Some studies have reported that taking vitamin D may help prevent and treat autoimmune diseases, including diabetes mellitus. A new study, however, finds no evidence to support this once the disease has developed.
Using significantly higher doses of vitamin D (greater than the daily recommended amount) for five years does not affect the incidence of type 2 diabetes in elderly men and women, according to a new study from the University of Eastern Finland.
Vitamin D is a fat-soluble vitamin. It acts in the calcium and phosphorus metabolism in its active form (1,25-dihydroxy vitamin D). The vitamin is found in foods like oily fish and egg yolks.
In population studies, low levels of vitamin D in the body have been associated with a higher risk of type 2 diabetes. However, such observational studies cannot directly conclude whether using vitamin D supplements can reduce the risk of developing the disease.
Experimental studies have shown that the use of significantly higher doses of vitamin D than recommended slightly reduces the risk of developing type 2 diabetes in individuals with impaired glucose metabolism, that is those with prediabetes.
The range of studies for non-prediabetic subjects have either used relatively small doses of vitamin D or have only been run over the short-term. There has been little in the way of research data on the effects of long-term use of high doses of vitamin D on the risk of type 2 diabetes in individuals without glucose metabolism disorders.
The Finnish Vitamin D Trial (FIND) set out to address this knowledge gap. The study ran from 2012 to 2018 and it included 2,495 men aged 60 and older and women aged 65 and older. The subject were randomised for five years into either a placebo group or groups receiving either 40 or 80 micrograms of vitamin D3 per day.
Comprehensive information was collected from the participants on lifestyle, nutrition, diseases, and their risk factors. In addition, one-fifth of the subjects were randomly selected for more detailed examinations, and blood samples were taken from them.
During the five year period, 105 participants developed type 2 diabetes: 38 in the placebo group, 31 in the group receiving 40 micrograms of vitamin D3 per day, and 36 in the group receiving 80 micrograms of vitamin D3 per day.
There was no statistically significant difference in the number of cases between the groups. In addition, the effects of vitamin D on blood glucose and insulin levels, body mass index, and waist circumference were examined during the first two years of the study, but no differences were observed between the groups.
The findings of the FIND study reinforce the view that the use of higher doses of vitamin D than recommended does not significantly affect the risk of developing type 2 diabetes in individuals without prediabetes and who already have a good vitamin D status.
The study appears in the journal Diabetologia and it is titled: “The effect of vitamin D3 supplementation on the incidence of type 2 diabetes in healthy older adults not at high risk for diabetes (FIND): a randomised controlled trial.”
