PHYTOSTEROLS IN HUMAN NUTRITION

该子项目是利用NIH/NCRR资助的中心赠款提供的资源的许多研究子项目之一。子项目和研究者（PI）可能从另一个NIH来源获得主要资金，因此可以在其他CRISP条目中表示。所列机构为中心，不一定是研究者所在机构。植物甾醇是胆固醇样分子，存在于所有植物性食物中，植物油中的浓度最高。它们仅以痕量被吸收，但抑制肠胆固醇的吸收，包括再循环内源性胆汁胆固醇，这是胆固醇消除的关键步骤。天然膳食摄入量约为167-437毫克/天。在喂养研究中测量生物效应的尝试受到水和脂肪中有限溶解度的阻碍。植物甾醇与长链脂肪酸的酯化使脂肪溶解度增加10倍，并允许每天在脂肪食物如人造黄油中递送几克。2g/天的剂量作为酯降低低密度脂蛋白胆固醇10%，并且在δ（5）-甾醇和5 α-还原甾醇（甾烷醇）之间观察到很小的差异。植物甾醇也可以分散在水中乳化后与卵磷脂和减少胆固醇的吸收时，添加到非饲料。与这些补充研究相反，对天然饮食中低植物甾醇水平的影响知之甚少。然而，在不含固醇的测试餐中，仅以150 mg的剂量就可以测量到胆固醇吸收的减少，这表明天然食物植物固醇可能具有临床重要性。目前的文献表明，植物甾醇添加到饮食中是安全的，并且测量的吸收和血浆水平非常小。增加各种食物中植物甾醇的摄入总量可能是降低人群胆固醇水平和预防冠心病的重要途径。

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Phytosterols are cholesterol-like molecules found in all plant foods, with the highest concentrations occurring in vegetable oils. They are absorbed only in trace amounts but inhibit the absorption of intestinal cholesterol including recirculating endogenous biliary cholesterol, a key step in cholesterol elimination. Natural dietary intake varies from about 167-437 mg/day. Attempts to measure biological effects in feeding studies have been impeded by limited solubility in both water and fat. Esterification of phytosterols with long-chain fatty acids increases fat solubility by 10-fold and allows delivery of several grams daily in fatty foods such as margarine. A dose of 2 g/day as the ester reduces low density lipoprotein cholesterol by 10%, and little difference is observed between Delta(5)-sterols and 5alpha-reduced sterols (stanols). Phytosterols can also be dispersed in water after emulsification with lecithin and reduce cholesterol absorption when added to nonf at f oods. In contrast to these supplementation studies, much less is known about the effect of low phytosterol levels in the natural diet. However, reduction of cholesterol absorption can be measured at a dose of only 150 mg during otherwise sterol-free test meals, suggesting that natural food phytosterols may be clinically important. Current literature suggests that phytosterols are safe when added to the diet, and measured absorption and plasma levels are very small. Increasing the aggregate amount of phytosterols consumed in a variety of foods may be an important way of reducing population cholesterol levels and preventing coronary heart disease.