Fish-eating linked with a reduced risk of death from prostate cancer
Posted Sep 16 2010 7:26am
Prostate cancer is the most common form of cancer in men in the Western world. However, many of these cancers are slow growing, and do not prove to be fatal. Many men, actually, will die with prostate cancer that never showed itself when they were alive. However, prostate cancer can and does kill with enough frequency to take this condition very seriously. And some men may want to do what they can to reduce the risk of developing this condition and ultimately succumbing to it.
I was interested to read a study published yesterday which assessed the relationship between one dietary factor – fish eating – and prostate cancer risk. There has been previous evidence linking higher fish consumption with lower prostate cancer risk. This latest study was a ‘meta-analysis’ of relevant studies (an amassing together of available data from more than one study) .
This review of the evidence did NOT find an association between fish consumption and risk of prostate cancer. However, and perhaps crucially, it DID find that higher fish consumption was associated with a reduced risk of death from prostate cancer. Overall, the protective effect associated with fish consumption was 63 per cent (a lot).
This finding is interesting and potentially relevant as one could argue that where prostate cancer is concerned, it is more important to reduce the risk of death of this condition rather than reduce more the incidence of this cancer. As mentioned above, a significant percentage of men will get the disease but not die from it. The suggestion is that higher fish consumption might protect against more aggressive tumours that are more likely to prove fatal.
Now, so-called ‘epidemiologica’l studies of this nature can only really be used to judge associations between things. They cannot be used to confirm ‘causality’ – in this case, the eating fish causes a reduced risk of prostate cancer. However, if the link does turn out to be causal, how might eating fish exert its protective effect?
Some species of fish (so-called ‘oily fish’, such as mackerel, herring, sardine, trout and salmon) contain an abundance of ‘omega-3’ fats, principally in the form of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). As the authors of the review point out, these fats have an anti-inflammatory effect within the body. The relevance of this is that inflammation is a potential underlying factor in the development of cancer, along with other pathogenic processes that can go alongside it such as cell proliferation and angiogenesis (the production of new blood vessels that can ‘feed’ cancer).
The authors also point to research which has found that in animal studies, omega-3 fats have some capacity to reduce the progression of cancer cells.
We don’t have all the answers regarding omega-3 and cancer, including prostate cancer. However, the fact that omega-3 fats have known anti-inflammatory effects helps explain their links with not just a reduced risk of cancer, but a reduced risk of other conditions including heart disease and dementia.
Another nutritional tactic worth considering to quell inflammation in the body is to cut back on carbohydrates that tend to disrupt blood sugar and insulin levels. For more on this, see here .
1. Szymanski KM, et al. Fish consumption and prostate cancer risk: a review and meta-analysis. Am J Clin Nutr 15 September 2010 [epub ahead of print]