Grein þessi er eftir Dr. Henk Hendriks sem fjallar um kísil sem næringarefni og mikilvægi hans fyrir líkaman. Greinin er á ensku fyrir þá sem hafa áhuga á því að lesa hana hér að neðan:
Dr. Henk Hendriks
Silica is a mineral which is highly abundant in nature. Silica consists of one atom of silicon bound to two atoms of oxygen, chemically named silicon dioxide (SiO2). Silicon is neither a metal nor a non-metal; it is a metalloid. This means that it has properties of both a metal and a non-metal. The human body uses silicon and has health benefits . Scientists believe silicon is involved in several important processes in the body and consider it an essential nutrient [2,3].
The common mineral silica is usually found as quartz, an abundant ingredient in sand. Silica is mainly present as a solid, because it poorly dissolves in water. Silica exists as molecules, but mainly as particles of various sizes and in various forms. Some of these particles may be detrimental to health. Specifically when silica particles are inhaled on a regular basis and when inhaled silica particles are large, these may become deleterious in the long-term .
Conversely, silica molecules and silica particles consumed through the mouth are beneficial. Silica consists of 47% silicon and is a natural constituent of our diet. Dietary silicon consumption mainly occurs as silica dissolved in water and as monosilicic acid present in food stuffs. Silica consumption is accepted as being safe by both European  and United States authorities .
However, the human body gets little silicon from the diet, because our diet contains low quantities of it and because it is poorly absorbed in the intestines. Whereas some foods contain relatively high concentrations of silicon such as some cereals, some fruits and vegetables and some beverages , absorption of silicon from it is generally low . Bodily uptake from the diet (in another term: bioavailability) varies. It seems that the higher the concentration of silicon in a food the lower its bioavailability. Beverages in general appear to have a high bioavailability of silicon. Silica containing waters have also been shown to increase the uptake of silicon, because it increased urinary silicon excretion . In other words: silicon dissolved in beverages is best taken up by the body [10-12].
Silicon deficiency has not been described for humans, but animals which were made silicon deficient have deformities in skull and bones, poorly formed joints, reduced cartilage, and a disturbed mineral balance in bones [3,13]. This shows that silicon is an important dietary factor in bone health. Therefore, scientists propose that healthy diets should include foods that provide trace elements like silicon in amounts that promote health even if currently not considered essential. A dietary intake of silica of 25 mg/day corresponding to ~10 mg/day of silicon, would be an adequate intake without adverse effects .
Silicon appears to be important for bone health. Various population studies have supported such a role [15-18]. Supplementation with silicon increased bone volume and bone mineral density in people with osteoporosis [17,19]. Also, studies in cells have shown that silicon stimulates processes important for healthy bones [20,21]. Animal studies show that supplementation with silicon improves bone health of mice and rats [22-25]. It is not clear how silicon affects bone health. Scientists suggest that silicon supports the production of a protein important for the structure of bones and skin: collagen . Others suggest that silicon may support the stabilization of collagens or similar structural molecules .
Bone implants (e.g. dental implants, surgical bone replacements) combined with silicon and silica stimulated new bone growth by increasing collagen production [28,29]. Various forms of silicon are currently being investigated for their possible application as a new fracture healing biomaterial [30,31]. Also, very small particles of silica are being studied for their antimicrobial effects [32-34]. Silicon may not only improve bone health by stimulating collagen synthesis. An optimized collagen synthesis by silicon may also improve the structural integrity of skin [35,36], contribute to healthier hair  and nails [38,39] and support wound healing .
Some studies suggest that silica in drinking water and other forms of silicon in beverages may counteract the detrimental effects of aluminium in the diet and may therefore help in the prevention of Alzheimer’s disease [10,41,42].
Although the specific biochemical or physiological roles of silicon in the human body are largely unknown, these functions are generally considered to exist. As a result, there is growing interest in the potential therapeutic effects of water-soluble silica on human health. GeoSilica Iceland products combine silica with other minerals depending on your preference to stimulate various functions. Silica in all GeoSilica Iceland products provides your daily portion of silicon.
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