Seafood Showdown: Fatty Acids vs. Heavy Metals

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Ever feel like we’ve just totally screwed ourselves with the oceans? I’m not even talking about BP’s gushing well: It’s this recent report from the Telegraph that U.K. nutritionists are now advising pregnant women to eat more fish.

Fish, of course, contains mercury, a heavy metal pollutant that comes from human industry (and, to be fair, from some natural sources like volcano eruptions). Pregnant women, children, the elderly–nutritional convention has been to watch how much you eat. Except seafood also is a rich source of omega-3s, and nutritionists now say that the fatty-acid benefits, especially for pregnant women, could outweigh the heavy-metal risks.

What benefits, you say? The star of the omega-3 cast is docosahexaenoic acid (DHA), and as The Economist tidily explains:

DHA is a component of brains, particularly the synaptic junctions between nerve cells, and its displacement from modern diets by the omega-6 acids in cooking oils such as soya, maize and rape is a cause of worry.

Many researchers think this shift–and the change in brain chemistry that it causes–explains the growth in recent times of depression, manic-depression, memory loss, schizophrenia and attention-deficit disorder. It may also be responsible for rising levels of obesity and thus the heart disease which often accompanies being overweight.

Stateside nutritionists are also changing their minds. A group has petitioned the Food and Drug Administration to adjust its stance on pregnant women’s diets, and the Department of Defense plans to launch a program to augment soldiers’ diets with omega-3s, The Economist reports. Low levels of DHA are a suicide risk factor for people in the service.

So here’s the positive take-away, if there is one: Should you wish to get more fish-based omega-3s into your diet, eating lower on the fish food chain is the best way to make that happen, keep mercury levels low, and, oh yeah, stop straining the ocean’s ecosystems by gobbling up big predators like tuna, swordfish, and grouper. (For what it’s worth, there are also plant-based sources of omega-3s, although there have been studies that shed doubt on whether they are as beneficial as the fish-based ones.)

For some excellent reading about eating lower on the fish food chain, follow the link to an excerpt from Taras Grescoe’s book Bottomfeeder, which is one of the most illuminating studies I’ve read on how to eat fish ethically. (And he’s a big fan of the omega-3s.)

Sources: Telegraph, The Economist, Bottomfeeder

Image by L. Marie, licensed under Creative Commons.

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