Recommended Dietary Allowances Spread Vitamin Needs over Several Days
Recommended Dietary Allowances (RDAs) were designed to make planning meals easy. The D in RDA stands for dietary, not daily, because the RDAs are an average. You may get more of a nutrient one day and less the next, but the idea is to hit an average over several days.
The amounts recommended by the RDAs provide a margin of safety for healthy people, but they’re not therapeutic. In other words, RDA servings won’t cure a nutrient deficiency.
RDAs offer recommendations for protein and essential vitamins and minerals. The following table covers 5 basic vitamins:
|Age (Years)||Vitamin A (RE/IU)†||Vitamin D (mcg/IU)‡*||Vitamin E (a-TE)||Vitamin K (mcg)*||Vitamin C (mg)|
|Older than 70||900/2,970||15/600||15||120||90|
|Older than 70||700/2,310||15/600||15||90||75|
Adequate Intake (AI)
† The “official” RDA for vitamin A is still 1,000 RE/5,000 IU for a male, 800 RE/4,000 IU for a female who isn’t pregnant or nursing; the lower numbers listed on this chart are the currently recommended levels for adults.
‡ The current recommendations are the amounts required to prevent vitamin D deficiency disease; recent studies suggest that the optimal levels for overall health may actually be higher, in the range of 800–1,000 IU a day.
In addition to the RDAs, the Food and Nutrition Board created Estimated Safe and Adequate Daily Dietary Intakes (ESADDI), now renamed Adequate Intake (AI), for eight nutrients considered necessary for good health, even though nobody really knows exactly how much your body needs.