et al. Dietary L-arginine supplementation increases muscle gain and reduces body fat mass in growing-finishing pigs. Amino Acids 2008; doi:10.1007/s00726–008–0148–0.
- Nisoli E, Clementi E, Paolucci C, Cozzi V, Tonello C, Sciorati C, Bracale R, Valerio A, Francolini M, et al. Mitochondrial biogenesis in mammals: the role of endogenous nitric oxide. Science. 2003;299:896–9.
- Fannin B. Arginine discovery could help fight human obesity. AgriLife News, Jan 30, 2009. http://agriliferesearch.tamu.edu/agnews/index.php?id=956.
Will Block is the publisher and editorial director of Life Enhancement magazine.