Micronutrient deficiencies and CVD: a binational analysis of National Health and Nutrition Examination Survey (NHANES) and China Health and Retirement Longitudinal Study (CHARLS).

Micronutrient deficiencies are modifiable risk factors for CVD, yet their relative importance and combined effects across populations require further characterisation. We performed a binational analysis integrating cross-sectional data from the US National Health and Nutrition Examination Survey (NHANES, 2007-2018; n 3848) and prospective data from the China Health and Retirement Longitudinal Study (CHARLS, 2011-2018; n 11 391). Associations of specific micronutrient biomarkers (vitamin D, folate, vitamin B12, Ca and Fe) and dietary patterns with CVD were assessed using multivariable-adjusted logistic regression, Cox proportional hazards models and restricted cubic splines. A composite micronutrient deficiency score evaluated cumulative risk. In NHANES, Fe deficiency was independently associated with prevalent CVD after full adjustment (OR 1·49, 95 % CI: 1·09, 2·01), with a population prevalence of 23·4 %. Although most prevalent (33·1 %), vitamin D deficiency showed no independent association. Nonlinear analyses revealed a U-shaped relationship for Fe (P-nonlinearity = 0·003) and an inverse association for vitamin D (P-nonlinearity < 0·001). A dose-response relationship was observed for cumulative deficiencies; participants with ≥ 2 deficiencies had 91 % higher CVD odds (OR 1·91, 95 % CI: 1·20, 2·99). In CHARLS, frequent consumption of fruits/vegetables (adjusted hazard ratio (aHR) 0·81, 95 % CI: 0·70, 0·93), nuts (aHR 0·82, 0·71, 0·95) and fish (aHR 0·85, 0·74, 0·98) was associated with reduced incident CVD risk. Fe deficiency is an underrecognised independent risk factor for CVD, and multiple concurrent deficiencies synergistically increase risk. Plant-based dietary patterns are consistently protective. Findings advocate for Fe status screening in cardiovascular risk assessment and emphasise holistic nutritional approaches.