OSA bioavailability cross-over study

Absorption of silicon in healthy subjects

Silicon is next to oxygen the most abundant element in the earth’s crust. The distribution of Si deficiency indicate that Si influences bone formation by affecting cartilage composition and ultimately cartilage calcification. The dietary intake of Si was estimated for US citizens to be between 20-50 mg with the lower intake of animal-based diets and the higher intake for plant-based diets. However, studies on the minimum Si requirement and supplementation experiments, comparing the bio-availability of different Si compounds, are lacking. Orthosilicic acid was suggested to have an important function in Si metabolism and is found in both fresh water and sea water.

This monomeric form of silicic acid is stable in dilute concentrations of about 10^-4M, but condenses into silica gels at higher concentrations and low pH. The absorption and urinary excretion of Si from stabilized orthosilicic acid (OSA), standardized herbal silica extract from the Si-accumulator plant Equisetum arvense, and colloidal silicic acid were compared in a double-blind study with healthy subjects.