ABSTRACT
Silicon is the second most abundant element in nature behind oxygen. As a metalloid, silicon has been used in many industrial applications and as an additive in the food and beverage industry. As a result, humans come into contact with silicon through both environmental exposures and as a dietary component. Moreover, many forms of silicon, as oxides, are water-soluble, absorbable, and potentially bioavailable to humans with presumably biological activity. However, the specific biochemical or physiological functions of silicon, if any, are largely unknown although generally thought to exist. As a result, there is a growing interest in the potential therapeutic effects of water-soluble silica on human health. For example, silicon has been suggested to exhibit roles in the structural integrity of nails, hair, and skin, overall collagen synthesis, bone mineralization and bone health and reduced metal accumulation in Alzheimer’s disease, immune system health, and reduction of the risk for atherosclerosis. Although emerging research is promising, much additional, corroborative research is needed particularly regarding speciation of health-promoting forms of silicon and its relative bioavailability. Orthosilicic acid is the major form of bioavailable silicon whereas thin fibrous crystalline asbestos is a health hazard promoting asbestosis and significant impairment of lung function and increased cancer risk. It has been proposed that relatively insoluble forms of silica can also release small but biologically meaningful quantities of silicon into cellular compartments. For example, colloidal silicic acid, silica gel, and zeolites, although relatively insoluble in water, can increase concentrations of water-soluble silica and are thought to rely on specific structural physicochemical characteristics. Collectively, the food supply contributes enough silicon in the forms aforementioned that could be absorbed and significantly improve overall human health despite the negative perception of silica as a health hazard. This chapter discusses the biological potential of the metalloid silicon as bioavailable orthosilicic acid and the potential beneficial effects on human health.
