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 💰 Industry COI noted
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
19 support 0 contradict 0 tested null 0 mixed · 19 sources, 18 independent groups
The evidence (29)
| Source | Grade | Stance | Quality | Finding |
|---|---|---|---|---|
| Ayyad M et al 2025 · Case Reports in Medicine | observational | supports | low | Case series, n=2. A malnourished 76-year-old with inadequate dietary intake had vitamin C 'undetectable at < 0.1 mg/dL'; a 68-year-old with alcohol use disorder who 'described poor access to food and mentioned his inability to cook for himself' had vitamin C 'markedly low at 0.2' (drawn after empiric therapy had begun). Both improved on repletion, but the authors caution that 'the presence of concurrent conditions - such as atrial fibrillation, infection, alcohol use, and malnutrition - necessitates a cautious interpretation of causality', and Case 1 was lost to follow-up so the abstract's 'resolution of cardiopulmonary abnormalities' is not evidenced in the body. |
| 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 | Authors' perspective piece, no new data: 'Here we argue that Phase III RCTs-designed principally to test the safety and efficacy of pharmaceutical drugs-are ill suited to assess the health benefits of essential nutrients.' Scurvy appears only as background for the existing RDA ('The recommended dietary allowance (RDA) of vitamin C has traditionally been based on the prevention of the vitamin C deficiency disease, scurvy'); the paper's own argument is about chronic-disease endpoints and concludes '200 mg per day is the optimum dietary intake of vitamin C for the majority of the adult population.' |
| King J, Wang Y, Welch RW, Dhariwal KR, Conry-Cantilena C, Levine M 1997 · Am J Clin Nutr | observational # was RCT — single-cohort non-randomized depletion-repletion, diet-methods companion of Levine 1996 same 7 volunteers (reread #292, precedent k) | supports | low | Diet-methods companion to Levine 1996 (PMID 8623000) — SAME seven-volunteer NIH depletion/repletion cohort, so zero-weighted as duplicate-population. Finding: on a diet restricted to <=5.0 mg/d (mean intake <3.9 mg/d), 'Within 3 wk of admission the diet induced vitamin C deficiency as indicated by plasma concentrations, which decreased from 23 +/- 6.9 to 6.9 +/- 2.0 mumol/L' (n=7, single arm, no control). Scurvy was NOT an endpoint and no clinical deficiency occurred: 'There were no complications from the diet during the depletion and repletion phase.' Abstract-grade. |
| Yew TT, Lui TH, Abdul Rahman AQ, Lim AN, Tan SL 2026 · BMC Pediatr 2026;26:294 | observational | supports | low | Uncontrolled 2-patient case series, Sarawak General Hospital, Malaysia (BMC Pediatrics, article-type Case Report). Case 1: 7-year-old girl with learning disability and a fruit-and-vegetable-poor diet, presenting with painless right proptosis initially treated as orbital cellulitis; 'Her serum vitamin C was undetectable, thus she was started on high-dose vitamin C therapy, 300 mg four times daily for a week', then 300 mg daily for 3 months, after which 'she was symptom-free and proptosis was resolved. A repeat MRI revealed complete resolution of the hematoma' at 6 months. Case 2: 2-year-5-month-old boy of low socioeconomic status refusing to ambulate, worked up for osteoarticular infection - 'A blood workup excluded infection and blood dyscrasia', joint aspirate sterile, and 'the symptoms persisted despite antibiotics' - until low serum vitamin C confirmed scurvy and 100 mg three times daily was started; 'During clinic review after two weeks, he was pain-free and able to walk with minimal support.' The authors' own summary: 'This was evident in both patients, who responded well to vitamin C treatment, with resolution of the hematoma observed in case 1 on follow-up MRI.' TWO CAVEATS THE ABSTRACT-ERA EXTRACT MISSED: (1) case 1's improvement is CONFOUNDED by concurrent surgery - 'Another FESS was performed to remove the residual blood clots to prevent secondary orbital infection' - so only case 2 gives clean temporal attribution to ascorbate; (2) dietary inadequacy is documented for case 1 only, case 2's exposure being low socioeconomic status plus the measured serum level. Neither child showed classic radiographic scurvy signs - 'these radiographic features did not manifest in both of our patients' - so the diagnosis rested on serum vitamin C plus treatment response. No competing interests; university open-access funding only. n=2, uncontrolled, unblinded, retrospective: the floor of the human-evidence ladder, hence quality low. |
