Daily Vitamin D Intake for Adults — 600 IU, 800 After 70

The adult RDA is 600 IU (15 mcg) of vitamin D a day, rising to 800 IU (20 mcg) after age 70. What changed recently is not the number but the advice around it: the 2024 Endocrine Society guideline endorses those DRI figures and suggests against routine blood testing and against empiric supplementation above them for most adults. Pick your life stage below.

The RDA, in both units

Life stage	Vitamin D per day
Children 1 to 8	600 IU (15 mcg)
Ages 9 to 18	600 IU (15 mcg)
Adults 19 to 70	600 IU (15 mcg)
Adults over 70	800 IU (20 mcg)
Pregnancy and lactation	600 IU (15 mcg)

1 mcg of cholecalciferol equals 40 IU, which is the conversion behind every line of that table. Supplement bottles are usually labeled in IU and Nutrition Facts panels in micrograms, so the same product can look like two different doses.

Two footnotes from the National Academies are worth keeping. These values assume minimal sunlight — they are the amount needed if the skin contributes nothing, which makes them a safe target rather than an estimate of what you personally need. And the tolerable upper intake level is 4,000 IU (100 mcg) a day from age 9, food and supplements together.

The FDA Daily Value is the 800 IU figure

The FDA sets the vitamin D Daily Value at 20 mcg, equal to 800 IU — the older-adult RDA applied to the whole population. A carton reading 15% DV supplies 3 mcg, which is 20 percent of a 600 IU adult target. As with calcium and potassium, read the micrograms rather than the percentage.

What the 2024 guideline actually recommends

The Endocrine Society reviewed vitamin D for disease prevention in people without an established reason to test or treat, and the conclusions run against the popular direction of travel:

• Adults under 50: suggests against empiric supplementation beyond the DRI, and against routine 25(OH)D testing.
• Adults 50 to 74: same on both counts — follow the RDA of 600 IU, or 800 IU past 70.
• Adults 75 and older: suggests empiric supplementation, for a potential reduction in mortality, with daily low-dose preferred over intermittent high doses.
• Pregnancy: suggests empiric supplementation, given potential reductions in preeclampsia, preterm birth and neonatal mortality — while still suggesting against routine testing.
• High-risk prediabetes: suggests supplementation alongside lifestyle change, to reduce progression to diabetes.

The recurring reason for the “against testing” recommendations is stated the same way each time: 25(OH)D levels that produce outcome-specific benefits have not been established in clinical trials. That is a statement about missing evidence, not about vitamin D being unimportant, and it does not apply to people with an established clinical indication such as hypocalcemia.

Why it matters for bone, and what it needs alongside

Vitamin D’s defining job is enabling calcium absorption in the gut — the reason the National Academies reviewed the two nutrients in one report rather than two. Calcium intake that meets the RDA with poor vitamin D status is partly wasted; the paired figures are on the daily calcium intake page. Magnesium belongs in the same skeletal picture, with about half the body’s supply stored in bone: see daily magnesium intake.

Food, sun and the honest limits of both

Food sources are few: fatty fish such as salmon and sardines, egg yolk, liver, and fortified milk and cereal. That short list is exactly why fortification exists in the US food supply.

Skin makes vitamin D from ultraviolet light, but production varies with latitude, season, time of day, skin pigmentation, clothing and sunscreen — enough variation that the DRIs deliberately assume none of it. The practical reading: treat 600 IU as the target from diet and any supplement, and treat sun exposure as a bonus you cannot quantify, rather than a substitute you can count on.

This content is informational and does not replace evaluation by a physician. Testing and supplementation are clinical decisions.