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Abstract
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 α-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 α- and β-carotene and β-cryptoxanthin were significantly lower with BMI ≥ 30. In contrast to carotenoids, both plasma levels of γ-tocopherol and lipid-adjusted γ-tocopherol were significantly higher with obesity compared to those with BMI < 30.
Conclusion: Plasma α- and β-carotene and β-cryptoxanthin were negatively associated with obesity, whereas γ-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.
We are indebted to the participants of the Fiber is Fine project staff (Fiber Adherence and Marker Development in Black Churches) for their dedication and informed partnership. We wish to acknowledge Kellogg’s generous provision of the wheat bran supplement spiked with 28 mg of riboflavin/0.5 cup serving. β-Cryptoxanthin was graciously provided by Hoffmann-LaRoche, Inc. This study was supported in part by NIH, National Institute of Nursing Research, R01 NR03552, NIH GCRCRR00046, by awards from University of NC-Chapel Hill Lineberger Comprehensive Cancer Center, and University of Nebraska Medical Center, College of Nursing and the UNMC/Eppley Cancer Center.