Effect of whole grains on insulin sensitivity in overweight hyperinsulinemic adults.
BACKGROUND
Epidemiologic studies have found whole-grain intake to be inversely associated with the risk of type 2 diabetes and heart disease.


OBJECTIVE
We tested the hypothesis that whole-grain consumption improves insulin sensitivity in overweight and obese adults.


METHODS
This controlled experiment compared insulin sensitivity between diets (55% carbohydrate, 30% fat) including 6-10 servings/d of breakfast cereal, bread, rice, pasta, muffins, cookies, and snacks of either whole or refined grains. Total energy needs were estimated to maintain body weight. Eleven overweight or obese [body mass index (in kg/m(2)): 27-36] hyperinsulinemic adults aged 25-56 y participated in a randomized crossover design. At the end of each 6-wk diet period, the subjects consumed 355 mL (12 oz) of a liquid mixed meal, and blood samples were taken over 2 h. The next day a euglycemic hyperinsulinemic clamp test was administered.


RESULTS
Fasting insulin was 10% lower during consumption of the whole-grain than during consumption of the refined-grain diet (mean difference: -15 +/- 5.5 pmol/L; P = 0.03). After the whole-grain diet, the area under the 2-h insulin curve tended to be lower (-8832 pmol.min/L; 95% CI: -18720, 1062) than after the refined-grain diet. The rate of glucose infusion during the final 30 min of the clamp test was higher after the whole-grain diet (0.07 x 10(-4) mmol.kg(-1).min(-1) per pmol/L; 95% CI: 0.003 x 10(-4), 0.144 x 10(-4)).


CONCLUSIONS
Insulin sensitivity may be an important mechanism whereby whole-grain foods reduce the risk of type 2 diabetes and heart disease.
Pereira
Mark A
MA
Department of Pediatrics, Harvard Medical School, and the Department of Medicine, Children's Hospital, Boston, MA, USA. mark.pereira@channing.harvard.edu
Jacobs
David R
DR
Pins
Joel J
JJ
Raatz
Susan K
SK
Gross
Myron D
MD
Slavin
Joanne L
JL
Seaquist
Elizabeth R
ER
D000328:Adult; D001835:Body Weight; D018592:Cross-Over Studies; D004032:Diet / Q000009:adverse effects; D002523:Edible Grain; D005215:Fasting / Q000097:blood; D005260:Female; D015309:Glucose Clamp Technique; D006706:Homeostasis; D006801:Humans; D006946:Hyperinsulinism / Q000503:physiopathology*; D007328:Insulin / Q000097:blood; D007333:Insulin Resistance / Q000502:physiology*; D008297:Male; D009765:Obesity / Q000150:complications* / Q000503:physiopathology*; D019518:Postprandial Period; D012528:Satiety Response
D007328:Insulin