Written by Jessica Patella, ND. Mice supplemented with L-Arginine were 34% more glucose tolerant than those not supplemented.
Metabolic Syndrome is a cluster of signs that increase the risk of heart disease, stroke and diabetes (2). The cluster includes three or more of the following signs: abdominal obesity, high triglycerides, low HDL or “good” cholesterol, high blood pressure, high blood sugar and insulin resistance (2). Metabolic syndrome is a serious condition and it affects an estimated 35% of U.S. adults (2). Despite being a serious condition, there are lifestyle changes that can improve metabolic syndrome and recent research has found that supplementing with the amino acid L-Arginine may also help (1,2).
The research was a mice study and was the first study to investigate the effect of L-Arginine on metabolic functions (1). The mice were all male and were fed a low-protein diet (8% kcal from protein vs. 18% in normal chow) to mimic diet-induced obesity in humans (1). The L-Arginine group was supplemented with L-Arginine (2% kcal from L-Arginine) and the control group was supplemented with a mixture of amino acids (2% kcal from mixed amino acids) for 10 weeks (n=10 in each group) (1).
Body Composition
After 10 weeks, there was no difference in body weight, body fat percentage or lean mass percentage between the two groups (1). The L-Arginine mice did have significantly less abdominal fat (P=0.012), indicating that L-Arginine decreases abdominal fat (specifically epididymal white adipose tissue), but has no overall effect on body composition (1).
Feeding
L-Arginine supplementation resulted in an increase in food intake. The total amount of calories consumed was 15% higher in the L-Arginine group than the control group (P<0.001), which was interesting since there was not a significant difference in body weight between the two groups. This may be because the energy expenditure was higher in the L-Arginine mice (1).
Energy Expenditure
Energy expenditure was significantly higher in L-Arginine mice (P<0.04 at night, P=0.06 during the day; measured by oxygen consumption), indicating an increase in metabolism (basal metabolic rate). Movement or activity was only slightly elevated in the L-Arginine group compared to the control, although not significantly (1).
Sugar Metabolism
Mice supplemented with L-Arginine were significantly more glucose tolerant (p<0.03, 34% reduction in the area under the curve, measured by oral glucose tolerance test). The fasting blood glucose levels were significantly lower in the L-Arginine group (7.9 +/- 0.4 mmol/L) compared to the control group (9.7 +/- 0.2 mmol/L, P=0.003). Yet, there was no significant difference in insulin levels between the two groups (1).
In conclusion, increasing dietary L-Arginine improves metabolic markers in mice fed a low-protein diet, including a reduction in abdominal fat, improved glucose levels and increased energy expenditure (1). This was the first study to explore the effects of L-Arginine supplementation on body composition, appetite regulation, glucose metabolism and energy expenditure in mice (1). Based on this mice study, L-Arginine should be researched in the future as a possible supplement to reduce the burden of metabolic syndrome in humans (1).
Source: Clemmensen, C., Madsen, A.N., Smajilovic, S., Holst, B. and Bräuner-Osborne, H., 2012. L-Arginine improves multiple physiological parameters in mice exposed to diet-induced metabolic disturbances. Amino acids, 43(3), pp.1265-1275.
© Springer-Verlag 2011
Posted September 24, 2013.
Jessica Patella, ND, is a naturopathic physician specializing in nutrition and homeopathic medicine and offers a holistic approach to health. She earned her ND from Southwest College of Naturopathic Medicine in Tempe, AZ, and is a member of the North Carolina Association of Naturopathic Physicians. Visit her website at www.awarenesswellness.com.
References:
- Clemmensen C, et al. L-Arginine improves multiple physiological parameters in mice exposed to diet-induced metabolic disturbances. 2012. Amino Acids. 43:1265-75.
- About Metabolic Syndrome. American Heart Association.
