Association between Obesity and Low Serum Vitamin D Concentrations in Healthy Adult Females: A Public Health Perspective

Abstract

Objective: To find out the association between obesity and low serum vitamin D concentrations among females. Materials and Methods: This cross sectional study was conducted in females aged 20-45 years reporting to dietitian and family OPD of PNS Shifa Hospital from September 2014 to January 2015. Three forty seven females underwent physical examination for anthropometric data. Weight was measured using weight scale. Height was recorded using wall mounted stadiometer in erect position without shoes. BMI was calculated by weight in kilogram (kg) divided by height in square meter (m2). Waist was recorded by placing measuring tape at midpoint of upper border of iliac crest and lower margin of last palpable rib (WHO STEPS protocol). Serum Vitamin D level was measured by electro-chemiluminiscence immunoassay. Results: Mean serum vitamin D level was significantly lower among over weight (>18.5-24.9 kg/m2) and obese females(>30 kg/m2) as compared to normal weight (>18.5-24.9kg/m2) and underweight category (< 18.49 kg/m2). Univariate regression analysis for BMI and age showed every 1 kg/m2 increase in BMI associated with 0.61 nmol/l decrease in serum vitamin D levels. It also showed that every one year increase in age decreased 0.22 nmol/l of serum vitamin D level. Multivariate regression analysis was performed to control the effect of age and demonstrated only significant association with BMI. Pearson correlation showed that serum vitamin D level was inversely related to both BMI and waist circumference Conclusion: Vitamin D level was low among overweight and obese females and showed an inverse association with BMI and waist circumference.