Associations of Dietary Zinc-Vitamin B6 Ratio with All-Cause Mortality and Cardiovascular Disease Mortality Based on National Health and Nutrition Examination Survey 1999-2016

Previous studies have suggested a possible association among dietary zinc and vitamin B6 intake and CVD mortality and all-cause mortality. However, evidence on the association of dietary zinc and vitamin B6 intake and their interactions with CVD mortality and all-cause mortality remains unclear. This prospective study utilized data from the US National Health and Nutrition Examination Survey (NHANES) from 1999 to 2016. After a median follow-up of 10.4 years, 4757 deaths were recorded among 36,081 participants. Higher dietary zinc intake levels (>= 9.87 mg/day) were associated with lower CVD mortality (hazard ratio (HR) = 0.85, 95% confidence interval (CI): 0.83-0.87). Vitamin B6 intake levels (>= 1.73 mg/day) were associated with lower CVD mortality (HR = 0.91, 95% CI: 0.86-0.96) and all-cause mortality (HR = 0.91, 95% CI: 0.90-0.93). Higher dietary zinc intake and higher vitamin B6 intake were associated with a lower risk of CVD mortality, with an interaction between dietary zinc intake levels and vitamin B intake levels (LZLV group (HR, CI): 1.21,1.12-1.29; LZHV group (HR, CI): 1.42, 1.34-1.50; LZHV group (HR, CI): 1.28, 1.14-1.45; HZHV group (HR, CI): ref). There was also a J-type association (p for nonlinear < 0.001) between the dietary zinc-vitamin B6 ratio and CVD mortality, with a high dietary zinc-vitamin B6 ratio increasing the risk of CVD mortality (HR = 1.27, 95% CI: 1.19-1.35), whereas a moderate dietary zinc-vitamin B6 ratio appeared to be beneficial for CVD mortality. These results suggest that increasing the appropriate proportion of dietary zinc and vitamin B6 intake is associated with a lower risk of CVD mortality. Furthermore, precise and representative studies are needed to verify our findings.