The incidence of vitamin D deficiency in the obese: a retrospective chart review

OBJECTIVE: To determine whether the obese population is more likely to be vitamin D deficient compared to healthy and overweight individuals. PATIENTS AND METHODS: A retrospective chart review was performed for patients seen in two ambulatory clinics in South Florida over a 1-year period (n=402). Patients’ vitamin D levels drawn during annual wellness visits were analyzed. Subjects were categorized based on body mass index (BMI) as normal (BMI <24.9), overweight (BMI 25.0–29.9), and obese (BMI >30.0). Their 25-OH vitamin D status was defined as normal (>30 ng/mL), insufficient (20.0–29.9 ng/mL), and deficient (<20 ng/mL). The study included both men and women of black, white, Hispanic, and Asian races. Other variables in the study included age, history of hypertension, and diabetes. Patients with conditions leading to vitamin D malabsorption (chronic pancreatitis, celiac disease, Crohn's disease, cystic fibrosis, ileocecal resection) were excluded. Patients with prior vitamin D supplementation were also excluded. RESULTS: The results of the study indicated a significant association of vitamin D deficiency and obesity (p<0.05). Patients who were obese had a relative risk of 3.36 (95% CI: 1.50–7.54) for vitamin D deficiency compared to subjects with normal BMI. The study also showed a significant association between vitamin D levels and obesity when controlling for age, race, and presence of hypertension (p <0.05), with Asians and blacks more likely to be vitamin D deficient. CONCLUSION: These results demonstrated that obesity was a risk factor for vitamin D deficiency in all races, especially the Asian and black populations. This suggests that physicians should screen for vitamin D deficiency in the obese populations, especially among Asian and black races.