Association between Zinc and Vitamin D Intake and Obesity among Women: A Cross-Sectional Analysis of NHANES 2017-2018
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Abstract
Background: Micronutrient intake, particularly zinc and vitamin D, has been hypothesized to influence obesity risk through metabolic and inflammatory pathways. However, evidence on these associations in women remains limited and mixed. The current study aimed to examine the relationship between zinc and vitamin D intake and obesity among adult women using nationally representative data.
Methods: We conducted a cross-sectional analysis of 1,043 adult women from the NHANES 2017–2018 dataset. Obesity was defined as body mass index (BMI)≥30 kg/m2. Zinc and vitamin D intake was categorized as adequate or inadequate based on dietary guidelines (zinc>8 mg/day; vitamin D>15 mcg/day). Logistic regression models estimated adjusted odds ratios (ORs) and 95% confidence intervals (CIs) for the association between micronutrient intake and obesity. The models were adjusted for diabetes, exercise status, age, Hispanic origin, smoking, and other comorbidities.
Results: Vitamin D intake>15 mcg/day was associated with higher odds of obesity in the unadjusted analysis (OR =1.37; 95% CI: 1.05–1.78;p=0.02), but it was not statistically significant after adjustment (adjusted OR = 1.28; 95% CI:0.95–1.71;p=0.09). Zinc intake of>8 mg/day was not significantly associated with obesity (adjusted OR = 1.38; 95%CI: 0.33–5.86;p=0.66). Key predictors of higher obesity risk included the presence of diabetes (adjusted OR = 2.13; 95%CI: 1.48–3.07;p<0.01) and comorbidities>1 (adjusted OR = 2.33–2.37 across models; p <0.01). Protective factors included physical activity (adjusted OR = 0.62; 95% CI: 0.47–0.81;p<0.01), Hispanic ethnicity (adjusted OR = 0.82;95% CI: 0.74–0.92;p<0.01), and increasing age (adjusted OR = 0.99 per year; 95% CI: 0.98–0.99;p<0.01). Smoking and total fat intake were not significantly associated with obesity.
Conclusions: In this cross-sectional analysis of U.S. women, neither zinc nor vitamin D intake was significantly associated with obesity after adjustment for confounders. Diabetes, comorbidities, exercise, and Hispanic ethnicity emerged as important predictors of obesity. These findings highlight the multifactorial nature of obesity and underscore the need for longitudinal research using biomarker-based assessments of nutrient status to better understand these relationships.