Vitamin C function and status in chronic disease.
Level 5 - mechanism / opinion, no new human data
Narrative review of mechanisms, epidemiology, and clinical trials without systematic search or meta-analysis.
PubMed 12134712 · doi:10.1046/j.1523-5408.2002.00005.x
What was done
This narrative review synthesized evidence on vitamin C (ascorbic acid) biology, dietary recommendations, and its relationship to chronic disease prevention. The review evaluated its role as an antioxidant and enzyme cofactor, regulation across body tissues, established RDAs and upper intake levels, and findings from population studies and controlled clinical trials regarding heart disease, cancer, eye diseases, and neurodegenerative conditions.
What was found
The abstract reports no primary quantitative data or effect estimates. It reports that population studies show individuals with high vitamin C intake have lower risk of heart disease, cancer, eye diseases, and neurodegenerative disorders, but controlled clinical trials have not demonstrated prevention of chronic degenerative diseases from vitamin C alone. It notes the RDA of 75 mg for women and 90 mg for men, states amounts above the RDA do not appear helpful in healthy individuals, and reports a Tolerable Upper Level of 2 g based on gastrointestinal upset.
Why it matters
The paper highlights that observational associations between vitamin C and reduced disease risk may reflect overall healthy diet and lifestyle rather than a direct protective effect of supplementation.
Limits
This is a narrative review with no systematic search criteria, quality appraisal, or quantitative meta-analysis reported in the abstract. No primary numerical effect sizes or confidence intervals are provided. Observational findings reviewed are subject to healthy-user confounding.
Cited by
- supports The Recommended Dietary Allowance (RDA) for vitamin C is 90 milligrams per day for healthy men and 75 milligrams per day for healthy women.