Vitamin D Levels in Overweight/Obese Adults With and Without Metabolic Syndrome

Abstract

Background: Vitamin D role is not only associated with mineral metabolism and bone health but also in globally important diseases such as obesity and metabolic syndrome. The aims of this observational study were to investigate: 1) 25(OH) vitamin D levels in overweight/obese persons with and without metabolic syndrome and compare these with levels in healthy subjects, 2) the relationship between serum 25(OH) vitamin D levels and metabolic syndrome components such as body mass index, waist circumference, blood pressure, fasting blood glucose, lipid parameters and insulin resistance:Homeostasis Model Assesment of Insulin Resistance (HOMA-IR).

Methods: Participants (n = 287) were 94 overweight/obese adults with metabolic syndrome, 120 overweight/obese adults without metabolic syndrome, and 73 non-obese healthy subjects (controls). Overweight/obese subjects were classified as metabolic syndrome (MetS) positive according to the recent International Diabetes Federation criteria. HOMA-IR was calculated as serum glucose (mg/dL) /span> insulin level (U/mL)/405. Vitamin D nutritional status was assessed as deficient if 25(OH) vitamin D levels were < 20 ng/mL, insufficient if greater than or equal to 20 - < 30 ng/mL, and sufficient if greater than or equal to 30 ng/mL.

Results: Serum 25(OH) vitamin D deficiency, defined as a level < 20 ng/mL, was more common in overweight/obese adults with (72%) andwithout (69%) metabolic syndrome than in controls (49%) (P = 0.006). Serum 25(OH) vitamin D levels were significantly lower in overweight/obese metabolic syndrome adults (16.8 7.3 ng/mL) and overweight/obese non-metabolic syndrome adults (18.3 8.6 ng/mL) than healthy subjects (21.2 8.9 ng/mL, P = 0.001). A negative relationship was found between serum 25(OH) vitamin D levels and body mass index (r = -0.159, P = 0.007) and serum triglyceride levels (r = -0.149, P = 0.012). Serum 25(OH) vitamin D levels correlated inversely (not statistically significant) to waist circumference, fasting blood glucose, HOMA-IR, and blood pressure, but positively (not statistically significant) to HDL cholesterol levels.

Conclusions: Vitamin D deficiency is very common in overweight/obese adults, more so than in healthy controls. Vitamin D deficiency is not more common in those with metabolic syndrome than in those without. Reduced 25(OH) vitamin D levels are associated with an increased risk of overweight/obesity and metabolic syndrome.




J Endocrinol Metab. 2013;3(3):47-56
doi: https://doi.org/10.4021/jem166e