A global clinical view on vitamin A and carotenoids.
Level 5 - mechanism / opinion, no new human data
Narrative review without systematic search methodology
PubMed 23053551 · doi:10.3945/ajcn.112.034868
What was done
Narrative clinical review examining the role of vitamin A and major carotenoids (beta-carotene, lycopene, lutein, and zeaxanthin) in human physiology, global deficiency, chronic disease prevention, and adverse outcomes reported in clinical trials.
What was found
The abstract notes that vitamin A deficiency causes over one million preventable deaths and cases of blindness each year worldwide, and that dietary beta-carotene bioconversion to vitamin A is less efficient than previously thought. While observational studies link high carotenoid intake to reduced chronic disease risk, clinical trials have not demonstrated clinical benefits for non-provitamin A carotenoids, and high-dose beta-carotene trials demonstrated an increased risk of lung cancer in smokers and asbestos-exposed workers. The abstract provides no specific statistical estimates, trial counts, or sample sizes.
Why it matters
It highlights the critical need to address global vitamin A deficiency while cautioning against unproven claims for high-dose carotenoid supplementation, which has demonstrated clear harm in high-risk populations.
Limits
This is a narrative review with no systematic search protocol, explicit inclusion criteria, or quantitative data synthesis reported in the abstract.
Cited by
- context Vitamin A deficiency causes approximately 1 million deaths per year worldwide.