A study just published in the Journal of the National Cancer Institute suggests that omega-3 fish oil supplements could potentially increase the risk of prostate cancer. As usually is the case when it comes to negative supplement studies, this analysis is nothing more than fear mongering.
This study followed 834 men diagnosed with prostate cancer (156 had high-grade cancer). The researchers found that, compared with men with the lowest levels of long-chain omega-3 polyunsaturated fatty acids, men in the highest levels had increased risks for low-grade, high-grade, and total prostate cancer. Higher linoleic acid was associated with reduced risks of low-grade and total prostate cancer.
The researchers concluded that men with high blood concentrations of omega-3 fatty acids had an increased prostate cancer risk, and that recommendations to increase its intake should be carefully considered with this potential risk in mind.
The first thing you should know is this study was based on data analysis. In other words, it doesn’t actually demonstrate that fish oil causes prostate cancer.
The amount of fish oil in the bloodstream was determined by a one time measurement, not an evaluation of each participant’s intake of fish or fish oil over a period of time. It simply found that when the blood lipid test was given, those with prostate cancer had more of the fish oil components in their blood than those without prostate cancer. It could be that more of the participants with prostate cancer were taking fish oil because it's commonly used to protect against cancer, and they already knew they had prostate cancer and were trying to address the situation. Furthermore, this study didn’t even look at what the men ate or what other supplements they took.
These researchers also didn’t go back and look at the relationship between fatty acid levels and the outcome of the disease. In past studies, it appears that fish oil is associated with a reduced mortality rate from prostate cancer.
For some reason, it is also mentioned in this study that the most aggressive and worse cases of cancer occurred in the oldest patients--especially those who had been taking the benign prostatic hypertrophy (BPH) drug finasteride. In addition, diabetes played a role in that those with a history of diabetes had a greater incidence of more serious prostate cancer.
There are so many holes and unanswered questions that the results, to me, seem pretty unreliable.
Many studies have definitively shown that fish oil is protective (or at least neutral) when it comes to prostate health. Here are a few such studies that show fish oil in a much more favorable light when it comes to prostate cancer. (Of course, we'll never hear about these in the media…)
- A study in the Japanese Journal of Cancer Research found that men with higher levels of omega-3 fatty acids in the blood had reduced risk of prostate cancer.
- A Lancet study of 6,272 Swedish men found that, during 30 years of follow-up, those who ate no fish had a two-fold to three-fold higher frequency of prostate cancer than those who ate moderate or high amounts.
- A study in New Zealand of 317 prostate cancer patients and age-matched controls (published in the British Journal of Cancer) showed reduced rates of cancer in those with higher levels of EPA and DHA.
- An American Journal of Clinical Nutrition study that followed 47,866 men (who at the start of the study did not have prostate cancer) over 14 years found that higher intakes of EPA and DHA lowered prostate cancer risk.
Please don't let this latest study on fish oil scare you away from this extremely beneficial and necessary nutrient. I will continue taking my omega-3s every day with total confidence, and you should too.