fish

New Study: Will Omega-3s Boost Your Risk of Prostate Cancer?

Two yesterdays ago, I said I was going to “post this tomorrow.” On one hand, that didn’t happen. On the other hand, a one-day delay is still more timely than usual for me, so I’m counting this as a blogging victory. Whip out the kazoos!

As some of you’ve already seen, a major study came out this week with some unexpected findings about DHA, an omega-3 fat abundant in fish. The study linked high blood levels of DHA to aggressive prostate cancer (and trans fats to lower prostate cancer rates). To date, it’s the biggest fat-and-prostate-cancer study of its kind—which makes these findings all the more peculiar. Given the widespread use of fish oil supplements for quelling inflammation and boosting cardiovascular health, it’s a little spooky to think DHA is really a double-edged sword. But is this study really a slam against fish fat?

This analysis wound up as a guest post for Mark’s Daily Apple, so head over there to read the full thing:

Overall, the study itself isn’t too shabby—and the researchers readily admitted their findings surprised them. But this study is far from a harbinger of doom for seafood lovers. The take-home points, and some additional thoughts:

  • Serum fatty acids aren’t a perfect mirror of diet—and the men with higher levels of DHA weren’t necessarily eating more fish. In fact, it seems low-fat diets can actually increase DHA status in the blood the same way omega-3 supplementation can.
  • The “highest levels of serum DHA” reported here were based on percentage of fatty acids—not absolute value. Here’s a great explanation of why percentage-based measurements may be misleading in studies like these.

Another major study, the European Prospective Investigation into Cancer and Nutrition, also found a slight (but non-statistically-significant) link between prostate cancer and DHA levels in the blood—but at the same time, found zero association between dietary fish fat and the disease. And as I wrote in the post on Mark’s Daily Apple, nearly all previous studies have shown fish consumption to have either a neutral or protective association with prostate cancer. Blood levels of DHA and dietary intake don’t seem to follow the same pattern in relation to this disease.

That said: I’m pretty weary of long-term mega-dosing of fish oil for other reasons. Thanks to all their double bonds, omega-3s are relatively unstable and prone to oxidation, just like other polyunsaturated fats. It’s quite possible that the anti-inflammatory benefits appearing short term could eventually collide with a new set of problems that take longer to appear: those stemming from oxidative stress. Moderate supplementation probably won’t cause harm, but regularly taking huge doses of fish oil should probably be done with caution. The best strategy for achieving a great omega-3/omega-6 ratio is reducing your intake of high-omega-6 foods like grains and industrial oils, rather than simply chugging back more omega-3 to compensate.

Edit: Paul at Perfect Health Diet has a more technical discussion of omega-3s, angiogensis, and cancer that does make DHA seem a little fishy. Highly worth reading!

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A Closer Look at the China Study: Fish and Disease

In my last post, I explored what the China Study data says about meat and disease—which turns out to be a far cry from what Campbell reports in his book of the same name. In a nutshell, meat has no statistically significant correlations with any diet-related disease, and actually has a negative correlation with death from all causes and death from all cancers. That means the populations that ate more meat generally had fewer chronic diseases than the populations that ate less of it. While it’s impossible to tell from the China Project alone whether this is because meat was protective of illness or simply corresponded with other helpful factors (like better health care), it does undermine Campbell’s assertion that animal product consumption always went hand-in-hand with disease in the China Project.

(If you’re not sure what the China Study is or why I’ve suddenly made it my life’s purpose to examine every modicum of its data, take a gander at the previous entry for an explanation.)

Of course, the “meat” category doesn’t include fish, eggs, or dairy—so these foods aren’t out of the hot seat yet. In this post, I’ll be looking at fish. Sushi lovers, listen up. (more…)