Healthy Diet Reduces Risk for Insulin Resistance and Metabolic Syndrome

March 14, 2007 — A healthy dietary pattern rich in fruit, vegetables, poultry, and legumes is linked with reduced risk for insulin resistance and the metabolic syndrome in a group of 40- to 60-year-old women, according to the results of a study reported in the March issue of the American Journal of Clinical Nutrition.

"Although individual foods and nutrients have been associated with the metabolic syndrome, whether dietary patterns identified by factor analysis are also associated with this syndrome is not known," write Ahmad Esmaillzadeh, from the Isfahan University of Medical Sciences in Iran, and colleagues.

In this cross-sectional study, 486 Tehrani female teachers aged 40 to 60 years provided information on their usual dietary intakes. Other outcome measures were anthropometric and blood pressure measurements and fasting blood samples for biomarker assessment. Metabolic syndrome was defined according to guidelines from the Adult Treatment Panel III, and insulin resistance was defined as the highest quartile of the homeostasis model assessment scores.

Factor analysis revealed 3 major dietary patterns: the healthy dietary pattern (rich in fruit, vegetables, poultry, and legumes), the Western dietary pattern (lower amounts of beneficial foods and nutrients and higher intakes of refined grains and saturated fat), and the traditional dietary pattern (high intake of fruit, vegetables, poultry, legumes, refined grains, potatoes, and hydrogenated fats).

Compared with subjects in the lowest quintile of the healthy dietary pattern scores, those in the highest quintile had a lower odds ratio (OR) for the metabolic syndrome (OR, 0.61; 95% confidence interval [CI], 0.30 - 0.79; P for trend < .01) and insulin resistance (0.51; 95% CI, 0.24 - 0.88; P for trend < .01), after adjustment for potential confounders.

Compared with those in the lowest quintile of the Western dietary pattern scores, women in the highest quintile were at higher risk for the metabolic syndrome (OR, 1.68; 95% CI, 1.10 - 1.95; P for trend < .01) and insulin resistance (OR, 1.26; 95% CI, 1.00 - 1.78; P for trend < .01).

Adherence to the traditional dietary pattern was significantly associated with abnormal glucose homeostasis (OR, 1.19; 95% CI, 1.04 - 1.59; P < .05) but not with other features of the metabolic syndrome. All of the above associations were independent of other lifestyle factors.

"Significant associations exist between dietary patterns identified by factor analysis, the metabolic syndrome, and insulin resistance," the authors write. "The healthy dietary pattern was associated with lower risks of insulin resistance and the metabolic syndrome, whereas the Western dietary pattern was associated with higher risks of insulin resistance and the metabolic syndrome. We found no significant association between the traditional dietary pattern and these conditions."

Study limitations include use of food intake data only and not of eating behaviors, cross-sectional design, and lack of generalizability to all Iranian populations.

"The current findings indicate that a dietary pattern characterized by high consumption of fruit, vegetables, poultry, and legumes is associated with reduced risk of insulin resistance and the metabolic syndrome in Tehrani female teachers," the authors conclude. "In contrast, a dietary pattern with high amounts of refined grains, red meat, butter, processed meat, and high-fat dairy products and low amounts of vegetables and low-fat dairy products is associated with a greater risk of the metabolic syndrome."

The National Nutrition and Food Technology Research Institute, and the School of Nutrition and Food Science, Shaheed Beheshti University of Medical Sciences supported this study. The authors have disclosed no relevant financial relationships.

Am J Clin Nutr. 2007;85:910-918.

Source: http://www.medscape.com/viewarticle/553589?src=mp