September Views of the Vis from WellSpring Naturopathic

What's this? A sink? - No, this month's Of the Month topic is ZINC, not sink! Okay, so the picture of zinc just isn't very exciting. Plus, did it make you smile? (See last month's "Of the Month"!) Anyway, isn't it kind of weird thinking about metals in our bodies? They're there and they're important!
Zinc as an Element. Zinc, abbreviated Zn and with an atomic number of 30, is the 24th most abundant element in the Earth's crust. It was used as an alloy long before it was identified as a separate element, being found in coins, weapons and ornaments thousands of years old. Today, zinc's most common use is in galvanization - which is basically coating something to prevent it from rusting. It is also a component in brass and solder, and has several other industrial uses.
Zinc in the Body. In 1940 it was discovered that zinc was a required piece of the biological enzyme carbonic anhydrase and then in 1955 as a part of the digestive enzyme carboxypeptidase. Since then, zinc has been identified as a part of over 100 enzymes in the body and in all enzyme classes. Enzymes are critical to our biochemical function, assisting with the making, degrading and transport of nutrients, proteins, energy, nucleic acids and much more.
   There are between 1.5-4.0 grams of zinc in the body. Most of that is in bone tissue and not available for use in enzymes or other reactions. Higher concentrations are found in the prostate gland, parts of the eye, and skin, hair and nails and lesser amounts in the brain, muscles, kidney, pancreas and liver.
Uses for Zinc. Probably most people have heard about using zinc for colds. In the scientific community, this use is quite controversial. While we know that a deficiency in zinc inhibits the optimal functioning of the immune system, studies conflict about whether extra zinc actually stimulates the immune system. We know that zinc is a great anti-oxidant (in our bodies as well as over an iron nail!), it speeds wound healing (and is part of calamine lotion), protects against sun and windburn (the white stuff on the lifeguard's nose), soothes diaper rash (like in Desitin ointment). It plays a role in DNA metabolism, gene expression, brain modulation, and apoptosis regulation. Apoptosis is the built-in progam for individual cell death - on purpose. It's an important piece of maintaining healthy cells in the body.
Zinc Deficiency. A deficiency in zinc usually results from low intake, but can be made worse by some genetic variations, chronic disease or heavy metal exposure. Symptoms vary greatly but may include decreased growth in children, diarrhea, impotence, hair loss, eye and skin lesions, decreased immune function and the loss of smell.
   Decreased zinc in the soil may lessen zinc content of food and food processing often significantly decreases zinc levels. For example, brown rice has 6.5 ug/mg where white rice has only 1.6.
Requirements and Sources. The recommended amounts for zinc are 12 mg and 15 mg per day for adult women and men respectively. It has been suggested that the average dietary intake for Americans is about 10 mg/day. Oysters, by far, provide the highest concentration of zinc of all foods with about 76 mg in 6 medium oysters. Then we fall to about 8 mg in 3 oz of beef. Other meats and organ meats, cheese, lima & kidney beans and other legumes, nuts and seeds all have small amounts of zinc.
   In supplement form, zinc picolinate, gluconate, citrate or glycinate are the most absorbable forms. Zinc oxide and zinc carbonate are poorly absorbed.
Toxicity and Interactions. You can take too much zinc. Acutely, high doses (taken in grams, not milligrams), can cause severe nausea, vomiting, diarrhea and headaches. Chronic high intake of zinc (in the 100s of milligrams range) can cause a copper deficiency, depressed immune function, decreased HDL levels (the "good" cholesterol) and interfere with iron absorption. The Food and Nutrition Board has established 40 mg/day for adults as a Tolerable Upper Limit. Under supervision of a doctor, higher doses may be appropriate for medical use.
   Zinc has the potential to interact with some antibiotics, but this can be managed by taking them a couple hours apart. Zinc may be significantly decreased when using some diuretic medications, so long term use of those drugs may suggest a need for higher intake of zinc.
Zinc is also less well absorbed when antacids are being used.

So, Zinc! An important trace mineral for our general health. Always look to get nutrients from food when you can. Most multi-vitamin/mineral products will have zinc in them - and often with copper to balance that relationship. And if you're one of the people who swears by a zinc lozenge when you're coming down with a cold - never mind what the studies say! Just don't eat the whole box at once!