Doctor’s Tip: Are there health or environmental issues with seafood?

Dr. Greg Feinsinger
Doctor's Tip

Previous columns have discussed the harmful effects of an animal-based diet on human health and the health of the planet. How about fish and other seafood?


The protein in fish and other seafood is meat protein, and meat of any type — including seafood —contains cholesterol. However, seafood lacks cholesterol-raising saturated fat that land animals have. Instead, seafood has healthy omega-3 fat. (You don’t have to eat fish to obtain omega-3 though — plant sources include flax, chia, and hemp seeds; nuts — particularly walnuts; and vegan, algae-derived omega-3 supplements).

 The evidence for avoiding seafood for optimal health not as strong as the evidence for avoiding land-animal products. Seafood is eaten to some degree by several long-lived populations such as the Japanese. However, health concerns do exist.

The main problem with eating fish is bioaccumulation, where toxins like mercury and PCBs in small fish are concentrated in their flesh. Big fish eat the smaller fish, and have even higher levels of environmental toxins. This is of particular concern in pregnant women, breast-feeding women, and young children — all of whom are advised to avoid shark, bigeye tuna, swordfish, king mackerel, orange roughy, marlin, and tilefish from the Gulf of Mexico. Other people should at least limit these larger fish in their diet.

Raw and undercooked shellfish pose a high risk of bacterial contamination and should be avoided. The healthiest fish according to “How to Eat,” by Mark Bittman and David L. Katz, M.D., are wild-caught fatty fish like salmon, halibut and mackerel.

Other health concerns linked to eating fish include the following, although again these links are not as strong as with eating land animals:

  • prediabetes and diabetes
  • weight gain
  • carcinogens when fish is grilled
  • parasites such as fish tapeworm in raw or undercooked fish
  • as with meat from land animals, fish meat causes acid urine, which contributes to kidney stones


“How to Eat” points out that the fish supply is dwindling worldwide. The book notes that “there aren’t a lot of fish left,” so it recommends that if you’re going to eat fish, do so only occasionally. Wild catfish and farmed mollusks (oysters, mussels, scallops) are said to have the lowest environmental impact.

SUMMARY: “How to Eat” summarizes the seafood versus health situation like this: “Eating fish is clearly and decisively good for people when the baseline diet is anything like the prevailing American diet … Fish instead of meat: For sure. Fish instead of plants: Maybe not.”

Dr. Feinsinger is a retired family physician with special interest in disease prevention and reversal through nutrition. Free services through Center For Prevention and The People’s Clinic include: one-hour consultations, shop-with-a-doc at Carbondale City Market and cooking classes. Call 970-379-5718 for appointment, or email

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