Study: Fatty Fish Can Protect Against Some Cancers (Kidney and Prostate) [View All]

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Kidney Cancer:

http://www.sciencedaily.com/releases/2006/09/060920092447.htm

Fatty Fish Protects Against Cancer

If you want to avoid cancer of the kidneys, a new major study from Karolinska Institutet in Sweden shows that eating salmon or other kinds of fatty fish a few times a month would be one good way to go about it.

At the end of the 1980s, 90,000 Swedish women were sent a questionnaire on their dietary habits in connection with their mammography scan. Now, with the help of another questionnaire a decade later and the cancer registry, scientists at Karolinska Institutet have concluded that women who eat fatty fish gain significant protection against renal cancer.

At least one portion of fatty fish a week during the period (1987-2004) reduced the risk of renal cancer by 74 per cent compared with those who never ate fatty fish. The group who ate fresh fish at least once a week but for whom follow-up information were unavailable, saw a 40 per cent reduction.

"This is the first time that a link between the consumption of fatty fish and renal cancer has been studied," says Professor Alicja Wolk, one of the scientists working with the study. "The reason previous studies have been unable to demonstrate a link between fish consumption and renal cancer is that they made no distinction between fatty and non-fatty fish."

One significant difference between oily and non-fatty fish lies in how much omega-3 fatty acids and vitamin D they contain -- substances that, according to earlier cell studies, seem to protect against cancer. Fatty fish contains more omega-3 fatty acids than non-oily fish, and 3 to 5 times as much vitamin D. As fatty fish, the study included salmon, raw herring, sardines and mackerel; as non-fatty, cod and tuna (amongst other kinds).

And Some Prostate Cancers:

http://www.physorg.com/news81526973.html

In Sweden, prostate cancer is by far the most common form of cancer; in countries such as China and Japan, it is much rarer. Just why the risk of developing the disease is country-dependent is hard to know for certain, but one reason could be differences in dietary habits. Substances that have often been identified as important in this context are EPA and DHA, two omega-3 fatty acids, which are found in abundance in fatty fish such as salmon, herring and mackerel. In cell experiments, scientists have seen that omega-3 fatty acids can prevent the development of cancer, but the exact value of having an omega-3-rich diet remains an open question.

To find out whether omega-3 fatty acids in food affect the chances of developing cancer, scientists asked 1,500 Swedish men with diagnosed prostate cancer about their eating habits and then compared the answers with a healthy control group. The results strongly support the hypothesis of the healthiness of omega-3 fatty acids. Men who eat salmon more than once a week run a 43 per cent less chance of developing prostate cancer than men who never eat salmon.

The scientists also analysed blood tests to find any genetic factors behind prostate cancer. Their results show that men who carried a special variant of the COX-2 gene were the only ones to benefit from the protective properties of fatty fish. The group of men who carried this gene variant and who often ate salmon had a 72 per cent lower chance than men who never ate fatty fish.

The researchers’ explanation for this is that the gene controls the outcome when omega-3 and omega-6 fatty acids, which are found in vegetable oils, compete for inclusion in hormone-like substances in the body known as prostaglandins. Prostaglandins derived from omega-3 fatty acids are anti-inflammatory and might well counteract the development of cancer, while prostaglandins derived from omega-6 fatty acids have the opposite effect.

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Edited for emphasis