Processing of vegetable-borne carotenoids in the human stomach and duodenum

Abstract

Carotenoids are thought to diminish the incidence of certain degenerative diseases, but the mechanisms involved in their intestinal absorption are poorly understood. Our aim was to obtain basic data on the fate of carotenoids in the human stomach and duodenum. Ten healthy men were intragastrically fed three liquid test meals differing only in the vegetable added 3 wk apart and in a random order. They contained 40 g sunflower oil and mashed vegetables as the sole source of carotenoids. Tomato purée provided 10 mg lycopene as the main carotenoid, chopped spinach (10 mg lutein), and carrot purée (10 mg β-carotene). Samples of stomach and duodenal contents and blood samples were collected at regular time intervals after meal intake. all -trans and ciscarotenoids were assayed in stomach and duodenal contents, in the fat and aqueous phases of those contents, and in chylomicrons. The cis-trans β-carotene and lycopene ratios did not significantly vary in the stomach during digestion. Carotenoids were recovered in the fat phase present in the stomach during digestion. The proportion of all -trans carotenoids found in the micellar phase of the duodenum was as follows (means ± SE): lutein (5.6 ± 0.4%), β-carotene (4.7 ± 0.3%), lycopene (2.0 ± 0.2%). The proportion of 13- cis β-carotene in the micellar phase was significantly higher (14.8 ± 1.6%) than that of the all -trans isomer (4.7 ± 0.3%). There was no significant variation in chylomicron lycopene after the tomato meal, whereas there was significant increase in chylomicron β-carotene and lutein after the carrot and the spinach meals, respectively. There is no significant cis-transisomerization of β-carotene and lycopene in the human stomach. The stomach initiates the transfer of carotenoids from the vegetable matrix to the fat phase of the meal. Lycopene is less efficiently transferred to micelles than β-carotene and lutein. The very small transfer of carotenoids from their vegetable matrices to micelles explains the poor bioavailability of these phytomicroconstituents.

High dietary intake of phytosterol esters decreases carotenoids and increases plasma plant sterol levels with no additional cholesterol lowering

“…This may have been attributable to increases in fiber, especially for lycopene, which is less efficiently transferred from the fat phase to the micellar phase than lutein (20).…”

The Influence of Iron and Zinc Supplementation on the Bioavailability of Provitamin A Carotenoids from Papaya Following Consumption of a Vitamin A-Deficient Diet

“…The chylomicron responses in b-carotene, a-carotene, lycopene and lutein were similar in the old and in the young groups (26)(27)(28). Zinc (a-and b-carotene) and iron1zinc (iron and zinc group) (b-cryptoxanthin) showed highest intact chylomicron appearance of provitamin A carotenoids.…”

Overview of carotenoid bioavailability determinants: From dietary factors to host genetic variations

“…The fraction of cis isomers present in our diet 303 is usually produced by technological treatments, in particular elevated temperatures 304 (Milanowska & Gruszecki, 2005;Rodriguez-Amaya, 1999;Updike & Schwartz, 2003). A 305 "trans to cis" conversion in the acidic environment of the stomach has also been proposed 306 (Mortensen & Skibsted, 2000), although it has not been observed in vivo (Richelle, et al, 307 2010;Tyssandier, et al, 2003). However, Richelle et al reported lycopene conversion to 308 occur within the enterocyte (Richelle, et al, 2010).…”