Zinc Intake Linked to Lower Risk for Type 2 Diabetes

The study results suggest that a diet with high zinc-to-heme iron ratio is significantly associated with lower risk of Type 2 diabetes.

Qi Sun, MD, ScD, from Harvard School of Public Health, Boston, Massachusetts, writes, “Despite the evidence from animal studies that zinc intake may have protective effects against Type 2 diabetes, few studies in humans have been conducted to examine this relationship.”

“The hypothesis that dietary zinc intake is associated with a reduced risk of Type 2 diabetes has not been examined in a prospective study. Also, it would be useful to examine the associations for supplemental zinc and zinc from food sources separately because the former is more bioavailable than the latter.”

The goal of this analysis was to determine the interaction of zinc intake with risk for Type 2 diabetes in US women. The study cohort consisted of 82,297 women who were aged 33 to 60 years at baseline in 1980 and who were followed up to 2004 in the Nurses’ Health Study. From 1980 to 2002, a validated food frequency questionnaire (FFQ) was administered to measure dietary intakes of zinc and other nutrients.

There were 6,030 incident cases of Type 2 diabetes during 24 years of follow-up. Comparing the highest with the lowest quintiles of intake, the relative risks (RRs) of Type 2 diabetes were 0.90 for total zinc and 0.92 for dietary zinc from food sources, after adjustment of lifestyle and dietary risk factors.

There was also an inverse association between Type 2 diabetes and dietary zinc-to-heme iron ratio. RRs across quintiles of this ratio, after multivariate adjustment of covariates, were 1.0 (reference), 0.93, 0.86, 0.82, and 0.72, respectively (P trend < .0001).

“Higher zinc intake may be associated with a slightly lower risk of Type 2 diabetes in women,” the study authors write. “More studies are warranted to confirm this association and to explore potential mechanisms.”

Limitations of this study include possible residual confounding; some measurement error in assessment of zinc intake; possible lack of generalizability to nonwhite women or to those of other professions; and significant associations observed only after using cumulative average of diet and stopping diet updates after participants developed chronic diseases.

“Our results also suggest that a diet with high zinc-to-heme iron ratio is significantly associated with lower risk of Type 2 diabetes,” the study authors conclude. “These findings are considered preliminary and thus, further studies are warranted to confirm these findings.”

Diabetes Care. April, 2009;32:629-634.
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