Vitamin A status

Savoure, N. et al., Vitamin A status and metabobsm of cutaneous polyamines in the hairless mouse after UV irradiation action of P-carotene and astaxanthin, Int. J. Vitamin Nutr. Res., 65, 79, 1995. 

Studies in humans and animals suggest that carotenoid absorption depends on several factors including vitamin A status. Sklan and others (1989) demonstrated that vitamin A supplementation reduced (3-carotene and canthaxanthin absorption in chickens. Dietary carotenoids absorption and bioconversion to vitamin A varied inversely with the vitamin A status of Philippine children (Ribaya-Mercado and others 2000). Some studies (Lecomte and others 1994 Albanes and others 1997) have suggested a possible negative effect of alcohol consumption on carotenoid absorption however,... 

Ribaya-Mercado JD, Solon FS, Solon MA, Cabal-Barza MA, Perfecto CS, Tang G, Solon JA, Fjeld CR and Rusell RM. 2000. Bioconversion of plant carotenoids to vitamin A in Filipino school-aged children varies inversely with vitamin A status. Am J Clin Nutr 72 455-465. 

Mercier, M., G. Pascal, and V. Azais-Braesco. 1990. Retinyl ester hydrolase and Vitamin A status in rats treated with 3,3, 4,4 -tetrachlorobiphenyl. Biochim. Biophys. Acta 1047 70-76. 

FIGURE 5.1 Influence of vitamin A status on epithelial phenotypes. 

An impairment of the mucociliary clearance increases the susceptibility against respiratory infectious diseases frequently associated with marginal vitamin A deficiency (Sommer et ah, 1984). Interestingly vitamin A status following supplementation with 15-mg RP monthly for 2.5 months (Rahman et ah, 1996) was not improved in the presence of respiratory tract infections (Sommer et ah, 1986). 

Biesalski, H. K., and Weiser, FI. (1990). Microdetermination of retinyl esters in Guinea pig tissues under different vitamin A-status conditions. Micronutr. Anal. 7, 97-116. 

Biesalski, H. K., Reifen, R., Ftirst, P., and Edris, M. (1999). Retinyl palmitate supplementation by inhalation of an aerosol improves vitamin A status of preschool children in Gondar (Ethiopia). Br.. Nutr. 82,179-182. 

Rahman, M. M., Mahalanabis, D., Alvarez, J. O., Wahed, M. A., Islam, M. A., Habte, D., and Khaled, M. A. (1996). Acute respiratory infections prevent improvement of vitamin A status in young infants supplemented with vitamin A. /. Nutr. 126,628-633. 

Shah, R. S., and Rajalekshmi, R. (1984). Vitamin A status of the newborn in relation to gestational age, body weight, and maternal nutritional status. Am. J. Clin. Nutr. 40, 794-800. 

Chapman K, Prabhudesai M, Erdman JW. 1992. Effects of ethanol and carbon tetrachloride upon vitamin A status of rats. Alcoholism Clinical and Experimental Research 16 764-768. 

Life Sci 1991 48(12) 1173-1177. Crebelli, R., L. Conti, S. Fuselli, P. Leopardi, A. Zijno, and A. Carere. Put-ther studies on the comutagenic activity of cigarette smoke condensate. Mutat Res 1991 259(1) 29-36. Padma, P. R., A. J. Amonkar, and S. V. Bhide. Effect of long-term treatment of two tobacco-specific N-nitro-samines on the vitamin A status of mice. Nutr Cancer 1991 15(3—4) 217-220. 

Daqono, Sleight SD, Stowe HD, et al. 1983. Vitamin A status, polybrominated biphenyl (PBB) toxicosis, and common bile duct hyperplasia in rats. Toxicol Appl Pharmacol 71 184-193. 

Hakansson H, Waem F, Ahlborg UG. 1987. Effects of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) in the lactating rat on maternal and neonatal vitamin A status. J Nutr 117 580-586. 

A measure of an individual child s serum retinol level may not be a good indicator of the vitamin A status of the child. Why is this ... 

