Fish

Is fish a health food? The question is, compared to what? Compared to some of the healthiest foods—for example, fruits, vegetables, beans, and whole grains—fish are low in antioxidants and phytonutrients, lacking fiber, and do contain some cholesterol and saturated animal fat. While the consumption of whole plant foods has been associated with longer protective telomeres, the tips on each of our chromosomes that keep our DNA from unraveling and fraying, in contrast, consuming refined grains, soda, dairy, and meat, including fish, has been linked to shortened telomeres, a sign of cellular aging.

Unless one can access a time machine and teleport back to the days before the Industrial Revolution, fish will remain the leading source of many toxic pollutants. In 2012, researchers published an analysis of the diets of kids aged two to seven. (Children are thought to be especially vulnerable to chemicals in the diet because they are still growing and thus have a comparatively greater intake of food and fluids relative to their weight.) Chemicals and heavy metals in kids’ bodies from the foods they ate were indeed found to exceed safety levels by a larger margin than in adults. Cancer risk ratios, for instance, were exceeded by a factor of up to 100 or more. For every child studied, benchmark levels were surpassed for arsenic, the banned pesticide dieldrin, and potentially highly toxic industrial by-products called dioxins. They were also too high for DDE, a by-product of DDT.

Which foods contributed the most heavy metals? The number-one food source of arsenic was poultry among preschoolers and, for their parents, tuna. The top source for lead? Dairy. For mercury? Seafood. Eating just a single serving of fish each week during pregnancy, for example, can lead to more mercury in their infant’s body than injecting them directly with about a dozen mercury-containing vaccines.

Where in the food supply are these pollutants found? Today, most DDT comes from meat, particularly fish. The oceans seem to have become, essentially, humanity’s sewer: Everything eventually flows into the sea. The same is true when it comes to dietary exposure to PCBs—another set of banned chemicals. A study of more than 12,000 food and feed samples across 18 countries found that the highest PCB contamination was found in fish and fish oil, followed by eggs, dairy, and then other meats. The lowest contamination was found at the bottom of the food chain, in plants.

Hexachlorobenzene, another pesticide banned nearly a half century ago, today may be found mainly in dairy and meat, including fish. Perfluorochemicals, or PFCs? Overwhelmingly found in fish and other meats. The contaminants in fish may help explain studies showing an association between fish consumption and diabetes. To lower our pollutant exposure, we should try to eat as low on the food chain as possible.

Image Credit: SvetlanaK / Thinkstock. This image has been modified.