By David Liu, PHD

Friday Oct 19, 2012 (foodconsumer.org) -- Obesity is linked to increased risk for metabolic syndrome, cardiovascular disease and liver disorders.  But a study in Food Function suggests that long term L-arginine supplementation may help improve these conditions in people who live with diet-induced obesity.

M.A. Alam of The University of Queensland in Brisbane, Australia and colleagues conducted the animal model study and found rats fed a high sugar, high fat diet showed symptoms of metabolic syndrome including obesiy and high blood pressure with heart and liver injury.

The researchers also found oral L-arginine supplementation attenuated or even normalised obesity-related pathological changes in the heart, liver and pancreas in rats by reducing inflammation and oxidative stress induced by the high sugar, high fat feed.

L-Arginine is known to be an important dietary amino acid for cardiovascular health.   Together with vitamin C, L-arginine can help prevent heart disease.  The current study was meant to examine whether oral supplementation with L-arginine reduces cardiovascular, metabolic, pancreatic and hepatic changes in an animal model of the human metabolic syndrome.

For the study, male Wistar rats aged 8 to 9 weeks were fed either a corn starch-rich diet or a high sugar, high fat diet with 25 percent fructose in drinking water for a 16-week period.  Rats on the corn starch rich diet were divided into two groups with one group given 5% L-arginine in their food in the last eight weeks of dietary intervention.  The same protocol was applied to rats on the high sugar high fat with 25 percent fructose.

The corn starch diet had about 68% carbohydrates mainly as long chain polysaccharides, whereas the high-carbohydrate, high-fat diet contained also about 68% carbohydrates but mainly fructose and sucrose together with 24% fat, mainly saturated and monounsaturated fats from beef tallow.   Sugars like fructose found high in high fructose corn syrup and sucrose have been associated with obesity epidemic in the United States.

The researchers found "the high-carbohydrate, high-fat diet-fed rats showed the symptoms of metabolic syndrome including obesity and hypertension with heart and liver damage." 

L-arginine supplementation reduced impairment in left ventricular and liver structure and function, glucose tolerance, and lowered blood pressure, abdominal fat, inflammatory cellular infiltration, pancreatic cell hypertrophy, and oxidative stress, which were associated with the high sugar high fat diet and obesity in th rats. 

The researchers concluded "oral supplementation with L-arginine attenuated or normalised obesity-related changes in the heart, liver and pancreas by reducing inflammation and oxidative stress associated with high carbohydrate, high fat feeding in rats."