Dosage considerations in the combined use of ocular-specific vitamins and nutrients and multivitamin products: A systemic review and analysis.

Objectives: To provide guidance for safe and appropriate vitamin and mineral supplementation regimens for patients who use vitamins marketed for ocular use concurrently with general-purpose multivitamin (MVI) supplementation.

Data Sources: Primary and tertiary evidence was compiled from secondary literature reference databases.

Study Selection: Dosage exposure with the use of supplements marketed for the prevention of ocular disease, including those recommended by the Age-Related Eye Disease Studies (AREDS), when used in combination with conventional MVI/nutrient products was determined. An analysis of the data was performed to suggest appropriate supplement recommendations.

Data Extraction: Combined dosages for single and duplicate ingredients found in ocular supplements and select MVI/nutrient supplements were compared with U.S. Food and Drug Administration--recommended daily value intake levels and the National Academy of Medicine recommendations on vitamin and nutrient tolerable upper intake levels (TUILs).

Results: With the exception of copper, all studied product components that conformed to AREDS guidelines for vitamin and nutrient levels far exceeded U.S. Food and Drug Administration--recommended daily value intake level limits. Furthermore, vitamin A and zinc exceeded the National Academies of Medicine TUIL when a multivitamin product was combined with an ocular-specific vitamin or nutrient that conformed with AREDS-recommended dosage levels. Several products marketed specifically for ocular use failed to provide AREDS-recommended vitamin or nutrient levels even when combined with MVI products.

Conclusion: With the exception of vitamin A and zinc, the addition of typical multivitamin preparations to AREDS-recommended vitamin and nutrient regimens do not result in vitamin and mineral dosages that exceed TUIL as outlined by the National Academy of Medicine. However, combined AREDS and MVI regimens can create a substantial vitamin or mineral burden that is not appropriate for all older adult populations, particularly those with comorbidities, contributing to susceptibility of component toxicity.