The antioxidants--vitamin C,vitamin E, selenium, and carotenoids.
Level 5 - mechanism / opinion, no new human data
Narrative review summarizing an expert panel report without systematic review methodology.
PubMed 14563626 · doi:10.1300/J096v09n01_07
What was done
This paper reviewed the April 2000 Food and Nutrition Board (National Academy of Sciences) Dietary Reference Intakes update for vitamin C, vitamin E, selenium, and carotenoids, focusing on changes from the 1989 Recommended Dietary Allowances.
What was found
No primary numerical trial data or specific intake thresholds are reported in the abstract. The review notes that the panel found insufficient scientific evidence to sustain claims that megadose antioxidants prevent chronic diseases such as cardiovascular disease or cancer. For the first time, tolerable upper intake levels were established for vitamin C, vitamin E, and selenium. No intake recommendations or upper tolerable levels were set for beta-carotene or other carotenoids, but the panel advised avoiding provitamin A intakes beyond what is needed to prevent vitamin A deficiency. Additionally, the estimated amount of provitamin A carotenoids required to produce a unit of retinal was revised to reflect a twofold higher conversion requirement than previously estimated.
Why it matters
It documents a shift in nutritional guidance that rejected popular claims for megadose antioxidant supplementation to prevent chronic disease, emphasizing safety thresholds and revised provitamin conversion metrics instead.
Limits
The abstract describes a narrative summary of an expert panel report and contains no original experimental data, systematic review methodology, or specific numerical milligram targets. Findings reflect the scientific evidence available up to 2000.
Cited by
- supports The established tolerable upper intake level for oral vitamin C in healthy adults is 2,000 milligrams per day.