A diet rich in natural antioxidants improves insulin sensitivity in insulin-resistant obese adults and enhances the effect of the insulin-sensitizing drug metformin, a preliminary study from Italy finds. The results will be presented Monday at The Endocrine Society's 92nd Annual Meeting in San Diego.
"The beneficial effects of antioxidants are known, but we have revealed for the first time one of their biological bases of actionimproving hormonal action in obese subjects with the metabolic syndrome," said principal author Antonio Mancini, MD, an endocrinology researcher at Catholic University of the Sacred Heart in Rome.
The metabolic syndrome is a cluster of metabolic risk factors for developing diabetes, heart disease and stroke. People with this syndrome cannot efficiently use insulin, the hormone that regulates glucose (sugar) in the blood.
Some evidence exists that oxidative stress may play a role in the metabolic syndrome, according to Mancini. Oxidative stress, a biochemical mechanism which can lead to damage to blood particles and to cells, results from an imbalance between an excessive amount of oxidants and decreased antioxidant defenses. Oxidative stress also plays a part in aging.
Antioxidants, which are found naturally in fruits, vegetables, legumes and nuts, include vitamins E and C, selenium and carotenoids, such as beta-carotene. Past research shows that antioxidants can prevent oxidative damage to cells and in some cases also help repair damage.
Mancini and his colleagues studied the effects of dietary antioxidants on insulin resistance, with partial financial support from MIUR, the Italian Department for University and Research. The study included 16 men and 13 women, ages 18 to 66 years, who were obese and insulin-resistant, but were not yet diabetic.
The researchers randomly assigned the subjects to one of four treatment groups. All groups ate a low-calorie, Mediterranean-type diet av
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The Endocrine Society