Calcium, vitamin D and heart disease.
Explains Donald Beitz, one of the researchers at Iowa State University in Ames, "Vitamin D plays a role in calcium deposition." Since plaque hardens as it matures, there was some suspicion that an excess of vitamin D might aid in this calcification. Working with groups of six male kids, the researchers fed each group of goats a diet with a different milk ration: plain goat milk, milk with 2 to 2.5 times the recommended calcium level, milk with 100 times the recommended vitamin D, and milk with double the calcium and 100 times the vitamin D. Kids receiving the calcium-only supplement had the healthiest arteries of all; those with the calcium/vitamin D combo fared worst, with serious calcification and atherosclerosis.
Beitz says they chose a 100-fold excess of vitamin D to accelerate the onset of any related effect during their 20-week study. If a comparable effect occurs in humans, he speculates, it might take only a 5- or 10-fold excess of the vitamin -- over a 50-year period -- to achieve a similar effect. As to why calcium alone might be protective, Beitz says one theory is that it may form a calcium salt of the bile acid, thereby causing a drain on cholesterol, from which these bile acids are synthesized.
The Iowa State researchers plan to study the vitamin D/calcium interaction next in pigs -- an animal that better models what one might expect to occur in humans.
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|Title Annotation:||nutrition research|
|Date:||Mar 2, 1985|
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