I'm sure that you've all seen the headlines and hype about the humble fish oil and those yummy omega-3 fatty acids down the years. Good for the heart, good for developing foetuses, good for mental health. There is even some suggestion that it might be a useful complementary therapy for some cases of autism. Blimey! Why don't they just add it to tap water.
Well, there might be a good reason for keeping an open mind about oily fish and fish oil supplements based on a new piece of research suggesting some potential drug interaction. The study in question is this one by Roodhart and colleagues* published in the journal Cancer Cell. The main message has been summarised by various news sources but the BBC carry as good as any description. Cancerous tumours generally don't like to be destroyed by the various chemotherapy drugs currently on offer. One of the ways in which they develop resistance to one drug, cisplatin, according to Prof. Emile Voest's team, is via the production of two fatty acids, an n-6 (omega-6), 12-oxo-5,8,10-heptadecatrienoic acid (KHT) and an n-3 (omega-3), hexadeca-4,7,10,13-tetraenoic acid (16:4), so-called platinum-induced polyunsaturated fatty acids, which start a chemical chain reaction leading to resistance. I should perhaps also point out that these fatty acids are made endogenously via mesenchymal stem cells. Such fatty acids are also apparently "abundantly present in commercially available fish oil products".
The point Voest and colleagues are making is that additional fish oil supplementation may not be the best course of action when such chemotherapeutics are being taken; at least until more investigations are carried out.
There are lots of interesting points to be made from research such as this. Of course there are lots of reasons for drug resistance, some genetic and some more environmental. Hippocrates (I think) was quoted as suggesting that we let food be thy medicine. I don't fundamentally disagree with this notion, but highlight the possibility that food might also be our poison as is the case of gluten in coeliac disease, or for certain food constituents as in this case, at least contra-treatment. Diet or dietary supplements and drug interactions is an important point. Grapefruit for example, has quite a few noted adverse drug interactions, which either limit the effectiveness of medications or sometimes potentially much worse. There are others being discovered regularly.
Human biochemistry is a complicated thing. Most of us try to keep the body machine in good working order through diet, exercise and the odd supplement here and there. What research like this tells us is that when taking our medicine for whatever ailment, treat your dietary supplements like the drugs they are and check with your physician about any possible interactions.
* Roodhart JML. et al. Mesenchymal stem cells induce resistance to chemotherapy through the release of platinum-induced fatty acids Cancer Cell. September 2011.