Intake of Vitamin and Mineral Supplements and Longitudinal Association with HbA(1c) Levels in the General Non-Diabetic Population—Results from the MONICA/KORA S3/F3 Study

BACKGROUND: Lower levels of hemoglobin A(1c) (HbA(1c)) are associated with a decreased risk of cardiovascular complications in diabetic and non-diabetic individuals. The aim of the study was to longitudinally investigate the association between the use of 11 vitamins and minerals (vitamins E, C, D, B(1), folic acid, carotenoids, calcium, magnesium, zinc, iron, and selenium) and change in HbA(1c) levels over 10 years in non-diabetic individuals drawn from the general population. METHODS: Baseline data were available from 4447 subjects included in the population-based “Monitoring of Trends and Determinants in Cardiovascular Diseases” (MONICA) Augsburg S3 survey (1994/95). Follow-up data were derived from 2774 participants in the follow-up survey named “Cooperative Health Research in the Region of Augsburg” (KORA) F3 (2004/05). Vitamin/mineral intake from supplements and medications was assessed in a personal interview, where participants were asked to bring product packages of preparations that had been ingested during the last 7 days prior to the examination. Associations between regular vitamin/mineral intake amounts and HbA(1c) levels measured at baseline and follow-up were investigated using generalized estimating equation models. For carotenoids, analyses were stratified by smoking status. RESULTS: None of the investigated nutrients except for carotenoids was significantly associated with changes in HbA(1c) levels after 10 years. Regular intake of carotenoids from supplements and medications in amounts > 6.8mg/d (upper tertile) was associated with an absolute –0.26% (95% CI: –0.43 to –0.08) lower increase in HbA(1c) levels compared with no intake of carotenoids. An inverse association was observed in those who never smoked but not in (former) smokers. CONCLUSION: Larger prospective and intervention studies in non-diabetic/non-smoking individuals are needed to confirm the results and to assess whether the observed associations between carotenoid intake and change in HbA(1c) levels are causal. If our results are confirmed, high carotenoid intake could be one strategy for the prevention of cardiovascular complications in non-diabetic people.