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(Arteriosclerosis, Thrombosis, and Vascular Biology. 2001;21:e34.)
© 2001 American Heart Association, Inc.

Atherosclerosis and Lipoproteins

Bioavailability of Vitamin E as Function of Food Intake in Healthy Subjects

Effects on Plasma Peroxide–Scavenging Activity and Cholesterol-Oxidation Products

L. Iuliano; F. Micheletta; M. Maranghi; G. Frati; U. Diczfalusy; F. Violi

From the Dipartimento di Medicina Interna (L.I., F.M., M.M.) and Istituto di Terapia Medica Sistematica (F.V.), Università La Sapienza, Rome, Italy; Istituto di Chirurgia Toracica e Cardiovascolare (G.F.), Università di Siena, Siena, Italy; and the Department of Medical Laboratory Sciences and Technology (U.D.), Karolinska Institutet, Huddinge University Hospital, Huddinge, Sweden.

Correspondence to Luigi Iuliano, MD, The Institute of Clinical Medicine I, University La Sapienza, 00161 Rome, Italy. E-mail luigi.iuliano{at}uniroma1.it

Abstract—— Clinical trials with vitamin E have yielded contrasting results. In these trials, the amount of vitamin E given was different, and the compliance was not assessed in all studies. In addition, the modality of intake, ie, in relation to food, was not specified in any trial. Vitamin E is lipophilic, and its absorption is expected to be increased by food. We studied the bioavailability of vitamin E in relation to food intake and the effect on the lipid peroxide–scavenging activity of plasma and on 7ß-hydroxycholesterol and 7-ketocholesterol (oxysterols) as markers of oxidant stress. Twenty healthy Italian subjects were randomly assigned to take vitamin E at 300 mg/d on an empty stomach (group A) or during dinner (group B) for 15 days. Plasma vitamin E markedly increased in group B (84%) compared with group A (29%). The lipid peroxide–scavenging activity of plasma increased significantly in group B (14%, P=0.005) but did not change in group A. All subjects showed very low levels of plasma oxysterols, which were not affected by vitamin E supplementation in either group. This study shows that plasma concentration of vitamin E and plasma antioxidant activity in response to oral supplementation are markedly affected by food intake. Healthy Italian subjects show very low levels of cholesterol oxidation products; these low levels are possibly related to the Mediterranean diet. To obtain maximal absorption, vitamin E must be given at meals. These data should be taken into account in clinical trials with vitamin E.

Key Words: atherosclerosis • antioxidants • oxidant stress • oxysterols • vitamin E