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ARS Home » Northeast Area » Boston, Massachusetts » Jean Mayer Human Nutrition Research Center On Aging » Research » Publications at this Location » Publication #165356

Title: CARBOHYDRATE NUTRITION, INSULIN RESISTANCE, AND THE METABOLIC SYNDROME IN THE FRAMINGHAM OFFSPRING COHORT

Author
item MCKEOWN, NICOLA - TUFTS-HNRCA
item MEIGS, JAMES - MASS GENERAL HOSPITAL
item LIU, SIMIN - HARVARD SCH OF PUB HEALTH
item SALTZMAN, EDWARD - TUFTS-HNRCA
item WILSON, PETER - FRAMINGHAM HEART STUDY
item JACQUES, PAUL - TUFTS-HNRCA

Submitted to: Diabetes Care
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/29/2003
Publication Date: 2/1/2004
Citation: Mckeown, N.M., Meigs, J.B., Liu, S., Saltzman, E., Wilson, P.W., Jacques, P.F. 2004. Carbohydrate nutrition, insulin resistance, and the metabolic synedrome in the framingham offspring cohort. Diabetes Care. 27:538-546.

Interpretive Summary: People with a disease condition know as the metabolic syndrome, are at increased risk of developing type 2 diabetes mellitus. One metabolic characteristic of this syndrome is a high level of insulin in the blood. The higher the insulin level in the blood, the more insulin resistant is a person and the more likely they are to develop the metabolic syndrome. Diet effects blood insulin levels and may play a role in the development of the metabolic syndrome. One aspect of diet that may control insulin levels is the source and quality of dietary carbohydrates. In the present study, people who ate more dietary fiber, particularly fiber from fruit and cereal sources, had lower insulin levels and were less insulin resistant than people who had low intakes of dietary fiber. People who ate more cereal fiber were less likely to have the metabolic syndrome. The quality and quantity of carbohydrate in the diet can be measured using the dietary glycemic index and glycemic load to classify foods that contain carbohydrates. The higher the dietary glycemic index and glycemic load, the poorer the quality of the carbohydrate. We found that people whose diets were higher in foods with a high glycemic index, the higher the degree of insulin resistance and the more likely these people had the insulin resistance syndrome. Whole grain foods are higher in cereal fiber and have a lower glycemic index than refined grain foods. In this study, people who ate three of more servings per day of whole grain foods were less insulin resistance and had a lower risk of having the metabolic syndrome than people who ate less than one serving per week of whole grains. Because of the high cereal fiber content and lower glycemic index of whole grain foods, increasing whole grains foods may reduce the potential untoward effects of carbohydrate on risk of type 2 diabetes.

Technical Abstract: We examined cross-sectional associations between carbohydrate-related dietary factors, insulin resistance and the prevalence of the metabolic syndrome in 2834 subjects at the fifth examination (1991-1995) of the Framingham Offspring Study. Insulin resistance (HOMA-IR) was calculated using the following formula (fasting plasma insulin x plasma glucose)/22.5. The metabolic syndrome was defined using the National Cholesterol Education Program criteria. After adjustment for potential confounding variables, intakes of total dietary fiber, cereal fiber, fruit fiber, and whole grains were inversely associated with HOMA-IR. The prevalence of the metabolic syndrome was significantly lower among those in the highest quintile of cereal fiber (OR, 0.62; 95% CI, 0.45-0.86) and whole grain (OR, 0.67; 95% CI, 0.48-0.91) intakes relative to those in the lowest quintile category, after adjustment for confounding lifestyle and dietary factors. Conversely, the prevalence of the IRS was significantly higher among individuals in the highest relative to the lowest quintile category of glycemic index (OR, 1.41; 95% CI, 1.04-1.91). Total carbohydrate, dietary fiber, fruit fiber, vegetable fiber, legume fiber, glycemic load and refined grain intake were not associated with prevalence of the IRS. Whole grain intake, largely attributed to the cereal fiber, is inversely associated with HOMA-IR and a lower prevalence of the metabolic syndrome. Dietary glycemic index is positively associated with HOMA-IR and prevalence of the syndrome. Dietary recommendation to increase whole-grain intake may reduce the risk of developing the metabolic syndrome.