Phytosterol-Deficient and High-Phytosterol Diets Developed for Controlled Feeding Studies

Abstract

Phytosterols reduce cholesterol absorption and low-density lipoprotein (LDL) cholesterol concentrations, but the quantity and physiological significance of phytosterols in common diets are generally unknown because nutrient databases do not contain comprehensive phytosterol data. The primary aim of this study was to design prototype phytosterol-deficient and high-phytosterol diets for use in controlled feeding studies of the influence of phytosterols on health. A second aim was to quantify the phytosterol content of these prototype diets and three other diets consumed in the United States. This study was Publisher's Disclaimer: This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final citable form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. diet, a relatively high-phytosterol diet based on the Dietary Approaches to Stop Hypertension (DASH) diet, American Heart Association (AHA) diet, Atkins® lifetime maintenance plan, and a vegan diet. A single day of meals for each diet was homogenized and the resulting composites were analyzed for free, esterified, and glycosylated phytosterols by gas chromatography. Independent samples t tests were used to compare the diets' total phytosterol content. The total phytosterol content of the experimental phytosterol-deficient diet was 64 mg/2000 kcal, with progressively larger quantities in Atkins®, AHA, vegan, and the high-phytosterol DASH diet (163, 340, 445 and 500 mg/ 2000 kcal, respectively). Glycosylated phytosterols, which are often excluded from phytosterol analyses, comprised 15.9 ± 5.9% (mean±SD) of total phytosterols. In summary, phytosterol-deficient and high-phytosterol diets that conform to recommended macronutrient guidelines and are palatable can now be used in controlled feeding studies. NIH Public Access

Impact of plant-based diet on lipid risk factors for atherosclerosis

“…In terms of TC and LDL-C concentrations, this is well established because replacement of saturated fatty acids with polyunsaturated and monounsaturated fatty acids diminishes these parameters [22]. Additional higher contents of phytosterols in the vegan diet may cause a lipidlowering effect [8]. Our study also confirms recent reports observed by Bradbury et al [23] in the large European population which show positive results in reduction of apoB and also a lower concentration of non-HDL-C in the vegan group.…”

“…Of particular importance may also be a greater supply of phytosterols, plant derived compounds similar to cholesterol which have lipid-lowering properties. Phytosterols reduce absorption of cholesterol in the digestive tract and influence lipoprotein metabolism, which in turn may lead to a decrease in total cholesterol (TC) and low density lipoprotein (LDL) cholesterol (LDL-C) concentration [8,9].…”

Response to Letter Regarding Article, “Combined Effects of Ezetimibe and Phytosterols on Cholesterol Metabolism: A Randomized, Controlled Feeding Study in Humans”

“…On the one hand, serum levels rise with increasing intake and can reflect a potentially beneficial effect of reduced cholesterol absorption efficiency. 1 On the other hand, it is well established that serum phytosterol levels are also positively correlated with intrinsic cholesterol absorption efficiency, a potentially harmful characteristic that may predispose to coronary heart disease. 2 Therefore, we believe that simple serum phytosterol levels have limited utility in epidemiological studies because it is not clear what elevated levels represent.…”

Plant sterols: Friend or foe in CNS disorders?

“…The hydroxyl group at C3 is linked to a hexose or a 6-fatty-acyl hexose moiety for phytosterol glucosides and acyl glucosides, respectively [32]. Glycosylated phytosterols are present in particular foods and plants, and efficiently lower plasma cholesterol levels [33][34][35][36][37]. It is unclear to what extent phytosterol glucosides are formed from non-modified phytosterols within the body.…”