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Antioxidant Vitamin Levels in Term and Preterm Infants and Their Relation to Maternal Vitamin Status
Archives of Medical Research 33 (2002) 276–280
ORIGINAL ARTICLE
Antioxidant Vitamin Levels in Term and Preterm Infants and Their Relation to Maternal Vitamin Status Giyasettin Baydas,a Fikret Karatas,b M. Ferit Gursu,c H. Ayse Bozkurt,d Nevin Ilhan,c Abdullah Yasara and Halit Canatanc a
Department of Physiology, College of Medicine, Firat University, Elazig, Turkey b Department of Chemistry, College of Science, Firat University, Elazig, Turkey c Department of Biochemistry, College of Medicine, Firat University, Elazig, Turkey d Department of Obstetrics and Gynecology, SSK Hospital, Istanbul, Turkey Received for publication August 7, 2001; accepted January 25, 2002 (01/030).
Background. Lipid peroxidation plays a vital role in the pathogenesis of many neonatal complications. Preterm babies are especially predisposed to lung diseases and retinopathy, probably due to a deficiency in their antioxidant systems. Vitamins E, A, and C are part of the natural antioxidant defense systems. We aimed to determine the levels of vitamins E, A, and C in maternal and cord blood plasma of term and preterm infants and to investigate the relationships between these levels. Methods. In the present study we determined vitamin E, A, and C levels in the umbilical cord blood of term (n 30) and preterm (n 22) infants and their mothers by HPLC. Blood samples were taken during delivery. Results. Levels of lipid soluble antioxidant vitamin E and A in cord blood were lower than maternal values (p 0.01, p 0.05, respectively). Conversely, the level of water-soluble vitamin C was higher in cord blood than in maternal level (p 0.05). Significantly higher levels of vitamins E, A, and C were found in term babies as compared with those born preterm (p 0.05). Conclusions. There was a positive correlation between maternal and cord blood levels of vitamins E and A (r 0.775, r 0.725, respectively). In conclusion, preterm babies have fewer lipid-soluble antioxidant vitamins in their serum compared to term infants. Therefore, it is possible to postulate that preterm infants are more susceptible to oxidative stress. © 2002 IMSS. Published by Elsevier Science Inc. Key Words: Antioxidant vitamins, Preterm infants, Term infants.
Introduction Oxygen radical injury is thought to be one of the common mechanisms for several neonatal diseases in premature infants. Bronchopulmonary dysplasia, intraventricular hemorrhage, and retinopathy of prematurity are accepted as caused by the excessive production of oxygen free radicals (1–3). High production of oxygen free radicals is partially dependent on low levels of antioxidant mechanisms including de-
Address reprint requests to: Giyasettin Baydas, Ph.D., Professor of Medical Physiology, Department of Physiology, College of Medicine, Firat University, Elazig, 23119 Turkey. Tel.: (90) (424) 237-0000, ext. 6046; FAX: (90) (424) 237-9138; E-mail: [email protected]
ficiency of vitamins E and A (4,5). Some studies demonstrated that administration of vitamin E reduces the severity of these diseases (6,7). There are complex antioxidant defense systems, including both enzymatic and nonenzymatic components, against the effects of oxygen free radicals on biological macromolecules such as proteins, nucleic acids, carbohydrates, and lipids (8). Vitamins such as E, A, and C are among the nonenzymatic antioxidants. Because vitamin E is the major lipid-soluble, chain-breaking antioxidant in biological systems (9–11) and its lipid solubility allows its broad diffusion into the different tissues and cells into which it is taken up (12,13), nutritional deficiency of vitamin E may consequently affect many organs. Vitamin E (-tocopherol) appears to be the most
0188-4409/02 $–see front matter. Copyright © 2002 IMSS. Published by Elsevier Science Inc. PII S0188-4409(02)0 0 3 5 6 - 9
Antioxidant Vitamins in Infants and Mothers
important micronutrient involved in the protection of LDL from oxidation: it increases mean HDL level while decreasing LDL level (14,15). It is well documented that placental transfer of vitamin E is limited (16). Accordingly, newborn infants were reported to have low circulating levels of vitamin E (17). Vitamin A plays an important role in cellular function, development, and maintenance of normal visual acuity (18,19). In addition, vitamin A is known as an important natural antioxidant (20). Carotenoids are substances that are consumed in the diet and some are converted into vitamin A. Carotenoids may also have antioxidant activity. -carotene is reported to quench singlet molecular oxygen effectively (21). There are controversial findings in previous studies concerning antioxidant vitamin levels in term and preterm babies. For example, Powers claimed that the vitamin A status of pregnant women has been found not to influence vitamin A levels in cord blood (22). However, it has been reported that cord plasma concentrations of carotenoids were significantly lower than those of maternal plasma (23,24). Vitamins E and A are essential micronutrients and can react with oxygen free radicals; thus, they exert a protective antioxidant effect (25). Ascorbic acid is also an antioxidant and is involved in cholesterol excretion. In addition, it is known to participate significantly, together with glutathione and lipoic acid, in the recycling of oxidized vitamin E (26). The aim of the present study was to determine vitamin A, E, and C concentrations in pair-matched maternal and cord serum samples of term and preterm infants. Furthermore, we extended our goal to include examining possible relationships or differences in antioxidant vitamin levels between maternal and cord bloods.
