Dietary iron in diabetes: A risk factor for mortality in men, protective in women

Dietary iron intake appears to have a nonlinear association with all-cause mortality among individuals with diabetes, such that higher intake levels may carry a risk increase in men but exert a protective effect in women, according to a study.

Researchers used data from the National Health and Nutrition Examination Survey and looked at 5,970 participants (average age 61.3 years, 51.3 percent male) with diabetes to examine how dietary iron intake correlated with mortality. Cox proportional hazard models were applied in the analysis.

The average iron intake in the entire cohort was 14.1 mg daily. Individuals with increased iron intake were more likely to be male, be non-Hispanic, and have a higher poverty–income ratio, serum iron levels, and energy intake compared with those who had lower iron intake levels.

Over 41,425 person-years of follow-up, 1,497 deaths were documented. Compared with intake levels <8.3 mg (reference), intake levels between 11.1 and 14.4 mg were associated with the lowest risk of all-cause mortality in the overall cohort (hazard ratio [HR], 0.83, 95 percent confidence interval [CI], 0.70–0.99; p<0.05).

Of note, iron intake had a nonlinear association with all-cause mortality. Analysis of dose-response curves showed an L-shaped pattern in men and a J-shaped pattern in women. No significant interaction was observed between baseline iron levels and iron intake (p=0.296).

The researchers advised caution when recommending appropriate ranges of iron intake for men and women with diabetes.