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?
Strong support Supplements
Part of: 🧪 vitamin C
RefutedContestedStrong support
consensus score 1.00
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.
📅 Last reviewed: 2026-07-14 ⓘ
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)
MechanismIn-vitroAnimalObservationalRCTMeta-analysis
How the studies fall
29 support 0 contradict 0 tested null 0 mixed · 29 sources, 29 independent groups
The evidence (29)
| Source | Grade | Stance | Quality | Finding |
|---|---|---|---|---|
| Ayyad M et al 2025 · study_type: observational | observational | supports | low | Two adults with malnutrition/alcoholism developed scurvy with undetectable serum vitamin C; oral/IV vitamin C supplementation led to marked clinical improvement. |
| 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. |
| Yew TT et al 2026 · study_type: observational | observational | supports | low | Two pediatric scurvy cases from chronic vitamin C deficiency, presenting with subperiosteal hematomas, both responding to vitamin C supplementation. |
| Guarino L et al 2025 · study_type: observational | observational | supports | low | A 55-year-old man with a severely limited diet lacking fruits/vegetables developed scurvy, rapidly improving with vitamin C supplementation. |
| Geiser M et al 2025 · study_type: observational | observational | supports | low | An 18-year-old with autism and extreme dietary selectivity developed profound vitamin C deficiency (scurvy-associated), with rapid behavioral improvement after high-dose supplementation. |
| Cram B et al 2024 · study_type: observational | observational | supports | low | A 14-year-old with severe anorexia nervosa developed cutaneous scurvy from lack of dietary vitamin C. |
| Lietz A et al 2026 · study_type: observational | observational | supports | low | Scoping review of 9 human studies on the Carnivore Diet found substantial risk of vitamin C (and vitamin D, calcium, magnesium, iodine, fiber) deficiency despite the diet's animal-based composition, alongside elevated LDL/total cholesterol. |
| Dao V et al 2025 · study_type: observational | observational | supports | low | A 24-year-old male with autism and restricted dietary intake developed severe anemia from undetectable vitamin C levels, with resolution after vitamin C supplementation. |
| Alsarhan A et al 2026 · study_type: observational | observational | supports | low | A 14-year-old boy with scurvy and failure to thrive developed superior mesenteric artery syndrome; scurvy was diagnosed as part of his nutritional deficiency picture. |
| Nenninger Leon A et al 2025 · study_type: observational | observational | supports | low | Case of a 50-year-old woman with severe vitamin C deficiency and functional decline, confirmed by undetectable serum ascorbic acid, with rapid improvement after supplementation. |
| Chieng ACR et al 2026 · study_type: observational | observational | supports | low | Case report of a 45-year-old woman with markedly restrictive dietary intake who developed pseudovasculitic scurvy, confirmed by profoundly reduced serum ascorbic acid; rapid improvement with vitamin C supplementation. |
| Ndukwe 2026 · PLoS One | observational | supports | low | Scurvy re-emerging with inadequate dietary vitamin C intake; confirms diet-dependence of the requirement. |
| Saeid L et al 2024 · study_type: observational | observational | supports | low | A 35-year-old male with poor dietary habits (deficient fruit/vegetable intake) developed classic scurvy signs, resolving within 10 days of vitamin C treatment. |
| Trangkanont T et al 2025 · study_type: observational | observational | supports | moderate | Retrospective study of 46 children with vitamin C deficiency (2004-2024) found diagnosis significantly associated with low fruit/vegetable intake; oral vitamin C treatment improved clinical outcomes. |
| Hahn A et al 2025 · study_type: mechanism | observational | supports | moderate | Reviews the historical and contemporary definition of vitamins as compounds preventing classical deficiency diseases (like scurvy from vitamin C) that the body cannot synthesize and must obtain from diet. |
| Di Nora A et al 2025 · study_type: observational | observational | supports | moderate | Case series of 8 children plus systematic review of 126 articles/253 scurvy cases; states humans are unable to synthesize vitamin C and depend entirely on dietary intake, with deficiency causing progressive multisystem disease reversed by s |
| Daswaney A et al 2026 · study_type: observational | observational | supports | low | A 6-year-old girl with a diet lacking fruits/vegetables (flavored milk and yogurt only) developed vitamin C deficiency confirmed by lab testing, improving with ascorbic acid supplementation. |
| 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. |
| Grădinaru AC et al 2025 · study_type: mechanism | observational | supports | moderate | Reviews vitamin C's role in scurvy prevention via collagen synthesis and explains humans lack functional GULO (L-gulono-1,4-lactone oxidase), an inborn pseudogenization shared with certain fish, birds, and mammals, making humans obligately |
| 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. |
| Jiries G et al 2025 · study_type: observational | observational | supports | low | A 74-year-old hemodialysis patient on restrictive diet developed scurvy with undetectable serum vitamin C, improving with oral supplementation. |
| Toscano F et al 2025 · study_type: observational | observational | supports | low | Case series of 5 pediatric scurvy patients with restrictive diets, all showing prompt symptom resolution after vitamin C administration, confirming the diagnosis. |
| Levine 1996 · PNAS | RCT | supports | high | Depletion-repletion in humans: near-zero vitamin C diet drove deficiency; RDA needed ~200 mg/d from food. |
| Abou Zeid R et al 2025 · study_type: observational | observational | supports | low | A 3-year-old child with a rice-dominant diet developed scurvy confirmed by severely low vitamin C, with complete resolution of symptoms after oral supplementation. |
| 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. |
| Hemilä H et al 2026 · study_type: RCT | observational | supports | low | Critical commentary noting the 1953 Sheffield controlled trial established 10 mg/d prevents scurvy, and that multiple pre-1991 controlled trials showed benefits from vitamin C supplementation even above 40 mg/d baseline intake. |
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