Dietary triglycerides, up to 40 g/meal, do not affect preformed vitamin A bioavailability in humans

Borel, Patrick; Dubois, C.; Mekki, Nadia; Grolier, Pascal; Partier, Anne; Alexandre-Gouabau, Marie Cécile; Lairon, Denis; Azaı̈s-Braesco, Véronique

doi:10.1038/sj.ejcn.1600466

Cited by 16 publications

(22 citation statements)

References 25 publications

(38 reference statements)

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“…(VLDLA) fractions. Measuring the appearance of retinyl esters only in the chylomicron component of the TRL underestimates total vitamin A absorption (34). In a previous study, after subjects ingested a b-carotene dose, we observed postprandial appearances of retinyl palmitate in both the plasma chylomicron and VLDLA fractions that coincided in time and magnitude (35).…”

Section: Discussionmentioning

confidence: 90%

Vitamin A equivalence of the β-carotene in β-carotene–biofortified maize porridge consumed by women

Nugroho

Rocheford

et al. 2010

The American Journal of Clinical Nutrition

108

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Section: Discussionmentioning

confidence: 90%

Vitamin A equivalence of the β-carotene in β-carotene–biofortified maize porridge consumed by women

Nugroho

Rocheford

et al. 2010

The American Journal of Clinical Nutrition

108

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“…HPLC was able to distinguish between retinyl myristate, palmitate, and stearate concentrations (26,27). Only retinyl myristate was present at significant levels before retinol incubation ( Table 2).…”

Section: Resultsmentioning

confidence: 99%

“…The cells were collected by scraping, resuspended in PBS, and sonicated on ice. All-trans retinol and retinyl esters were assayed from 1g of placental tissue, 5 ϫ 10 6 cells, or 0.5 mL of culture medium, as previously described with some minor modifications (26,27). An equal volume of ethanol containing an internal standard (retinyl laurate for vitamin A) was added to each sample.…”

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confidence: 99%

Esterification of Vitamin A by the Human Placenta Involves Villous Mesenchymal Fibroblasts

et al. 2000

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Vitamin A (retinol) and its active derivatives (retinoic acids) are essential for growth and development of the mammalian fetus. Maternally derived retinol must pass the placenta to reach the developing fetus. Despite its apparent importance, little is known concerning placental transfer and metabolism of retinol, and particularly of placental production and storage of retinyl esters. To elucidate this metabolic pathway, we incubated, in the presence of retinol, 1) human full-term placental explants and 2) primary cultures of major cells types contributing to placental function: trophoblasts and villous mesenchymal fibroblasts. We used HPLC to determine the types and concentrations of retinyl esters produced by these explants and cells. About 14% of total cellular retinol in placental explants was esterified. The most abundant esters were myristate and palmitate. Primary cell cultures showed that fibroblasts efficiently produced retinyl esters, but trophoblasts did not. In both types of experiments, no retinyl esters were detected in the culture medium, suggesting that retinyl esters were produced for storage purpose. These results suggest that villous mesenchymal fibroblasts are primary sites of retinol esterification and storage in the placenta. In addition to their essential roles in vision, growth, and maintenance of differentiated epithelia, vitamin A (retinol) and its active derivatives, the RAs, are required for normal mammalian reproduction and fetal development (1, 2). Maternal vitamin A deficiency can result in fetal death or in a spectrum of malformations, the fetal vitamin A deficiency syndrome (3-6). Excessive vitamin A intake can also produce a spectrum of congenital defects, in a dose-and developmental stagedependent manner (7,8). Because there is no de novo fetal synthesis of retinol, the developing mammalian embryo is dependent on the maternal circulation for its vitamin A intake. The presence of measurable hepatic vitamin A stored at birth is indicative of the functionality and importance of placental transport during pregnancy (9, 10). Abnormalities of placental transfer could have serious consequences on fetal development and integrity.Despite its apparent importance, little is known about placental transfer and metabolism of retinoids. This question has been approached in animal models (sheep, mouse, monkey), but the placental metabolism of retinoids is difficult to deduce from studies in the intact animal, and extrapolation of these results to humans is uncertain (11-13). Measurements of human placental, maternal, and cord retinoid concentrations have been reported, but they shed little light on the metabolic pathway (14,15). Experiments using human perfused placenta and full-term human placental tissues in vitro have yielded controversial results concerning retinoid metabolism, especially the ability of the placenta to produce and store retinyl esters from retinol (16,17).To better characterize retinoid metabolism, we have investigated placental capacity to esterify retinol into retinyl es...

