"Phytosterols are plant compounds, which are known for their cholesterol lowering activities. Because of these properties they are added to foods, like spreads and drinks, as a functional food ingredient. It is generally accepted that phytosterols lower plasma cholesterol concentration because they lower the absorption of cholesterol in the human intestinal tract. The unabsorbed cholesterol and phytosterols end up in the intestine and colon. There they may become available for microbial metabolism. In current scientific literature, there are hardly any studies available on the conversion or stability of phytosterols in the gastro-intestinal tract. Therefore, this research project will investigate the metabolism of phytosterols in the gastro-intestinal tract. Secondly, this projects aims at the development of protocols by which the phytosterols can be enzymatically modified to protected them against degradation. As a secondary effect, these modifications may also change the physical properties of the phytosterols. So this research should improve the understanding of the bioconversion routes of phytosterols, and could contribute to the development of more bioactive formulations, which can be used in a broader range of products."