By Asha Kreiling
Sorry, pregnant ladies, no fish for you. If you’ve ever had a baby in your belly, then a doctor’s warning to limit or remove fish from your diet during pregnancy probably sounds familiar. I first heard of this while I was having a family dinner at a Japanese restaurant. My pregnant, pescetarian sister announced that she couldn’t have anything with fish, “because of the mercury.” This led me to wonder: Is fish consumption ever safe or sustainable?
Mercury is probably best known as the liquid found in thermometers. Bound up in rocks and soil, it occurs naturally and has been released into the atmosphere by volcanoes for millions of years. However, with the rise of industrialization, mercury levels in the environment have increased drastically in the past two hundred years. Metal processing, incineration of trash, mining, and industrial production, especially coal-fired power plants, are all responsible for releasing mercury into the air. It then falls from the air into streams and oceans, binds with organic molecules and turns into methylmercury, the type of mercury that causes concern.
Unlike mercury, methylmercury is readily absorbed by living tissue and is highly toxic. In bodies of water, it is absorbed by small organisms and fish, which are then consumed by larger fish, and it begins to accumulate higher up the food chain. This explains why larger, long-lived predatory fish like tuna, shark and swordfish contain higher concentrations of methylmercury than others.
When you consume fish, raw or cooked — especially fish higher up the food chain — you also are consuming the accumulated methylmercury. During pregnancy, eating fish exposes the highly sensitive fetus to the chemical as well. Too much methylmercury in your bloodstream can harm your baby’s developing immune system and cause neurological damage.
The FDA and the EPA advise eating only up to 12 ounces per week of fish or shellfish considered to have lower concentrations of mercury such as shrimp, salmon 
and catfish; but the amount of fish considered “safe” to consume is debated frequently. Most experts agree on the recommendation to avoid consumption of shark, tuna, swordfish, king mackerel and tilefish, as they contain high concentrations of methylmercury. If you fancy eating seafood, take precaution and stick to fish with lower levels of mercury. Check here for more information. http://www.nrdc.org/health/effects/mercury/guide.asp
Fish can provide healthy protein, iron, and omega-3 fatty acids to your diet, but with detrimental declines in fish populations and the accumulation of toxic chemicals up and down the food chain, one may turn to safer, more sustainable alternatives. Flaxseed oil, walnuts, canola oil and wheat germ are excellent plant-based sources for omega-3 fatty acids; and there are countless sources of healthy plant-based proteins including soy, legumes, nuts, seeds and grains.
