The Furukawa Nutrition and Health Study assessed the data of 1790 factory workers, aged 18 to 69, who participated in a health survey at the time of a periodic health check-up. 1620 were male, 170 were female.
Writing in the journal Nutrition, academics in Japan said increasing evidence had suggested a protective role of vitamin D on metabolic syndrome.
However, studies addressing this issue were limited in Asia and it remained it unclear whether calcium could modify the association.
“Therefore, we examined the association of serum vitamin D) status with metabolic syndrome, and the potential effect modification by calcium intake in a Japanese working population,” they stated.
“Although there is no consensus on optimal levels of circulating vitamin D, levels below 20, 20 to 29, and over 30 ng/mL are considered by most experts to be deficient, insufficient, and sufficient, respectively, and we divided participants according to this definition.”
The proportion of participants with vitamin D deficiency and insufficiency were 40.8% and 51.4%, respectively.
Subjects with higher vitamin D levels were more likely to be older and male, current alcohol drinkers, physically active, and to have a higher intake of calcium.. They were less likely to be current smokers or engaged in shift work.
An assessment of the 219 subjects who had metabolic syndrome, researchers found “the odds of metabolic syndrome decrease steadily with increasing vitamin D levels.”
The link was also stronger in older individuals, aged over 44, and those overweight or obese.
It was also more pronounced among subjects with high calcium intake.
Although the underlying mechanisms by which vitamin D prevents metabolic syndrome remain unclear, several possible explanations were put forward, such as improving insulin secretion, preventing adipogenesis, and reducing body fat.
The paper concludes: “Higher vitamin D levels were associated with a lower likelihood of having metabolic syndrome among Japanese working adults, especially among relatively older individuals or those with high calcium intake. Longitudinal studies are required to confirm this cross-sectional association.”
“Serum 25-hydroxyvitamin D and metabolic syndrome in a Japanese working population: The Furukawa Nutrition and Health Study”
Authors: Shamima Akter, et al.