"For every PhD, there is an equal and opposite PhD." – Wilson's law
There was a recent folderol in the news about a study supposedly linking the use of omega-3 fatty acids and prostate cancer. It attracted my attention because I have recently written about the use of omega-3 fatty acids found in fish oils in decreasing and controlling cholesterol (see my patient education blog, www.IrisCityChiro.com). Many studies have found these nutrients more efficient than cholesterol busting drugs, and certainly they are much safer.
This study that was so widely reported caused quite a stir among people who gave second looks to their trusted omega-3. Making it worse was the fact that it came from an otherwise trusted source, the Fred Hutchinson Cancer Research and Institute in Seattle. The study cited was the Selenium and Vitamin E Cancer Prevention Trial (SELECT), which was originally designed to examine the relationship between vitamin E and cancer. The SELECT study has been troublesome and maligned due to design flaws.
Using the data from SELECT, researchers looked backward to find increased levels of omega-3 fatty acids among men with prostate cancer. They concluded that omega-3 presented a 71% increased chance of aggressive prostate cancer, a 44% chance of low grade prostate cancer, and they 43% overall risk. This finding sound quite ominous and causes flashbacks to all the frozen fish sticks I consumed growing up.
However, major studies can be dead wrong. Consider this: if these researchers' conclusions had merit, prostate cancer would be a leading cause of death among men with even moderate fish consumption in their diet. Studies in the larger population show just the opposite trend. In reality, the lowest prostate cancer rates on the planet are found in Southeast Asia and the Mediterranean, where fish (thus, omega-3 fatty acids that are found in the fish) consumption is very high.
There is a very powerful statistical methodology called meta-analysis, in which multiple studies that generated similar data have their data combined for a larger examination of trends. Multiple meta-analyses negate the findings of this single SELECT study that got all the news. For example, a 30 year study on over 6000 Swedish men found that men who ate no fish had a two or three fold increase in prostate cancer compared to those who did consume large amounts of fish in their daily diet. The Physician's Health Study spanned 22 years, finding that fish consumption at least five times per week reduced the risk of dying from prostate cancer by 36%. The Harvard School of Public health study followed almost 50,000 men over 12 years, observing that men who ate fish more than three times weekly reduced the risk of prostate cancer, but had an even better effect on preventing the spread of cancer into bones or organs once it occurred. In that study, every 500 mg of omega-3 that was consumed reduced the risk of metastatic disease by 24%. A New Zealand study found that higher levels of omega-3 fatty acids reduce the risk of prostate cancer by 40%.
There are many other such studies demonstrating not only the positive benefits of omega-3 consumption, but the ability of this nutrient to reduce the risk of many health problems. The overwhelming preponderance of evidence supports the use of omega-3 fatty acids on a regular basis to maintain and maximize health, particularly among those of us who do not consume large amounts of fresh fish.
How does a single flawed study garner so much attention from the press? Is something really fishy going on? Perhaps it is the hunger on the part of the press for a scoop. If you are a reporter, seeing a study like this might tempt you to report it in case it really is true in order to get ahead of the story. Maybe it gathers attention because it flies in the face of the mainstream of knowledge. It does make us wonder, though, how to make sense of information thrown at us.
When looking at published research, one must carefully critique the methodology used by the researchers in order to interpret the conclusions. The SELECT study, already criticized for design flaws, was not even focused on omega-3 from the beginning of the study. It appears that the authors were mining their own data looking for something—anything---they could publish.
Generally, studies are strengthened by the use of large samples, long periods of time (longitudinal studies), and the elimination of extraneous or interfering factors. In assessing their relevance, you should also see who funded the project. Be very suspicious when anything is funded by a drug or insurance company.
So the bottom line is that in my view, the conclusions drawn by the authors of the SELECT study were "fishy" at best. If studies were fish, SELECT would be a salmon, swimming against the stream of what is well known. I will keep taking my omega-3, and I still recommend it for you, too.