Vitamin A: which form, what each one does, and the dose that worked
Vitamin A comes in many forms, and what it does depends on the form. Every result below names the form it came from. Pick the form you take to see its own studies, products and what the biohackers say about it. This page is educational, not medical advice.
What it does, by goalMembersThe top 5 of 19 goals
1 of these 128 human studies gave vitamin a by injection, not by mouth.
| Goal | What the studies show | Studies | Dose that worked |
|---|---|---|---|
| Improved in studies Retinol: 13 of 20 improved · Retinyl palmitate: 6 studies, no clear result | 26 | retinol 0.002 % | |
| Improved in studies Retinol: 12 of 19 improved · Retinyl palmitate: 1 of 1 improved · Beta-carotene: 1 study, no clear result | 21 | retinol 500 mg | |
| Improved in studies Retinol: 10 of 22 improved · Retinyl palmitate: 2 of 6 improved, 1 no effect | 28 | – | |
| Improved in studies Retinol: 7 of 19 improved, 2 no effect · Retinyl palmitate: 1 of 6 improved, 1 no effect | 25 | retinol 50 mcg | |
| Improved in studies Retinyl palmitate: 2 of 7 improved, 1 no effect · Beta-carotene: 2 of 6 improved, 2 no effect · Retinol: 1 of 3 improved, 1 no effect | 16 | retinyl palmitate 15,000 IU · retinol 7 mg | |
| Improved in studies Retinol: 3 of 7 improved · Retinyl palmitate: 1 of 7 improved | 14 | retinol 0.4 % | |
| Improved in studies Retinyl palmitate: 2 of 3 improved · Beta-carotene: 2 of 3 improved, 1 no effect · Retinol: 1 study, no clear result | 7 | retinyl palmitate 25,000 IU | |
| Improved in studies Retinol: 2 of 3 improved, 1 no effect · Retinyl palmitate: 1 of 2 improved, 1 no effect · Beta-carotene: 6 studies, 3 no effect · 1 by drip, injection or inhaler | 11 | retinol 10,000 IU | |
| Improved in studies Beta-carotene: 2 of 6 improved, 2 no effect · Retinyl palmitate: 2 studies, no clear result · Retinol: 1 study, no effect | 9 | – | |
| Improved in studies Beta-carotene: 2 of 3 improved, 1 no effect · Retinol: 1 study, no effect · Retinyl palmitate: 1 study, no effect | 5 | – | |
| Improved in studies Retinol: 1 of 3 improved · Retinyl palmitate: 1 of 1 improved | 4 | retinol 2 mg · retinyl palmitate 25,000 IU | |
| Improved in studies Beta-carotene: 1 of 2 improved, 1 no effect · Retinol: 1 of 1 improved | 3 | – | |
| Improved in studies Retinol: 1 of 3 improved · Retinyl palmitate: 2, both no effect | 5 | retinol 18,000 IU | |
| Improved in studies Beta-carotene: 1 of 3 improved · Retinol: 1 study, no clear result | 4 | – | |
| Too few studies Beta-carotene: 2 studies, no clear result | 2 | – | |
| Too few studies Beta-carotene: 1 study, no clear result | 1 | – | |
| No effect in studies Beta-carotene: 1 of 3 improved, 1 no effect · Retinol: 5 studies, 3 no effect · Retinyl palmitate: 3 studies, 2 no effect | 11 | – | |
| No effect in studies Beta-carotene: 1 of 5 improved, 1 no effect | 5 | – | |
| No effect in studies Beta-carotene: 1 study, no effect | 1 | – |
Members see which goal each result is for, and the products for it. Start My 7-Day Free Trial →
Products – highest ranked firstMembersThe top 3 of 18
Dose and safetyThe dose that worked and the upper limit
The doses that worked, by form, in the studies taken by mouth: retinyl palmitate 15,000 to 200,000 IU, retinol 0.002 to 0.5 % a day.
The upper limit for adults is 3,000 mcg of vitamin a a day; above it, members see a note and are told they can take less.
Biohacker panelMembersWhich forms of vitamin a our 10 biohackers name
Questions people askMembersAnswered from the figures on this page
Which form of vitamin a is best?
Answer for members.
How much vitamin a a day?
Answer for members.
Can I take vitamin a with my meds?
Answer for members.
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Educational, not medical advice. Figures come from the human studies on PubMed we have graded; a study counts for a form when it names the form it used. Updated as new studies arrive. How we grade →