Silver: The need for evaluation of nutritional and biological role

Since ancient times, silver coins, leaves, and cutlery have been used to guard against infections. A large number of Traditional Knowledge Granthas have described numerous benefits of silver and its processed products. Work on its biological role and potential use as a nutrient has not received much attention. The present paper provides a comprehensive review of these aspects based on available literature. It was found that the main sources of silver include dry fruits, nuts, and seeds, followed by seafoods and cereal products. Animal studies suggest that soluble silver compounds like silver nitrate were more readily absorbed than their metallic and insoluble forms in the intestinal and respiratory mucosa, depending on the route of exposure. Like other nutrients, absorption was influenced by age, physiological condition, and the composition of the diet. Studies provide conflicting observations with regard to the extent of absorption (10%–99%). Silver was primarily deposited in the liver, followed by the skin. The toxicity of silver is rare but attributed to the ingestion/exposure of silver salts. The most common toxic effect is argyria, which has been seen in individuals with chronic exposure. Available literature indicates a possible role of silver in maintaining health; however, the scarcity of recent studies highlights the need for further investigation, including the establishment of permissible exposure limits for metallic silver and soluble silver compounds.