Question explored with the scientific record
What is the recommrnd rda of vitamin d aand has the cream been reduced over say the last y50 years
The official RDA is 600 IU a day for adults, and it has gone up, not down, over the past 50 years.
The current US RDA for adults is 600 IU daily, and 800 IU after age 70 [3]. That is the number the Institute of Medicine set in 2010. Before that, the old 1997 recommendation was 200 IU for adults under 50 and 400 IU for older adults. So the trend over the last half century is upward, not downward. The 1968 era figure was 400 IU. The direction has been up.
The bigger fight is not the RDA. It is what blood level you are aiming for. The IOM said there is no proven benefit above 20 ng/mL [2]. A geriatrics group pushed 30 ng/mL and at least 1,000 IU a day [2]. A reanalysis of a large database argued the RDA should be far higher, around 3,875 IU to get 97.5% of people to 20 ng/mL [1]. Those are competing claims, not settled science.
| Source | Daily vitamin D | Target blood level |
|---|---|---|
| IOM RDA (adults) | 600 IU | 20 ng/mL [2] |
| IOM RDA (70+) | 800 IU | 20 ng/mL [3] |
| Geriatrics consensus | ≥1,000 IU | 30 ng/mL [2] |
| GrassrootsHealth reanalysis | ~3,875 IU | 20 ng/mL [1] |
On the cream question, I read that as a typo for "the RDA." If you meant something else, say so. The evidence here does not cover any topical vitamin D product.
My call: the RDA went up over the decades, and the real uncertainty is the target blood level, where credible experts disagree by a factor of several. Confidence: moderate on the RDA history, low on the optimal dose.
Sources used 3
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Letter to Veugelers, P.J. and Ekwaru, J.P., A Statistical Error in the Estimation of the Recommended Dietary Allowance for Vitamin D. Nutrients 2014, 6, 4472–4475; doi:10.3390/nu6104472
This study presents data from the GrassrootsHealth database to estimate the Recommended Dietary Allowance (RDA) for vitamin D, suggesting it is higher than previously published values by the Institute of Medicine.
DOI: 10.3390/nu7031688 -
Recommendations Abstracted from the American Geriatrics Society Consensus Statement on Vitamin D for Prevention of Falls and Their Consequences
A geriatrics workgroup recommends older adults—especially frail ones—reach 25(OH)D ≥30 ng/mL (75 nmol/L) via ≥1,000 IU/d vitamin D with calcium (≈4,000 IU/d total intake) in community and institutional settings to reduce falls and fractures, with no routine 25(OH)D testing neede…
DOI: 10.1111/jgs.12631 -
Vitamin D status is not associated with reproductive parameters in young Spanish men
In 198 young Spanish university men, serum and dietary vitamin D were not associated with semen quality or reproductive hormones, despite low dietary vitamin D intake and mostly adequate serum 25-hydroxyvitamin D levels.
DOI: 10.1111/andr.12690