Science News You Can (Carefully) Use
In the July 2013 Issue of the Journal of the National Cancer Institute there is an article suggesting an association between high levels of omega-3 fatty acid in the blood and an increased risk of prostate cancer. A “ready for prime time” summary of the study appeared on the MSNBC website shortly thereafter. The MSNBC story, penned by a “senior staff writer”, drew the following conclusion: As little as two servings of fish per week could increase your risk of prostate cancer. There is so much wrong here that it is hard to know just where to begin.
Let’s take the easier problem first. News writers are rarely scientists. Science news stories are neither written nor produced as science per se, but rather as a means to entertain. News writers for mass media are looking for drama, even if it means overlooking some very salient details, which is the case here. This brings us to the second issue: drawing conclusions from research that just aren’t supported by the data.
Reasons why the above-referenced conclusion isn’t supported by the study’s research data.
- The original study was not designed to reach( or support) any of the conclusions in the article and the subsequent analysis of the article on msnbc.com.
- Other studies, which were designed to determine if omega-3 fatty acids provided a protective benefit against prostate cancer, conflict with the findings of this study. Want to know more? Try this link: http://www.ncbi.nim.nih.gov/pmc/articles/PMC3629172/
- Association is not the same as causation. Elevated omega-3 levels in men with prostate cancer is an association, it does not mean that the omega-3 caused the cancer.
- The study did not look at dietary or supplement intake by the subjects with cancer and is based on the results of a single blood test.
- Using plasma omega-3 levels (i.e., blood test) is a very unreliable method of measuring long-term omega-3 intake. Takeaway: we really don’t know how much omega-3 the test subjects actually had in their system.
- Finally, here are just a few of the confounding factors that could have influenced the findings:
- 53% of the subjects with prostate cancer were smokers;
- 64% regularly consumed alcohol;
- 30% had at least one first-degree relative with prostate cancer; and finally (my personal favorite)
- 80% of the cancer subjects were overweight or obese.
What does it mean? Given the inconsistencies of this study and the broad range of health benefits associated with omega-3 fatty acid consumption, there is no compelling reason to stop eating fish or taking omega-3 nutritional supplements on the basis of this study. Do, however, make sure your fish is wild caught and that your omega-3 supplements are pure and of high quality.
Another takeaway: Science articles produced for mass media are written at about an eighth grade reading level (roughly the same as your local newspaper). In order to keep the story simple, complex (but highly relevant) information is often left out in order to make the piece more “accessible” to the target audience. While the headlines may seem exciting and scientific, the story that follows is all to frequently just exciting.
Final takeaway: If you’re going to use mass media as your source of health science information, make sure you’re up to speed on assessing the validity, reliability and relevance of the scientific studies being covered. Don’t let an anonymous staff writer do your critical thinking for you.