Vitamin D Level in Association with Body Fat Distribution among Obese Populations in Egypt

Background: Both obesity and vitamin D inadequacy are closely related; yet the relationship between body fat (BF) distribution pattern and vitamin D concentration needs further scrutiny. Study Aim: Analyze the relationship between visceral fat area (VFA) and impaired vitamin D levels among Qena populations, Upper Egypt.

Methods: Adults aging 20 and above seeking care at the outpatient department (OPD) of Qena University Hospital (QUH) were examined, fatness indices including body mass index (BMI) and waist circumference (WC) were measured, and VFA was assayed using bioelectrical impedance analysis (BIA). Visceral fat obesity (VFO) was specifically measured in association with serum vitamin D3 [25(OH) D3)] level.

Results: The study comprised 420 subjects, 246 men, 174 women (125 pre-menopausal, 49 post-menopausal). VFO in the case group (46.2%) was higher than overall obesity (21.2%); men had higher VFO indices [median (IQR)] vs. women: BMI=28.8(13) vs. 25.4(4), WC=95.2(5) vs. 82.8(8), VFA=117.3(27) vs. 85.5(26), respectively. Men had a lower 25(OH) D3 [31.1(14.3)] level than women [36.2(19)]. The prevalence of vitamin D deficiency (VDD) accounted 35.5% in men and 23.7% in all women (p= 0.009). Subjects’ 25(OH) D3 levels [median (IQR)] and VFA quartiles (Qs) were inversely related both in men [38.8(18), 31.4(15), 28.8(16), 23.2(14), p= 0.005] and pre-menopausal women [42.7 (26), 41.2 (25), 36.8 (21), p=0.03]. Only men suffer increasing vitamin D insufficiency across VFA quartiles (Q1=10.1%, Q2=13.3, Q3=37.7, Q4=39.8, p= 0.002); while both men and pre-menopausal women sustain escalating VDD pattern under VFA quartiles (Q1 20.1%, Q2 39.6, Q3 45.2, Q4 55.3, p<0.0001), (Q1 18.7%, Q2 20.3, Q3 23.6, Q4 37.1, p =0.00032), respectively. Men and pre-menopausal groups with the highest VFA were prone to 25(OH) D3 insufficiency/deficiency, compared with the lowest VFA groups [OR men 5.7 (95% CI 3.1 – 9.2; p=0.02), OR women 95% CI 2.2 - 4.5, p= 0.009].

Conclusions: Higher VFA may be risk for vitamin D inadequacy in men and pre-menopausal women. That VFA assessment using BIA provides a sex-specific adiposity measurement in identifying vitamin D inadequacy; VFA can be used as a simple and cost-effective method in population-based screening to prevent VDD, especially among high risk groups.