Nutritionally Enriched

The mineral zinc is essential to your health, but dietary deficiencies are on the increase. Vermonters in particular may be getting less in their foods. How can this be?

Zinc is probably best recognized as a treatment for metal - called galvanized metal - that slows the rusting process. Metals such as nails, water pipe, and sheet metal are dipped and coated in zinc. This prevents corrosion and greatly extends their life. Would adequate dietary zinc extend your life span too? Most likely! But you won't be coated with it - its biological functions are quite different.

Zinc functions primarily as part of hundreds of enzymes. Enzymes are cellular catalysts that speed up the rate of chemical reactions so that they happen much more quickly than they would in a laboratory test tube. There are thousands of enzymes in every cell in your body, and they operate continuously to keep cellular mechanisms working rapidly. If even one enzyme fails, a lot can go wrong.

Although enzymes are made mainly of protein, some require zinc in their structure. If zinc is deficient many enzymes stop functioning. Among the hundreds of things they do, here are just a few. They are needed for skin growth, bone growth, sexual development, ability to taste, reproduction, embryonic development, blood formation, wound healing, and antibody production.

In a severe zinc deficiency, hair falls out and the skin appears rough and dark. Movie stars and cosmetologists sometimes promote zinc supplements to keep your skin young and beautiful. Sorry, it doesn't quite work that way; zinc is used in make-up powders and in that sense you do coat yourself with zinc, but that doesn't make you healthier. (Yes, zinc oxide ointment is used for skin infections, but that's not a nutritional effect).

A curious case of zinc deficiency occurs in children. If severely deficient, they do not grow well and do not develop sexually. At 18-20 years of age, they look like they are 10-12 years old. In girls, there is little breast development, lack of pubic hair and immature body shape. In boys, they retain central baby fat, penises do not grow, and muscles remain immature. This occurs because zinc is needed for the production of sex hormones, and the deficiency is sometimes referred to as nutritional castration. Add zinc to the diet and normal development restarts within weeks. It's really quite remarkable. This has been seen mostly in the Middle East.

Although such severe zinc deficiencies are rare in the U.S., marginal or borderline deficiencies seem to be on the increase. We now know that dietary zinc is needed for our immune systems to function properly, and if deficient, the risk of getting a viral or bacterial disease increases. Because higher amounts of zinc are found in eyes and prostate glands, it's been proposed that zinc also prevents macular degeneration and prostate cancer. This is being tested, and we shall see. Zinc deficiency can also lead to diabetes, problems with taste and smell, poor wound healing, and sick babies.

Food, not supplements, is the best way to get zinc. The best food source is meats, next are unrefined grains. So a highly refined diet lacking in meat is a culprit in causing borderline zinc deficiencies. Yes, vegetarians can especially be at risk. But because zinc leaches from galvanized metals into water and food, the increase in marginal deficiencies is also associated with the replacement of galvanized metals with plastic and other materials.

Maple syrup (the real stuff we Vermonters use) was once considered the most potent source of zinc. We use lots of it on pancakes, ice cream and cereal. But now galvanized sap buckets are being replaced with plastic tubing and stainless steel is used in the construction of sap evaporators instead of galvanized sheet metal. Alas, our intake of zinc in Vermont is decreasing. So as technology changes, our health is becoming less and less galvanized. -and that's the uncoated truth.

As a professor of Animal Science and Nutrition and Food Sciences at UVM, Shelburne resident, Lyn Carew, has taught more than 20,000 students. He has received many teaching awards at UVM, plus two national recognitions. He was named Carnegie Foundation Vermont Teacher of the Year in 2001. The Shelburne News is pleased to be able to share Lyn Carew's expertise in the latest nutritional information with our readers once a month.