The intestinal absorption and metabolism of vitamin A and beta-carotene in man.

Goodman, DeWitt S.; Blomstrand, Rolf; Werner, B.; Huang, Helen S.; Shiratori, Tatsuji

doi:10.1172/jci105468

Cited by 320 publications

(127 citation statements)

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“…Interestingly, in humans, b-cryptoxanthin-rich fruits have been reported to be more efficient in raising retinol serum levels than green vegetables, suggesting a higher bioavailability of provitamin A carotenoids from fruits (De Pee et al, 1998). In addition, similar to what was observed in control subjects, about two-thirds of the bcarotene absorbed is effectively converted into retinol in type I diabetics (Goodman et al, 1966;Van Vliet et al, 1995;Granado et al, 2001). Thus, a potential overestimation of b-carotene intake along with a relatively higher bioavailability of b-cryptoxanthin (and the half provitamin A value) may explain, at least in part, the higher serum level despite a lower intake of b-cryptoxanthin, compared to that of b-carotene.…”

Section: Discussionmentioning

confidence: 72%

Assessment of carotenoid status and the relation to glycaemic control in type I diabetics: a follow-up study

et al. 2006

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Objective: To assess the carotenoid status in young type I diabetic patients and its relationship to the glycaemic control of the disease. Design: A follow-up study. Setting: Hospital Universitario Puerta de Hierro, Health Area VI of Madrid (Spain). Subjects: Forty-seven type I diabetic patients, followed for 2.5 years. Interventions: Coinciding with physical examination and laboratory tests, serum levels of carotenoids were analysed by HPLC, and dietary intake of carotenoids was evaluated by a semiquantitative food frequency questionnaire and 3-day prospective dietary records. Results: In type I diabetic patients, average intake, serum levels and correlations between diet and serum levels of carotenoids were comparable to those in reference non-diabetic groups. Between-subjects seasonal variations were observed for bcryptoxanthin intake and serum levels (higher in winter) and serum lycopene (higher in summer). Significant within-subjects seasonal changes were shown for dietary and serum b-cryptoxanthin and serum b-carotene. Serum carotenoids were unrelated to glycaemic control markers. Subjects with clinically acceptable glycaemic control showed lower lycopene intake than those with unacceptable control. Intake of carotenoids did not explain variance in insulin dose, fasting glycaemia, fructosamine or HbA 1c . With the exception of lycopene, serum carotenoids were predicted by dietary intake, but in no case by fasting glycaemia, HbA 1c or fructosamine. Conclusion: In type I diabetic patients, serum carotenoid concentrations and their variance are determined by dietary intake patterns, and are unrelated to the glycaemic control of the disease, as assessed by biochemical markers.

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Section: Discussionmentioning

confidence: 72%

Assessment of carotenoid status and the relation to glycaemic control in type I diabetics: a follow-up study

et al. 2006

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“…Retinal produced in the intestine from carotenoids by BCMO1 is mainly reduced to retinol and esterified to retinyl esters before packaging into chylomicrons [34]. Enzymatic activities that carry out reduction of retinal have been reported for both cytosolic and microsomal fractions of intestine [11].…”

Section: Ralr1 May Act As a Physiologically Significant Retinal Reducmentioning

confidence: 99%

In vitro and in vivo characterization of retinoid synthesis from β-carotene

Fierce

Vieira

Piantedosi

et al. 2008

Archives of Biochemistry and Biophysics

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Retinoids are indispensable for the health of mammals, which cannot synthesize retinoids de novo. Retinoids are derived from dietary provitamin A carotenoids, like β-carotene, through the actions β-carotene 15,15′ monooxygenase (BCMO1). As the substrates for retinoid metabolizing enzymes are water insoluble, they must be transported intracellularly bound to cellular retinol-binding proteins. Our studies suggest that cellular retinol binding protein, type I (RBP1) acts as an intracellular sensor of retinoid status that, when present as apo-RBP1, stimulates BCMO1 activity and the conversion of carotenoids to retinoids. Cellular retinol binding protein, type II (RBP2), which is 56% identical to RBP1 does not influence BCMO1 activity. Studies of mice lacking BCMO1 demonstrate that BCMO1 is responsible for metabolically limiting the amount of intact β-carotene that can be absorbed by mice from their diet. Our studies provide new insights into the regulation of BCMO1 activity and the physiological role of BCMO1 in living organisms. Keywordsβ-carotene; cleavage; β-carotene 15; 15′ monooxygenase; retinoid; metabolism; cellular retinol binding protein Retinoids (vitamin A, its natural metabolites and synthetic analogs) are required for survival of mammals and are needed to support vision, normal cell differentiation and proliferation, embryonic development, normal immune function and reproduction [1]. Aside from in vision, all of the essential actions of retinoids within the body are thought to involve the transcriptional activity of retinoic acid [1]. Retinoic acid is a potent transcriptional regulator whose effects are mediated by two families of nuclear receptors, the retinoic acid receptors (RARs) and the retinoid X receptors (RXRs) [2][3][4]. When retinoic acid is not available, RAR/RXR heterodimers bind to retinoic acid response elements in promoter of genes and form complexes with transcriptional corepressors resulting in chromatin condensation and transcriptional silencing. In the presence of retinoic acid, corepressors are released from the RAR/RXR heterodimer which is now free to recruit and bind coactivators resulting in chromatin *Corresponding author: Jisun Paik, Department of Comparative Medicine, Raitt Hall, 324, Seattle, WA 98195. Phone: 206-221-2682; Fax: 206-685-1696; E-mail: jpaik@u.washington.edu. 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. NIH Public Access NIH-PA Author ManuscriptNIH-PA Author Manuscript NIH-PA Author Manuscript decondensation and transcriptional activation. In excess of 500 genes may be responsive to retinoic acid [5].Since ani...

