Good Things Come in [Omega] Threes

By Rachel Johnson, Ph.D, M.P.H., R.D., January/February 2007

"Fish fats" prove a powerful way to protect the heart.

As someone with a family history of heart problems, I struggle with far-from-perfect cholesterol numbers. I’m ever hopeful for a science breakthrough I can act on. I once ate oats every day for three months in an attempt to nudge my lipid values into healthier ranges; it worked, but alas, not enough. I still enjoy my oat cereal, but I know I need to do more. Lately, I’m eating more fish.

Last October, Harvard scientists analyzed two decades of research and concluded that modest consumption of fish (one to two servings per week), especially salmon, tuna and other types rich in the fatty acids known as omega-3s, reduced risk of heart disease death by 36 percent and overall deaths by 17 percent. The data were so compelling the authors claimed the health benefits of eating seafood outweigh the risks of exposure to environmental contaminants in fish such as methyl mercury or PCBs. (That said, women who are nursing, pregnant or planning to become pregnant and children younger than 12 should avoid fish with higher mercury levels, such as swordfish.)

Ever since my grad-student days I’ve been intrigued by the story of pioneering epidemiologists who sought to learn why heart disease was practically unheard of in Greenland’s Inuit people—despite their diet of high-fat, high-cholesterol whale and seal meat. The scientists discovered that two omega-3 fatty acids predominant in fish—eicosapentaenoic acid (EPA) and docosahexanoic acid (DHA)—were widespread in the Inuit blood and were likely protecting their hearts.

How? When it comes to fats, we are what we eat: our cell membranes reflect the fat content of our diet. When we eat ample omega-3s, our membranes—including those of the heart and blood vessels—are more elastic (that’s how fish stay flexible in icy waters). Blood moves through the body more easily, reducing the risk of high blood pressure and blood clots. All this can help prevent hardened arteries and stroke, and lowers risk of an irregular heart rate. Lastly, EPA fights inflammation, a known disease risk factor. Inflammation is the body’s normal response to injury, but chronic inflammation seems to play a role in causing hardened arteries and other heart problems.

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