Lately, lots of people have been claiming that seafood is an important part of a health-promoting diet for human beings. Some of the hype comes from the seafood industry, and some of it comes from people who simply want an excuse to eat seafood. In reality, the health benefits of the so-called pescetarian diets (a vegetarian diet plus seafood) result from the fact that they include a lot more starch and vegetables than is customary in the standard American diet, while excluding some of the most dangerous animal-based foods. The starch and vegetables are good for you. Avoiding meat and milk from mammals and meat and eggs from birds is good for you. Unfortunately, the wine and seafood and olive oil in the “Mediterranean” diet do more harm than good.
It has always struck me as illogical for people to call themselves vegetarian if they eat seafood, which is the general term used to include edible fish and shellfish. (Yes, there are some edible plants that grow in seawater, but they’re generally called sea vegetables rather than seafood.) Fish are not vegetables. They are animals. So are shellfish, a category that includes mollusks such as oysters and crustaceans such as shrimp and lobster. If you are eating animals, you’re not vegetarian.
Many people eat fish because they are afraid that a purely plant-based diet wouldn’t provide enough protein to maintain their health. That’s nonsense. Protein deficiency is simply not a real concern. As long as you get enough calories from any practical diet based on unrefined plant foods, you will automatically get enough protein--unless you have some bizarre digestive or metabolic disease.
Rather than worrying about not getting enough protein, most people should be worried about the effects of eating too much protein. When you eat more protein than you need, your body turns the excess amino acids to sugar, releasing toxic waste products such as ammonia and sulfuric acid. In contrast, burning carbohydrates and fats for energy produces just carbon dioxide and water. The toxic byproducts of a high-protein diet can harm the liver and kidneys, as well as promoting osteoporosis. One study showed that people from the North Slope of Alaska had high rates of bone loss as a result of their high-protein diet, even though their calcium intake was high because they were eating fish bones.
Seafood is animal tissue, and it has the same faults as any other animal tissue. It contains cholesterol, too much protein and fat, and no starch or fiber. Fish and other sea creatures don’t provide any essential nutrients that you can’t easily get from other sources. Plants contain all of the nutrients that are essential in human nutrition except for vitamin D (which you get from sunshine) and vitamin B12 (which comes from bacteria). Even the omega 3 fatty acids in fish oil came from the plants that were at the bottom of the fish’s food chain.
Another problem with animal tissue, including seafood, is the buildup of toxic substances, including heavy metals and fat-soluble chemicals such as dioxin. This problem is called bioaccumulation. The higher up in the food chain an animal is, the worse this problem tends to be. You can avoid this problem by eating plants instead of animals.
In short, the hype about a “pescetarian” diet is just hype. People are better off just eating plants.