JAPAN

Vitamin D status linked to metabolic syndrome in older adults: Furukawa study

29-Jun-2016 - Last updated on 30-Jun-2016 at 00:31 GMT

"Higher circulating vitamin D is associated with decreased likelihood of having MetS among Japanese adults," said the researchers

Related tags Metabolic syndrome Vitamin d Nutrition

Low vitamin D levels could be linked to a higher risk of developing metabolic syndrome as we age, according to a new population study from Japan.

Published in the journal Nutrition, the study used data from more than 1,700 Japanese workers in the Furukawa Nutrition and Health Study to investigate a suggested association between vitamin D levels, measured as serum 25-hydroxyvitamin D (25(OH)D), and metabolic syndrome.

Led by Shamima Akter from the National Center for Global Health and Medicine in Tokyo, the authors of the research noted that there is increasing evidence to suggest a protective role for vitamin D on metabolic syndrome (MetS).

“However, studies addressing this issue are limited in Asia and it remains unclear whether calcium could modify the association,” said the Japanese team.

“Our results suggest that higher circulating vitamin D is associated with decreased likelihood of having MetS among Japanese adults,” they added – noting that the relationship was most clear in older adults and was also found to be more pronounced in people with a high calcium intake.

Metabolic syndrome

Akter and colleagues analysed data from 1,790 Japanese workers aged between 18 and 69 years, who participated in the Furukawa Nutrition and Health Study. As part of the study, serum 25(OH)D was measured by a protein binding assay and MetS was defined according to the joint interim statement.

The team then analysed the association between vitamin D status and MetS using multilevel logistic regression that adjusted for potential confounding factors.

Compared with those with serum 25(OH)D of less than 20 ng/ml, the team found the odds of developing MetS were significantly lower in people with serum levels of between 20-29 ng/mL (odds ratio of 0.79) and more than 30 ng/ml (odds ratio of 0.52).

However, this significant inverse association was confined to older individuals (aged 44 years or older), said the team, who noted that there was inverse, but statistically non-significant, associations between 25(OH)D and each component of MetS.

Furthermore, the association between serum 25(OH)D and MetS was found to be more pronounced among subjects with high calcium intake than compared to low calcium intake.

“Although the underlying mechanisms by which serum vitamin D prevents MetS remain unclear, several possible explanations have been suggested,” noted Akter and colleagues – who pointed to previous work suggesting that vitamin D may improve insulin secretion by changing the balance of intra- and extracellular calcium pools, and a 2006 experimental study reporting that vitamin D inhibited adipogenesis.

Source: Nutrition
Published online ahead of print, doi: 10.1016/j.nut.2016.02.024
“Serum 25-hydroxyvitamin D and metabolic syndrome in a Japanese working population: the Furukawa Nutrition and Health Study”
Authors: Shamima Akter, et al