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“…The presence of dietary fat in the intestine usually increases intestinal absorption of preformed vitamin A and provitamin A carotenoids by enhancing the secretion of pancreatic enzymes and of bile salts that provide components (lysophospholipids, monoglycerides, free fatty acids) to form luminal mixed micelles of lipids and for intracellular assembly of chylomicrons (Roels et al, 1958;Roels et al, 1963;Reddy and Srikantia, 1966;Figueira et al, 1969;Jayarajan et al, 1980;Borel et al, 1997;Jalal et al, 1998;Li and Tso, 2003;Unlu et al, 2005).…”

Section: Intestinal Absorptionmentioning

confidence: 99%

Scientific Opinion on Dietary Reference Values for vitamin A

Products¹

2015

EFSA Journal

125

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Following a request from the European Commission, the Panel on Dietetic Products, Nutrition and Allergies derived Dietary Reference Values for vitamin A. The Panel considered that a concentration of 20 µg retinol/g liver can be used as a target for establishing the Average Requirement (AR) for vitamin A. In the absence of a better characterisation of the relationship between vitamin A intake and liver stores, a factorial approach was applied. This approach considered a total body/liver retinol store ratio of 1.25, a liver/body weight ratio of 2.4 %, a fractional catabolic rate of body retinol of 0.7 % per day, an efficiency of storage in the whole body for ingested retinol of 50 % and reference weights for women and men in the EU of 58.5 and 68.1 kg, respectively. ARs of 570 µg retinol equivalent (RE)/day for men and 490 µg RE/day for women were derived. Assuming a coefficient of variation (CV) of 15 %, Population Reference Intakes (PRIs) of 750 µg RE/day for men and 650 µg RE/day for women were set. For infants aged 7-11 months and children, the same equation as for adults was applied by using specific values for reference weight and liver/body weight ratio. For catabolic rate, the adult value corrected on the basis of a growth factor was used. ARs range from 190 µg RE/day in infants aged 7-11 months to 580 µg RE/day in boys aged 15-17 years. PRIs for infants and children were estimated using a CV of 15 % and range from 250 to 750 µg RE/day. For pregnancy and lactation, additional vitamin A requirements related to the accumulation of retinol in fetal and maternal tissues and transfer of retinol into breast milk were considered and PRIs of 700 and 1 300 µg RE/day, respectively, were set. Vitamin A is involved in vision as retinal, which plays a central role in the mechanisms of phototransduction, and in the systemic maintenance of the growth and integrity of cells in body tissues through the action of retinoic acid, which acts as regulator of genomic expression. The most specific clinical consequence of vitamin A deficiency is xerophthalmia, which encompasses a clinical spectrum of ocular manifestations. In low-income countries, vitamin A deficiency in young infants and children has been associated with increased infectious morbidity and mortality, including respiratory infection and diarrhoea. © EuropeanPreformed vitamin A is efficiently absorbed (70-90 %). The absorption of β-carotene appears to be highly variable (5-65 %), depending on food-and diet-related factors, genetic characteristics and the health status of the subject. The intestine is the primary tissue where dietary provitamin A carotenoids are converted to retinol. Retinol, in the form of retinyl esters, and provitamin A carotenoids enter the body as a component of nascent chylomicrons secreted into the lymphatic system. Most dietary retinol (in chylomicrons and chylomicron remnants) is taken up by the liver, which is the major site of retinol metabolism and storage. Hepatic retinyl esters are hydrolysed to free retinol, and delivered to ti...

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Dietary triglycerides, up to 40 g/meal, do not affect preformed vitamin A bioavailability in humans

Cited by 16 publications

References 25 publications

Vitamin A equivalence of the β-carotene in β-carotene–biofortified maize porridge consumed by women

Vitamin A equivalence of the β-carotene in β-carotene–biofortified maize porridge consumed by women

Esterification of Vitamin A by the Human Placenta Involves Villous Mesenchymal Fibroblasts

Scientific Opinion on Dietary Reference Values for vitamin A

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