Silica
Related Terms
- Aluminum silicate, amorphous silica, attapulgite, bentonite, calcium silicate, crystalline silica, diatomite, fuller's earth, hectorite, kaolin, lithium magnesium silicate, lithium magnesium sodium silicate, magnesium aluminum silicate, magnesium silicate, magnesium trisilicate, monomeric silicic acid, monosilicic acid, montmorillonite, orthosilicic acid, pyrophyllite, quartz, SiO2, Si(OH)4, silicate, silicic acid, sodium magnesium silicate, zeolite, zirconium silicate
- Note: This monograph does not cover silicon-based manufactured materials, including microelectronics and biomedical devices and materials.
Background
- Silicon is the second-most abundant element in the earth's crust, after oxygen. It binds to oxygen, forming crystalline or amorphous silica (silicon dioxide, SiO2), silicic acid (Si(OH)4), and silicates, such as quartz. Silicon is present in rocks, soil, sand, and dust as crystalline silica. Silicic acid is formed naturally from silica and is readily absorbed in the human gastrointestinal tract.
- Silicon is an ultratrace element, meaning that it is suspected as being required in quantities of less than 1 milligram, but is associated with no known essential role in biological processes. A recommended dietary allowance (RDA) or adequate intake (AI) has not been established for silicon.
- In the diet, silicon is found mainly in drinking water and plant-based foods, such as beer, unrefined grains (oats, barley, rice, and wheat bran), fruits, vegetables (spinach), and beans (red lentils).
- Silicon is included as silicates in cosmetic and pharmaceutical preparations. Silicates are also added to processed foods and beverages, where they serve as anticaking agents, thickeners, and stabilizers, and they are used as clarifying agents in beer and wine.
- Silicon is biocompatible and has been used in many implantable medical devices, including pacemakers, defibrillators, stents, materials for plastic and reconstructive surgery (including breast implants and bone grafts), devices for sustained-release delivery of drugs, sheeting (to treat and prevent the formation of scars following surgery), and liner sockets, or sleeves (to attach prostheses after amputation).
- Although researchers have examined the use of silicon for various purposes, its use for reducing aluminum toxicity associated with Alzheimer's disease is controversial. Some evidence suggests that silicon may be essential in humans for bone growth and health and development of other tissues in the body. High-quality scientific evidence supporting the use of silicon to treat any condition in humans is lacking.
Evidence Table
These uses have been tested in humans or animals. Safety and effectiveness have not always been proven. Some of these conditions are potentially serious, and should be evaluated by a qualified healthcare provider. |
GRADE * |
These uses have been tested in humans or animals. Safety and effectiveness have not always been proven. Some of these conditions are potentially serious, and should be evaluated by a qualified healthcare provider. |
GRADE * |
Preliminary studies suggest that dietary silicon supplementation may reduce aluminum absorption and prevent or reduce aluminum accumulation in tissues. It has been proposed that this may be useful in preventing or reducing aluminum accumulation in the brain in Alzheimer's disease. Additional research is needed before a conclusion can be made.
|
C |
Preliminary studies suggest that dietary silicon supplementation may reduce aluminum absorption and prevent or reduce aluminum accumulation in tissues. It has been proposed that this may be useful in preventing or reducing aluminum accumulation in the brain in Alzheimer's disease. Additional research is needed before a conclusion can be made.
|
C |
Daily doses of 10 milligrams of silicon or 10 milliliters of colloidal silica have been used effectively to treat brittle nail syndrome. Additional research is required in this area.
|
C |
Daily doses of 10 milligrams of silicon or 10 milliliters of colloidal silica have been used effectively to treat brittle nail syndrome. Additional research is required in this area.
|
C |
Evidence suggests that silicon is involved in bone and collagen mineralization. Limited studies have demonstrated an association between silicon intake and bone mineral density.
|
C |
Evidence suggests that silicon is involved in bone and collagen mineralization. Limited studies have demonstrated an association between silicon intake and bone mineral density.
|
C | * Key to grades
A: Strong scientific evidence for this use
B: Good scientific evidence for this use
C: Unclear scientific evidence for this use
D: Fair scientific evidence for this use (it may not work)
F: Strong scientific evidence against this use (it likley does not work)
| * Key to grades
A: Strong scientific evidence for this use
B: Good scientific evidence for this use
C: Unclear scientific evidence for this use
D: Fair scientific evidence for this use (it may not work)
F: Strong scientific evidence against this use (it likley does not work)
| Tradition / Theory
The below uses are based on tradition, scientific theories, or limited research. They often have not been thoroughly tested in humans, and safety and effectiveness have not always been proven. Some of these conditions are potentially serious, and should be evaluated by a qualified healthcare provider. There may be other proposed uses that are not listed below.
Dosing
Adults (18 years and older)
- The U.S. Food and Drug Administration (FDA) has not established a recommended dietary allowance (RDA) for silicon. The Food and Nutrition Board of the Institute of Medicine of the National Academies has not recommended a daily adequate intake (AI) for silicon. It has been suggested that an "apparent beneficial intake (ABI)" might be established for silicon and other ultratrace elements that have beneficial, if not essential, effects that can be extrapolated from animal research to humans.
- Dietary intake of silicon in Western populations ranges from 20 to 50 milligrams daily. Further human research has shown that the mean daily intake of silicon is 30-33 milligrams in men and 24-25 milligrams in women. Higher levels of intake are associated with predominantly plant-based diets and lower levels with primarily meat-based diets.
- Increasing the amount of silicon provided to adults with functioning kidneys who are receiving long-term parenteral nutrition to at least 10 milligrams daily may benefit bone health.
- For brittle nail syndrome, 10 milligrams of silicon or 10 of milliliters colloidal silica have been taken by mouth daily.
- For dementia (Alzheimer's disease), 10 milligrams has been taken by mouth daily.
Safety
The U.S. Food and Drug Administration does not strictly regulate herbs and supplements. There is no guarantee of strength, purity or safety of products, and effects may vary. You should always read product labels. If you have a medical condition, or are taking other drugs, herbs, or supplements, you should speak with a qualified healthcare provider before starting a new therapy. Consult a healthcare provider immediately if you experience side effects.
Interactions
Interactions with Drugs
- Silica particles in combination with 5-aminosalicyclic acid or acetaminophen may increase liver toxicity.
- Taking silicon by mouth may affect aluminum absorption and excretion.
- Silicon may interact with iron.
- Silica particles in combination with tetracycline may be lethal, although this has not been well-studied in humans.
- Silicon may have additive effects with drugs used for osteoporosis.
Attribution
-
This information is based on a systematic review of scientific literature edited and peer-reviewed by contributors to the Natural Standard Research Collaboration (www.naturalstandard.com).
Bibliography
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