Study of the Possible Effect of Obesity on Vitamin D Level among a Sample of Adult Men in the Western Region of Kingdom of Saudi Arabia

Aim of the Study: This cross sectional study was aimed to investigate the effect of obesity on vitamin D levels in adult male in the western region of Saudi Arabia.

Study Design and Methods: One hundred twenty two Healthy men, aged 20–45 years are included in this study. They were divided into normal (n=48), overweight (n=26) and obese (n=48), according to their body mass index (BMI). Serum 25[OH]D, parathyroid hormone (PTH) and calcium were measured in different BMI groups. We also measured total body fat percentage (TBF%) and bone mineral density (BMD) in Spine (L1–L4), Femur Neck and Total Body, by DXA technique.

Results: Of the total participants, 94.9% had vitamin D deficiency with a mean 27.6±10.78 nmol/L (normal level; 75-250 nmol/L). The mean serum levels for 25(OH)D for the normal, overweight and obese groups were 28.7±12.16 nmol/L, 27.0±8.71 nmol/L and 27.0±10.43 nmol/L, respectively. Of the total participants, 89.4% had an above-average TBF%, and it was negatively correlated with serum 25(OH)D. Serum calcium was significantly lower in the obese group compared with the normal BMI group (P<0.001). Serum PTH was significantly higher in the obese group compared with the normal BMI group (P<0.023). The BMI was significantly positively correlated with the different BMD measurements. Of our participants, 62% were physically inactive and only 14% were exposed to sunlight.

Conclusion: The prevalence of vitamin D deficiency in Saudi Arabian men is high, regardless of differences in BMI. Elevations in TBF% in different BMI categories play an important role in elevated vitamin D deficiency rates. A sedentary lifestyle and elevated adiposity contribute to an elevation in the vitamin D deficiency rate.