Vitamin D Supplements Demonstrate Potential to Reduce Heart Attacks and Major Cardiovascular Events

A recent clinical trial has shed light on the potential benefits of vitamin D supplements in reducing the risk of major cardiovascular events, including heart attacks, among individuals aged 60 and above. The study revealed a noteworthy 9% decrease in such events among those who were taking vitamin D, indicating the need for further investigation, particularly in individuals concurrently using cardiovascular medications.

According to the findings published on June 28 in The BMJ, monthly doses of vitamin D may offer protection against heart attacks in people over the age of 60. The researchers emphasize that although the absolute difference in risk was small, this trial stands as the largest of its kind to date and justifies additional evaluation, especially in those who are taking statins or other drugs for cardiovascular diseases.

Cardiovascular disease (CVD) encompasses various conditions that affect the heart or blood vessels and remains one of the leading causes of mortality worldwide. As populations continue to age and chronic diseases become more prevalent, the occurrence of CVD events such as heart attacks and strokes is expected to rise.

While observational studies consistently suggest a link between vitamin D levels and the risk of CVD, randomized controlled trials have previously failed to provide evidence supporting the preventive effects of vitamin D supplements on cardiovascular events. This discrepancy may be attributed to differences in trial design, which can impact the results obtained.

To address this uncertainty, a team of researchers in Australia conducted an investigation to determine whether monthly supplementation of vitamin D in older adults alters the incidence of major cardiovascular events. The D-Health Trial, conducted from 2014 to 2020, involved 21,315 Australians aged 60-84 who were randomly assigned to receive either one 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 up to 5 years.

Participants with a history of hypercalcemia (high calcium levels), hyperparathyroidism (overactive thyroid), kidney stones, osteomalacia (soft bones), sarcoidosis (an inflammatory disease), or those already taking more than 500 IU/day of vitamin D were excluded from the trial.

The researchers analyzed data on hospital admissions and deaths to identify major cardiovascular events, including heart attacks, strokes, and coronary revascularization (treatments 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, 1,336 participants experienced a major cardiovascular event (6.6% in the placebo group and 6% in the vitamin D group).

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

Furthermore, the vitamin D group exhibited a 19% lower rate of heart attacks and an 11% lower rate of coronary revascularization, although no significant difference in the rate of strokes was observed between the two groups.

While the results indicated a potential stronger effect in individuals who were already using statins or other cardiovascular drugs at the beginning of the trial, the researchers note that these findings did not reach statistical significance.

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

It should be noted that the researchers acknowledge a slight underestimation of events and caution that the findings may not be applicable to other populations, particularly those with a higher prevalence of vitamin D deficiency. Nonetheless, the study was extensive, with exceptional participant retention and adherence, and comprehensive data on cardiovascular events and mortality outcomes.

Consequently, the findings suggest that vitamin D supplementation may indeed reduce the risk of major cardiovascular events. The researchers add that this protective effect could be more prominent in individuals using statins or other cardiovascular drugs at the start of the trial and recommend further evaluation to gain a clearer understanding of this matter.

In conclusion, the researchers argue that premature conclusions regarding the ineffectiveness of vitamin D supplementation in altering cardiovascular disease risk should be avoided based on these findings.

Reference: Thompson, B., Waterhouse, M., English, D.R., McLeod, D.S., Armstrong, B.K., Baxter, C., Romero, B.D., Ebeling, P.R., Hartel, G., Kimlin, M.G., Rahman, S.T., van der Pols, J.C., Venn, A.J., Webb, P.M., Whiteman, D.C., Neale, R.E. (2023). Vitamin D supplementation and major cardiovascular events: D-Health randomised controlled trial. The BMJ. DOI: 10.1136/bmj-2023-075230

Funding: National Health and Medical Research Council

Frequently Asked Questions (FAQs) about Vitamin D supplementation

More about Vitamin D supplementation

• The BMJ: Vitamin D supplementation and major cardiovascular events: D-Health randomised controlled trial
• National Institutes of Health (NIH): Vitamin D Fact Sheet for Health Professionals
• Mayo Clinic: Vitamin D
• American Heart Association: Vitamin D and Heart Health