| Guarino L et al 2025 · Medicine (Baltimore) | observational | supports | low | n=1 case report. A 55-year-old Crohn patient eating 'only 5 foods, with no fruit or vegetable intake for over a year' presented with extensive hematomas and follicular purpura; serum vitamin C was at the lower limit of normal (18.3 µmol/L; ref 17.0 < N < 85), measured on day 5 after a balanced diet had been reintroduced, so the diagnosis was explicitly 'presumptive'. Ascorbic acid 1000 mg/day x 5 days then 500 mg BID for 1 month, given alongside dietary modification and a red-cell transfusion, produced progressive resolution of the hematomas. |
| Geiser M, Guggisberg N, Convertini J, Crettol S, Ansermot N, Guinchat V 2025 · Frontiers in Psychiatry | 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 · Cureus | observational | supports | low | A 14-year-old with severe anorexia nervosa developed cutaneous scurvy from lack of dietary vitamin C. |
| Lietz A, Dapprich J, Fischer T 2026 · Nutrients 2026;18(2):348 (MDPI) | observational | supports | low | OFF-SCOPE for a scurvy-requirement claim. PRISMA-ScR scoping review of nine human studies (five case studies/series, two social-media surveys, one exploratory study, one modeling study); no new data. Its vitamin C finding is an INTAKE comparison — 'In two of the three studies examining potential micronutrient deficiencies associated with the CD' reported intakes fell below reference values, 'vitamin C (male DRV: 45 mg, CD: 1.21–33.2 mg; female DRV: 45 mg, CD: 1.22–16.8 mg)', alongside thiamine, vitamin D, magnesium, iron, iodine, potassium and calcium, with 'dietary fiber intake ... far below the recommended Adequate Intake (AI)'. Scurvy itself is never an outcome, and where the review does touch it, it runs the other way: O'Hearn (2020) 'hypothesized that strict adherence to a CD might alter requirements for certain micronutrients, particularly vitamin C, due to metabolic adaptations', and 'Although meat contains very little vitamin C, no clinical cases of scurvy associated with CD adherence have been reported to date.' The review declines to settle it — 'However, this hypothesis remains speculative and requires empirical validation.' So this paper neither demonstrates nor refutes the dietary requirement; it documents low intake with no measured deficiency endpoint over short, uncontrolled follow-up ('Overall, the quality of evidence is very limited due to small sample sizes, short study durations, and the absence of control groups'; NHMRC III–IV). Full text PMC12845189 read 2026-08-19. |
| Dao V et al 2025 · Cureus | 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 · Journal of Medical Case Reports | observational | supports | low | Single-patient case report (n=1, 14-year-old Syrian boy, BMI approximately 11.2) of superior mesenteric artery syndrome. It votes on nothing about dietary vitamin C because it measured nothing about vitamin C: 'Although no laboratory confirmation of serum vitamin C was performed, the diagnosis of scurvy was made clinically on the basis of poor weight gain, mucosal fragility, chronic anorexia, and repeated pediatric consultations', restated in the Discussion as 'While serum vitamin C levels were unavailable, the clinical diagnosis of scurvy was based on accepted criteria, including poor growth, mucosal bleeding, and dietary history.' No serum ascorbate, no quantified dietary vitamin C, and no ascorbate repletion trial - the boy was treated surgically, by 'a successful side-to-side anastomosis', not with vitamin C, so the case contains no exposure-to-outcome link the claim could be tested against. Two details in the history cut further against a clean dietary-deficiency reading: 'His medical history was notable for the use of nutritional supplements, diagnosed scurvy, and failure to thrive', and 'The family belonged to a working middle-class background, with the father employed as an ambulance driver and cultivating citrus orchards.' What the paper actually measured were the compression parameters - 'an aortomesenteric distance of less than 2 mm and an angle not exceeding 10 degrees' - and the surgical outcome, 'At the 3-month follow-up, the patient remained stable, without vomiting or abdominal pain.' Even the scurvy-to-SMA link is offered as conjecture: 'Although scurvy is rarely reported as a trigger for SMA syndrome, its role in promoting cachexia provides a plausible mechanistic explanation for our case.' Off-scope: measured duodenal compression and surgical recovery, asserted dietary vitamin C requirement. |
