Silicon: The essence of good health?


The vast variety of nutritional supplements sold at health food stores clearly reflects the American consumer's shift towards a more health-conscious life style. While the increase in variety has made product pricing more competitive, it has also made choosing vitamins and supplements all the more difficult. Take for example silicon supplements, which are commonly used for promoting healthy bones, nails, hair and skin. A host of products can be found at your local health food store that include plant extracts of horsetail, bamboo and algae, colloidal silicon, silicon-enriched yeast, liquid silicon (stabilized orthosilicic acid) concentrate and even eggshell products. How is a person to know which source of silicon is the most effective or the safest? In this brief article I will provide some helpful information concerning the health benefits of silicon supplements and their most useful forms.

Silicon is a trace mineral in the human diet but found abundantly in nature, comprising 28 percent of the earth's crust. It is the major component of many minerals found in clay, sand, rocks, loam and other soils. The chemical form of silicon found in these soils is known as silicates. The silicon in silicates is bound to oxygen and metals such as aluminum. All silicates have one thing in common: these compounds have extremely low solubility in water. The slow and lengthy process of soil erosion breaks down rocks into clay and loam; eventually the silicates react with water to form soluble silicon molecules. These soluble silicon molecules are called orthosilicic acid or monomeric silicic acid and are commonly found in both fresh water and sea water. However, natural mineral water has extremely low concentration levels of orthosilicic acid (0.1-1.0 parts per million) due to the molecule's instability. Attempts to increase the concentration levels found in nature result in the linking of several small orthosilicic acid molecules to form larger, insoluble polymer-molecules. The chemical reaction of orthosilicic acid molecules into larger, insoluble polymer-molecules is typical of silicon (bio)chemistry and is known as polymerization.

The human body contains approximately 7 grams of silicon, which is present in various tissues and body fluids. The silicon in tissues is usually complexed to glycoproteins such as cartilage, whereas the silicon in blood is almost entirely found as free orthosilicic acid. The biological requirement for silicon was first demonstrated by Edith Carlisle and Klaus Schwarz in experiments with rats and chickens that were fed silicon-deficient diets. These experiments demonstrated that nutritional silicon deficiency causes skeletal deformities such as abnormal skull and long bone structure, as well as poorly-formed joints with decreased cartilage content. Detailed biochemical analysis revealed that silicon is an essential nutrient for the structural integrity and development of connective tissue.

Connective tissue is composed of cells which produce the fibrous protein matrixes of collagen and elastin, as well as the hydrated (water retaining) network of amino-sugars called glycosaminoglycans (GAG) or mucopolysaccharides (MPS). Silicon is believed to act as a cross-linking agent which stabilizes the glycosaminoglycan network.

The amino-sugar glucosamine, which is also needed for the biosynthesis of GAGs, has recently been recommended as an effective alternative treatment for arthritis. Given silicon's chemical association with GAGs, it seems that the combination of both glucosamine and silicon could have a promising therapeutic value in the treatment of arthritis and other related connective tissue diseases.

A special type of connective tissue in our body is bone. Silicon is a major ion in osteogenic cells, which are the bone-forming cells in young, uncalcified bone. As the bone matures, the silicon concentration declines and deposits of calcium and phosphorous are formed simultaneously. In other words, the more "mature" the bone tissue, the lower the silicon concentration in the bone. Therefore, it has been concluded that silicon acts as a regulating factor for the deposition of calcium and phosphorous in bone tissue. Silicon's regulatory action in bone calcification and its vital role as a structural component of connective tissue more than justify silicon's classification as an essential trace element in animal and human nutrition.

Silicon plays an ongoing role in maintaining bones after their formation. Bone is a dynamic, living tissue system that balances bone formation by osteoblast cells and the ongoing reabsorption of bone tissue by osteoclast cells (bone minerals are dissolved and organic bone matrix components such as collagen are digested by the action of osteoclast cells). Osteoporosis occurs when there is a low rate of bone formation and a high rate of bone reabsorption, thus leading to a decline in bone mineral density.

Studies with animals indicate that silicon supplementation reduces the number of osteoclast cells, thus partially preventing bone reabsorption and bone loss. In a clinical study of 53 osteoporotic women, silicon supplementation was associated with a significant increase in the mineral bone density of the femur. The positive results of these studies suggest that silicon supplementation, along with calcium and vitamin D, may be useful in the fight against osteoporosis.

In addition to connective tissue and bone health, several other promising health benefits of silicon have been reported: protection against aluminum toxicity and protection of arterial tissue.

