In the Dietary Reference Intakes (DRIs), the Recommended Dietary Allowance (RDA) for vitamin B12 for most adults is 2.4 mcg per day. Which statement best describes what 2.4 mcg means?

• A. It is the average daily intake estimated to meet the requirement of half of healthy adults.
• B. It is the maximum safe daily intake before toxicity is expected in most healthy adults.
• C. It is the daily intake amount recommended to meet the needs of nearly all (97–98%) healthy adults.
• D. It is the minimum intake needed to prevent any possibility of deficiency in all individuals, including those with malabsorption.

Answer: (C)

Verified step by step guidance

1. Understand that the Recommended Dietary Allowance (RDA) is a nutrient intake value used to plan and assess the diets of healthy people.
2. Recognize that the RDA is set to cover the needs of nearly all (97–98%) individuals in a specific age and gender group, not just the average or minimum requirement.
3. Differentiate the RDA from other dietary reference intakes such as the Estimated Average Requirement (EAR), which meets the needs of 50% of the population, and the Tolerable Upper Intake Level (UL), which is the maximum safe intake.
4. Interpret the value 2.4 mcg of vitamin B12 as the daily intake amount recommended to meet the nutritional needs of nearly all healthy adults, ensuring adequate intake to prevent deficiency.
5. Conclude that the correct description of 2.4 mcg is that it is the daily intake amount recommended to meet the needs of nearly all (97–98%) healthy adults.