A large, long-term study in the U.K. has found that people who eat fish or who are vegetarians are less likely to develop cancer than people who describe themselves as meat-eaters. Surprisingly, for some types of cancer, risk was lower for those who ate fish than for strict vegetarians.
Led by a team at Oxford University, researchers studied 61,566 British men and women for several years. More than half of the people enrolled or 32,403 identified as meat eaters, 8562 as non-meat eaters who did eat fish ("fish eaters"') and 20,601 as vegetarians.
Some of the difference favoring fish consumption over vegetarianism may arise from known benefits of fish oil and some from known or risks from high consumption of dairy foods.
The authors write: "Vegetarians do not eat meat or fish. Meat has been suspected of influencing the risk for several types of cancer."
A previous study concluded that "both red meat and processed meat are convincing causes of colorectal cancer, and . . . there was some evidence suggesting that high intakes of red or processed meat increased the risk for cancers of the oesophagus, stomach, pancreas, lung, endometrium and prostate."
This current study, after an average follow-up of 12.2 years, found that prostate cancer risk "did not differ significantly between the dietary groups, although there was a significantly lower risk among fish eaters compared with meat eaters."
The authors say that the role of diet in prostate cancer "is poorly understood." The cite "some evidence that high intakes of dairy products might be associated with an increase in risk (Chan et al, 2005)."
As for vegans, who are vegetarians who do not eat dairy foods or eggs, this study did not find enough begans with cancer to include. The authors say: "to explore this hypothesis further in our data we would need to examine the cancer rates among vegans, among whom there are currently too few cancers to be informative."
Published June 16, 2009 British Journal of Cancer (BJC). the study is available free online:
Cancer incidence in British vegetarians
By T J Key, P N Appleby, E A Spencer, R C Travis, N E Allen, M Thorogood and J I Mann.
Chan JM, Gann PH, Giovannucci EL (2005) Role of diet in prostate cancer development and progression. J Clin Oncol 23: 8152–8160