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E, A, and C were tested; p values 0.05 were considered to be statistically significant. Results Gestational age of term babies was between 37 and 41 weeks, and birth weight was between 2,500 and 3,700 g. Weight of preterm babies at 29–36 weeks gestational age was between 1,200 and 2,450 g. Serum vitamin E, A, and C levels in term and preterm infants and in their mothers are shown in Figures 1–3. There was a weak but statistical correlation between cord blood vitamin E levels and gestational age (r 0.324, p 0.05). Maternal blood levels of vitamin E and vitamin E/lipid ratio were significantly higher than cord blood values (p 0.01, p 0.05, respectively). In addition, there was a significant correlation between maternal and cord blood vitamin E levels (r 0.775, p 0.01). Premature infants have lower levels of serum vitamin E than term infants (p 0.05) (Figure 1). Maternal vitamin A levels were also higher than cord values (p 0.05) (Figure 2), and there was a positive correlation between maternal and cord vitamin A levels (r 0.725, p 0.01). Additionally, we found higher levels of Vitamin A in cord blood of term infants compared with preterm babies (p 0.05) (Figure 2). Contrary to vitamins E and A, cord vitamin C levels were higher than maternal levels (p 0.05) (Figure 3). We found no significant correlation between cord and maternal vitamin C levels.
Materials and Methods Twenty two preterm and 30 term babies and their mothers were included in the study. Only healthy mothers and their infants were admitted into the protocol. Infants with a gestational age of 36 weeks were considered premature. Mixed venous-arterial cord blood was collected in glass tubes at delivery. Maternal venous blood samples were collected after delivery. Blood samples were centrifuged (3,000 rpm, 10 min), and sera were removed and stored at 20C until analysis. Serum extraction was carried out as described previously (27). Levels of vitamins E and A were determined by the method of Catignani and Bieri (28) and Miller et al. (29) using HPLC, as we recently described (30). To determine serum vitamin C levels, proteins were precipitated as previously described (31) and vitamin C levels were determined by the method of Tavazzi et al. (32). Recovery of vitamins A and E were 97.8 and 99.5%, respectively. Statistical analysis was performed using Student t test for assessment of mean differences between two groups. Correlations between maternal and cord serum levels of vitamins
Figure 1. Vitamin E levels in cord blood of term and preterm babies and in blood of their mothers. MPrT: mother of preterm babies; MT: mother of term babies. *** p 0.001 vs. cord blood; b: p 0.01 vs. preterm infants.
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Baydas et al./ Archives of Medical Research 33 (2002) 276–280
Figure 2. Vitamin A levels in cord blood of term and preterm babies and in blood of their mothers. MPrT: mother of preterm babies, MT: mother of term babies. **p 0.01 vs. cord blood; b: p 0.01 vs. preterm infants.
Figure 3. Vitamin C levels in cord blood of term and preterm babies and in blood of their mothers. MPrT: mother of preterm babies; MT: mother of term babies. * p 0.05 vs. cord blood; b: p 0.01 vs. preterm infants.
