Women who eat fatty fish, but not other fish, may cut their risk of kidney cancer by about half according to a Swedish study.

The same Swedish hospital studied men for a period of 30 years and found eating fatty fish could reduce prostate cancer risk by one third.

The main purpose of the women’s study was to see if mammography lowers deaths from breast cancer.

Researchers at Karolinska Hospital followed over sixty thousand apparently cancer-free women aged 40 to 76 years for 15 years. The main purpose was to see if mammography lowers deaths from breast cancer. Additional health data collected and analyzed included food frequency questionnaires, which participants filled out on joining the study between 1987 and 1990 and midway through in September 1997.

By 2004, after roughly 15 years of follow-up, 150 cases of renal cell cancer (RCC) were diagnosed in these sixty thousand women. One thing that stood out was that women who ate fatty fish had less risk of this cancer.

Women who ate one or more servings of fatty fish per week during the fifteen year period had about half the rate of kidney cancer compared to women who reporting no fish consumption. No association was found with lean fish consumption or other seafoods.

The researchers considered fatty fish to include salmon, herring, sardines, and mackerel; lean fish included cod, tuna, and sweet water fish; and other seafood included shrimp, lobster, and crayfish.

The authors conclude “Our study suggests that consumption of fatty fish may reduce the occurrence of RCC in women.”

See Abstract (free) and link to full article (for fee): Long-term Fatty Fish Consumption and Renal Cell Carcinoma Incidence in Women. Alicja Wolk, DMSc; Susanna C. Larsson, MSc; Jan-Erik Johansson, MD, PhD; Peter Ekman, MD, PhD. JAMA. 2006;296:1371-1376.

JAMA (Journal of the American Medical Association) is available in many US public libraries.

COMMENT:

Although the result comes from a long term study of fish eating in women only, it may have meaning for men too. The finding is consistent with earlier indications that fatty fish protects men against prostate cancer and protects men and women against heart disease and Alzheimer’s. All these diseases may have an inflammatory component.

A team at the same Swedish hospital studied men for a period of 30 years and found eating fatty fish could reduce prostate cancer risk by one third.

WebMD reported in 2004 that “New evidence may further explain why people who regularly eat heart-healthy fish seem to have a lower risk of developing Alzheimer’s disease. A new study indicates that high amounts of one of the omega-3 fatty acids found in salmon, mackerel, and herring — docosahexaenoic acid, or DHA — may protect against the memory loss caused by Alzheimer’s, even when there are already brain lesions indicating advanced disease. The study also indicates that DHA may protect against brain cell damage, similar to that seen in Alzheimer’s. ”

Mercury and pesticide contamination in fish are a concern especially for pregnant women , infants and young people. See Farmed Salmon Show High Levels of Cancer-Causing PCBs

American Heart Association says that for older people the benefits of eating fatty fish outweight the risks
Fish, Levels of Mercury and Omega-3 Fatty Acids American Heart Association

The American Heart Association recommends eating fish, “particulary fatty fish,” at least twice a week. AHA adds: “We also recommend eating tofu and other forms of soybeans, canola, walnut and flaxseed, and their oils. These contain alpha-linolenic acid (LNA), which can become omega-3 fatty acid in the body. The extent of this modification is modest and controversial, however. More studies are needed to show a cause-and-effect relationship between alpha-linolenic acid and heart disease.”