Plasma vitamin D levels and risk of metabolic syndrome in Canadians

Abstract

Purpose: Vitamin D deficiency has been implicated in susceptibility to the development of metabolic syndrome, obesity and type 2 diabetes mellitus. The present study aimed to quantify the association between vitamin D plasma level, the number of metabolic syndrome components and insulin resistance in Canadians. Methods: Vitamin D plasma level and clinical data were determined from 1,818 subjects from the Canadian Health Measures Survey; a representative health survey of the general population of Canada conducted from 2007 to 2009. The definition of metabolic syndrome was based on the National Cholesterol Education Program, Adult Treatment Panel III criteria. Adjusted general linear models were used to estimate the association between vitamin D level and probability of having metabolic syndrome, as well as the association between plasma vitamin D and insulin resistance (homeostasis model assessment for insulin resistance, or HOMA-IR). Results: The prevalence of metabolic syndrome in the study population was 8.9%. The number of metabolic syndrome components was inversely correlated with plasma vitamin D level (ρ= -0.1, p < 0.0001). Subjects in the highest vitamin D quartile had lower odds ratio of metabolic syndrome compared with their counterparts in the lowest vitamin D quartile (0.50, 95% CI= 0.24-1.06). Increasing plasma vitamin D level (by 10 nmol/L) was inversely associated with HOMA-IR score (β= -0.08, p=0.006) in a model adjusted for physical activity, smoking status, month of interview, age, sex and ethnicity. Conclusion: Vitamin D plasma levels are associated with the occurrence of metabolic syndrome components and insulin resistance among Canadians and are linked to increased level of insulin resistance.

Vitamin D and inflammation in the prevention of type 2 diabetes: public health relevance

“…proposition is supported by our recent findings that increasing plasma vitamin D level by 10 nmol/l was significantly inversely associated with HOMA-IR (p = 0.006) and results in 14% lower probability of having metabolic syndrome, a major risk factor in T2DM (CI = 0.75-0.99) [23]. To our knowledge, there are no long-term studies (≥ 6 months) examining the effects of higher vitamin D doses (≥ 4000 IU/day) on 2 hr post-challenge glucose, insulin sensitivity and secretion, disposition index, "omics"-based inflammatory markers and markers of hepatic steatosis in pre-diabetic subjects with vitamin D deficiency.…”

“…Data from the Third National Health and Nutrition Examination Survey (NHANES III) showed that serum 25(OH)D was inversely associated with T2DM and HOMA-IR [54]. We have also reported an inverse association between vitamin D serum levels and HOMA-IR in a population of non-diabetic adults [23]. This inverse association suggests that 25(OH)D may play a role in decreasing insulin resistance upon sufficiency.…”

“…Indeed, this inverse relationship between vitamin D serum levels and the risk of T2DM has been recently addressed from the perspective of the role of this micronutrient (and others) in disease intervention [56]. To further substantiate the role of vitamin D in T2DM risk, we have also reported that increasing plasma vitamin D level by 10 nmol/l can reduce predisposition to T2DM by 14% in a population of healthy adults [23]. Moreover, a higher prevalence of severe vitamin D deficiency (< 14 nmol/l) was also observed among diabetic women than healthy controls (39% in T2DM vs. 25% in controls) [52].…”

“…Prevalence of vitamin D deficiency may be higher among subjects of non-Caucasian origin [33], due to a decreased rate of ultraviolet radiation absorption by dark skin that results in diminished vitamin D production [34]. Indeed, we have shown recently that the average serum 25(OH)D concentration in individuals with dark skin color (East Asians and South Asians) is 1.5-fold lower than that in Caucasians [23].…”

“…Reduced sun exposure, either due to living in latitudes with seasonal shortages of UV radiation (e.g., in the Northern hemisphere) or due to extensive body coverage by clothes (e.g., in many countries of the Middle East), often translates into difficulties maintaining an adequate vitamin D status and a need to obtain this micronutrient orally, e.g., via supplementation [21]. The elderly, certain ethnocultural groups, and individuals with malabsorption diseases are at risk of becoming vitamin D deficient [22,23]. In addition, recent genome-wide association studies suggest that common genetic variations, e.g, in CYP2R1, may also affect vitamin D status [24][25][26].…”