Many nutritional guidelines suggest eating fatty fish several times a week or taking fish oil capsules. Do we really need to eat this much fish, and if so, how long before the world is fished out? This is discussed in an article in an upcoming article in the Canadian Medical Association Journal (Jenkins et al.).

In the news, at least once a month, there are stories about topics such as crashes of different populations of fish, dead zones, and reductions in fishing quotas. The numbers of fish were declining rapidly even before this recent push for eating fish or fish products. As more and more people increase the amount of fish or fish oil that they consume, the decline in fish stocks worldwide will be even more rapid.

At what point are there so few of some types of fish that they become extinct? What does this selective removal of parts of food chains do to the oceans and lakes? Algal blooms? Jellyfish swarms? Upsurge in inedible species? Changes in the climate? We can guess, but nobody really knows.

From a health point of view, do we really need to eat fish? I might say no, since I hated fish as a kid. We lived inland and the only fish we could buy was a bit old. I refused to eat it, and did not like to be around anybody eating it. I had to be in my thirties the first time I ate fish, and now probably eat it about 4 times per year. I seem to be healthy enough.

The health evidence for eating fish or fish oil is probably slightly on the positive. There are many reports of lowered triglycerides (a type of blood fat, that is increased in poorly-controlled diabetes, obesity, liver disease etc.), lowered risk of cardiovascular events such as heart attack. However, there are also quite a few reports where consumption of fish or fish products made no difference.

The main component in fish that are thought to have benefits are the omega-3 fatty acids. It is now thought that it not the amount of omega-3 fatty acids that are consumed, but the ratio of omega-3 to omega-6 fatty acids. The modern diet has increased amounts of omega-6 fatty acids particularly from oils such as corn and soybean, and decreased the amount omega-3 fatty acids from nuts and a range of plants, that we eat.

Walnuts are a good source of omega-3 fatty acids, and flax meal is now widely available, and a number of fruits, such as kiwifruit, and plants, such as broccoli, have reasonable levels of the omega-3 fatty acids. Apparently, omega-3 fatty acids from a brown alga (kelp) are used in infant formula, and yeast are being engineered to make high levels of omega-3 fatty acids. Perhaps non-fish omega-3 fatty acid supplements and capsules will soon be widely available.

Should we start to again eat more plant and less fish omega-3 fatty acids, as well as less omega-6 fatty acids?

photo credit: Donna S Rutherford

[tags]fish, fish oil, omega-3 fatty acids, omega-6 fatty acids[/tags]