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Dietary iron, copper, zinc associated with type 2 diabetes risk
In Japanese adults with type 2 diabetes, higher dietary intakes of iron and copper were associated with an increased risk for developing type 2 diabetes, whereas higher dietary zinc intake was associated with a reduced risk for the disease, according to findings from a prospective study.
“These major elements are important cofactors of numerous enzymes, and their abnormal homeostasis is associated with the development of [type 2 diabetes] and its complications; however, disturbed serum levels of these elements were found to be induced by conditions like insulin resistance and hyperglycemia,” Ehab S. Eshak, of the department of social medicine at the Graduate School of Medicine at Osaka University, Japan, and colleagues wrote. “Thus, their serum levels can be both contributors to the development of [type 2 diabetes] and/or results of metabolic distress in [type 2 diabetes]. In the current study, we examined the associations of dietary intakes rather than serum levels of these elements with risk for [type 2 diabetes].”
Eshak and colleagues analyzed data from 16,160 adults aged 40 to 65 years at baseline participating in the Japan Collaborative Cohort Study for Evaluation of Cancer Risk (5,955 men). Participants, who were free of diabetes or cardiovascular disease at baseline, completed a 40-item food-frequency questionnaire assessing intake of food and drink over 1 year without specifying portion size; possible responses included rarely, one to two times per month, one to two times per week, three to four times per week and almost every day. Researchers multiplied iron, copper and zinc content from each food by the participants’ frequency scores to measure dietary intake. Participants who self-reported a diagnosis of type 2 diabetes on the 5-year follow-up survey were considered to have incident type 2 diabetes.
At 5 years, 396 participants developed type 2 diabetes (200 men); those reporting a diabetes diagnosis were more likely to be older, have a higher BMI, smoke or drink alcohol and have a family history of diabetes.
Researchers found that participants in the highest quartile of iron intake were more likely to develop type 2 diabetes (OR = 1.33; 95% CI, 1.05-1.75) compared with those in the lowest quartile, as were those in the highest quartile for copper intake (OR = 1.55; 95% CI, 1.13-2.02). However, participants in the highest quartile for zinc intake saw a reduced risk for developing type 2 diabetes vs. those in the lowest quartile (OR = 0.65; 95% CI, 0.57-0.99), according to researchers. Results persisted after adjustment for nondietary factors.
“The associations of iron and copper intakes with diabetes risk appeared more evident for those at high risk: older, overweight smokers and those with a family history of diabetes,” the researchers wrote. – by Regina Schaffer
Disclosure: The researchers report no relevant financial disclosures.