| Nenninger Leon A et al 2025 · Cureus | observational | supports | low | n=1 case report, Cureus (JATS article-type 'case-report'), open access, no external funding and no declared conflicts. Full text read. The dietary exposure the claim needs is explicit: 'Her diet had consisted almost entirely of crackers and water for several months, resulting in significant unintentional weight loss and clinical malnutrition.' Deficiency was confirmed biochemically - 'Subsequent confirmatory testing revealed an undetectable serum vitamin C concentration (<0.1 mg/dL), establishing the diagnosis of scurvy' - alongside the classic signs ('perifollicular petechiae, corkscrew hairs, and multiple ecchymoses', plus 'poor dentition with diffuse gingival bleeding'), after roughly six months in which a tertiary centre missed it across 'approximately seven specialists, multiple MRI scans of the brain and spine, two electromyography studies'. Repletion response: 'Notably, her condition improved within days of supplementation, with rapid resolution of fatigue and progressive recovery of strength and mood.' HONEST CAVEATS: n=1, uncontrolled; the patient's vitamin C dose is never stated and no repeat level was drawn; recovery is confounded by co-interventions - 'The patient was started on a structured physical therapy program' and 'By the midpoint of her hospitalization, she was also started on a daily multivitamin with iron supplementation' against a presenting haemoglobin of 6 g/dL; and the paper contradicts itself on the patient's age (abstract 'a 50-year-old woman', case presentation 'a 45-year-old woman'). Every quantitative statement in the Discussion (NHANES 7.1% deficiency, 85% of adult US cases delayed >6 weeks, 100-500 mg resolving symptoms in 48-72 hours) is cited to other papers, not measured here - only the single patient is this source's data. |
| Chieng ACR et al 2026 · Reports (MDPI) | 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 | Scoping review PROTOCOL, not a study: 'No datasets were generated or analysed during the current study.' The paper only plans a future search of Canadian scurvy literature (Jan 2000-Dec 2025) and reports no prevalence, no cases, no measurements. Its supporting statement - 'The human body's inability to synthesize vitamin C, combined with the important role played by vitamin C in immune development and total body functioning, makes the body dependent on exogenous sources for vitamin C intake' - is cited background, and its premise that 'scurvy has re-emerged among specific Canadian populations, driven by factors such as inadequate dietary intake' rests on other authors' reports. Directionally consistent with the claim, but zero new data, so review-role per CONVENTIONS 5. |
| Saeid L et al 2024 · Case Reports in Dermatological Medicine | 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, Puwanant M, Chotsampancharoen T 2025 · Nutrients 2025;17(23):3755 (MDPI) | observational | supports | low | Retrospective chart review, 46 Thai children aged 1-15 y diagnosed with vitamin C deficiency 2004-2024 at one tertiary hospital (30 confirmed by serum ascorbic acid, 16 by clinical + pathognomonic radiographic findings); median serum ascorbic acid 0.021 mg/dL (IQR 0.001-0.110). Diet was near-absent in vitamin C sources: 33/43 (76.7%) consumed no vegetables and 33/45 (73.3%) no fruit. Within the cohort, measured ascorbate tracked intake in a clean gradient: both fruit and vegetables median 0.344 mg/dL (IQR 0.323-0.365) > fruit only 0.097 > vegetables only 0.042 > neither 0.010 mg/dL (IQR 0.010-0.023), p=0.04; vegetable consumers 0.059 vs 0.018 mg/dL (p=0.039); excessive (mostly UHT) milk intake, median 1040 mL/day against a 400 mL/day guideline, was associated with LOWER ascorbate (p=0.033). Oral vitamin C ~293 mg/day for one week then ~109 mg/day for three months produced clinical improvement in all 46 (median 3 days to response); at follow-up 26/41 (63.4%) had full symptom resolution and 15/41 (36.6%) mild residual symptoms, and 12 of 14 rechecked normalised biochemically. IMPORTANT SCOPE LIMIT: there is no non-deficient comparison group, so this tests the dose-gradient and the repletion response, NOT deficiency risk versus controls; exposure is caregiver recall (authors list recall bias as a limitation) and the paper explicitly declines to estimate prevalence. No external funding, no declared conflicts. |
| Hahn A et al 2025 · Nutrients | observational | supports | low | Narrative definitional review; the authors state 'No new data were created or analyzed in this study.' and 'expressly regard this definition, as well as the entire article, as a proposal for discussion'. It restates vitamin C's dietary essentiality as textbook history — 'The discovery of virtually all vitamins originated from the observation that certain well-known diseases could be traced back to insufficient intake of previously unidentified organic compounds: vitamin C in scurvy, thiamine in beriberi, and cobalamin in pernicious anemia of pregnancy' — and grounds nutritional essentiality in 'the inability of the human body to synthesize the substance in sufficient amounts'. Supports the claim at review weight only; it measures nothing and is not an independent line of evidence. |
