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Open WellbeingWhat the studies actually measured

Skin, hair and nails

Vitamin A Beta Caroteneand Skin Health

Two sources here, and they say different things: one measured higher skin Health and one reported mixed results.

How sure anyone can be

Low certainty, level 2 of 4

Further research is likely to change this.

The most certain of the two findings here; each record carries its own.

The numbers reported

0.5
standardized mean difference increase in photoprotective effect per additional month of supplementation (minimum 10 weeks)

One further source recorded only which way the numbers went, without a number.

None of these sources gave a likely range — the band the real answer probably sits in — so how precise these numbers are is still an open question here.

Two sources, newest first

We do not pick between these or average them into one number.

What we read is the published abstract, not the full paper, so a blank below may still be printed in the paper itself. Some of these ratings came from a fixed rule with nobody checking them by hand, and some from a person. Each working below says which.

  • Randomised trial, 2010

    Very low certainty, level 1 of 4

    Differential effects of low-dose and high-dose beta-carotene supplementation on the signs of photoaging and type I procollagen gene expression in human skin in vivo.

    Dermatology. 2010;221(2):160-71. doi:10.1159/000305548. PMID:20516658.

    Number reported
    Not in the abstract
    Which way it went
    Mixed results
    Likely range
    Not in the abstract
    Source’s own words
    facial wrinkles and elasticity vs baseline; magnitude not reported in the abstract
    Who was studied
    Adult female over 50
    Compared with
    baseline (no placebo arm)
    Amount taken
    30 to 90 mg/d
    For how long
    90 days
    Disagreement between studies
    Not in the abstract
    Kind of record
    Journal article
    How this rating was reachedstarts at High, 3 steps down: risk of bias, imprecision and inconsistency
    1. Starts at High
    2. Risk of bias brought it down to Moderatethe abstract reports no risk-of-bias or quality appraisal, so study limitations cannot be ruled outNot in the abstract
    3. Imprecision brought it down to Lowthe abstract reports no confidence interval for the estimateNot in the abstract
    4. Inconsistency brought it down to Very lowpooled studies disagree on the direction of effectReported in the abstract
    5. Ends at Very low3 steps down.
    Checked, nothing to step it down for
    indirectness

    Imprecision stops at the first check that applies; others may apply too.

    Source saved; quote checked byte-for-byte against it by software; no signature.

    Read the abstract on PubMed

  • Systematic review, 2008

    Low certainty, level 2 of 4

    Protection from sunburn with beta-Carotene--a meta-analysis.

    Köpcke W, Krutmann J. Protection from Sunburn with β-Carotene—A Meta-analysis. Photochem Photobiol. 2008;84(2):284-288. doi:10.1111/j.1751-1097.2007.00253.x. PMID:18086246.

    Number reported
    0.5
    Which way it went
    Higher
    Likely range
    Not in the abstract
    Source’s own words
    standardized mean difference increase in photoprotective effect per additional month of supplementation (minimum 10 weeks)
    Who was studied
    Adult
    Compared with
    placebo or control
    Amount taken
    Not in the abstract
    For how long
    Not in the abstract
    Disagreement between studies
    Not in the abstract
    Kind of record
    Meta-analysis
    How this rating was reachedstarts at High, 2 steps down: indirectness
    1. Starts at High
    2. Indirectness brought it down to ModerateThe reason for this step is not on record here.
    3. Indirectness brought it down to LowThe reason for this step is not on record here.
    4. Ends at Low2 steps down.
    Not written down for this rating
    risk of bias, imprecision and inconsistency

    Published before the signing gate; not yet re-verified.

    Read the abstract on PubMed

What is still missing from these readings

  • One give no number at all, only which way it went.
  • Two give no likely range, so how precise those numbers are is unknown.
  • Two do not say how many people took part.
  • Amount taken — One of Two readings: Not in the abstract.
  • For how long — One of Two readings: Not in the abstract.

Something nobody wrote down is never a zero and never a guess.

Vitamin A Beta Carotene is not on our to-read list

Vitamin A Beta Carotene is not on our to-read list, so nothing here is set out to read next for it.

Still to read means nobody here has got to it, not that it was tried and did nothing or that no research exists. A pairing on no list is not a gap: we never set out to read it.

Read next

This is a library, not advice. No recommendation, no dose, no diagnosis, no ranking. We never ask about your symptoms, and nothing here is tailored to you.