Discussion There are a limited number of studies dealing with status of vitamins A, E, and C in cord blood of term and preterm babies and their mothers. The majority of these studies have controversial findings. Therefore, we determined the levels of vitamins A, E, and C in pair-matched maternal and cord (term and preterm) plasma samples and also examined any relationship between these oxidant vitamins. Present findings clearly demonstrate that vitamin E levels in cord blood are lower than in maternal blood. This finding is in agreement with previous reports (5,17,23). A positive correlation between cord and maternal serum vitamin E, as determined in the present study, has also been reported by other investigators (17,33,34). It is obvious that neonatal vitamin E concentration is dependent on maternal vitamin E levels. Viana et al. have shown that treatment of pregnant rats with -tocopherol caused an increase in its concentration in maternal and fetal plasma (7). However, the 4:1 ratio between maternal and newborn serum vitamin E levels persisted. The reason behind the low level of cord blood vitamin E is limited transportation of vitamin E from placenta (35). Nonetheless, the mechanism of the transportation still must be clarified. In this study we demonstrated that cord blood vitamin E concentrations of term babies were higher than in preterm babies. Similar findings have been reported by other investigators (33). However, Chan et al. reported that there was no significant difference between vitamin E levels of preterm and term babies (5). Nevertheless, these investigators re-
ported that preterm babies had a higher incidence of vitamin E deficiency compared to term babies. Shah et al. have reported that serum vitamin E levels were lower in premature infants and low birth weight fullterm infants than full-term normal infants (33). These results are in agreement with our findings. The low values of vitamin E seen in preterm infants may have consequential clinical importance. This may be potentiated by maternal vitamin E levels because there was a significant correlation between cord and maternal blood vitamin E levels. In agreement with our results, previous studies show that maternal vitamin E levels correlated with neonatal vitamin E levels (17). Taken together with the results of Chan et al. (5), present findings show that vitamin E accumulates in the fetus throughout the third trimester. Therefore, preterm infants are predisposed to vitamin E deficiency. In the present study, maternal serum vitamin A levels were determined as higher than cord vitamin A levels as described previously (24,25). We also found a significant correlation between maternal and cord vitamin A levels. These results were in agreement with previous findings (17,23,24,36). Lower plasma vitamin A levels in newborns can be induced by inefficient placental transfer of vitamin A as well. However, maternal vitamin A administration leads to accumulation of vitamin A in perinatal rat tissues (37). Therefore, fetal vitamin A level can be affected by maternal vitamin A status. Yeum et al. reported that the nutritional status of babies is affected by the nutritional status of their mothers, by
Antioxidant Vitamins in Infants and Mothers
means of certain fat-soluble nutrients such as vitamins A and E (24). In this study we found a lower concentration of vitamin A in preterm than in term infants. Navarro et al. reported that low birth weight infants had significantly lower levels of vitamin A than normal infants (38). Vitamin A also appears to accumulate predominantly in the third trimester. Although levels of vitamins E and A were lower in cord blood than in maternal blood, the level of vitamin C was higher in cord blood than in maternal blood. These results were in agreement with other studies (38–40). Vitamin C levels in preterm babies were lower than those of full-term babies. Guajardo et al. also reported that umbilical cord venous plasma ascorbic acid levels were significantly lower in the preterm group than in the term group (41). In contrast to these results, reduction in vitamin C levels is reported associated with an increase in gestational age (42). Placenta is permeable to dehydroascorbic acid but not to ascorbic acid. The fetus then converts dehydroascorbic acid to ascorbic acid and accumulates it (43,44). At the same time, lipid-soluble antioxidant vitamins have limited placental transfer; thus, infants have low levels of lipid-soluble vitamins. Increased lipid peroxidation caused by oxygen free radicals is believed to be one of the common pathogenic mechanisms for so-called oxygen radical diseases of prematurity. Reactive oxygen species are generated endogenously under physiologic and pathologic conditions. The organism maintains defense systems including antioxidant vitamins such as vitamins E, A, and C against reactive species. Vitamin E inhibits lipid peroxidation; hence, it prevents membrane damage and modification of low-density lipoproteins. It is regenerated by the water-soluble vitamin C. In vitro studies have shown that various forms of vitamin A can exert antioxidant effects more potent than those of vitamin E (45). Hydroperoxide concentrations were found to be high, especially in premature infants. Erythrocyte membranes were also found to contain low levels and/or low activities of antioxidant defense mechanisms, which was more evident in premature newborns who demonstrated -tocopherol levels significantly lower in comparison to full-term infant levels. Furthermore, when premature infants underwent oxygen therapy these effects were exacerbated (46). Conversely, high levels of water-soluble antioxidant vitamin C in babies, particularly in premature babies, may exacerbate oxidant damage by inhibiting ferroxidase activity of ceruloplasmin (40). In conclusion, lipid-soluble antioxidant vitamins A and E are lower in cord blood than in maternal plasma, and term babies have higher levels of these vitamins than do preterm infants. These antioxidant vitamins appear to accumulate during the third trimester, so preterm infants are more susceptible to oxidative stress.
