Silicon: the health benefits of a metalloid

Our plain-English summary of Silicon: the health benefits of a metalloid, by K.R. Martin (Metal Ions in Life Sciences, 2013).

The study

• Author: K.R. Martin
• Journal: Metal Ions in Life Sciences
• Published: 2013;13:451-73
• Type of article: Review
• Cited by: 44 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Silicon is the second most abundant element in nature behind oxygen. As a metalloid, silicon has been used in many industrial applications including use as an additive in the food and beverage industry. As a result, humans come into contact with silicon through both environmental exposures but also as a dietary component. Moreover, many forms of silicon, that is, Si bound to oxygen, are water-soluble, absorbable, and potentially bioavailable to humans presumably with 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 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 meaningful quantities of silicon into biological 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 review discusses the possible biological potential of the metalloid silicon as bioavailable orthosilicic acid and the potential beneficial effects on human health.

In plain English

This was a review chapter, not an original study. It reviewed published research on silicon, the element in silica and silicates. Its main focus was possible health benefits of water-soluble forms, especially orthosilicic acid, taken in through food, drinks and supplements, for bone health, atherosclerosis, Alzheimer's disease, diabetes and wound healing. A shorter section covered toxicity. The author wrote that toxic forms of silicon include long fibrous crystalline forms such as asbestos. The author listed six asbestos types: chrysotile and the amphiboles crocidolite, amosite, anthophyllite, tremolite and actinolite. Asbestosis was described as a lung disease that typically appears after high-intensity and/or long-term exposure. Of the proposed ways asbestos causes damage, the author called oxidative stress probably the most compelling. The review cited another group's study of 92 former asbestos workers. That study found higher levels of an oxidative stress marker in exposed subjects than in control subjects (69.5 versus 47.0 pg/mL). The author concluded that silicon compounds may have health benefits but also toxic effects, depending on form, water-solubility, route of exposure and amount, and called for larger human studies.

We wrote this plain-English summary from the full article with the help of AI, and a second AI model checked each sentence against the article. It is not the authors' wording; the abstract and the article are their own account.

What the study did and found

• Design: narrative review (book chapter)
• Who was studied: No study population of its own; the chapter reviewed published human, animal and laboratory research on silicon and silica
• Exposure: Dietary and supplemental silicon (mainly orthosilicic acid), and, in a toxicology section, inhaled crystalline silica and asbestos fibers (chrysotile, crocidolite, amosite, anthophyllite, tremolite, actinolite)
• Main results:
  • The review described asbestos as six types of silicate fibers: chrysotile and the amphiboles crocidolite, amosite, anthophyllite, tremolite and actinolite
  • The review described asbestosis as typically appearing after high-intensity and/or long-term asbestos exposure
  • Of the proposed mechanisms of asbestos and silica toxicity (adsorption, chromosome tangling, oxidative stress), the author considered oxidative stress probably the most compelling
  • A cited study (Pelclova et al., not this chapter's own work) of 92 former asbestos workers with an average exposure of 24 years found higher 8-isoprostane levels in exposed subjects than in control subjects (69.5 versus 47.0 pg/mL)
  • The review stated there is no evidence of cancer when silica was fed to rodents for about 2 years
• The authors' conclusion: The author concluded that silicon, as silica and silicates, may have health benefits but also toxic effects, depending on form, water-solubility, route of exposure and amount consumed
• Limitations the authors state:
  • The author stated that data on medicinal uses are preliminary
  • The author stated that larger human studies are needed

Topics

Medical terms in this study, explained in our Lexicon: Environmental Exposure, Collagen, Crystalline, Zeolite.

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