Zinc gluconate

Zinc gluconate is the salt of gluconate and zinc II. It is an ionic compound consisting of two moles of gluconate for each mole of zinc.

Zinc gluconate is a popular form for the delivery of zinc as a dietary supplement.

It is found naturally, and is industrially manufactured by the fermentation of glucose, typically by Aspergillus niger, but also by other fungi, e.g. Penicillium, or by bacteria, e.g. Acetobacter, Pseudomonas and Gluconobacter. In its pure form, it is a white to off-white powder. It can also be manufactured by electrolytic oxidation, although this is a more expensive process. The advantages are a lower microbiological profile, and a more complete reaction, yielding a product with a longer shelf life.

Zinc gluconate may interfere with the absorption of antibiotics, so combinations may be unsafe.

Zinc gluconate glycine
Zinc gluconate glycine is a formulation containing zinc gluconate and the amino acid glycine. It is available as an over-the-counter remedy for the common cold.

Zinc gluconate, when made into a lozenge by itself, has a mildly acidic taste, which will turn into a bitter taste over a period of time. The addition of large amounts of glycine to the lozenge produces a much milder and more stable taste. The resulting commercial products have a nearly unlimited shelf life.

This compound was patented in 1985 by John C. Godfrey of Godfrey Science & Design. The Quigley Corporation has trademarked the name ZIGG™ for the compound. The company is also the only major supplier of zinc gluconate glycine, distributed under the brand name Cold-Eeze. All clinical trials of the compound to date have involved the lozenges in this product family.

Like zinc gluconate, zinc gluconate glycine has been shown in clinical trials to shorten the mean and median duration of symptoms of the common cold The amount of glycine added can range anywhere from two to twenty moles of glycine for each mole of zinc gluconate (US Patent 4,684,528, Claim 1).

The manufacturer claims that their product reduces the duration of common cold symptoms by 42%, compared to the natural duration. However, the actual benefits gained from the product depend heavily on how quickly the treatment is started after the first appearance of symptoms. Repeated clinical trials of the compound have generally shown a measurable, but varied, benefit relative to a placebo, typically on the order of a one to four day reduction in symptom duration.

Safety Concerns
In September 2003, Zicam, a brand of homeopathic zinc cold remedy, faced lawsuits from users who claimed that the product negatively affected their sense of smell, and sometimes taste. In January 2006, 340 lawsuits were settled for $12 million. In early 2004, at the height of the controversy, Matrixx Industries, the maker of Zicam, claimed that only a small number of people had experienced problems and that anosmia (loss of smell) can, amongst others, also be caused by the common cold itself. Matrixx Industries also claimed that zinc gluconate dissolves into zinc ions and gluconate, and that both are naturally occurring compounds which are found in all human tissues. They also claim that Zicam is a buffered gel that is formulated to have a neutral pH. Others countered Matrixx Industries, claiming that many of the patients had experienced a strong and very painful burning sensation when they used the product, indicating damage to the nasal tissue. Nonetheless the nasal gel continues to be sold.

The U.S. Food and Drug Administration (FDA) considers zinc gluconate to be generally recognized as safe (GRAS) when used in accordance with good manufacturing practice, although this does not constitute a finding by the FDA that the substance is a useful dietary supplement.