Dietary intake of B vitamins and cancer risk in women: a mixture analysis approach of NHANES 2007-2020.

[BACKGROUND] Although B vitamins are often consumed through multivitamin containing foods, their potential synergistic effects on cancer risk remain insufficiently elucidated.

[OBJECTIVE] We aimed to study the relationship between mixed intake of B vitamins, cancer, and overall and site-specific cancer risk in women.

[METHODS] A survey of dietary B vitamins intake and cancer risk was conducted using the National Health and Nutrition Examination Survey (NHANES) data from 2007 to 2020.Generalized linear regression (GLM), weighted quantile, and regression (WQS) were used to evaluate the relationship between seven B vitamins intakes and cancer in the female population.

[RESULTS] A total of 17,495 adult women aged ≥ 20 years were included, with a mean age of 48.8 years and an average daily energy intake of 1,779 kcal. Dietary B-vitamin intake was obtained from two 24-h dietary recalls and reflected food-based (non-supplement) consumption. In the fully adjusted model, the mixed intake of seven B vitamins was inversely associated with overall cancer risk (adjusted OR = 0.91, 95% CI 0.85-0.98) and colorectal cancer (adjusted OR = 0.73, 95% CI 0.56-0.96). Folate, niacin, and choline contributed the greatest weights in the mixture model. In age-stratified analyses, the inverse association was present only in women younger than 65 years (adjusted OR = 0.86, 95% CI 0.79-0.94).

[CONCLUSION] Synergistic intake of B vitamins demonstrates cancer-protective effects, with niacin and folate as primary contributors. These findings highlight the importance of consuming B vitamin-rich whole foods rather than from high-dose isolated supplements, particularly among younger women.