Whole-grain intake and insulin sensitivity: the Insulin Resistance Atherosclerosis Study.
BACKGROUND
Increased intake of whole-grain foods has been related to a reduced risk of developing diabetes and heart disease. One underlying pathway for this relation may be increased insulin sensitivity.


OBJECTIVE
We assessed the relation between dietary intake of whole grain-containing foods and insulin sensitivity (S(I)).


METHODS
We evaluated data from the Insulin Resistance Atherosclerosis Study (IRAS Exam I, 1992-1994). Usual dietary intakes in 978 middle-aged adults with normal (67%) or impaired (33%) glucose tolerance were ascertained by using an interviewer-administered, validated food-frequency questionnaire. Whole-grain intake (servings per day) was derived from dark breads and high-fiber and cooked cereals. S(I) was assessed by minimal model analyses of the frequently sampled intravenous-glucose-tolerance test. Fasting insulin was measured by using a radioimmunoassay. We modeled the relation of whole-grain intake to log(S(I) + 1) and to log(insulin) by using multivariable linear regression.


RESULTS
On average, IRAS participants consumed 0.8 servings of whole grains/d. Whole-grain intake was significantly associated with S(I) (beta = 0.082, P = 0.0005) and insulin (beta = -0.0646, P = 0.019) after adjustment for demographics, total energy intake and expenditure, smoking, and family history of diabetes. The addition of body mass index and waist circumference attenuated but did not explain the association with S(I). The addition of fiber and magnesium resulted in a nonsignificant association that is consistent with the hypothesis that these constituents account for some of the effect of whole grains on S(I).


CONCLUSIONS
Higher intakes of whole grains were associated with increases in insulin sensitivity.
Liese
Angela D
AD
Department of Epidemiology and Biostatistics, Arnold School of Public Health, University of South Carolina, Columbia, 29208, USA. liese@sc.edu
Roach
Amy K
AK
Sparks
Karen C
KC
Marquart
Len
L
D'Agostino
Ralph B
RB
Mayer-Davis
Elizabeth J
EJ
D001161:Arteriosclerosis / Q000209:etiology / Q000517:prevention & control; D001824:Body Constitution; D015992:Body Mass Index; D003920:Diabetes Mellitus / Q000235:genetics; D004032:Diet; D004043:Dietary Fiber / Q000008:administration & dosage; D002523:Edible Grain; D002149:Energy Intake; D004734:Energy Metabolism; D005215:Fasting; D005260:Female; D018149:Glucose Intolerance; D006801:Humans; D007328:Insulin / Q000097:blood*; D007333:Insulin Resistance; D016014:Linear Models; D008274:Magnesium / Q000008:administration & dosage; D008297:Male; D008875:Middle Aged; D012907:Smoking
D004043:Dietary Fiber; D007328:Insulin; D008274:Magnesium