July 01, 2019
3 min read
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Vitamin D may protect against metabolic syndrome in men

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Chinese men younger than 65 years with higher levels of vitamin D in their blood are less likely to develop metabolic syndrome compared with men with lower measures, according to findings published in the Journal of Diabetes Investigation.

“Epidemiological studies show that serum concentrations of vitamin D are inversely associated with [metabolic syndrome],” Hui-Hua Li, PhD, a professor at Dalian Medical University School of Public Health in China, and colleagues wrote. “Conversely, other studies failed to replicate this relationship. ... Thus, the reports on the inverse relationship between serum 25-hydroxyvitamin D and [metabolic syndrome] remained inconsistent.”

Li and colleagues conducted a comparative, cross-sectional study based on the physical examinations of 2,585 adults aged at least 50 years that took place from 2017 to June 2018 at Dalian Port Hospital in China. The researchers measured waist circumference, HDL and LDL cholesterol levels, blood pressure, plasma glucose levels and serum 25-(OH)D levels while also calculating BMI and establishing the presence of diabetes by self-report or an HbA1c of more than 7%.

Researchers stratified the cohort by serum 25-(OH)D quartiles, including 646 participants with levels of 9.84 ng/mL or less (quartile one; mean age, 61.8 years; 77.9% women; 20.1% had diabetes), 648 with levels ranging from 9.85 ng/mL to 13.99 ng/mL (quartile two; mean age, 61.7 years; 63.3% women; 21% had diabetes), 641 with levels ranging from 14 ng/mL to 19.49 ng/mL (quartile three; mean age, 61.8 years; 52.7% women; 23.4% had diabetes) and 650 with a 25-(OH)D levels of at least 19.5 ng/mL (quartile four; mean age, 62.6 years; 40% women; 23.5% had diabetes).

In the entire study cohort, 326 cases of metabolic syndrome were identified, but significantly reduced serum 25-(OH)D was only found in men with metabolic syndrome vs. men without the condition (P = .007), according to the researchers, who added that in all participants (OR = 0.98; 95% CI, 0.96-0.99) and men alone (OR = 0.96; 95% CI, 0.94-0.98), metabolic syndrome was negatively correlated with serum 25-(OH)D in men.

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Chinese men younger than 65 years with higher levels of vitamin D in their blood are less likely to develop metabolic syndrome compared with men with lower measures.
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In fully adjusted models, participants with the highest amounts of serum 25-(OH)D (quartile four) were less likely to develop metabolic syndrome compared with those with the lowest levels (OR = 0.67; 95% CI, 0.28-0.84).

In addition to quartiles for the entire study group, the researchers created sex-specific quartiles, with men in quartile four having at least 22.91 ng/mL of serum 25-(OH)D and men in quartile one having no more than 12.08 ng/mL while women in quartile four had at least 16.92 ng/mL and women in quartile one had no more than 8.6 ng/mL. Using these quartiles, the researchers found that men with the highest levels of serum 25-(OH)D were at reduced risk for metabolic syndrome in the unadjusted model (OR = 0.51; 95% CI, 0.3-0.88) as well as when adjusting for age, how much a participant smoked or drank alcohol and physical activity (OR = 0.5; 95% CI, 0.29-0.87), and in the fully adjusted model (OR = 0.48; 95% CI, 0.28-0.84).

Based on the fully adjusted model, men younger than 65 years retained a lower likelihood for metabolic syndrome in combination with high serum 25-(OH)D (OR = 0.96; 95% CI, 0.92-1), but the significance of this finding was lost in men aged at least 65 years, the researchers wrote.

“The inverse correlation between serum 25-(OH)D concentrations and [metabolic syndrome] in men and not in women could be elucidated by the difference in age, visceral adiposity, lean muscle, free fatty acid-induced peripheral insulin resistance, hormonal regulation of body weight and lifestyle (physical exercise and vitamin supplementation), and an influence of the menopausal change,” the researchers wrote. “Health policymakers should take note that lower circulating levels of serum 25-(OH)D do not only inform the status of vitamin D deficiency but might also predict the risk of [metabolic syndrome] in men of middle-aged categories.” – by Phil Neuffer

Disclosures: The authors report no relevant financial disclosures.