The health benefits of eating the Omega-3 amino acids found in fish may not outweigh the cost to the oceans of our continued fishing, according to an analysis in the Canadian Medical Association Journal this week.
Dr David Jenkins argues that although some studies show that eating fish rich in Omega 3 oils can prevent heart disease and other chronic illnesses, the evidence is not hugely convincing compared to the evidence for the dramatic falls in fish stocks worldwide.
Looking at the results from many individual studies, along with meta –analyses which themselves take many studies into account; they found that there is a suggestion that higher Omega-3 consumption could lead to a 15% benefit in the prevention of cardiovascular disease. Some of the studies they looked at found benefits in only a few situations, and follow up studies occasionally showed the benefit to have reversed 3 years later.
In contrast, the evidence for falling fish stocks and collapsing populations is as compelling as it is frightening. Fish catches have not increased since the early 1990s, despite increased fishing effort, and the percentage of collapsed stocks has been increasing exponentially since the 1950s.
There are also socio-economic factors to consider, such as the fact that collapsed fisheries in the United States, Europe and Japan mean that these countries are increasingly relying on importing fish from developing countries. This means that these countries either have to allow foreign fishing fleets into their waters, or export their fish to foreign markets, depriving local communities of an important source of protein. Food security is just one contributing factor to political and social instability, and these countries often face nutrition and health challenges.
Even farming fish may not be the solution. To farm Salmon, Blue fin Tuna or Sea Bass, you need to feed them a high-protein diet of fishmeal and fish oils – ironically, farming fish puts even more pressure on wild fish stocks, and it actually takes between 2.5-5kg of feed fish for every 1kg of farmed fish produced.
There is a potential solution – bacteria, and genetically modified yeasts and plants may be able to supply our Omega-3 needs, but these sources have not been properly investigated to determine what doses would be healthy, and cannot yet supply the demand.
The report concludes by saying: “Until renewable sources of long-chain omega-3 fatty acids become more generally available, it would seem responsible to refrain from advocating to people in developed countries that they increase their intake of long-chain omega-3 fatty acids through fish consumption.”
Food for thought.
Ref: David J.A. Jenkins, John L. Sievenpiper, Daniel Pauly, Ussif Rashid Sumaila, Cyril W.C. Kendall, Farley M. Mowat , Are dietary recommendations for the use of fish oils sustainable?; Canadian Medical Association Journal; March 17, 2009; 180(6); pp. 633-637