Zinc and the special senses.

There is evidence that zinc is important for maintenance of the special senses: vision, taste, and smell. Rod function is impaired in zinc deficiency due partly to its role in vitamin A metabolism. However, optic nerve function may also be affected by zinc status. Microophthalmia, anophthalmia, and optic nerve abnormalities have all been found in the offspring of female rats fed zinc-deficient diets. Zinc deficiency clearly decreases taste acuity in both animals and humans. However, other nutritional and non-nutritional conditions also produce hypogeusia. There is limited evidence that zinc deficiency impairs olfactory acuity in humans. New approaches to the assessment of taste and smell abnormalities may provide reliable and reproducible associations between zinc deficiency and taste and smell defects.