The Claim

In two adult subjects, the molar vitamin A value of beta-carotene increased from 0.62 to 0.85 mol vitamin A per mol beta-carotene and from 0.54 to 0.74 mol vitamin A per mol beta-carotene, respectively, following 21 days of daily 10,000 IU vitamin A supplementation, suggesting an increase in net vitamin A yield despite reduced cleavage activity.

Source: Absorption and retinol equivalence of β-carotene in humans is influenced by dietary vitamin A intake Published, JLR Papers in Press, June 1, 2003. DOI 10.1194/jlr.M300116-JLR200

What the research says

Supports is higher

Support is ahead, but a single strong opposing study can change this.

Supports
24score
Challenges
0score

These are independent scores, not a percentage. Higher-grade studies count more, so a single strong opposing study can outweigh several weaker ones.

Quantitative
1 study reviewed
In plain English

After taking vitamin A supplements for three weeks, two people ended up getting more usable vitamin A from beta-carotene—even though their bodies were breaking it down less, which is kind of surprising.

See the scientific wording

The molar vitamin A value of beta-carotene increased from 0.62 to 0.85 mol vitamin A per mol beta-carotene in one adult and from 0.54 to 0.74 in another after 21 days of 10,000 IU/day vitamin A supplementation, indicating higher net vitamin A yield despite reduced cleavage.

What the research says

1 study
  1. Study: Absorption and retinol equivalence of β-carotene in humans is influenced by dietary vitamin A intake Published, JLR Papers in Press, June 1, 2003. DOI 10.1194/jlr.M300116-JLR200

    The study found that when people took vitamin A supplements, their bodies absorbed more beta-carotene and turned it into usable vitamin A, even though less of it was being broken down—just like the claim says.

Score breakdown, mechanism chain, raw evidence, ideal studies needed & 1 supporting studies

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