References 1. Sullivan JL. Iron, plasma antioxidants, and the oxygen radical disease of prematurity. Am J Dis Child 1998;142:1341–1344.
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2. Hittner HM, Godio LB, Rudolph AJ, Adams JM, García-Prats JA, Friedman Z, Kautz JA, Monaco WA. Retrolental fibroplasia: efficacy of vitamin E in a double-blind clinical study of preterm infants. N Engl J Med 1981;305:1365–1371. 3. Johnson L, Quinn GE, Abbasi S, Gerdes J, Bowen FW, Bhutani V. Severe retinopathy of prematurity in infants with birth weights less than 1250 grams: incidence and outcome of treatment with pharmacologic serum levels of vitamin E in addition to cryotherapy from 1985 to 1991. J Pediatr 1995;127:632–639. 4. Miller NJ, Rice-Evans C, Davies MJ, Gopinathan V, Milner A. A novel method for measuring antioxidant capacity and its application to monitoring the antioxidant status in premature neonates. Clin Sci (Colch) 1993;84:407–412. 5. Chan DK, Lim MS, Choo SH, Tan IK. Vitamin E status of infants at birth. J Perinat Med 1999;27:395–398. 6. Viana M, Herrera E, Bonet B. Teratogenic effects of diabetes mellitus in the rat. Prevention by vitamin E. Diabetologia 1996;39:1041–1046. 7. Viana M, Barbas C, Castro M, Herrera E, Bonet B. Alpha-tocopherol concentration in fetal and maternal tissues of pregnant rats supplemented with alpha-tocopherol. Ann Nutr Metab 1999;43:107–112. 8. Sies H, Krinsky NI. The present status of antioxidant vitamins and beta-carotene. Am J Clin Nutr 1995;62(Suppl):1299S–1300S. 9. Cho SH, Choi YS. Lipid peroxidation and antioxidant status is affected by different vitamin E levels when feeding fish oil. Lipids 1994;29:47–52. 10. Hu ML, Frankel EN, Tapel AL. Effect of dietary menhaden oil and vitamin E on in vivo lipid peroxidation induced by iron. Lipids 1990;25:194–198. 11. Ercel E, Baydas G, Akyol A, Eksioglu E, Canpolat L. The effect of vitamin E on the sciatic nerve lipid peroxidation in streptozotocin induced diabetes mellitus. Biomed Res 1999;10:95–101. 12. Meydani M. Vitamin E. Lancet 1995;345:170–175. 13. Bieri JG, Evarts RP. Gamma tocopherol: metabolism, biological activity and significance in human vitamin E nutrition. Am J Clin Nutr 1974;27:980–986. 14. Kagan VE, Serbinova EA, Forte T, Scita G, Packer L. Recycling of vitamin E in human low density lipoproteins. J Lipid Res 1992;33:385–397. 15. Paolisso G, D’Amore A, Galzerano D, Balbi V, Giugliano D, Varricchio M, D’Onofrio F. Daily vitamin E supplements improve metabolic control but not insulin secretion in elderly type II diabetic patients. Diabetes Care 1993;16:1433–1437. 16. Specker BL, DeMarini S, Tsang RC. Vitamin and mineral supplementation. In: Sinclair JC, Bracken MB, editors. Effective care of the newborn infant. London: Oxford University Press;1992. pp. 161–177. 17. Chen HW, Lii CK, Ou CC, Wong YC, Kuo BJ, Lui CH. Plasma vitamin A and E and red blood cell fatty acid profile in newborns and their mothers. Eur J Clin Nutr 1996;50:556–559. 18. Maden M. The role of retinoic acid in embryonic and post-embryonic development. Proc Nutr Soc 2000;59:65–73. 19. Smith J, Steinemann TL. Vitamin A deficiency and the eye. Int Ophthalmol Clin 2000;40:83–91. 20. Livrea MA, Tesoriere L. Antioxidant activity of vitamin A within lipid environment. Subcell Biochem 1998;30:113–143. 21. Krinsky NI. Antioxidant functions of carotenoids. Free Radic Biol Med 1989;7:617–635. 22. Powers HJ. Micronutrient deficiencies in the preterm neonate. Proc Nutr Soc 1993;52:285–291. 23. Kiely M, Cogan PF, Kearney PJ, Morrisey PA. Concentration of tocopherols and carotenoids in maternal and cord blood plasma. Eur J Clin Nutr 1999;53:711–715. 24. Yeum KJ, Ferland G, Patry J, Russell RM. Relationship of plasma carotenoids, retinol and tocopherols in mothers and newborn infants. J Am Coll Nutr 1998;17:442–447. 25. Di Mascio P, Murphy ME, Sies H. Antioxidant defense systems: the role of carotenoids, tocopherols, and thiols. Am J Clin Nutr 1991; 53(Suppl 1):194S–200S. 26. Packer L. Interactions among antioxidants in health and disease: vitamin E and its redox cycle. Proc Soc Exp Biol Med 1992;200:271–276.
