How this instrument works
This calculator looks up the NIH Office of Dietary Supplements' Recommended Dietary Allowance for one of three micronutrients — Vitamin C, Vitamin B12, or Folate — for adults ages 19 to 50. These three are covered here specifically because they aren't covered by this site's other nutrition calculators: a separate vitamin A calculator handles the mcg RAE to IU conversion, a separate vitamin D calculator covers that nutrient, and a separate micronutrient calculator handles the minerals calcium, iron, and zinc. This tool fills the remaining gap for Vitamin C, B12, and folate specifically.
Of the three, only Vitamin C's RDA differs by sex at this age range: 90 mg per day for men versus 75 mg per day for women, set out in the NIH ODS Vitamin C fact sheet. Vitamin B12's RDA is 2.4 mcg per day for both men and women 19-50, and folate's RDA is 400 mcg DFE (dietary folate equivalents) per day, also the same for both sexes at this age. Selecting Sex is female therefore only changes the displayed figure when Vitamin C is the selected nutrient.
The RDA figures shown here apply specifically to healthy adults ages 19-50 and deliberately don't extend beyond that. Several life stages call for different, higher values that this calculator doesn't attempt to cover — folate's RDA rises to 600 mcg DFE during pregnancy and 500 mcg DFE during lactation, for instance, and requirements can also shift for older adults, adolescents, and people with specific medical conditions. Anyone in one of those situations should consult the full NIH ODS fact sheet or a clinician rather than reading this tool's adult 19-50 figure as their own target.
- Set Sex is female to No or Yes — this only changes the result when Vitamin C (mg) is selected, since Vitamin B12 and folate use the same RDA for both sexes.
- Select Vitamin: Vitamin C (mg), Vitamin B12 (mcg), or Folate (mcg DFE).
- Read RDA, adults 19-50 for the combination selected.
- Remember the figure applies to healthy adults 19-50 only — pregnancy, lactation, and other life stages use different, higher values not shown by this calculator.
Worked example — three nutrients, one age range
With Sex is female set to No and Vitamin set to Vitamin C (mg), the calculator returns an RDA of 90 mg per day — the NIH Office of Dietary Supplements figure for adult men ages 19-50.
Vitamin B12 doesn't vary by sex at this age: switching Vitamin to Vitamin B12 (mcg) with Sex is female set to Yes returns 2.4 mcg per day, the same RDA the calculator would show with the toggle set to No.
Folate follows the same both-sexes pattern. With Sex is female set to No and Vitamin set to Folate (mcg DFE), the RDA reads 400 mcg DFE per day — a figure that rises to 600 mcg DFE during pregnancy, a life stage this adults-19-50 calculator doesn't cover.
Questions
Why does Vitamin C have separate RDAs for men and women but B12 and folate don't?
At this age range, the NIH Office of Dietary Supplements sets Vitamin C's RDA at 90 mg/day for men and 75 mg/day for women, while Vitamin B12 (2.4 mcg/day) and folate (400 mcg DFE/day) are set at the same level for both sexes. The three nutrients simply have different Dietary Reference Intake values published for adults 19-50 — Vitamin C happens to be the one of these three where sex is a factor at this life stage.
What does 'mcg DFE' mean for folate?
DFE stands for dietary folate equivalents. The NIH Office of Dietary Supplements uses this unit because folic acid, the synthetic form used in fortified foods and supplements, is absorbed more efficiently than folate that occurs naturally in food, so DFE adjusts for that difference to give one comparable figure. The adult RDA of 400 mcg DFE per day is expressed in this unit rather than plain micrograms.
Does this calculator apply during pregnancy or to older adults?
No. Every figure here is the NIH ODS Recommended Dietary Allowance specifically for adults ages 19-50. Pregnancy and lactation raise several of these values — folate's RDA rises to 600 mcg DFE per day during pregnancy and 500 mcg DFE during lactation, for example — and other life stages, including adolescence and older adulthood, can also carry different requirements not shown by this tool.
Where do these RDA numbers come from?
They come from the NIH Office of Dietary Supplements' Health Professional Fact Sheets for Vitamin C, Vitamin B12, and Folate, which report the Dietary Reference Intakes established by the Food and Nutrition Board of the National Academies of Sciences, Engineering, and Medicine.
Is this the same as the site's Vitamin A, Vitamin D, or micronutrient calculators?
No, they're deliberately separate tools. Vitamin A needs a source-specific mcg RAE to IU conversion, Vitamin D has its own dedicated calculator, and calcium, iron, and zinc are handled by a separate micronutrient calculator. This calculator covers only Vitamin C, Vitamin B12, and folate, the three RDAs not addressed by those other pages.
What counts as 'adults 19-50' here?
It's the specific age band the NIH Office of Dietary Supplements uses for these RDA figures in its fact sheets. Requirements can differ for adults over 50 and for younger age groups, and this calculator doesn't include those separate values — only the 19-50 adult figures for Vitamin C, Vitamin B12, and folate.
References
- NIH Office of Dietary Supplements — Vitamin C, Health Professional Fact Sheet
- NIH Office of Dietary Supplements — Vitamin B12, Health Professional Fact Sheet
- NIH Office of Dietary Supplements — Folate, Health Professional Fact Sheet
Read this first: This instrument computes a screening figure from population formulas — it is not a diagnosis, and it cannot see the whole picture a clinician can. Use it to inform a conversation, not to replace one.