Sunday, November 19, 2006

More press for fatty fish, Eat 1-2 times/week

Fatty fish linked to lower kidney cancer risk in women

Many studies have found a relationship between regularly eating fish and a reduced risk for heart disease and stroke. But with respect to fish and cancer, the research has been less consistent, and much of it has failed to distinguish between lean fish and fatty fish. The distinction is important: While lean and fatty fish are both good sources of protein, fatty fish are far richer in omega-3 fatty acids and vitamin D — essential nutrients that various studies associate with reduced cancer risk.

According to the results of a long-running nutritional investigation in Sweden, where fish consumption is high, women who regularly eat fatty fish have a lower risk for renal cell carcinoma than women who don’t eat such fish on a regular basis. Renal cell carcinoma accounts for more than 90% of kidney cancers. Each year, more than 14,000 American women are diagnosed with kidney cancer, and more than 4,000 die of it.
The Swedish researchers investigated the association between the risk of developing renal cell carcinoma and consumption of fatty versus lean fish in 61,433 women, ages 40–76. The investigators collected dietary data at the beginning of the study and again 10 years later and followed the women for an average of 15 years. They identified as fatty fish salmon, herring, sardines, and mackerel. Lean fish included cod and various freshwater species.

Women who reported having at least one weekly serving of fatty fish (both when they entered the study and again 10 years later) were 74% less likely to develop renal cell carcinoma than those who ate little or no fatty fish. No similar benefit was found for eating lean fish or other seafood, such as shrimp, lobster, or crayfish. The findings were published in the Sept. 20, 2006, Journal of the American Medical Association.

According to the study authors, several mechanisms could explain how fatty acids — in particular, eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) — might influence the development of cancer. These include their role in producing compounds that affect inflammation, cell proliferation, and new blood vessel growth (angiogenesis) triggered by malignant tumors. Fatty fish are also rich in vitamin D; other studies have found an association between low blood levels of vitamin D and renal cell carcinoma.

This is the first study to find a relationship between fatty fish consumption and kidney cancer risk, so its findings will need to be corroborated. In the meantime, there’s no harm (and many benefits) in including fatty fish in your diet. Several health agencies already recommend eating fish several times a week, with an emphasis on fatty varieties, which include anchovies, bluefish, herring, mackerel, salmon, sardines, fresh albacore tuna, halibut, and lake trout.

All rights reserved.Harvard Women's Health Watch Volume 14 - Number 3 - November 2006

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