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27. Cetinkaya N, Ozcan H. Investigation of seasonal variation in cow serum retinol and beta-carotene by high performance liquid chromatographic method. Comp Biochem Physiol 1991;100:1003–1008. 28. Catignani GL, Bieri JG. Simultaneous determination of retinol and alpha-tocopherol in serum or plasma by liquid chromatography. Clin Chem 1983;29:708–712. 29. Miller KW, Lorr NA, Yang CS. Simultaneous determination of plasma retinol, alpha-tocopherol, lycopene, alpha-carotene, and beta-carotene by high-performance liquid chromatography. Anal Biochem 1984;138: 340–345. 30. Karatas F, Halifeoglu I, Canatan H, Ustundag B. Comparative analysis of antioxidant vitamin (A,C,E) levels in milks from smoking and nonsmoking mothers. Res Commun Alcohol Subst Abuse 2001; in press. 31. Cerhata D, Bauerova A, Ginter E. Determination of ascorbic acid in blood serum using high-performance liquid chromatography and its correlation with spectrophotometric (colorimetric) determination. Ceska Slov Farm 1994;34:166–168. 32. Tavazzi B, Lazzarino G, Di Pierro D, Giardina B. Malondialdehyde production and ascorbate decrease are associated to the reperfusion of the isolated postischemic rat heart. Free Radic Biol Med 1992;13:75–78. 33. Shah RS, Rajalakshmi R, Bhatt RV, Hazra MN, Patel BC, Swamy NB, Patel TV. Vitamin E status of the newborn in relation to gestational age, birth weight and maternal vitamin E status. Br J Nutr 1987;58:191–198. 34. Vobecky JS, Vobecky J, Shapcott D, Demers PP, Cloutier D, Blanchard R, Fisch C. Biochemical indices of nutritional status in maternal, cord, and early neonatal blood. Am J Clin Nutr 1982;36:630–642. 35. Abbasi S, Ludomirski A, Bhutani VK, Weiner S, Johnson L. Maternal and fetal plasma vitamin E to total lipid ratio and fetal RBC antioxidant function during gestational development. J Am Coll Nutr 1990;9:314–319. 36. Karakilcik AZ, Aksakal M, Baydas G, Sozen R, Ayata A, Simsek M.
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Plasma -carotene concentrations in pregnancies, newborn infants and their mothers. J Pak Med Assoc 1996;46:77–80. Shenai JP, Chytil F. Effect of maternal vitamin-A administration on fetal lung vitamin-A stores in the perinatal rat. Biol Neonate 1990;58: 318–325. Navarro J, Causse MB, Desquilbet N, Herve F, Lallemand D. The vitamin status of low birth weight infants and their mothers. J Pediatr Gastroenterol Nutr 1984;3:744–748. Lindeman JH, van Zoeren-Grobben D, Schrijver J, Spee AJ, Poorthuis BJ, Berger HM. The total free radical trapping ability of cord blood plasma in preterm and term babies. Pediatr Res 1989;26:20–24. Powers HJ, Loban A, Silvers K, Gibson AT. Vitamin C at concentrations observed in premature babies inhibits the ferroxidase activity of ceruloplasmin. Free Radic Res 1995;22:57–65. Guajardo L, Beharry KD, Modanlou HD, Aranda JV. Ascorbic acid concentrations in umbilical cord veins and arteries of preterm and term newborns. Biol Neonate 1995;68:1–9. Das S, Powers HJ. The effects of maternal intake and gestational age on materno-fetal transport of vitamin C in the guinea-pig. Br J Nutr 1998;80:485–491. Raika N. On the placental transfer of vitamin C. Acta Physiol Scand 1958;45(Suppl):155. Norkus EP, Bassi J, Rosso P. Maternal-fetal transfer of ascorbic acid in the guinea pig. J Nutr 1979;109:2205–2212. Stahl W, Sies H. Antioxidant defense: vitamins E and C and carotenoids. Diabetes 1997;46(Suppl 2):S14–S18. Huertas JR, Palomino N, Ochoa JJ, Quiles JL, Ramírez-Tortosa MC, Battino M, Robles R, Mataix J. Lipid peroxidation and antioxidants in erythrocyte membranes of full-term and preterm newborns. Biofactors 1998;8:133–137.
