Friday, October 20, 2006

Fish Oils

The FDA has decided the benefits of eating more fish outweigh the risks. ($ubscription required) There is a clear link between eating fish and reduced chances of heart disease. There is also a risk of picking up pollutants from the fish, but that is small compared to the risk of heart disease. The FDA does caution consumers to limit the amount of fish (a couple of times a week is good, three times a day could be bad) and to eat different types of fish to limit the intake of a specific pollutant. They also suggest women who are pregnant or nursing, and kids under twelve should avoid big predatory fish (sharks, swordfish, and mackerel), and limit the intake of tuna, to avoid the highest pollutant risk.

In a related story, researchers working with prisoners have discovered that an adequate supply of omega-3 in the diet reduces violent incidents by a statistically significant amount. Part of the fatty acids we eat are incorporated into the membranes of cells in the brain. The researchers speculate that cells with more omega-3 fatty acids have more flexible membranes, and pick up neurotransmitters more easily. They think that the prisoners who got a boost of omega-3 fatty acids are now more receptive to dopamine, which makes one feel good, and to seratonin, which helps with impulse control.

I'm usually quite sceptical of claims made on the behalf of foods and herbs to cause weight loss, change mood, prevent illness, etc. Those claims usually lack 1)empirical evidence, and 2)a plausible mechanism for causing the benefit. This study has both--the behavioral studies were conducted in double-blind trials (where one group gets the treatment, and the other gets a placebo, and no one knows who's getting what), and a plausible hypothesis whereby the effect is linked by the food to something we already know about how brains work. It seems fish really is brain food.

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