Silica is a mineral. Silica gel is found in simethicone.

Use by consumers for hair, skin and nails
Many people email me whether they should take this supplement for healthy hair and skin. I know some websites are promoting supplementation as a way to have healthier skin and hair, but I think it is premature to make such claims.

Is a silica supplement a good and safe product to use for your hair, skin and nails?
    Long term human studies are not available to determine the benefit and safety of such supplementation. There is always a concern that adverse reactions or side effects could occur, especially when taking mineral supplements since the body has a difficult time in getting rid of excess amounts and they could cause long term health problems.

What are your thoughts on using either horsetail silica or bamboo silica for nails – hair and skin.
    Most people who consume a normal diet are not deficient in this mineral and therefore it is not likely they will benefit from such supplements, but I am not fully certain since I have not seen such studies.

Alzheimer's disease
A high concentration of silica in drinking water seems to protect against Alzheimer's disease.

Silica hydride information, benefit
Silica hydride appears to have good antioxidant properties, but so do hundreds of other nutrients and herbs. The role of silica hydride in terms of adding to one's supplementation program is not clear since there are already so many other antioxidants to choose from.

Effects of microhydrin supplementation on endurance performance and metabolism in well-trained cyclists.
Int J Sport Nutr Exerc Metab. 2004.
This study investigated whether the supplement Microhydrin contains silica hydride bonds (Si-H) and if Microhydrin supplementation increased performance or altered metabolism compared to placebo during prolonged endurance cycling. Seven endurance-trained male cyclists consumed 9.6 g of Microhydrin or placebo over 48 h in a randomized, double-blind, crossover design. The results indicate that oral Microhydrin supplementation does not enhance cycling time trial performance or alter metabolism during prolonged submaximal exercise in endurance-trained cyclists.

Evaluation of hydroxyl radical-scavenging abilities of silica hydride, an antioxidant compound, by a Fe2+-EDTA-induced 2-hydroxyterephthalate fluorometric analysis.
J Med Food. 2003. Stephanson CJ, Stephanson AM, Flanagan GP. Flantech Group, Watsonville, California, USA.
The hydroxyl radical scavenging capacity and efficacy of a novel organosiliceous anionic hydride compound, silica hydride, were quantified by a recently developed method. The method measures a direct relationship between the hydroxyl radical scavenging capability of the silica hydride antioxidant compound and the linear decrease in signal from a fluorescent 2-hydroxyterephthalate product created by reacting an Fe(2+)-EDTA complex in the presence of a potential radical scavenger.

Antioxidant capability and efficacy of Mega-H silica hydride, an antioxidant dietary supplement, by in vitro cellular analysis using photosensitization and fluorescence detection.
J Med Food. 2002. Stephanson CJ, Stephanson AM, Flanagan GP. Department of Chemistry, University of Minnesota, Minneapolis, MN, USA.
Treatment of Chinese hamster ovary and mouse hybridoma cells with Mega-H brand silica hydride, a marketed antioxidant, after photosensitization with singlet oxygen and hydroxyl/superoxide reactive oxygen species through the use of rose bengal diacetate and malachite green resulted in an effective method of reducing free radical activity by more than 96% against singlet oxygen species and more than 86% for hydroxyl and superoxide free radicals with the dosage recommended by the manufacturer. The reduction of the introduced free radicals and singlet oxygen species and the consequent high levels of cell viability may be the result of effective and efficient antioxidant and radical scavenging properties of silica hydride.

Silica disease
More than one million U.S. workers are exposed to inhaled crystalline silica in a variety of industries and occupations, including construction, sandblasting, and mining. Silicosis, an irreversible but preventable disease, is the illness most closely associated with occupational exposure to the material, which also is known as silica dust. Occupational exposures to inhaled crystalline silica are associated with the development of silicosis, lung cancer, pulmonary tuberculosis, and airways diseases. These exposures may also be related to the development of autoimmune disorders, chronic renal disease, and other adverse health effects.

Silica exposure and Lupus
Epidemiologic studies have demonstrated moderate to strong associations between occupational silica exposure and SLE. Recent experimental studies of silica in lupus-prone mice provide support for the idea that, in addition to its known adjuvant effect, silica exposure increases the generation of apoptotic material, an important source of self-antigen.

Silica hydride emails
Q. Please tell me if silica hydride is really the magic formula they are saying it is.
   A. Little human research is available. It appears to have antioxidant properties but so do a lot of other supplements. At this time it is better to stick with the true and tested antioxidants such as lipoic acid and others.

Q. I am doing some research on an excipient used in dietary products. The excipient is silica and is regularly used in supplements. I understand that when silica is manufactured it is converted into a "fused" form which is purportedly harmless or inert. Yesterday, I read a very lengthy article online written by a male nurse who had taken supplements containing silica and strongly felt that his overall health was adversely affected by this excipient or ingredient. What is the difference, chemically, between silica and silica hydride? Evidently, many dietary supplement companies have been using it for years as an excipient in their products. Does "fused" silica cause chronic lung problems even if ingested in small doses as it may have a cumulative effect on people? On a personal note, I have been taking Vitamin C for years using a product by Country Life that contains silica as an excipient. Yet, ConsumerLabs dot com, however reputable they are, tested Country Life products and apparently the company does not meet their standards regarding ingredients tested. Country Life is a GMP approved facility and meets FDA standards. Yet, the FDA has regularly allowed pharmaceuticals to be introduced into the marketplace that have seriously injured and killed thousands of people. What does one believe regarding the safety and efficacy of excipients used in manufacturing dietary supplements?
   A. I have not studied these topics in enough detail to have a good answer. An excipient is an inactive substance used as a carrier for the active ingredients of a medication. Since the amounts placed in dietary supplement pills is so small, it is difficult to do studies to see what effect they have in these tiny amounts.

Found in nature
Silica (silicon dioxide) occurs in crystalline and amorphous forms. Of the several crystalline polymorphs of silica found in nature, quartz is by far the most common, being abundant in most rock types. Silica occurs commonly in nature as sandstone, silica sand or quartzite. It is the starting material for the production of silicate glasses and ceramics. Silica is one of the most abundant oxide materials in the earth's crust.