DEAR DR. BLONZ: I have been reading about our bodies' need for enzymes. While the companies selling enzyme supplements certainly have an interest in promoting their importance, I'm concerned that there is something to their claims. Does cooking really destroy enzymes, and do we stop producing them as we age? -- E.I., Oakland, California
DEAR E.I.: A defining characteristic of an enzyme is that it effects change in another substance while remaining unchanged itself. The enzymes in our body are specialized proteins that not only help us make use of the energy in foods, but also play a role in the building and taking apart of complex substances.
There are situations where it might be reasonable to take an enzyme supplement. For example: Many adults no longer produce a sufficient amount of lactase, the enzyme that breaks down the lactose carbohydrate found in milk. The symptoms of "lactose intolerance" can include intestinal gas, cramping and diarrhea. Taking lactase supplements with milk products can reduce the annoying side effects. Another popular enzyme supplement (Beano) is based on alpha-galactosidase, an enzyme that helps digest a type of carbohydrate found in beans and some other vegetables.
There are also medical situations in which dietary enzymes might be prescribed. The pancreas produces many of our digestive enzymes. If a medical problem develops that affects the pancreas's ability to either produce or deliver its enzymes to the digestive tract, the body will be unable to digest and absorb a variety of essential nutrients.
Problems with enzymes can also be experienced by those who have undergone a gastric bypass. Those with such issues would have a legitimate reason to take specialized enzyme supplements.
But what about those who don't have an enzyme-related malady?
There is an unsubstantiated theory that our lifespan is closely intertwined with our ability to produce enzymes. It is based on the dubious idea that we can only manufacture a fixed amount of enzymes in our life; when we run out, the game, so to speak, is over. The theory posits that fresh fruits and vegetables contain "live enzymes." By eating a diet rich in raw, whole foods (because cooking kills the enzymes, they say), or by taking enzyme supplements, we effectively spare the "drain" on our bodies' resources and help extend our lives.
There is no foundation for this enzyme theory, especially the part about the body having a fixed amount of enzymes. Fresh foods are healthful not because they contain enzymes, but because they are our richest source of nutrients and phytochemical substances. Given that enzymes are protein substances, those in foods will be inactivated in the stomach's acid environment and disassembled by the protein-digesting enzymes in our digestive tract.
By all means, eat and enjoy fresh, whole plant foods -- but don't hold them in any special esteem for their enzymatic powers.
Send questions to: "On Nutrition," Ed Blonz, c/o Universal Uclick, 1130 Walnut St., Kansas City, MO, 64106. Send email inquiries to email@example.com. Due to the volume of mail, personal replies cannot be provided.