Supplements · Diets
vitamin C is-required-from dietary intake to prevent scurvy
In plain terms: Do people still need dietary vitamin C, even low-carb?
Part of: 🧪 vitamin C
Yes — humans cannot synthesize vitamin C and develop scurvy without a dietary source; low-carb does not abolish the requirement, though meat contains small amounts.
Evidence ladder
How far up the ladder this claim has climbed. A high consensus on a low rung means "consistent so far," not "proven in people."
Top evidence so far: Human trials (RCT / n-of-1)
How the studies fall
The evidence (9)
| Source | Grade | Stance | Quality | Finding |
|---|---|---|---|---|
| Sharp 2020 · J Dev Behav Pediatr | observational | supports | moderate | Systematic review documents scurvy from restrictive low-vitamin-C diets, showing deficiency arises when dietary intake fails. |
| Frei 2012 · Crit Rev Food Sci Nutr | observational | supports | moderate | Argues optimal dietary vitamin C intake (~200 mg/day) from fruits/vegetables is needed for health beyond scurvy prevention. |
| King 1997 · Am J Clin Nutr | RCT | supports | high | Depletion diet under 5 mg/day drove plasma vitamin C into deficient range within 3 weeks, demonstrating obligate dietary requirement. |
| Ndukwe 2026 · PLoS One | observational | supports | low | Scurvy re-emerging with inadequate dietary vitamin C intake; confirms diet-dependence of the requirement. |
| Mullie 2021 · Int J Circumpolar Health | observational | supports | moderate | Reanalysis of Greenland near-carnivore diet shows adequate vitamin C came from organ meats/traditional foods, not zero requirement. |
| Levine 2001 · PNAS | RCT | supports | high | Depletion-repletion in women confirmed a dietary requirement; RDA set at 90 mg/d. |
| Chabalout 2025 · Cureus | observational | supports | low | Restrictive-diet adult developed profound vitamin C deficiency (anemia, hematomas) reversed by supplementation. |
| Levine 1996 · PNAS | RCT | supports | high | Depletion-repletion in humans: near-zero vitamin C diet drove deficiency; RDA needed ~200 mg/d from food. |
| Rowe 2020 · Nutrients | observational | supports | moderate | Global review finds hypovitaminosis C and deficiency common where dietary vitamin C intake is inadequate, confirming ongoing dietary need. |
Disagree, or know a study we missed?
We grade by evidence, not opinions. The way to weigh in is to point us to a study we haven't cited (check the evidence table above first), or to flag a problem with one we have. Every submission is reviewed; if it holds up, the grade updates and shows in Science Changes Its Mind.
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Educational only, not medical advice. Grades and scores reflect published evidence weighted by study design and quality; see the methodology.