Use of oral contraceptives and serum beta-carotene

Objective: Antioxidants, in particular carotenoids, may influence the risk for cardiovascular disease. This study investigates the influence of oral contraceptives (OC) on the serum concentration of beta-carotene, which may in turn affect the risk of cardiovascular diseases due to its antioxidative impact. Design: Cross-sectional epidemiologic study. Examinations included a detailed questionnaire on medical history and lifestyle factors, a 7 day food record, and blood samples. Setting: National health and nutrition survey among healthy people living in private homes in West Germany in 1987-1988. Subjects: Nonpregnant and nonlactating women aged 18-44 (n=610). Results: Overall, the use of OC was negatively associated with serum beta-carotene concentration in bi- and multivariable analyses after adjustment for age, smoking, alcohol consumption, dietary intake of beta-carotene, use of vitamin supplements, body mass index, pregnancies, and serum concentrations of total triglyceride and cholesterol. A strong interaction between OC use and age on beta-carotene concentration was observed. While no relationship between OC use and serum beta-carotene was seen in the youngest age-group (18-24 y), there was a modest but significant negative association between OC use and beta-carotene levels among 25-34 y old women. The use of OC was associated with a strong decrease in beta-carotene levels among 35-44 y old women. The interaction between OC use and age could partly be explained by age dependent use of OC with higher estrogen content. Conclusions: OC use seems to be strongly related to serum beta-carotene levels, particularly among women above the age of 35. Further studies are needed to clarify the underlying mechanisms of this association and its implications for health risks of OC use.