Fatty fish protects against cancer

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).

The study is to be published in the Journal of the American Medical Association (JAMA) on 20 September.