| Di Nora A et al 2025 · Open Medicine (Wars) | observational | supports | moderate | Hybrid paper: an ORIGINAL uncontrolled case series of 8 children (17 months to 12 years, M6/F2) admitted to two Catania hospitals Oct 2021–Oct 2023, plus a PRISMA systematic review pooling 253 published pediatric cases. The primary half is what votes here. Presenting with limb pain and refusal to walk after failed NSAIDs, 'Personal history showed an absolute lack of nutrients with vitamin C content and absence of citrus fruits supply (ID-01, ID-02, ID-03, ID-05, and ID-08)'; 'The diagnosis was confirmed by low content of vitamin C' in all eight; 'Scurvy treatment consisted of 100–300 mg daily according to the age of children. After treatment a rapid improvement of the symptoms were obtained within 2 weeks.' Mechanistic basis stated: humans 'lack the active form of the enzyme l -gulonolactone oxidase required for synthesizing ascorbic acid and therefore it must be obtained through the diet', with deficiency symptoms appearing 'within 4–12 weeks by the reduced supply'. Caveats: uncontrolled, n=8, no quantified outcome scale, single region; the review half is pooled case reports (no denominator, publication bias) and the paper contradicts itself on its own corpus size — abstract says 126 articles, Results say 'At the end of the selection, 106 articles were included in this systematic review' with '253 patients... described within the 106 selected studies'. 106 is the number. No external funding; authors declare no conflict of interest. |
| Daswaney A et al 2026 · Pediatr Rep (MDPI) | 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, Deliens, Clarys 2021 · Int J Circumpolar Health | observational | supports | low | Reanalysis of the Hoygaard 1936-37 East-Greenland records (n=35 adults, 13 families, 340 record-days): median vitamin C intake 79 mg/d (males) and 59 mg/d (females), all of it from traditional foods and 0 mg/d from imported foods, with 95%/93% above 20 mg/d. The supply was NOT carnivorous - 'Approximately 50% of the vitamin C came from animal foods, where Hoygaard et al. found a 50% loss when cooked', leaving 18/15 mg/d from animal sources; algae supplied 21/19 mg/d and 'The number of adults consuming algae during the research days was 67% for males and 71% for females, this was only 24% and 21% for narwhal skin.' The classic animal sources were marginal: 'Narwhal skin and eyes had a marginal contribution to the vitamin C consumption.' Requirement is evidenced biochemically, not clinically: 'The reported vitamin C blood determinations reflect hypovitaminosis C for 47% of the sample, and scurvy levels for 18% of the population', and 'It is remarkable that all 6 with extreme low blood concentrations of vitamin C, lived near the trading centre consuming more imported food and less traditional food.' Quality lowered to low: 1930s dichlorophenolindophenol titration, as few as 6 record-days per family, no clinical scurvy outcome, and the authors' own caveat that 'converting household consumption to individual consumption will obscure differences in intake among people of differing age and body weight'. |
| Grădinaru AC et al 2025 · Life (Basel) 2025;15(2):238 | observational | supports | moderate | Narrative review (MDPI Life, no Materials and Methods, no search strategy, 187 cited references, no primary data). Directly on-topic for both halves of the claim: 'Some fishes and several bird and mammalian species, including humans and non-human primates, have lost their ability to synthesize vitamin C, becoming dependent on exogenous sources' and 'As a member of the water-soluble vitamin family, vitamin C cannot be stored in the body; therefore, it is essential to obtain it regularly through diet or supplements'. On the scurvy endpoint specifically: 'The minimal dietary intake of vitamin C to prevent scurvy is about 10 mg per day', with 'Clinical signs of scurvy usually develop once vitamin C levels drop below 11.4 μmol/L'. Supports the claim, but every figure is attributed to a cited reference, so this carries review-layer weight only. |
