Classification of Zinc Rich Yeast Preparations

Zinc supplements have gone through four stages. The first generation of zinc supplements that first appeared were inorganic salts such as zinc sulfate and zinc chloride. It has a simple structure, low price, and moderate supplementation can eliminate the symptoms caused by zinc deficiency. The second stage involves numerous organic zinc supplements, such as zinc gluconate, zinc glycyrrhizinate, zinc citrate, zinc lactate, and so on. The third stage is amino acid chelation of zinc.
Inorganic Zinc
Including zinc sulfate, zinc oxide, zinc carbonate, zinc sulfide, etc. The typical representative of inorganic zinc is zinc sulfate, which has a simple structure and low price. Moderate supplementation can eliminate the symptoms caused by zinc deficiency. According to the Chinese Pharmacopoeia, the absorption rate of the human body is only 7%. Due to its reaction with stomach acid, zinc chloride produced is a highly toxic corrosive agent, resulting in significant adverse reactions. Common gastrointestinal reactions include decreased appetite, nausea, vomiting, abdominal pain, diarrhea, etc., which can easily cause zinc poisoning.
Disadvantages of inorganic zinc: a. Zinc exists as an inorganic ion and is difficult to be absorbed by the human body under antagonistic effects; b. Easy to form insoluble substances with carbonic acid and phytic acid in plants, affecting absorption; c. In the neutral environment of the intestine, inorganic zinc salts are prone to hydrolysis; d. It has a stimulating effect on the gastrointestinal tract and may cause diarrhea.
Organic synthesis of zinc
Including zinc gluconate, zinc oxalate, zinc citrate, zinc lactate, zinc glycyrrhizinate, etc., it is the earliest developed type of organic zinc. Compared with inorganic zinc, its most significant feature is that its stimulating effect on the gastrointestinal tract is significantly reduced, and its oral absorption and utilization rate is improved compared to non-polar zinc.
The zinc glycyrrhizic acid in organic zinc is a product of the combination of glycyrrhizic acid extracted from plant licorice and zinc. It releases glycyrrhizic acid and zinc ions in the body, and is used as an oral anti ulcer drug. However, due to its high cost, its wide application is limited. Zinc gluconate has a high content and good absorption, but it is irritating to the gastrointestinal tract. Oral administration may cause mild nausea, vomiting, constipation, and a certain degree of irritation to the gastric mucosa. There is no significant difference in maximum peak drug concentration and bioavailability between zinc sulfate and zinc gluconate [1] consumed by the population, but zinc gluconate absorbs faster, maintains longer duration, and has higher maximum peak drug concentration and bioavailability compared to zinc sulfate. 2.5-3.0 kg healthy rabbits were orally administered with 20 mg/kg of zinc sulfate and zinc gluconate, with the latter having a bioavailability equivalent to four times that of zinc sulfate [2]. Zinc lactate is an organic acid salt that has been used orally to treat epilepsy. It has a high absorption rate and is not affected by phytic acid and phytate salts. According to reports [3], the bioavailability of zinc lactate in experimental rats is approximately 1.3-1.5 times that of zinc gluconate. Sun Guoping studied the pharmacokinetics of oral zinc gluconate tablets in cancer patients and found that it has the characteristics of fast absorption, high peak concentration, and fast elimination [4].
Although this type of product has improved the drawbacks of the first generation zinc salts, it still has an antagonistic effect and low absorption rate. According to the Chinese Dictionary of Materia Medica, taking organic zinc still "often results in gastrointestinal irritation symptoms such as stomach discomfort, nausea, and vomiting", and "continuous use may cause adverse reactions such as potassium and sodium excretion, mild edema". There are also literature reports that its bioavailability is relatively low, only about 14%. People are conducting further research and improvement on its bioavailability, toxic side effects, absorption, and metabolic mechanisms.
Amino acid complex form
Amino acid complexes were first developed by the American "Aibiwang" biological laboratory. In the early 1980s, it was sold to China and now it has been produced in China. Firstly, protein iron was synthesized from animal plant proteins and iron elements, and after achieving good results, it was promoted and developed to form zinc amino acid complexes. This complex is formed by the combination of amino acids and metal elements such as zinc under certain process conditions.
Amino acid zinc has fundamental differences in chemistry and biochemistry compared to inorganic zinc. The metal elements in inorganic salts, such as zinc sulfate, enter the intestine in an ionic state and react with other elements due to pH and environmental factors, becoming insoluble substances that are difficult to digest and absorb. Amino acid zinc is formed by the carboxyl group in amino acids and zinc elements to form salts. At the same time, the nitrogen atom on the amino group in amino acids has an unshared electron pair, which can form a structurally stable six membered ring complex with zinc through coordination bonds, thus having good chemical stability. In addition, amino acid zinc is easily absorbed and utilized by the human body due to its neutral intramolecular charge, good solubility in the pH environment of the body, and easy release of metal ions. The chemical stability of this complex is moderate, and amino acids have a protective effect on metal ions, which can prevent zinc from becoming insoluble compounds in the intestine or being adsorbed on insoluble colloids that hinder element absorption, thus facilitating absorption by the body. Inorganic zinc requires carrier molecules to encapsulate metal ions and form an organic lipid soluble complex outside the cell membrane in order to allow ions to pass through the cell membrane. On the contrary, after entering the body, zinc amino acid complexes can directly transport zinc to specific tissues and enzyme systems according to the different proportions and quantities of certain amino acids required by different tissues and enzyme systems. Zinc is released through the action of enzymes and tissues to meet the needs of the body. This eliminates the need for the growth state required for inorganic zinc, thereby improving the utilization efficiency of the complex.
In summary, the absorption and metabolism of zinc amino acid complexes in the body are different from inorganic zinc, and certain zinc amino acid complexes can stimulate certain biological processes. The study on oral administration of zinc lysine and zinc sulfate in dogs found that the bioavailability of zinc lysine was significantly higher than that of zinc sulfate [5].
Although amino acid zinc has good chemical stability, good solubility in the pH environment of the body, and is easily absorbed and utilized by the human body, experimental animal studies have found that [6]: when the content of calcium, phytic acid, and cellulose is low, the utilization rate of amino acid complex zinc is not better than that of inorganic zinc. When the content of zinc antagonist in the diet is high, the amino acid complex zinc prevents zinc from becoming insoluble compounds in the gastrointestinal tract or from being directly absorbed on dissolved colloids that hinder absorption, thus making it highly biologically effective. That is to say, its bioavailability only improves some of the influencing factors of inorganic zinc, without truly increasing its human absorption rate.