Dietary cholesterol is secreted in intestinally derived chylomicrons during several subsequent postprandial phases in healthy humans

• Published in: The American journal of clinical nutrition Vol. 73; no. 5; pp. 870 - 877
• Main Authors: BEAUMIER-GALLON, Gabrielle, DUBOIS, Christophe, SENFT, Michelle, VERGNES, Marie-France, PAULI, Anne-Marie, PORTUGAL, Henri, LAIRON, Denis
• Format: Journal Article
• Language: English
• Published: Bethesda, MD American Society for Clinical Nutrition 01-05-2001; American Society for Clinical Nutrition, Inc
• Subjects: Adult; Apolipoprotein B-48; Apolipoproteins B - blood; Biological and medical sciences; Cholesterol; Cholesterol - blood; Cholesterol, Dietary - pharmacokinetics; Chylomicrons - blood; Chylomicrons - metabolism; Deuterium; Digestive system; Fundamental and applied biological sciences. Psychology; Gas Chromatography-Mass Spectrometry; Humans; Intestinal Absorption; Intestine, Small - physiology; Intestine. Mesentery; Lipids; Lipoproteins, HDL - blood; Lipoproteins, LDL - blood; Male; Men; Metabolism; Nutrition; Postprandial Period - physiology; Reference Values; Triglycerides - blood; Vertebrates: digestive system; Human; Digestive system; Postprandial; Lipids; Digestion; Metabolism; Small intestine; Cholesterol; Feeding; Absorption; Chylomicron; Diet; Exocrine secretion; Macronutrient
• ISSN: 0002-9165; 1938-3207
• DOI: 10.1093/ajcn/73.5.870

The process of intestinal absorption and chylomicron resecretion of dietary cholesterol in humans is poorly understood.
The present study aimed to test the hypothesis that dietary cholesterol ingested during a given meal is resecreted into chylomicrons (and plasma) during several subsequent postprandial periods.
Seven healthy subjects ingested 3 comparable mixed test meals (at 0, 8, and 24 h) containing a given amount of fat (49 g) and cholesterol (157 mg); blood samples were taken 3 and 6 h after each test meal and 48 and 72 h after the beginning of the experiment. Heptadeuterated dietary cholesterol was present in the first test meal only, enabling its specific determination with use of gas chromatography-mass spectrometry. Chylomicrons, LDL, and HDL were isolated and lipids were quantified.
In apolipoprotein B-48-containing chylomicrons, deuterated cholesterol concentrations were moderate after the first meal (1.3 x 10(-4) mmol/L), reached a maximum after the second meal (2.4 x 10(-4) mmol/L), and were still elevated after the third meal (1.7 x 10(-4) mmol/L). In plasma, LDL and HDL cholesterol enrichment in deuterated cholesterol was lower than in chylomicrons and plateaued after 24--48 h. Estimates of newly secreted exogenous deuterated cholesterol in chylomicrons indicate that 30.7%, 55.2%, and 14.1% of the total was secreted after the first, second, and third meals, respectively.
Ingested dietary cholesterol is secreted by the small intestine in chylomicrons into the circulation during > or =3 subsequent postprandial periods in healthy humans. This likely results from a complex multistep intestinal processing of cholesterol with dietary fat as a driving force.