[Anticancer Effect of Fish Oil - a Fable or the Truth?].

Omega-3 fatty acids from fish oil have several health benefits for cancer patients. Recent findings indicate that, besides their well-known anti-cachectic effect, they can act synergistically with chemotherapeutic agents and may enhance tumor radio-sensitivity. The mechanisms underlying their anti-tumor effects are complex. The following effects have been reported after administration of omega-3 fatty acids: increased lipid peroxidation during therapy; disturbed tumor receptor signal pathways; lower levels level of pro-inflammatory cytokines that induce tumor cell proliferation; promotion of apoptosis in tumor tissues; immune modulation; and changes in hormonal metabolism. Epidemiological and experimental evidence support the conjecture that fish oil has an anticancer benefit for both animals and humans. However, Western countries have a diet rich in omega-6 fatty acids, which interfere with the health benefits of omega-3 fatty acids because they compete for the same rate-limiting enzymes. For this reason, the consumption of omega-6 fatty acids in Western diet needs to be lowered to observe the anti-tumor effect of omega-3 fatty acids. Some epidemiological studies report conflicting results, which may be explained by inconsistencies in the methodologies employed.