ORIGINAL ARTICLE
Antioxidant Vitamin Levels in Term and Preterm Infants and Their Relation to Maternal Vitamin Status Giyasettin Baydas,a Fikret Karatas,b M. Ferit Gursu,c H. Ayse Bozkurt,d Nevin Ilhan,c Abdullah Yasara and Halit Canatanc a
Department of Physiology, College of Medicine, Firat University, Elazig, Turkey b Department of Chemistry, College of Science, Firat University, Elazig, Turkey c Department of Biochemistry, College of Medicine, Firat University, Elazig, Turkey d Department of Obstetrics and Gynecology, SSK Hospital, Istanbul, Turkey Received for publication August 7, 2001; accepted January 25, 2002 (01/030).
Background. Lipid peroxidation plays a vital role in the pathogenesis of many neonatal complications. Preterm babies are especially predisposed to lung diseases and retinopathy, probably due to a deficiency in their antioxidant systems. Vitamins E, A, and C are part of the natural antioxidant defense systems. We aimed to determine the levels of vitamins E, A, and C in maternal and cord blood plasma of term and preterm infants and to investigate the relationships between these levels. Methods. In the present study we determined vitamin E, A, and C levels in the umbilical cord blood of term (n 30) and preterm (n 22) infants and their mothers by HPLC. Blood samples were taken during delivery. Results. Levels of lipid soluble antioxidant vitamin E and A in cord blood were lower than maternal values (p 0.01, p 0.05, respectively). Conversely, the level of water-soluble vitamin C was higher in cord blood than in maternal level (p 0.05). Significantly higher levels of vitamins E, A, and C were found in term babies as compared with those born preterm (p 0.05). Conclusions. There was a positive correlation between maternal and cord blood levels of vitamins E and A (r 0.775, r 0.725, respectively). In conclusion, preterm babies have fewer lipid-soluble antioxidant vitamins in their serum compared to term infants. Therefore, it is possible to postulate that preterm infants are more susceptible to oxidative stress. © 2002 IMSS. Published by Elsevier Science Inc. Key Words: Antioxidant vitamins, Preterm infants, Term infants.
Introduction Oxygen radical injury is thought to be one of the common mechanisms for several neonatal diseases in premature infants. Bronchopulmonary dysplasia, intraventricular hemorrhage, and retinopathy of prematurity are accepted as caused by the excessive production of oxygen free radicals (1–3). High production of oxygen free radicals is partially dependent on low levels of antioxidant mechanisms including de-
Address reprint requests to: Giyasettin Baydas, Ph.D., Professor of Medical Physiology, Department of Physiology, College of Medicine, Firat University, Elazig, 23119 Turkey. Tel.: (90) (424) 237-0000, ext. 6046; FAX: (90) (424) 237-9138; E-mail: [email protected]
ficiency of vitamins E and A (4,5). Some studies demonstrated that administration of vitamin E reduces the severity of these diseases (6,7). There are complex antioxidant defense systems, including both enzymatic and nonenzymatic components, against the effects of oxygen free radicals on biological macromolecules such as proteins, nucleic acids, carbohydrates, and lipids (8). Vitamins such as E, A, and C are among the nonenzymatic antioxidants. Because vitamin E is the major lipid-soluble, chain-breaking antioxidant in biological systems (9–11) and its lipid solubility allows its broad diffusion into the different tissues and cells into which it is taken up (12,13), nutritional deficiency of vitamin E may consequently affect many organs. Vitamin E (-tocopherol) appears to be the most
0188-4409/02 $–see front matter. Copyright © 2002 IMSS. Published by Elsevier Science Inc. PII S0188-4409(02)0 0 3 5 6 - 9
Antioxidant Vitamins in Infants and Mothers
important micronutrient involved in the protection of LDL from oxidation: it increases mean HDL level while decreasing LDL level (14,15). It is well documented that placental transfer of vitamin E is limited (16). Accordingly, newborn infants were reported to have low circulating levels of vitamin E (17). Vitamin A plays an important role in cellular function, development, and maintenance of normal visual acuity (18,19). In addition, vitamin A is known as an important natural antioxidant (20). Carotenoids are substances that are consumed in the diet and some are converted into vitamin A. Carotenoids may also have antioxidant activity. -carotene is reported to quench singlet molecular oxygen effectively (21). There are controversial findings in previous studies concerning antioxidant vitamin levels in term and preterm babies. For example, Powers claimed that the vitamin A status of pregnant women has been found not to influence vitamin A levels in cord blood (22). However, it has been reported that cord plasma concentrations of carotenoids were significantly lower than those of maternal plasma (23,24). Vitamins E and A are essential micronutrients and can react with oxygen free radicals; thus, they exert a protective antioxidant effect (25). Ascorbic acid is also an antioxidant and is involved in cholesterol excretion. In addition, it is known to participate significantly, together with glutathione and lipoic acid, in the recycling of oxidized vitamin E (26). The aim of the present study was to determine vitamin A, E, and C concentrations in pair-matched maternal and cord serum samples of term and preterm infants. Furthermore, we extended our goal to include examining possible relationships or differences in antioxidant vitamin levels between maternal and cord bloods.
