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Vitamin D deficiency associated with metabolic syndrome
In a Qatari population, more adults with metabolic syndrome were considered to be vitamin D deficient than those without metabolic syndrome, according to findings from a cross-sectional study.
“Despite the long hours of sunlight in Qatar and surrounding regions, vitamin D deficiency has been shown to be highly prevalent in this region,” Kawthar Al-Dabhani, a PhD student at the School of Public Health at Imperial College London, and colleagues wrote. “At the same time, the prevalence of [metabolic syndrome] was measured to be [approximately] 26.5%, according to the International Diabetes Federation criteria, amongst Qataris aged 20 [years] and over. ... Given the high prevalence of these two conditions in the region and the limited epidemiological evidence in this population so far, we aimed to investigate the prevalence of vitamin D deficiency, as well as the association between [metabolic syndrome] and its components with vitamin D, in the well-characterized Qatar Biobank.”
Al-Dabhani and colleagues analyzed data from 1,205 adults (702 women) from the Qatar Biobank recruited between December 2012 and February 2014. All biobank participants completed health, lifestyle and diet questionnaires, and 66 clinical biomarkers, including serum 25-hydroxyvitamin D, were routinely measured. Researchers used multivariate linear regression analyses to examine the association between metabolic syndrome, defined by International Diabetes Federation criteria, and prevalence of vitamin D deficiency, defined as serum vitamin D level 20 ng/mL or less.
Within the cohort, 64% were vitamin D deficient, with more men vitamin D deficient than women (68.6% vs. 61.3%); 25% had insufficient levels of serum vitamin D, defined as a level between 21 ng/mL and 29 ng/mL. The researchers noted that 49% of women and 25% of men reported taking vitamin D supplements.
After adjustment for age, sex, race, metabolic syndrome score and season of blood draw, researchers observed a positive association between vitamin D deficiency and the presence of metabolic syndrome (OR = 1.54; 95% CI, 1.09-2.18); age was the main confounder responsible for the statistical significance.
In those with metabolic syndrome, serum vitamin D was 8% lower (RR = 0.92; 95% CI, 0.87-0.98) when compared with those without metabolic syndrome. In analyzing individual components of metabolic syndrome, researchers found that waist circumference and high triglyceride levels were associated with lower levels of vitamin D. Researchers found no associations between the other components of metabolic syndrome or diabetes and the presence of vitamin D deficiency.
“Many mechanisms have been proposed to explain the association between vitamin D and future risk of [metabolic syndrome] component[s],” the researchers wrote. “Since vitamin D is fat soluble and could be stored in adipose tissue, it can be sequestered in the subcutaneous fat in obese individuals, reducing the levels of circulating vitamin D in the blood leading to less release of vitamin D into the blood. Vitamin D has also been shown to inhibit the release of cytokines from the immune cell, which is harmful to [beta] cells.”
The researchers noted that future studies should examine the potential causal association between vitamin D and metabolic syndrome using Mendelian randomization approaches or through vitamin D supplementation. – by Regina Schaffer
Disclosure: The researcher report no relevant financial disclosures.