Vitamin A Metabolism and Requirements in the Human Studied with the Use of Labeled Retinol

Sauberlich, Howerde E.; Hodges, Robert E.; Wallace, D. L.; Kolder, Hansjoerg E.; Canham, John E.; Hood, James; Raica, Nicholas; Lowry, Larry K.

doi:10.1016/s0083-6729(08)60015-1

Cited by 181 publications

(88 citation statements)

References 23 publications

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“…This can be seen, for example, in the study of Haskell et al, 71 where the relative bioefficacy of sweet potato and Indian spinach can be compared with β-carotene in oil. Bioefficacy for β-carotene in this study was 0.124, which is very much poorer than the values obtained by van Lieshout et al, 65 Sauberlich et al 40 and Hume and Krebs, 39 and this is probably because the amount of β-carotene fed on a daily basis to the Bangladeshi men (8.3 µmol) was larger than that provided by van Lieshout et al 65 (0.3 µmol) and not as efficiently utilised. In addition, the subjects were not as deficient as those in the depletion studies.…”

Section: Quantifying Retinol Formation From β-Carotenecontrasting

confidence: 83%

“…40 The American study went on for longer than the British study in order for eye changes to develop in all volunteers, and a tracer dose of 14 C-retinol was given to some to assess the body pool of vitamin A and the rate of depletion. The American workers also noted the appearance of follicular hyperkeratosis in all volunteers, appearing in some before plasma retinol concentrations fell below 1.05 µmol L −1 , but in one subject not until ophthalmological changes were evident.…”

Section: Carotenoids and Inflammationmentioning

confidence: 99%

“…In addition, the subjects were not as deficient as those in the depletion studies. 40,39 The remaining two studies illustrated in Table 6 were done to describe the variability in absorption and bioconversion in healthy American men and women. In both cases 20 mg (37 µmol) 2 H 6 β-carotene was given as a single dose and absorption and bioconversion were assessed from accumulated plasma concentrations of 2 H 6 β-carotene and 2 H 3 retinol quantified as AUC over the next 20 days.…”

Section: Quantifying Retinol Formation From β-Carotenementioning

confidence: 99%

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Bioequivalence of β‐carotene and retinol

Thurnham

2006

J Sci Food Agric

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For many years it was accepted that 6 mg of β-carotene were required to produce 1 mg of vitamin A in the form of retinol. The equivalence was based on the assumptions that two-thirds of dietary β-carotene are not absorbed, while in the metabolism of the remaining third 1 mol of β-carotene is converted to 1 mol retinol. Recently, the bioequivalence was raised to 12 mg β-carotene and 1 mg retinol. The objective of this review was to re-examine the data that were used to support the new equivalence ratio, especially since some of these data were obtained in developing countries where infestation with gut parasites and exposure to other infections is common, yet the influence of inflammation on plasma carotenoid and retinol concentrations is frequently ignored. Bioequivalence studies examined in this review include those done in developing and developed countries, depletion and repletion studies, feeding with vegetable sources of β-carotene or pure supplements, influence of helminths, carotenoid interactions and matrix effects and studies using stable isotopes (SI). SI studies show the bioefficacy of β-carotene conversion to retinol is generally poor even for pure β-carotene unless the dose is small and fed regularly until equilibration is reached. Retinol formation appears to be inversely influenced by previous vitamin A intake, the amount of material given and current vitamin A status. In spite of technical complexities, more SI studies where liver reserves of vitamin A are determined pre and post intervention are needed to evaluate β-carotene bioefficacy of different vegetable sources.

