Criteria and recommendations for vitamin C intake

Area of Science:

• Nutrition Science
• Biochemistry
• Public Health

Background:

• The Food and Nutrition Board is revising vitamin C intake recommendations, updating the 1989 Recommended Dietary Allowance (RDA) of 60 mg.
• Extensive new data from biochemical, molecular, epidemiologic, and clinical studies are available for consideration.
• The revision process considers nine key criteria, including dietary availability, bioavailability, and dose-response relationships for various health outcomes.

Purpose of the Study:

• To apply established criteria to develop new Dietary Reference Intakes (DRIs) for vitamin C.
• To propose updated reference values including Estimated Average Requirement (EAR), RDA, Adequate Intake (AI), and Tolerable Upper Intake Level (UL).
• To provide evidence-based guidance for physicians and the public on optimal vitamin C consumption.

Main Methods:

• Evaluation of available scientific data based on nine specified criteria.
• Calculation of the Estimated Average Requirement (EAR) for vitamin C.
• Determination of RDA, AI, and Tolerable Upper Intake Level (UL) based on EAR and other criteria.

Main Results:

• Proposed EAR for vitamin C is 100 mg/day, leading to a proposed RDA of 120 mg/day.
• Adequate Intake (AI) is set at 200 mg/day from 5 servings of fruits and vegetables, or 100 mg/day to prevent deficiency.
• The proposed Tolerable Upper Intake Level (UL) is less than 1 gram (1000 mg) of vitamin C daily.

Conclusions:

• Five servings of fruits and vegetables daily may support cancer prevention and adequate vitamin C intake for healthy individuals.
• Consuming 1 gram or more of vitamin C daily may lead to adverse effects in some individuals.
• The proposed DRIs provide updated, evidence-based guidelines for vitamin C nutrition.