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“…It is well established that P-carotene is the precursor of vitamin A and its conversion into vitamin A in vivo has been unequivocally demonstrated in rats, pigs, and humans (1)(2)(3)(4)(5)(6)(7).t Subsequently, the in vitro enzymatic conversion of 83-carotene to retinal by an enzyme preparation from rat intestine and liver was independently shown by Goodman et al (8) and Olson and Hayaishi (9). This was extended by a number of workers (10)(11)(12)(13)(14)(15)(16)(17)(18)(19)(20) using different species as the source ofthe enzyme.…”

mentioning

confidence: 99%

Enzymatic conversion of all-trans-beta-carotene to retinal by a cytosolic enzyme from rabbit and rat intestinal mucosa.

Lakshman

Mychkovsky

Attlesey

1989

Proc. Natl. Acad. Sci. U.S.A.

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Enzymatic conversion of all-trans--carotene to retinal by a partially purified enzyme from rabbit and rat intestinal mucosa was demonstrated. The enzymatic product was characterized based on the following evidence: (t) The product gave rise to its O-ethyloxime by treatment with Oethylhydroxylamine with an absorption maximum at 363 nm in ethanol characteristic of authentic retinal O-ethyloxime. Highpressure liquid chromatography (HPLC) of this derivative yielded a sharp peak with a retention time of 7.99 min corresponding to the authentic compound. The enzyme blank and boiled enzyme blank failed to show any significant HPLC peaks corresponding to retinal O-ethyloxime, retinal, or retinol. (it) The mass spectrum of the O-ethyloxime of the enzymatic product was identical to that of authentic retinal O-ethyloxime (m/z 327: 45%, Mt and m/z 282: 100%, Methoxy). (Wi) The specific activity of the enzymaticaily formed ["4CIretinal O-ethyloxime remained constant even after repeated crystallization. (iv) The enzymatic product exhibited an absorption maximum at 370 nm in light petroleum characteristic of authentic retinal. Furthermore, it was reduced by horse liver alcohol dehydrogenase to retinol with an absorption maximum at 326 nm in light petroleum. This retinol was enzymatically esterified to retinyl palmitate by rat pancreatic esterase with a retention time of 10 min on HPLC corresponding to authentic retinyl palmitate. Thus, the enzymatic product of f8-carotene cleavage by the partially purified intestinal enzyme was unequivocally confirmed to be retinal.It is well established that P-carotene is the precursor of vitamin A and its conversion into vitamin A in vivo has been unequivocally demonstrated in rats, pigs, and humans (1-7).t Subsequently, the in vitro enzymatic conversion of 83-carotene to retinal by an enzyme preparation from rat intestine and liver was independently shown by Goodman et al. (8) and Olson and Hayaishi (9). This was extended by a number of workers (10-20) using different species as the source ofthe enzyme. However, a more recent report (21) claimed that it could not duplicate the original work (8, 9, 15) and hence raised the possibility that retinal may not be the true product of (3-carotene conversion to vitamin A in vitro, although it did not question the validity of the formation of vitamin A from ,(-carotene in vivo.In view of this controversy, we decided to systematically repeat the work using the intestinal mucosa from rabbit and rat as the source of the (3-carotene cleavage (BCC) enzyme activity. It will be demonstrated conclusively in the present communication that retinal is, in fact, the product of BCC enzyme using (i) a method of synthesizing the O-ethyloxime of the enzymatic product as its derivative and subsequent separation, identification, and quantitation by high-pressure liquid chromatography (HPLC); (ii) unequivocal identification of the retinal O-ethyloxime derivative by its characteristic absorption spectrum, its mass spectrum, and its repeated crystallization to c...

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The intestinal absorption and metabolism of vitamin A and beta-carotene in man.

Cited by 320 publications

References 13 publications

Assessment of carotenoid status and the relation to glycaemic control in type I diabetics: a follow-up study

Assessment of carotenoid status and the relation to glycaemic control in type I diabetics: a follow-up study

In vitro and in vivo characterization of retinoid synthesis from β-carotene

Enzymatic conversion of all-trans-beta-carotene to retinal by a cytosolic enzyme from rabbit and rat intestinal mucosa.

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