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Plasma Carotenoid and Vitamins A and E Concentrations in Older African American Women after Wheat Bran Supplementation: Effects of Age, Body Mass and Smoking History

University of North Carolina at Chapel Hill, North Carolina (B.R.S., A.H.S., J.W.H., R.T., X.W., Y.C., J.L.S.)
University of Nebraska Medical Center at Omaha, Nebraska (J.R.A., F.U., E.R.L.)

Address reprint requests to: Boyd R. Switzer, Ph.D., Dept. of Nutrition, University of North Carolina-Chapel Hill, Chapel Hill, NC 27599-7461. E-mail: boyd_switzer{at}unc.edu

Objective: This study investigated the relationships of plasma vitamins A, E, and carotenoids with age, BMI and former/non-smoking history after adjusting for wheat bran supplementation.

Methods: All 39 African American women in the church-based, volunteer sample, 40–70 years old, supplemented their daily diets for 5–6 wks. with 1/2 cup of a riboflavin-spiked wheat bran cereal.

Results: Urinary riboflavin concentrations increased from 0.8 ± 0.1 mg/day at baseline to 7.5 ± 0.5 mg/day after supplementation, confirming the 99.2 ± 10.5% self-reported adherence. Plasma nutrient concentrations did not change significantly with supplementation nor was never/former smoking history related to diet. Plasma retinol and serum cholesterol were significantly higher (p < 0.0002) in persons older than 55 years compared to younger adults. Plasma retinol (µg/dL) but not serum cholesterol was associated significantly with menopausal status and hormone replacement therapy (HRT; p = 0.05); progressive increases in retinol concentrations were found in the women after adjusting for pre/post supplementation: lowest in pre-menopause (47.7 ± 4.8); intermediate concentrations in post-menopause on HRT (54.6 ± 3.0); highest level in post-menopause without HRT (61.1 ± 3.0). Similarly, a progressive increase was found in lipid-unadjusted -tocopherol concentrations and menopausal status with or without HRT. Vitamin A and cholesterol intakes were not significantly different by age group. Plasma carotenoids were not significantly different by age or fiber supplementation, but - and ß-carotene and ß-cryptoxanthin were significantly lower with BMI 30. In contrast to carotenoids, both plasma levels of -tocopherol and lipid-adjusted -tocopherol were significantly higher with obesity compared to those with BMI < 30.

Conclusion: Plasma - and ß-carotene and ß-cryptoxanthin were negatively associated with obesity, whereas -tocopherol measures were consistently elevated with high BMI. The increase in age-associated plasma retinol in postmenopausal women was likely related to decreased estrogen concentrations in the African American women. Smoking history was not influential in this study.

Key words: African American, women, vitamin A, vitamin E, age, BMI

Abbreviations: BMI = body mass index • HRT = menopausal status/hormone replacement therapy • AFFQ = Arizona Food Frequency Questionnaire • SE = standard error • NHANES III = National Health and Nutrition Examination Survey