The 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
This study watched what happened in just two people when they took a special form of vitamin A and then later took a supplement. It’s like telling a story about two friends trying something — it helps us notice ideas, but we can’t say it works for everyone or that one thing caused the other.
Analysis score
Maximum 44 for a cross-sectional study.
Where the score came from
Two adults took a special form of vitamin A from carrots, once before and once after taking vitamin A pills. Scientists watched how their bodies handled it using special tracking.
Where does this study sit?
Reviews of RCTs (Meta-analyses)
Max 100Randomized Trials
Max 90Reviews of Cohort Studies
Max 85Cohort Studies
Max 72Reviews of Case-Control Studies
Max 63Case-Control Studies
Max 58Cross-Sectional & Case Series
Max 50Expert Opinion
Max 524 / 100
Quality score
Snapshots of a population at a single point in time, or descriptions of small groups. Can identify correlations and prevalence, but cannot determine cause and effect.
Key takeaways
Summary
Based on the study abstract and findings.
- 1Even though the body broke down less beta-carotene, it absorbed more of it, so you still end up with more vitamin A overall.
- 2After taking vitamin A pills: absorption went up from 57% to 74% and 52% to 75%; urine waste dropped 10 times; less beta-carotene was chopped into vitamin A; but overall, each bite gave more vitamin A.
Score breakdown, methodology, conflicts of interest, evidence analysis & raw study data
Publication
Journal
Journal of Lipid Research
Year
2003
Authors
S. Lemke, S. Dueker, J. Follett, Yumei Lin, Colleen Carkeet, B. Buchholz, J. Vogel, A. Clifford
Related Content
Claims (4)
Taking a lot of vitamin A every day for about three weeks might help two healthy people absorb more beta-carotene from their food, based on how much showed up in their urine over the next month.
Taking a specific dose of vitamin A every day for about three weeks might make your body get rid of much less of a certain form of beta-carotene through urine, based on a small observation in two healthy adults.
Taking a lot of vitamin A every day for about three weeks might make your body break down beta-carotene (from food) into vitamin A less efficiently.
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.
Not medical advice. For informational purposes only. Always consult a qualified healthcare professional before making health decisions.