Omega-3s and Vitamin D: Are They Beneficial for CVD, Cancer Prevention?

Although previous findings have been mixed, a large study suggests omega-3 fatty acid and vitamin D supplementation may confer some preventive benefits when it comes to cardiovascular disease (CVD) and cancer, according to new research presented at the 2019 North American Menopause Society Annual Meeting.¹

Researchers arrived at their conclusion after performing the VITamin D and OmegA-3 TriaL (VITAL) – a nationwide, randomized, placebo-controlled, 2x2 factorial trial that included 25,871 US men aged at least 50 years and women aged at least 55 years. Of these participants, 5106 were African American. Specifically, the researchers measured the impact of 2000 IU vitamin D3 per day and 1 g marine omega-3 fatty acids per day in the primary prevention of CVD and cancer. Median treatment duration was 5.3 years.

Ultimately, omega-3 supplementation was not associated with a significant reduction in the primary cardiovascular endpoint, which was a composite of major CVD events including myocardial infarction (MI), stroke, and CVD mortality (hazard ratio [HR] 0.92). Furthermore, omega-3 supplementation was not associated with reductions in stroke or other CVD endpoints.

However, omega-3 fatty acid supplementation was linked to significant reductions in total MI (HR 0.72), percutaneous coronary intervention (HR 0.78), and fatal MI (HR 0.50). For MI risk, omega-3 fatty acid supplementation conferred the greatest benefit among African American participants. For major CVD events, omega-3 fatty acids provided a treatment benefit in participants with a dietary fish intake below, but not above, the cohort median of 1.5 servings per week.

Although omega-3 supplementation was not found to be associated with cancer endpoints during the full trial period, a signal for a slight increase in total cancer incidence was observed after excluding the first 2 years of follow-up (HR 1.13).

Vitamin D supplementation did not appear to reduce major CVD events (HR 0.97), other cardiovascular endpoints, or cancer incidence. However, vitamin D supplementation was associated with a suggestive 17% decrease in cancer mortality. In analyses excluding early follow-up, this association strengthened to a statistically significant 25% decrease in cancer mortality. Reductions in cancer incidence and mortality were observed in participants with normal weight (defined as a body mass index of less than 25 kg/m2), but not in those with overweight or obesity. The researchers also observed suggestive benefits for cancer incidence in African Americans.

“The pattern of findings suggests a complex balance of benefits and risks for each intervention and points to the need for additional research to determine which individuals may be most likely to derive a net benefit from these supplements,” said lead study author JoAnn Manson, MD, NCMP, from Brigham and Women's Hospital, in a press release.²

—Christina Vogt

References:

1. Manson JE. Vitamin D and omega-3 fatty acids: do they prevent cancer or cardiovascular disease? Paper presented at: North American Menopause Society Annual Meeting; September 25-28, 2019; Chicago, IL.
2. Vitamin D and fish oil show promise in prevention of cancer death and heart attacks [press release]. Cleveland, OH. North American Menopause Society. September 24, 2019. Accessed September 24, 2019.