CONDITIONALLY ESSENTIAL TRACE ELEMENTS IN NUTRITION OF VEGETARIANS AND VEGANS: FLUORINE, SILICON, BROMINE, BORON

A brief review of the physiology of conditionally essential trace elements and their status among vegetarians and vegans is presented. To date, the biological role of conditionally essential trace elements has been studied much worse than the role of essential trace elements and, especially, macroelements. Nevertheless, they perform a number of important functions in the human body, and the development of their deficiency may lead to unpleasant consequences. Fluorine plays an important role in calcium-phosphorus metabolism and bone tissue development. In addition, it is necessary to maintain normal oral flora. With its deficiency, the risk of osteoporosis development increases while the resistance of tooth enamel to bacterial damage decreases. Despite the evidence that vegetarians are more likely to develop caries than omnivores, it is premature to conclude that they are poorly supplied with fluoride, primarily because drinking water is still the main source of fluoride. The most studied function of silicon is its involvement in the collagen synthesis. Thus, with silicon defi-ciency, the formation of connective tissue, including the organic matrix of the bones, is disturbed. Despite the fact that silicon is mainly found in plant foods, vegans should be mindful about its status, since they have an increased risk of osteopenia and osteoporosis. There is a lack of data on the physiological significance of bromine. Presumably, it is involved in the activa-tion of certain digestive enzymes, inhibitory processes in the nervous system. Although vegetarians and vegans seem to consume less bromine than omnivores, they are probably at a higher risk of intoxication with this element. This is due to the fact that bromine-containing pesticides are actively used in agriculture and can accumulate in plants. Vegetarians and vegans consume more plant foods. The situation is aggravated by the fact that bromine accumulates more actively against the background of iodine deficiency, which is often observed in these population groups. Boron plays a role in the glucose and lipid metabolism, as well as in the vitamin D, calcium and phosphates exchange, thus participating in the formation of an inorganic matrix of bones. It is unlikely that vegetarians and vegans have an increased risk of developing nutritional deficiency of boron compared to omnivores. However, considering data on a higher risk of vitamin D and calcium deficiency and osteoporosis, monitoring and correction of boron status can affect the prevalence of metabolic disturbances in bone tissue among vegans.