Before I discuss how much Omega-3 fatty acids you should take and what precautions you should take, I want to discuss a very important question. Can fish oil in any form be a causative factor in the development of prostate cancer. The news media recently have warned men to cut back on using fish oil because some doctors reported a higher risk of developing prostate cancer in men who had higher levels of omega-3 fatty acids in their blood plasma. This study was published in the Journal of the National Cancer Institute July 2013. The investigators looked at blood samples from a large group of men and observed that those with the highest levels of Omega--3 fatty acids were more likely to develop prostate cancer than those with the lowest levels.
This is an example of drawing faulty conclusions from a study that was not properly designed to reach a meaningful conclusion. The information was drawn from a retrospective cohort design that was initially intended to study something completely different. A proper study design would have been to observe two identical groups of men. These men would need to be matched by age, eating habits, exercise habits, smoking and drinking habits and family history of no prostate cancer. Once the groups were matched, one group would be instructed to take fish oil supplements and the other to not take these supplements. The groups would then be followed for at least ten years in order to determine whether there was a significant difference between the groups in the incidence of prostate cancer. This was not done.
A simpler way to determine whether there is a risk in having a higher level of omega-3s is to look at large populations. For example Japanese men until recently have lived in fish loving culture and have the highest levels of EPA and DHA. They also have some of the lowest rates of prostate cancer of any culture studied.
The famous American Will Rogers once said "Believe nothing that you read and only half of what you see." This study is a perfect example. I will continue taking my fish oil supplements daily.