Inasmuch as aluminum has been found in brain lesions of Alzheimer's patients, several researchers have suggested that aluminum toxicity may be involved in the pathology of Alzheimer's disease and other neurological disorders. In studies with rats, silicon was found to prevent the accumulation of aluminum in the brain. It is believed that silicon complexes (bonds) with aluminum in food and beverages, thereby reducing the gastrointestinal absorption of aluminum. The protective role of silicon against aluminum was also confirmed in a French population study of elderly subjects: high levels of aluminum in drinking water had a deleterious effect upon cognitive function when the silicon concentration was low, but when the concentration of silicon was high, exposure to aluminum appeared less likely to impair cognitive function.

Atherosclerosis is a condition characterized by the formation of plaque in the arteries Plaque is formed when damaged artery tissue is not properly repaired, thus allowing scar tissue, cholesterol, and other materials to obstruct the normal blood flow. Experiments with rabbits fed a high-cholesterol diet demonstrated that supplementation with silicon protected the rabbits from developing atherosclerosis. Aside from protection against atherosclerosis, silicon is a vital structural component of arteries. However, the silicon concentration of arteries declines with age, most likely increasing the risk of lesions and plaque formations.

The daily dietary intake of silicon (from various silicates) is estimated to be between 20-50 ma, with lower intakes associated with animal-based diets and higher intakes associated with vegetarian diets. Plants absorb orthosilicic acid from the soil and convert it into polymerized silicon for mechanical and structural support. This explains why fiber-rich foods such as cereals, oats, wheat bran and vegetables have a high silicon concentration. While whole grain foods are a good, natural source of silicon, the silicon from these foods is insoluble and cannot be directly absorbed in the gastro-intestinal tract. Silicon in food is solubilized by stomach acid into orthosilicic acid, which absorbs directly through the stomach wall and the intestine into the blood. Lower stomach acidity, whether due to illness or age, diminishes our ability to metabolize silicon from food sources. The refining and processing of food, which removes silicon-containing fibers, contributes to a lower dietary silicon intake. Given all these factors, it is not surprising that silicon supplementation may be useful for a complete and balanced diet.

When selecting a silicon supplement, the most important considerations should be safety and bioavailability (bioavailability is a complex term for the degree of absorption and the biological response to the silicon compounds which are present in the product). Organic silicon compounds, which are laboratory synthesized, contain silicon-carbon bonds. These molecules are normally not present in biological systems and can be very toxic. For this reason it is safest to use silicon compounds that are already present in nature or compounds that are the derivatives of natural products. Common silicon supplements include:

Plant extracts: Horsetail, bamboo and algae usually have high silicate concentrations. However, plant extracts are often not standardized and the silicon concentration in these products varies greatly. Lack of standardization can also involve health risks associated with toxic compounds such as alkaloids, which are present in certain plant extracts. As the silicon from plant extracts cannot be absorbed directly through the stomach wall, the bioavailability of these products requires high stomach acidity in order to produce soluble orthosilicic acid.

Colloidal silicon gel: These products offer large, insoluble, polymer molecules of silicic acid suspended in water. Like plant extracts, these polymer-molecules cannot be absorbed directly through the stomach wall and therefore have a low rate of absorption. The stomach's ability to produce soluble orthosilicic acid is also limited to low concentration levels due to orthosilicic acid's limited stability.

Orthosilicic acid: A new product on the market is a liquid, stabilized orthosilicic acid concentrate. A research group from the University of Anwerp in Belgium has recently published a supplementation study describing a high rate of silicon absorption from a liquid silicon supplement containing two percent stabilized orthosilicic acid. In this six-month study with calves, the total dietary silicon intake was increased with only five percent in the form of orthosilicic acid. Even with such a small dose of orthosilicic acid, the supplemented group showed 70 percent higher blood silicon levels than the unsupplemented group. These higher silicon blood levels also translated into a 12 percent higher collagen concentration in the skin of supplemented animals compared to unsupplemented animals. This study clearly demonstrated that the bioavailability of stabilized orthosilicic acid concentrate is very high compared to dietary silicon.

Scientific studies evaluating the bioavailability and safety of silicon products are scarce. Yet the manufactures of silicon supplements bear a responsibility for providing consumers with accurate, reliable information concerning the toxicity, bioavailability and efficacy of their products. Consumers can protect themselves from buying useless and even harmful products by requesting that manufacturers and retailers provide sound, scientific product information.



By Mario R. Calomme

Mario R. Calomme, Ph.D., is an associate scientist of the Faculty of Medicine at the University of Antwerp and is director of research for Bio Minerals N.V. in Belgium. He is a contributor to scientific journals with peer review such as Mutation Research, Journal of Natural Products Neuropediatrics, Biological Trace Element Research, Planta Medical. He is engaged in research on the metabolism of silicon and selenium and the antioxidative activities of natural products.

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