Can Omega-3 Fatty Acid and/or Vitamin D Supplementation Reduce Cancer or CVD Risk?

Gerald Chodak, MD


February 27, 2019

This transcript has been edited for clarity.

Hello. I'm Dr Gerald Chodak for Medscape. Today's topic is the potential value of omega-3 fatty acids and vitamin D3 in preventing cancer and preventing heart disease.

We know from epidemiologic studies that both of these agents have potential value, but they have not been well studied in prospective, randomized trials. Now we have presentation of results from the VITAL study, a prospective, randomized trial that began in 2010 and enrolled about 25,000 men and women.[1] Men had to be over the age of 50 years and women had to be over the age of 55 years.

[This study was] a four-arm, prospective, randomized trial. In group one, patients received 1 g of omega-3 fatty acids plus 2000 mg of vitamin D3 daily. The second group received vitamin D3 plus a placebo for omega-3. The third group received omega-3 plus a placebo for vitamin D3. The fourth group received two placebos.

The study now has a median follow-up of a little over 5 years, and unfortunately, neither agent was able to reduce the risk for heart disease or cancer, alone or in combination. On the surface, this was seemingly a negative study.

There are two important weaknesses that we should acknowledge. First, the study is relatively short, with only a median of 5 years of follow-up. It is quite possible that we would see a significant change with longer follow-up. The second problem is that only one dose of the vitamin D3 was tested, so we don't know whether higher doses would have an effect.

It is unclear whether this study will continue with longer follow-up and whether funding is available. Certainly, it is important to know the answer.

On a different note, we must acknowledge that this kind of study is critically important for truly assessing whether the supplements and other nonprescription drugs that people take really work. Far too much money is spent on them without knowing whether there is a benefit. Hopefully, in the future, that will change.

I look forward to your comments. Thank you.

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