*I am in a five-year study regarding Vitamin D and Omega-3 (do these supplements reduce the risk for developing cancer, heart disease, and stroke in people who do not have a prior history of these illnesses). However, I do not know if I'm taking a placebo or Vitamin D/Omega-3 supplements.
UPDATE: On July 11, 2013 this made national news: Omega-3 fatty acids may raise prostate cancer risk. Effective immediately, I have stopped taking the supplement.
While I usually am not swayed by the "study of the day", I was taking the omega-3 supplement because I wanted to be part of this clinical study. I have no heart disease. So, at this point, there is no reason to be taking this supplement. And since I get my vitamin D from the Sun, I do not require that supplement either.
I did ask the people who are conducting the clinical trial about the above claim: This is their response:
I have consulted with our staff physician and this is her response to this new data:
1. these data are secondary analyses from SELECT, which was a randomized trial of selenium and vitamin E for prostate cancer prevention. That is, the study was NOT originally designed to look at fish oil and prostate cancer (unlike VITAL)
2. thus, the data are observational, not randomized (meaning, we can’t exclude the possibility that men at higher risk might have chosen to take more fish oil in the belief that this would help them – leading to the observation that high fish oil intake is associated with higher prostate cancer risk. Only a randomized trial like VITAL can answer this question)
3. even the authors admit surprise at their findings, because of “lack of a coherent mechanism” – i.e., no plausible biological explanation
Thus we do not feel that participants are at risk by taking our supplements. I hope this addresses your concerns.
I should add: Much of the medical community agrees with the above response.
For additional reading on this topic, check out: Fish Tales and Prostate Cancer