Safety · Supplement
Vitamin A: side effects, safety & interactions
Chronic excess of preformed A causes liver damage, bone effects, and, in pregnancy, birth defects. Smokers should avoid
- Overall grade
- Grade B
- Last revised
- 0
- graded outcomes
- 1
- reference listed
Assembled by the app from other entries in this library. It adds no evidence of its own — follow the links to the entries it draws on.
What is uncertain
Read off the same rows as above. Nothing here is added that the entry does not itself record.
- Watch with Vitamin D: Very high A can antagonize vitamin D's actions on bone.
The evidence in words
Safety profile
Chronic excess of preformed A causes liver damage, bone effects, and, in pregnancy, birth defects. Smokers should avoid beta-carotene supplements. Carotenoids from food are safe (at most, harmless skin yellowing).
Interactions to respect
Vitamin D — Very high A can antagonize vitamin D's actions on bone.
What Vitamin A is
Vitamin A covers preformed retinol (animal foods) and provitamin carotenoids like beta-carotene (plants) the body converts to retinol. It is essential for vision, epithelial integrity, immune function, and reproduction. Deficiency is a leading cause of preventable childhood blindness in low-income settings and a non-issue in well-fed populations.
The honest bottom line
A deficiency you fix, not a supplement you stack. Get it from food; avoid high-dose retinol in pregnancy and beta-carotene supplements if you smoke.
Related reading
Entries that share this one's tags or conditions.
- Andrographis: side effects, safety & interactionsGI upset, allergy; possible additive immune/anticoagulant effects; avoid in pregnancy.Evidence grade B
- Astragalus: side effects, safety & interactionsGenerally safe; immune-stimulating, so caution with immunosuppressants/autoimmunity.Evidence grade C
- Beta-Glucans: side effects, safety & interactionsVery safe; gas/bloating with the soluble-fiber form.Evidence grade B
- Chaga: side effects, safety & interactionsOxalate load — kidney-stone/injury risk; caution with anticoagulants and diabetes drugs.Evidence grade D
Sources
As this entry records them: title, journal and year. None carries a DOI or PubMed id, so none is linked as a verified paper. Each link searches PubMed for the title; check that what you find is what the entry describes.
- 1.Effect of beta-carotene and vitamin A on lung cancer (CARET) — N Engl J Med, 1996. Search PubMed (opens in a new tab)
Last revised . A grade is this entry's reading of the evidence, not medical advice.