The Claim
A multinutrient supplement containing 743 µg of vitamin A (as retinol) administered for 4 months has no significant effect on serum retinol, retinol-binding protein, or transthyretin levels in healthy vegans.
What the research says
Supports is higher
Support is ahead, but a single strong opposing study can change this.
These are independent scores, not a percentage. Higher-grade studies count more, so a single strong opposing study can outweigh several weaker ones.
Taking a multinutrient supplement with 743 micrograms of vitamin A as retinol for four months does not change blood levels of retinol, retinol-binding protein, or transthyretin in healthy vegans.
See the scientific wording
A multinutrient supplement containing 743 µg of vitamin A (as retinol) for 4 months does not significantly improve serum retinol, retinol-binding protein, or transthyretin levels in healthy vegans, despite baseline levels of retinol-binding protein consistently falling below reference ranges, suggesting the dose may be insufficient or that conversion efficiency limits efficacy.
The body takes in vitamin A from the supplement, but the liver does not release enough of it into the blood because the amount given is too low to overcome the body’s normal retention of stored vitamin A. Even though the protein that carries vitamin A in the blood is already low, the body does not make more of it or release more vitamin A to raise levels.
What the research says
1 studyScientists gave vegans a daily vitamin pill with 743 micrograms of vitamin A for four months and found their blood markers for vitamin A didn’t improve, even though many started with low levels. This means the pill didn’t work as expected.
Score breakdown, mechanism chain, raw evidence, ideal studies needed & 1 supporting studies
Not medical advice. For informational purposes only. Always consult a qualified healthcare professional before making health decisions.