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Section: Quantifying Retinol Formation From β-Carotenecontrasting

confidence: 83%

Section: Carotenoids and Inflammationmentioning

confidence: 99%

Section: Quantifying Retinol Formation From β-Carotenementioning

confidence: 99%

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Bioequivalence of β‐carotene and retinol

Thurnham

2006

J Sci Food Agric

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“…O ponto de corte de 1,05 mol/L (30 g/dl) de retinol sérico foi utilizado para indicar deficiência de vitamina A e foram adotados os intervalos de 1,049 a 0,70 mol/L, 0,69 a 0,35 mol/L, e <0,35 mol/L para a classificação da deficiên-cia em leve, moderada e grave, respectivamente 11,20,21 . A inadequação dos níveis de carotenóides foi definida como valores inferiores a 80 g/dL 22 .…”

Section: é T O D O Sunclassified

Níveis de retinol e carotenóides séricos e intercorrências gestacionais em puérperas

et al. 2008

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ObjetivoInvestigar a associação entre intercorrências gestacionais e níveis de retinol e carotenóides em puérperas atendidas em maternidade pública do Rio de Janeiro. MétodosA amostra foi constituída por 262 puérperas atendidas na Maternidade Escola da Universidade Federal do Rio de Janeiro. O estado nutricional antropométrico foi avaliado pelo do índice de massa corporal pré-gestacional e pelo ganho ponderal gestacional, e foram coletadas informações sobre intercorrências gestacionais nos registros médicos dos prontuários. Foram adotados os pontos de corte 1,05 mol/L e 80 g/dL para definir inadequação dos níveis de retinol e carotenóides séricos, respectivamente. ResultadosQuarenta e dois vírgula sete por cento da amostra foi acometida por intercorrências gestacionais, destacandose anemia (29,0%), inadequação dos níveis de retinol (24,4%), e síndromes hipertensivas da gravidez (5,7%). Observou-se maior proporção de obesidade pré-gestacional entre mulheres com síndromes hipertensivas da gravidez, em comparação com as não portadoras de tal intercorrência. Verificou-se menor nível médio de carotenóides séricos entre as que desenvolveram síndromes hipertensivas da gravidez e 91,7% destas apresentaram inadequação destes nutrientes.

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“…16 The cutoff used to indicate insufficient serum values of β-carotene was ≤ 40 µg/dL, as suggested by Sauberlich et al 17 Oxidative stress was determined through lipid peroxidation dosage estimated using TBARS levels in blood plasma, according to the method described by Ohkawa et al 18 CRP was assessed using nephelometry method. At the time the patients were enrolled, the Apache II score was calculated.…”

Section: Methodsmentioning

confidence: 99%

Retinol, β-carotene and oxidative stress in systemic inflammatory response syndrome

Nogueira

Borges²,

Lameu

et al. 2015

Rev. Assoc. Med. Bras.

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Objective: patients suffering systemic inflammatory response syndrome (SIRS) constitute a group susceptible to elevated levels of oxidative stress. This study's aim is to evaluate the state of oxidative stress and levels of serum retinol and β-carotene in these patients. Methods: forty-six patients were divided into 2 groups: those those without diet (G1; n=18) and those with enteral nutritional support (G2; n=28). Serum levels of retinol and total carotenoids were measured. C-reactive protein (CRP) levels and Apache scores were also calculated. Oxidative stress was estimated by measuring thiobarbituric acid reactive substance (TBARS) levels. Results: the patients' median age was 66.9 (SD=19.3) years. Lower concentrations of retinol and carotenoids were found in 68.6 and 66.7% of G1, respectively. In G2, despite average vitamin A levels being 8078 + 4035, retinol and β-carotene were considered insufficient (31.2 and 33.4%, respectively). No difference was noted between the 2 groups, according to the variables studied, with the exception being PCR and β-carotene (p=0.002; p=0.01).

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Vitamin A Metabolism and Requirements in the Human Studied with the Use of Labeled Retinol

Cited by 181 publications

References 23 publications

Bioequivalence of β‐carotene and retinol

Bioequivalence of β‐carotene and retinol

Níveis de retinol e carotenóides séricos e intercorrências gestacionais em puérperas

Retinol, β-carotene and oxidative stress in systemic inflammatory response syndrome

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