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E, A, and C were tested; p values 0.05 were considered to be statistically significant. Results Gestational age of term babies was between 37 and 41 weeks, and birth weight was between 2,500 and 3,700 g. Weight of preterm babies at 29–36 weeks gestational age was between 1,200 and 2,450 g. Serum vitamin E, A, and C levels in term and preterm infants and in their mothers are shown in Figures 1–3. There was a weak but statistical correlation between cord blood vitamin E levels and gestational age (r 0.324, p 0.05). Maternal blood levels of vitamin E and vitamin E/lipid ratio were significantly higher than cord blood values (p 0.01, p 0.05, respectively). In addition, there was a significant correlation between maternal and cord blood vitamin E levels (r 0.775, p 0.01). Premature infants have lower levels of serum vitamin E than term infants (p 0.05) (Figure 1). Maternal vitamin A levels were also higher than cord values (p 0.05) (Figure 2), and there was a positive correlation between maternal and cord vitamin A levels (r 0.725, p 0.01). Additionally, we found higher levels of Vitamin A in cord blood of term infants compared with preterm babies (p 0.05) (Figure 2). Contrary to vitamins E and A, cord vitamin C levels were higher than maternal levels (p 0.05) (Figure 3). We found no significant correlation between cord and maternal vitamin C levels.
Materials and Methods Twenty two preterm and 30 term babies and their mothers were included in the study. Only healthy mothers and their infants were admitted into the protocol. Infants with a gestational age of 36 weeks were considered premature. Mixed venous-arterial cord blood was collected in glass tubes at delivery. Maternal venous blood samples were collected after delivery. Blood samples were centrifuged (3,000 rpm, 10 min), and sera were removed and stored at 20C until analysis. Serum extraction was carried out as described previously (27). Levels of vitamins E and A were determined by the method of Catignani and Bieri (28) and Miller et al. (29) using HPLC, as we recently described (30). To determine serum vitamin C levels, proteins were precipitated as previously described (31) and vitamin C levels were determined by the method of Tavazzi et al. (32). Recovery of vitamins A and E were 97.8 and 99.5%, respectively. Statistical analysis was performed using Student t test for assessment of mean differences between two groups. Correlations between maternal and cord serum levels of vitamins
Figure 1. Vitamin E levels in cord blood of term and preterm babies and in blood of their mothers. MPrT: mother of preterm babies; MT: mother of term babies. *** p 0.001 vs. cord blood; b: p 0.01 vs. preterm infants.
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Figure 2. Vitamin A levels in cord blood of term and preterm babies and in blood of their mothers. MPrT: mother of preterm babies, MT: mother of term babies. **p 0.01 vs. cord blood; b: p 0.01 vs. preterm infants.
Figure 3. Vitamin C levels in cord blood of term and preterm babies and in blood of their mothers. MPrT: mother of preterm babies; MT: mother of term babies. * p 0.05 vs. cord blood; b: p 0.01 vs. preterm infants.
