The good, bad of eating fish

My dad used to love sardines. He’d sit down for a weekend lunch, use the metal key to roll back the top of the flat tin of tiny fish, (a process which fascinated me as a kid), roll them up in rye bread, and dispatch them with gusto. I didn’t appreciate the smelly, oily things back then, but dad was on to something.

Fish like sardines, herring and (my personal favorite) salmon are high in omega-3 fatty acids and help reduce the risk of heart disease, the number one killer in the United States today.

But fish can harbor toxins like mercury and polychlorinated biphenyls. The Food and Drug Administration and the Environmental Protection Agency issued a joint advisory in 2004 urging pregnant women and women who might get pregnant, nursing mothers and small children to eat two servings of fish or shellfish a week, but to stay away from fish that contain high levels of mercury. The Spokane Regional Health District warns us about eating fish caught from the Spokane River because of contamination with PCBs.

So is fish good or bad?

Researchers at Harvard Medical School set out to find the answer.

They sifted through all the studies in medical literature that looked at the good, the bad and the ugly of fish. Pooling all the studies and doing all the statistical analysis that those folks do, they found that moderate fish consumption led to a 36 percent decrease in cardiovascular deaths.

Most cardiac deaths are caused by a particularly ominous irregularity in the heartbeat called ventricular fibrillation. The heartbeat becomes so deranged that the heart muscle only quivers. Blood doesn’t make it to the lungs to get oxygen, and doesn’t flow to important organs like the brain and kidneys. Scientists think that omega-3 fatty acids act to stabilize the heart’s rhythm. It takes only a few weeks of regular fish-eating to get the protection that omega-3 fatty acids offer.

One of the omega-3 fatty acids, DHA, is important in neurological development. It is incorporated into the rapidly developing fetal and newborn brain and eyes. Studies show a relationship between the pregnant mother’s intake of DHA (usually in fish) and raised mental processing scores in 4-year-olds.

Help! Isn’t mercury in fish bad for pregnant women?

While there are studies out there that show the benefits of eating fish, especially during pregnancy, there really aren’t any that look at the effects of low levels of mercury and PCBs in humans. Some studies (not all) indicate lower neurological test scores in children exposed to low levels of mercury, so it seems prudent to limit fish that may contain high levels of mercury during pregnancy.

PCBs, also found in fish, were banned in 1977, but these contaminants persist for a long time in the environment. The concern is that PCBs may cause cancer. But the major sources of PCBs in our diet are meats, dairy products and vegetables, with fish distant in the pack. The heart benefits of fish far outweigh any cancer risks.

So, here are some common-sense recommendations, brought to you by the FDA, the EPA and the Spokane Regional Health District: Eat two 6-ounce servings of fish a week, preferably fish high in omega-3 fatty acids like salmon, herring, lake trout, albacore tuna and my dad’s sardines. Nonpregnant adults needn’t worry about mercury levels in fish, but pregnant women should stay away from swordfish, shark and tilefish, and limit their intake of albacore tuna to 6 ounces a week. (Canned light tuna is OK.) All of us should avoid fish caught from the Spokane River due to PCB contamination.

My dad, the sardine eater, ultimately died of a heart attack. I guess the sardines could only do so much to counteract the steaks and whole milk in his diet. But he was 78 years old and lived a good, full life. Love you, dad.