Fish eat worms and vice-versa
Over the past few years there have been several reports of live or dead parasitic worms in fish that is sold in supermarkets, big box stores and in restaurants that specialize in sushi. The past couple of months have seen more stories. This is not really news. I learned in medical school that we should avoid undercooked Great Lakes whitefish because of the possibility that an uncooked tapeworm might take up residence in our intestines. Uncooked is the key word. Thoroughly cooked and no longer alive, parasitic worms and their eggs are no threat to our health.
Worms are the largest parasites that live in the bodies of the animals that we have relied on for food for thousands of generations. Fresh water fish often contains the above-mentioned tapeworm’s eggs that hatch in the human digestive tract. Salt-water fish contain several species of worms, and salmon that spend their lives in both salt and fresh water carry them as well. Commercial cod fishermen often find their catch riddled with worms. When sushi is made from fish that has not been frozen there is a risk that a worm within it might make some customer’s stomach its new home.
The term parasite comes from the Greek words for alongside food and they recognized that such creatures were quite common in our food supply. In developing countries parasites are so common that virtually one hundred percent of the population carries them in the intestinal tract. That might explain why autoimmune diseases seldom occur in those groups. A new field of medical research, helminthic therapy, is exploring the ways in which certain parasitic worms favorably influence the course of multiple sclerosis, ulcerative colitis, celiac disease and asthma.
To be sure, parasitic worms are responsible for a host of diseases. Patients infected with fish tapeworm may develop anemia. Sushi lovers sometimes encounter worms that cause severe pain and discomfort when they attach themselves to the lining of the stomach. Trichinosis used to be fairly common when pigs were fed infected meat from other pigs; it still occurs among hunters who eat improperly cooked bear meat.
Finding a live worm – or several – in a package of store-bought fish can be unnerving and the product should be discarded (or returned for a refund). Cooking destroys worms that might not have been noticed, and so does freezing. Sushi restaurants usually – but not always – freeze their fish before it is prepared and served.
And who knows? Well-cooked worms might be good for you!
Humans have a natural aversion to physical activity. It’s actually hard-wired in us because it’s a survival mechanism: if we expend less energy we will retain more stored energy in the form of fat or glycogen*. Even hunter-gatherers of today rest whenever they are not engaged in something.
Our modern levels of physical activity are so low that we should go out of our way to burn off calories whenever possible. Persons on a diet should seek out ways to do that, even if the movement is not strenuous. Use your car as little as possible. When you do drive, park at the farthest corner of the lot. Takes the stairs instead of the elevator. Those few extra burned calories a day will add up.
Don’t go more than three or four days without moderate exercise, even if it’s only a half-hour walk in your neighborhood. Do a few push-ups while you’re watching the evening news.
* – Glycogen is also known as animal starch. It is composed of chains of glucose molecules and is stored mainly in the liver and muscles.