Scientists from the University of Eastern Finland found that taking a much higher dose of vitamin D than recommended for five years did not affect death risk or the risks of heart disease or cancer in older men and women.
The research is published in The American Journal of Clinical Nutrition and was conducted by Jyrki K Virtanen et al.
In population studies, low levels of vitamin D in the body have been linked to an increased risk of many chronic diseases as well as premature death.
However, it cannot be directly deduced from such observational studies whether the use of vitamin D supplementation can reduce the risk of disease or death.
In the study, researchers examined data from 2,495 participants (men 60 years or older and women 65 years or older) for five years.
These people either joined the placebo group or the groups that received either 40 or 80 micrograms (1600 or 3200 IU) of vitamin D3 per day.
All participants were free of heart disease and cancer at the start of the trial and were allowed to use their own vitamin D supplement of up to 20 micrograms (800 IU) per day.
During the five years of the trial, 119 participants developed heart disease, 129 people were diagnosed with cancer and 19 died.
There was no big difference in the number of events between the groups. The vitamin D doses proved to be safe as no differences in side effects were observed between the groups.
The team also found at the beginning the mean blood vitamin D (calcidiol) concentration, was 75 nmol/L (30 ng/mL).
After one year, the mean calcidiol concentration was 100 nmol/L (40 ng/mL) in the group taking 40 micrograms of vitamin D per day and 120 nmol/L (48 ng/mL) in the group taking 80 micrograms of vitamin D per day.
The findings are well in line with other similar studies that have shown that taking higher doses of vitamin D than recommended for many years does not have a big effect on the risk of developing heart disease or cancer if the body’s vitamin D status is already adequate.
Securing one’s vitamin D intake with vitamin D supplements is still recommended, especially during the winter, if the diet is low in sources of vitamin D, such as fish or vitamin D-fortified foods.
However, the study does not support the use of large vitamin D doses for the prevention of heart diseases or cancer.
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