But this secondary effect is greater with sterol esters than free sterols.
It is not yet known how plant sterols act on the bioavailability of carotenoids and alpha-tocopherol.
The researchers recruited 26 normocholesterolemic men to a double-blind, randomized, crossover study. Everyday subjects consumed either a low-fat milk-based beverage, the same beverage supplemented with 2.2 g plant sterol equivalents provided as free sterols and the same drink with plant sterol esters for one week, and then crossed over.
The researchers report in this month's American Journal of Clinical Nutrition that both of the milks enriched with plant sterols reduced cholesterol absorption by 60 per cent.
Both also reduced the bioavailability of beta-carotene by around 50 per cent and that of alpha-tocopherol by around 20 per cent but the reduction in beta-carotene bioavailability was significantly less with plant free sterols than with plant sterol esters.
At the limit of significance in the area under the curve, the reduction in alpha-tocopherol bioavailability was also less with plant free sterols than with plant sterol esters.