Vitamin D supplements may reduce the risk of major cardiovascular events such as heart attacks among people aged over 60, finds a study.

Cardiovascular disease (CVD) is a general term for conditions affecting the heart or blood vessels and is one of the main causes of death globally. CVD events such as heart attacks and strokes are set to increase as populations continue to age and chronic diseases become more common.

Published by The BMJ, the study of 21,315 people showed that the rate of major cardiovascular events was 9 per cent lower in the vitamin D compared with the placebo group (equivalent to 5.8 fewer events per 1,000 participants).

The rate of heart attack was 19 per cent lower and the rate of coronary revascularisation was 11 per cent lower in the vitamin D group, but there was no difference in the rate of stroke between the two groups.

Researchers including from QIMR Berghofer Medical Research Institute, in Queensland, Australia said their findings suggest that vitamin D supplementation may reduce the risk of major cardiovascular events.

There was some indication of a stronger effect in those who were using statins or other cardiovascular drugs at the start of the trial, but the researchers said these results were not statistically significant.

Overall, the researchers calculated that 172 people would need to take monthly vitamin D supplements to prevent one major cardiovascular event.

"This protective effect could be more marked in those taking statins or other cardiovascular drugs at baseline," said Rachel E Neale, Professor, from QIMR along with other researchers. The team suggested further evaluation to help to clarify this issue.

"In the meantime, these findings suggest that vitamin D supplementation does not alter the risk of cardiovascular disease are premature," they conclude.

The trial was carried out from 2014 to 2020 and involved 21,315 Australians aged 60-84 who randomly received one capsule of either 60,000 IU vitamin D (10,662 participants) or a placebo (10,653 participants) taken orally at the beginning of each month for up to 5 years.

During the trial, 1,336 participants experienced a major cardiovascular event (6.6 per cent in the placebo group and 6 per cent in the vitamin D group).

The researchers acknowledge that there may be a small underestimate of events and said the findings may not apply to other populations, particularly those where a higher proportion of people are vitamin D deficient.

However, this was a large trial with extremely high retention and adherence, and almost complete data on cardiovascular events and mortality outcomes.