Cardiovascular disease (CVD) is a broad term encompassing various conditions that affect the heart or blood vessels, and it stands as one of the leading causes of mortality worldwide. As populations age and chronic diseases become increasingly prevalent, the incidence of CVD events such as heart attacks and strokes is expected to rise.

In a clinical trial recently published by The BMJ, it has been discovered that Vitamin D supplements may diminish the risk of major cardiovascular events, particularly heart attacks, among individuals aged 60 and above. The trial, regarded as the largest of its kind thus far, highlights the significance of this finding. However, the researchers emphasize that the absolute difference in risk was relatively small. They believe that further evaluation is warranted, especially among individuals who are concurrently taking statins or other drugs for cardiovascular disease.

While observational studies have consistently indicated a connection between vitamin D levels and the risk of CVD, randomized controlled trials have not found concrete evidence supporting the preventive effect of vitamin D supplements on cardiovascular events. This discrepancy could potentially be attributed to variations in trial design that may impact the outcomes.

To address the uncertainty surrounding this issue, a group of researchers in Australia conducted the D-Health Trial between 2014 and 2020. The study involved 21,315 Australians aged 60-84 who were randomly assigned to receive either a monthly capsule containing 60,000 IU of vitamin D (10,662 participants) or a placebo (10,653 participants) taken orally at the beginning of each month for a period of up to 5 years. Individuals with a history of hypercalcemia (high calcium levels), hyperparathyroidism (overactive thyroid), kidney stones, osteomalacia (soft bones), sarcoidosis (an inflammatory disease), or those already consuming over 500 IU/day of vitamin D were excluded from the study.

By analyzing data on hospital admissions and deaths, the researchers identified major cardiovascular events including heart attacks, strokes, and coronary revascularization (treatment aimed at restoring normal blood flow to the heart). The average duration of treatment was 5 years, and over 80% of participants reported taking at least 80% of the study tablets.

Throughout the trial period, a total of 1,336 participants encountered a major cardiovascular event, with 6.6% of the placebo group and 6% of the vitamin D group experiencing such events.

In comparison to the placebo group, the rate of major cardiovascular events in the vitamin D group was 9% lower, which translates to 5.8 fewer events per 1,000 participants.

When analyzing specific outcomes, the rate of heart attacks was 19% lower in the vitamin D group, and the rate of coronary revascularization was 11% lower. However, there was no significant difference in the rate of strokes between the two groups.

There were indications that the effect of vitamin D supplementation might be more pronounced among participants who were already using statins or other cardiovascular drugs at the beginning of the trial. However, the researchers note that these results did not reach statistical significance.

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

The researchers acknowledge the possibility of a slight underestimation of events and suggest that the findings may not be universally applicable to other populations, particularly those with a higher prevalence of vitamin D deficiency. Nevertheless, they emphasize that the trial was extensive, with exceptional participant retention and adherence, and comprehensive data on cardiovascular events and mortality outcomes.

Therefore, they conclude that their findings imply that vitamin D supplementation could potentially reduce the risk of major cardiovascular events. They additionally suggest that this protective effect might be more pronounced in individuals taking statins or other cardiovascular drugs at the outset of the trial. Further evaluation is recommended to gain a better understanding of this matter.

“In the meantime,” the authors conclude, “these findings suggest that conclusions that vitamin D supplementation does not alter risk of cardiovascular disease are premature.”

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