Date

November 2012

Document Type

Thesis

Degree Name

M.S.

Institution

Oregon Health & Science University

Abstract

Vitamin E is an antioxidant that protects cell membranes from lipid peroxidation. Vitamin C, a water soluble antioxidant, helps replenish vitamin E in the body thus enhancing the action of vitamin E as an antioxidant. The recommended dietary allowance (RDA) of vitamin E increases for smokers because of increased oxidant damage from cigarette smoking. Research has linked low levels of vitamin E in mothers to an increased risk of asthma, wheezing, and other pulmonary problems in the neonate, suggesting that neonates of maternal smokers are at an increased risk of having inadequate plasma concentrations of vitamin E and developing a pulmonary disorder. Objective: This study aimed to determine if greater vitamin C intake in mothers who smoked during pregnancy increased their vitamin E concentrations similar to mothers who did not smoke during pregnancy. It further aimed to determine if there were differences in plasma vitamin E and vitamin E metabolite carboxyethyl hydroxychroman (CHEC) concentrations between pregnant smokers and non-smokers and their matched cord pairs. Methodology: This study was a sub-study of a larger ongoing study of vitamin C supplementation in pregnant smoking women being conducted at Oregon Health & Science University (OHSU) by Dr. Cynthia McEvoy. In this study 159 pregnant smokers and 76 non-smokers were consented to the study and were followed through their pregnancy to parturition with serial collections of blood, dietary intake information, and smoking history. From this cohort, 28 pregnant smokers and 34 pregnant non smokers were also included in the sub-study evaluating available samples for vitamin E and lipid levels. Maternal plasma samples were collected before or at delivery, from weeks 28-36 for vitamin C samples, and weeks 30-42 for vitamin E and lipid samples. Cord plasma samples were collected immediately post-partum. Dietary intake was determined by up to three, 24-hour dietary recalls, and analyzed using the computer software program Nutrient Data System for Research (NDSR). Blood samples used to determine vitamin E and CEHC concentrations were analyzed in Dr. Maret Traber’s lab at the Linus Pauling Institute at Oregon State University in Corvallis, Oregon via high performance liquid chromatography (HPLC), and samples for determining lipid concentration were analyzed at OHSU by colorimetric assay. Statistical Analysis: Study groups were compared via independent paired t-tests followed by correlation analysis to determine the relationships between intakes and concentrations of vitamin E in smokers, non-smokers, and their neonates. Correlation analyses were also used to determine relationships between plasma vitamin C, dietary intake of calories, fat, vitamin E, and vitamin C, and vitamin E concentrations in both mothers and neonates. Pearson’s correlations were conducted to determine if pre-pregnancy body mass index (BMI) and/or weight gain during pregnancy were related to vitamin E concentrations. We also performed a multiple linear regression analysis to determine the effect of BMI, weight gain during pregnancy, caloric intake, fat intake, and vitamin C concentration on vitamin E and CEHC concentrations. Results: Plasma vitamin C did not differ between our groups therefore we could not analyze the differences in vitamin E concentrations between smokers receiving the vitamin C supplement and smokers receiving the placebo. Thus, we compared only two groups: smokers and non-smokers. Maternal plasma α- and γ-tocopherol concentrations were not statistically different between smokers and non-smokers. Neonatal plasma α-tocopherol concentrations did not differ between smoking and non-smoking groups. However, γ-tocopherol concentrations were lower in neonates of mothers who smoked during pregnancy than neonates of non-smokers. Maternal and neonatal α-CEHC concentrations did not differ between our groups, but γ-CEHC concentrations were lower in mothers who smoked during pregnancy and their neonates than in non-smokers. Dietary vitamin E intakes and serum vitamin E concentration were not correlated in either group of mothers and neonates. Positive correlations existed between corresponding maternal and neonatal α-tocopherol, γ-tocopherol, α-CEHCs, and γ-CEHCs in both smokers and non-smokers. There were also positive correlations between maternal and neonatal α- and γ-tocopherol concentrations normalized to lipids in non-smokers, but not in smokers. Linear regression analysis showed that there was no significant effect of BMI, weight gain during pregnancy, caloric intake, fat intake, and vitamin C concentration on vitamin E and CEHC concentrations in any of our groups. Conclusion: Results of this study were contradictory to our hypotheses. We were unable to determine if providing a vitamin C supplement to smokers would increase plasma tocopherol concentration since plasma vitamin C concentrations were not affected by supplementation in our subset of patients. Second, we concluded that tocopherol concentrations did not differ between smokers and non-smokers except for neonatal γ-tocopherol concentrations which were lower in our smoking group. We also noted decreased concentrations of γ-CEHCs in our group of smokers perhaps because of increased utilization and, therefore, less degradation in the liver. Our results also suggest that fetal α- and γ-tocopherol concentrations are proportional to maternal concentrations. Also, in cases of smoke exposure during pregnancy, γ-tocopherol may be used as a reactive nitrogen species scavenger thus decreasing γ-tocopherol available to the fetus and reducing the amount of γ-tocopherol bound for catabolism.

Identifier

doi:10.6083/M4RX993F

Division

Graduate Programs in Human Nutrition

School

School of Medicine

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