Zinc is an important mineral involved in many bodily processes necessary for good health. Zinc is especially essential for immune function, protein synthesis, wound healing and cell growth and is required by the body to make many essential hormones.

Zinc deficiency is a worldwide problem, and is common even among otherwise well-nourished populations. Many soils are deficient in zinc, and much of the mineral is lost in food processing. The recommended daily allowance for zinc is 15 mg, but most Americans ingest approximately 10 mg daily from their diet. Metals such as copper and cadmium compete with zinc for transport in the body. Coffee, phytates from soy or nuts, calcium and phosphorus may interfere with zinc absorption. To be absorbed, zinc must be ionized by hydrochloric acid in the stomach, so medications such as protein pump inhibitors (PPIs) that reduce acid secretion interfere with absorption. Examples of PPIs include omeprazole (Prilosec®), lansoprazole (Prevacid®), and esomeprazole (Nexium®). Supplements in tablet form may not dissolve well in the stomach, so the zinc cannot be absorbed. Stress and infections can deplete zinc stores. Fitness enthusiasts are prone to zinc deficiency that results from sweating. Older patients with poor dietary habits are especially vulnerable to zinc deficiency. Alcohol, even in moderate amounts, can increase zinc excretion in the urine, resulting in low levels in the body.

Conditions associated with low zinc levels are intestinal malabsorption syndromes, cystic fibrosis, alcoholism, HIV infection, malignancy, uremia and chronic renal disease, and a weak immune system. Symptoms of deficiency include fatigue, poor appetite, digestive problems, and smell and taste dysfunction. Vision and hearing can be diminished by severe zinc deficiency. Some studies have associated zinc deficiency with depression. In deficient men, sexual function is affected and sterility is common.

Assessment of Zinc Deficiency – Methods of determining zinc levels include serum spectroscopy and analyses of white blood cells, hair or urine. However, the Zinc Taste Test is an easy, convenient method of assessing zinc deficiency in an office or other clinical setting. This test is based on the detection of gustin, a polypeptide in the mouth that distinguishes metals. The patient should not eat, drink, or smoke for 30 minutes before the test. About two teaspoonfuls of 0.1% zinc sulfate heptahydrate solution is swished in the mouth for 10 seconds. It is then swallowed or expectorated (spit out). After 30 seconds, the patient is asked to describe the taste. Responses are classified as follows:

1. No taste or the taste of water is noted. (Severe deficiency)

2. No taste noted initially, but a taste often described as dry, “minerally,” like a bicarbonate, or sweet develops in 10 or 15 seconds. (Moderate deficiency)

3. A definite but not strongly unpleasant taste is noted immediately and tends to intensify in time. (Mild deficiency)

4. An immediately unpleasant, obviously aversive taste that often causes the patient to grimace is noted. (No deficiency)

Results of performing the Zinc Taste Test on a sample of 20 family practice residents and faculty members indicated that 15% percent were severely deficient, 60% were moderately deficient, 5% were mildly deficient, and 20% were not deficient. The high prevalence of zinc deficiency and the importance of zinc in maintaining good health support the need for regular zinc level screenings.

When compared with other methods, the Zinc Taste Test is inexpensive, easy to perform, and reasonably accurate; it can be repeated to follow progress; and its range indicates mild to severe states of zinc deficiency. 

Treatment must be customized for each patient. If the zinc deficiency is severe, treatment should be initiated with the administration of a liquid preparation of zinc sulfate heptahydrate to replenish the metallothionein-1 transport system. In the elderly, 30 to 60 mg of zinc daily in divided doses may be needed. When requirements are great (for example, as a result of trauma, burns, etc.) then up to 150 mg of zinc may be given daily for a short time, but the effect on the patient’s level of copper can lead to anemia.

Special attention must be paid to copper and selenium levels when supplementing zinc. The zinc/copper dosing ratio is 10:1. If someone is taking 150 mg of zinc, then 15 mg of copper may be needed. Selenium may also be depleted by large doses of zinc. Supplementation with these minerals should be done under the supervision of a knowledgeable, experienced health care professional.

Ask our compounding pharmacist for more information about the Zinc Taste Test and customized treatment for zinc deficiency. 


Int’l J of Pharmaceutical Compounding 4(6); Nov/Dec 2000: 440-1


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