Discussion There are a limited number of studies dealing with status of vitamins A, E, and C in cord blood of term and preterm babies and their mothers. The majority of these studies have controversial findings. Therefore, we determined the levels of vitamins A, E, and C in pair-matched maternal and cord (term and preterm) plasma samples and also examined any relationship between these oxidant vitamins. Present findings clearly demonstrate that vitamin E levels in cord blood are lower than in maternal blood. This finding is in agreement with previous reports (5,17,23). A positive correlation between cord and maternal serum vitamin E, as determined in the present study, has also been reported by other investigators (17,33,34). It is obvious that neonatal vitamin E concentration is dependent on maternal vitamin E levels. Viana et al. have shown that treatment of pregnant rats with -tocopherol caused an increase in its concentration in maternal and fetal plasma (7). However, the 4:1 ratio between maternal and newborn serum vitamin E levels persisted. The reason behind the low level of cord blood vitamin E is limited transportation of vitamin E from placenta (35). Nonetheless, the mechanism of the transportation still must be clarified. In this study we demonstrated that cord blood vitamin E concentrations of term babies were higher than in preterm babies. Similar findings have been reported by other investigators (33). However, Chan et al. reported that there was no significant difference between vitamin E levels of preterm and term babies (5). Nevertheless, these investigators re-
ported that preterm babies had a higher incidence of vitamin E deficiency compared to term babies. Shah et al. have reported that serum vitamin E levels were lower in premature infants and low birth weight fullterm infants than full-term normal infants (33). These results are in agreement with our findings. The low values of vitamin E seen in preterm infants may have consequential clinical importance. This may be potentiated by maternal vitamin E levels because there was a significant correlation between cord and maternal blood vitamin E levels. In agreement with our results, previous studies show that maternal vitamin E levels correlated with neonatal vitamin E levels (17). Taken together with the results of Chan et al. (5), present findings show that vitamin E accumulates in the fetus throughout the third trimester. Therefore, preterm infants are predisposed to vitamin E deficiency. In the present study, maternal serum vitamin A levels were determined as higher than cord vitamin A levels as described previously (24,25). We also found a significant correlation between maternal and cord vitamin A levels. These results were in agreement with previous findings (17,23,24,36). Lower plasma vitamin A levels in newborns can be induced by inefficient placental transfer of vitamin A as well. However, maternal vitamin A administration leads to accumulation of vitamin A in perinatal rat tissues (37). Therefore, fetal vitamin A level can be affected by maternal vitamin A status. Yeum et al. reported that the nutritional status of babies is affected by the nutritional status of their mothers, by
Antioxidant Vitamins in Infants and Mothers
means of certain fat-soluble nutrients such as vitamins A and E (24). In this study we found a lower concentration of vitamin A in preterm than in term infants. Navarro et al. reported that low birth weight infants had significantly lower levels of vitamin A than normal infants (38). Vitamin A also appears to accumulate predominantly in the third trimester. Although levels of vitamins E and A were lower in cord blood than in maternal blood, the level of vitamin C was higher in cord blood than in maternal blood. These results were in agreement with other studies (38–40). Vitamin C levels in preterm babies were lower than those of full-term babies. Guajardo et al. also reported that umbilical cord venous plasma ascorbic acid levels were significantly lower in the preterm group than in the term group (41). In contrast to these results, reduction in vitamin C levels is reported associated with an increase in gestational age (42). Placenta is permeable to dehydroascorbic acid but not to ascorbic acid. The fetus then converts dehydroascorbic acid to ascorbic acid and accumulates it (43,44). At the same time, lipid-soluble antioxidant vitamins have limited placental transfer; thus, infants have low levels of lipid-soluble vitamins. Increased lipid peroxidation caused by oxygen free radicals is believed to be one of the common pathogenic mechanisms for so-called oxygen radical diseases of prematurity. Reactive oxygen species are generated endogenously under physiologic and pathologic conditions. The organism maintains defense systems including antioxidant vitamins such as vitamins E, A, and C against reactive species. Vitamin E inhibits lipid peroxidation; hence, it prevents membrane damage and modification of low-density lipoproteins. It is regenerated by the water-soluble vitamin C. In vitro studies have shown that various forms of vitamin A can exert antioxidant effects more potent than those of vitamin E (45). Hydroperoxide concentrations were found to be high, especially in premature infants. Erythrocyte membranes were also found to contain low levels and/or low activities of antioxidant defense mechanisms, which was more evident in premature newborns who demonstrated -tocopherol levels significantly lower in comparison to full-term infant levels. Furthermore, when premature infants underwent oxygen therapy these effects were exacerbated (46). Conversely, high levels of water-soluble antioxidant vitamin C in babies, particularly in premature babies, may exacerbate oxidant damage by inhibiting ferroxidase activity of ceruloplasmin (40). In conclusion, lipid-soluble antioxidant vitamins A and E are lower in cord blood than in maternal plasma, and term babies have higher levels of these vitamins than do preterm infants. These antioxidant vitamins appear to accumulate during the third trimester, so preterm infants are more susceptible to oxidative stress.
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