Low-glycemic diets may not improve cardiovascular outcomes when compared to high-glycemic diets

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What

A study comparing low- and high-glycemic index diets found no significant difference between the two plans in reducing cardiovascular risk or reversing insulin resistance.

A number of widely-followed diets have been based on the idea that focusing on foods with a low-glycemic index might improve cardiovascular risk factors and lower the risk of developing diabetes. But an NIH-funded study suggests that using the glycemic index to select foods may not improve insulin sensitivity, lower HDL or LDL lipid levels or reduce blood pressure levels. Results of the study appear Thursday online in the Journal of the American Medical Association.

The study, funded by the NIH’s National Heart, Lung and Blood Institute, included 163 overweight adults in a controlled feeding study. Participants had systolic blood pressure levels of between 120 and 159 mmHg, which means participants at the higher end of this range were considered to have high blood pressure.

Participants spent five weeks eating each of the four diets being tested. All foods and calorie-containing drinks were provided to participants for the duration of each five-week period on the test diets. Each diet used the DASH eating plan with variations in carbohydrate and glycemic index levels. The DASH eating plan emphasizes vegetables, fruits, and whole grains; includes fat-free or low-fat dairy products, fish, poultry, beans, nuts, and vegetable oils; and limits sweets, sugary beverages, and red meats.

The diets compared were: high-glycemic index/high carbohydrate; low-glycemic index/ high carbohydrate; high-glycemic index/low carbohydrate; and low-glycemic index/low carbohydrate. The low-glycemic index/low-carbohydrate diet resulted in similar insulin sensitivity, systolic blood pressure and HDL and LDL cholesterol levels when compared to the high-glycemic index/high-carbohydrate diet.

Who

Janet de Jesus, M.S., R.D., nutritionist, Center for Translation Research and Implementation Science/ Division of Cardiovascular Sciences at the NHLBI

Contact

For more information or to schedule an interview with Ms. de Jesus, please contact the NHLBI Communications Office at 301-496-4236 or nhlbi_news@nhlbi.nih.gov.

The National Heart, Lung, and Blood Institute (NHLBI) is a component of the National Institutes of Health. NHLBI plans, conducts, and supports research related to the causes, prevention, diagnosis, and treatment of heart, blood vessel, lung, and blood diseases and sleep disorders. The Institute also administers national health education campaigns on women and heart disease, healthy weight for children, and other topics. NHLBI press releases and other materials are available online at http://www.nhlbi.nih.gov.

About the National Institutes of Health (NIH): NIH, the nation's medical research agency, includes 27 Institutes and Centers and is a component of the U.S. Department of Health and Human Services. NIH is the primary federal agency conducting and supporting basic, clinical, and translational medical research, and is investigating the causes, treatments, and cures for both common and rare diseases. For more information about NIH and its programs, visit www.nih.gov.

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