Stable isotopes of retinal and (3-carotene have also been employed to assess liver vitamin A stores in healthy individuals, and the best measure of vitamin A status (Furr et ah, 1989). The relative ratio of circulating isotopically labeled retinol is later assessed to estimate liver levels (Wang et ak, 2000 Hickenbottom et ah, 2002b) and without this technique, a liver biopsy would be necessary to estimate liver levels. 

The state of body reserves of the vitamin may affect the extent to which it is absorbed (by affecting the synthesis of binding and transport proteins) or the extent to which it is metabolized after uptake into the intestinal mucosa [e.g., the oxidative cleavage of carotene to retinaldehyde is regulated by vitamin A status (Section 2.2.1)]. 

A small proportion of dietary retinol is oxidized to retuioic acid, which is absorbed into the portal circulation and bound to serum albumin. Some retinyl esters are also transferred into the portal circulation. Patients with abeta-lipoproteinemia, who are unable to synthesize chylomicrons, can nevertheless maintain adequate vitamin A status if they are provided with relatively high intakes of retinol. 

A mild infection, such as measles, commonly triggers the development of xerophthalmia in children whose vitamin A status is marginal. In addition to functional deficiency as a result of impaired synthesis of RBP (Section 2.2.3) and transthyretin in response to infection, there may be a considerable urinary loss of vitamin A because of increased renal epithelial permeability and proteinuria, permitting loss of retinol bound to RBP-transthyretin. The American Academy of Pediatrics Committee on Infectious Diseases (1993) recommended vitamin A supplements for aU children who have been hospitalized with measles. 

Table 2.3 Biochemical Indices of Vitamin A Status Liver Retinyl Esters (as Retinol) (j mol/kg...

Plasma Retinol Binding Protein Measurement of plasma concentrations of RBP may give some additional information. Indeed, it has been suggested that because retinol is susceptible to oxidation on storage of blood samples, measurement of RBP may be a better indication of the state of vitamin A status. In adequately nourished subjects, about 13% of immunologi-caUy reactive RBP in plasma is present as the apo-protein, whereas in vitamin A-deficient children, the proportion of apo-protein may rise to 50% to 90% of... 

Batres RO and Olson JA (1987) A marginal vitamin A status alters the distribution of vitamin A among parenchymal and stellate cells in rat liver. Journal of Nutrition 117, 874-9. 

Tanumihardjo S, Barua A, and Olson J (1987) Use of 3,4-didehydroretinol to assess vitamin A status in rats. International Journal of Vitamin and Nutrition Research 57, 127-32. 

Underwood B (1990) Methods for assessment of vitamin A status. Journal of Nutrition 56, 1459-63. 

A consequence of the lower levels of plasma RBP produced by pmtein malnutrition is impairment cjf vitamin A transport from the liver to other tissues however, vitamin A deficiency can also result from heavy reliance on foods that are extremely poor sources of vitamin A, such as rice or cassava. Both factors (lack of RBP or of vitamin A) can lead to deterioration of the epithelial cells of the ga.stm-intestlnal tract, respiratory tract, and eye, all signs of vitamin A deficiency. Another sign is nlghtblindness. Table 4.19 illustrates how feeding protein to malnourished children can result in an improvement in vitamin A status, even when the source of proteins contains little or no vitamin A. Some children with kwashiorkor were fed skim milk. The concentrations of RBP and vitamin A measured in the serum of these children before and after feeding show an increase in plasma RBP. A dramatic rise in plasma vitamin A also occurred, probably as a result of the liver s... 

Flores H, Azevedo MN, Campos FA, Barreto-Lins MC, Cavalcanti A A, Salzano AC, Varela RM, Underwood BA. Serum vitamin A distribution curve for children aged 2-6 y known to have adequate vitamin A status a reference population. Am J Clin Nutr 1991 54(4) 707-11. 

Chapman KM, Prabhudesai M, Erdman JW Jr. Vitamin A status of alcohohcs upon admission and after two weeks of hospitalization. J Am CoU Nutr 1993 12(l) 77-83. 

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