Vitamin A (retinol)

Research records

Historical source snapshot. Not freshly verified, not a recommendation. Study findings, community accounts and app defaults are not interchangeable.

Publication suitability · 2026-10-15: Historical reference only; not a clinical verification. Clinical, regulatory, efficacy, safety and dose claims are not independently established by this review.

Vitamin A (retinol)

Fat-soluble vitamin. Has a genuine upper limit — accumulates rather than clearing.

Evidence category: Reference only. This describes the source category, not approval or certainty.

Regulatory statement in source: Not separately recorded; do not infer approval from the evidence category.

A European Food Safety Authority opinion kept a tolerable upper intake level for preformed vitamin A, choosing birth defects as the critical harm, with liver damage and bone effects also reviewed. No upper level could be set for beta-carotene; the panel picked lung cancer risk as the critical effect of beta-carotene supplements, especially in smokers. A separate review describes laboratory evidence that excess vitamin A harms mitochondria. These are authority opinions and reviews, not trials of a supplement.

Benefits reported in the imported source

Risks and limits

• Birth defects were the critical harm behind the upper limit for preformed vitamin A.
• Liver damage and bone effects were also reviewed, and laboratory work shows harm to mitochondria.
• No upper level could be set for beta-carotene, whose critical effect is lung cancer risk in smokers.
• The linked sources set safe upper intake limits; they report no benefit from supplementation.

Source bottom line: These sources describe vitamin A's safe upper limits and harms, including birth defects, not benefits from supplements.

Uncertainty: Reference information only. Not medical advice.

Study protocols — reports, not instructions

No study protocol recorded in this snapshot. This does not establish that no study exists.

Community and practice descriptions

Accounts of a practice are not evidence of safety or effectiveness. Words such as “standard”, “safe” or “recommended” describe the source account, not verified consensus or this wiki’s advice. Commercial and self-published citations are retained for traceability, not vendor endorsement or independent clinical corroboration.

Pharmacokinetic context

No half-life recorded in this source snapshot. No value has been inferred.

Source references

• Office of Dietary Supplements - Vitamin A and Carotenoids (Consumer) (availability check 2026-10-15: source not retrieved; HTTP 403)
• Vitamin A and Retinoids as Mitochondrial Toxicants
• Scientific opinion on the tolerable upper intake level for preformed vitamin A and β-carotene (availability check 2026-10-15: possible access barrier; not independently inspected; HTTP 200)
• NIH ODS: Vitamin A (availability check 2026-10-15: source not retrieved; HTTP 403)