After about age 40, the thymus gland begins to shrink and blood serum levels of zinc begin to slide, falling by about 3 percent every 10 years thereafter. This decline is mirrored in the thymus glands declining output of thymulin, the hormone responsible for stimulating the production of immune-system T cells, the killer cells responsible for keeping tumors in check and protecting us from infections. By age 65 the thymus gland shrinks so much that it can only release about10 percent of the thymulin it did in our youth, greatly impairing our ability to stave of diseases. Recently researchers gave zinc supplements to animals and found that the thymus gland returned to 80 of normal size, and most importantly, thymulin output and T cell counts returned to youthful levels. Human studies soon followed, with similar results. Persons aged 65 and older, taking 15 milligrams of zinc per day soon evidenced the same restoration of youthful levels of thymulin and T cell activity. Similar studies with Downs Syndrome patients who are very prone to infections showed similar results, cutting the number of new infections by over 50 percent after treatment with zinc supplements.

A study conducted at Dartmouth college has reported that college students where able to recover from colds in half the normal time when given zinc lozenges. Those taking the zinc recovered from their symptoms in 4 days, while those students taking a placebo took over 9 days to fully recover from the illness. Carl C. Pfeiffer, MD, PhD, thought the whole human population was borderline deficient in the mineral zinc, which could account for our sensitivity to the common cold. Now, a new study shows that the common cold can be shortened significantly when ample zinc gluconate is made available.

While in vitro studies have long shown that zinc inhibits the common cold rhino-viruses, the experimental data has been mixed when the zinc studies have used throat lozenges. Scientists have now identified a flaw in the studies that used hard-candy zinc lozenges containing citric acid. It seems the low pH produced by the acidic formulation inhibited zinc delivery. 3

Building on this knowledge, the new study, conducted at Dartmouth College, found that college students given non-acidic throat lozenges one day into their cold had colds that were more than 50% shorter. For those students taking look-alike, taste-alike placebo candies, colds lasted 9.2 days on average versus 4.3 days for those taking zinc.

1. Pfeiffer, Carl C. Mental and elemental nutrients. Keats Publishing, Inc. New Canaan, CT. 1975.
2. Godfrey JC et al. "Zinc gluconate and the common cold: a controlled clinical study." JInt Med Rs. 1992;20:234-246.
3. Zarembo JE, Godfrey JC, Godfrey NJ. "Zinc (11) in saliva: determination of concentrations produced by different formulations of zinc gluconate lozenges containing common excipients." J Pharm Sci. 1992;81(2):128-130.

Foods highest in zinc include fish, legumes, meats, oysters, poultry, seafood, whole grains, egg yolks and brewers yeast.

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