New essential trace elements for the life sciences.

The possible importance of some new essential trace elements in nutrition is discussed. Most likely, insufficient intake of a specific trace element becomes obvious only when the body is stressed in some way that enhances the need for that element; this has been supported by recent findings with selenium. The trace elements boron and copper may be of nutritional significance in a manner similar to selenium. When the diets of animals and humans are manipulated to cause possible changes in cellular integrity or in hormone responsiveness, a large number of responses to dietary boron occur. The findings indicate that boron is important for optimal calcium and, thus, bone metabolism. High dietary cystine and fructose exacerbate the signs of copper deficiency in rats; this indicates that the response to copper deficiency by humans would vary with the amino acid and carbohydrate composition of the diet. There is some evidence that chromium, molybdenum, nickel, arsenic, and vanadium may also be of nutritional significance under stress conditions. In other words, an increasing number of studies have been performed that have examined the importance of trace element nutriture in various forms of nutritional, metabolic, hormonal, or physiologic stress in animals and humans. These studies indicate that situations will be found in which a trace element is of nutritional significance. It is likely that some of the trace elements are more important in human nutrition than is now generally acknowledged.