Dairy Does Not Appear to Cause Insulin Sensitivity in Non-Diabetics

COLUMBIA, S.C.--According to a team of researchers at the Arnold School of Public Health, University of South Carolina, dietary magnesium and calcium specifically, but not dairy intake generally, impact insulin sensitivity in people who do not have diabetes.

In their study, 1,036 U.S. adults without diabetes were evaluated from 1992 to 1999 as part of the Insulin Resistance AtherosclerosisStudy. Each participant's diet and supplement intake was monitored at baseline and after five years of follow-up; food frequency reviews were conducted to record dairy intake, and individuals' dosages of magnesium and calcium were taken and recorded from bottle labels.

Insulin resistance was directly measured with a validated, 12-sample, insulin-enhanced, intravenous glucose tolerance test with minimalmodel analysis. Using several statistical methods, no correlation was found between dairy in the diet and insulin sensitivity (p= 0.41), but after taking into consideration factors of demographics, non-dietary lifestyle/dietary factors and food groups--magnesium and calcium supplementation (p = 0.016) specifically affected insulin resistance. The Bayesian method further revealed magnesium intake was associated with insulin sensitivity in a threshold fashion, estimated at 325 mg/d (ß = 0.0607/100mg, p = 0.0008 for <325 mg/d of magnesium, and ß= 0.001/100 mg, p = 0.82 for 325 mg/d).
The study was published in the American Journal of Epidemiology (164, 5: 449-458, 2006).