Dietary calcium and phosphate precipitate in the small intestine to form insoluble amorphous calcium phosphate, said the researchers at the Friedrich Schiller University. They hypothesized that the ability of this substance to bind and inactivate luminal bile acids might have an effect on cholesterol metabolism.
To test their hypothesis, they gave bread fortified with pentacalcium hydroxy-triphosphate or a placebo to 31 young healthy volunteers. Then the groups crossed over.
The researchers found that cholesterol levels were lower after four weeks of supplementation than after the placebo.
Serum LDL cholesterol and the ratio of LDL to HDL cholesterol also tended to be lower after the supplement phase than after placebo, they report in this month's issue of the Journal of Nutrition (vol 135, pp1678-1682).
Analysing faecal samples, the researchers found no difference in the excretion of cholesterol but there was increased excretion of bile acid.
"The observed beneficial effects on cholesterol metabolism…might be explained by an increased bile acid excretion and a subsequent regeneration of bile acids from endogenous cholesterol in the liver," write the researchers.