Association Between dietary iron Levels and all-cause and cancer-cause mortality: a Prospective Cohort Study

Although there are many studies concentrate on the connection between dietary iron and tumors. Few studies elucidated the association between total dietary iron and all-cause or cancer-cause mortality. Conclusions about how total dietary iron influences all-cause/cancer-cause mortality were paradoxical. Our study collected dietary iron and survival data from National Health and Nutrition Examination Survey (NHANES) 1999-2019. Multivariate Cox proportional risk models and subgroup analysis were used to assess the relationship between dietary iron and all/cancer-cause death. Restricted Cubic Samples (RCS) were used to fit the non-linear relationship between them. Dietary iron was a protective factor against all-cause mortality ( p for trend = 0.004), as well as cancer-cause mortality( p for trend = 0.028). Dietary iron content had a nonlinear relationship with and all-cause mortality (p for overall < 0.001; p for non-linearity < 0.001) with an "L" curve, so as to the cancer-related death (p for overall=0.002，p for non-linearity= 0.046). The nonlinear association of dietary iron and cancer-cause mortality differed from all/cancer-cause mortality.Our study found that dietary iron was a protective factor for death of all-cause and cancer in population and they had an "L" shaped nonlinear curves. All-cause/cancer mortality was attenuated by dietary iron in people who were aged <=65 years, males, Non-Hispanic White and Non-Hispanic Black, as well as people without hypertension or diabetes mellitus(DM).