| Levine M, Wang Y, Padayatty SJ, Morrow J 2001 · PNAS | RCT | supports | moderate | Inpatient depletion-repletion in healthy young women 'hospitalized for 186 +/- 28 days, using vitamin C doses of 30-2,500 mg daily': dose vs steady-state plasma was sigmoidal and 'plasma and circulating cells saturated at 400 mg daily, with urinary elimination of higher doses'; 'the data indicate that the Recommended Dietary Allowance for young women should be increased to 90 mg daily.' Single-cohort, non-randomized, no control arm; n not stated in the readable text; scurvy itself was not an endpoint. |
| Chabalout MN, Sotomayor Barrera F, Yimit A 2025 · Cureus | observational | supports | low | Restrictive-diet adult developed profound vitamin C deficiency (anemia, hematomas) reversed by supplementation. |
| Jiries G, Vdovich O, Badran A, Kruzel-Davila E 2025 · Frontiers in Nephrology | observational | supports | low | Single-patient case report (n=1, uncontrolled), Frontiers in Nephrology 2025, no funding and no declared COI. A 74-year-old woman on maintenance hemodialysis since 2020, cachectic at BMI 16.8 kg/m2, had lost 8 kg over two years 'likely attributable to decreased appetite and dietary restrictions, including limited intake of fruits and vegetables'; she presented with perifollicular erythema, purpuric rash over both ankles and gingival bleeding. Serum vitamin C was 'markedly below the lower detection limit (4 mg/L)' on a deliberately timed pre-dialysis midweek sample, with normal platelets (308x10^3/uL) excluding the thrombocytopenia differential and no systemic features of vasculitis. Oral vitamin C 500 mg daily gave 'significant improvement in the perifollicular purpuric rash and resolution of gingival bleeding' by four weeks, sustained five months later on 250 mg every other day. This is the full deprivation-to-disease-to-repletion sequence the claim asserts, in a human, but it is n=1 and uncontrolled, and the authors concede the colorimetric assay omitted metaphosphoric acid so the absolute level may be underestimated; no repeat vitamin C level was drawn. The article's second half is a narrative literature review that pools no new data and bears on supplementation risk versus benefit in dialysis (oxalosis, pro-oxidant effects), not on this claim. |
| Toscano F et al 2025 · Ital J Pediatr | 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 | moderate | In-hospital depletion-repletion pharmacokinetic study, not a randomized trial: 'Because current data are inadequate, an in-hospital depletion-repletion study was conducted', in which 'Seven healthy volunteers were hospitalized for 4-6 months and consumed a diet containing <5 mg of vitamin C daily' and 'Steady-state plasma and tissue concentrations were determined at seven daily doses of vitamin C from 30 to 2500 mg.' Supports the dietary-requirement half of the claim quantitatively: 'The steep portion of the curve occurred between the 30- and 100-mg daily dose, the current RDA of 60 mg daily was on the lower third of the curve, the first dose beyond the sigmoid portion of the curve was 200 mg daily, and complete plasma saturation occurred at 1000 mg daily', concluding 'Based on these data and Institute of Medicine criteria, the current RDA of 60 mg daily should be increased to 200 mg daily, which can be obtained from fruits and vegetables.' Two honest limits. (1) Scurvy was never an endpoint - the paper reports no clinical deficiency in any volunteer, and its whole argument moves the RDA basis away from scurvy prevention toward tissue saturation ('Neutrophils, monocytes, and lymphocytes saturated at 100 mg daily'). (2) Design: single cohort of n=7, no control arm, no randomization, no blinding, sequential dose escalation; source note study_type: RCT overstates it. Quality moderate on n=7 and the uncontrolled design, matching the sibling cohort appraisal ev-s11504949. Abstract-grade read (PubMed efetch); Europe PMC served no full text for PMC39676. |
| Abou Zeid R et al 2025 · Cureus | observational | supports | low | n=1 case report: 3-year-old on a rice-dominant self-restricted diet (affluent family, unrestricted food access) had plasma vitamin C <0.1 mg/dL vs reference 0.6-2 mg/dL; oral ascorbic acid 500 mg/day gave complete resolution of gingival hyperplasia and edema within one week. |
| Rowe 2020 · Nutrients | observational | supports | moderate | Narrative (non-systematic) review of global vitamin C status - full text read, CC BY, PMC7400810. Its own compiled analysis is the exposure-outcome pair this claim names: habitual dietary intake against plasma status, with hypovitaminosis C at <=23-28 umol/L and deficiency at <=11 umol/L. The gradient runs in the claimed direction. Where intake is adequate, status is replete: EPIC-Norfolk (>22,400 adults, 85 mg/day) mean 54 umol/L, 1.4% deficient; SU.VI.MAX (>12,700, 100 mg/day) 56 umol/L, ~1% deficient; and German seniors on ~90 mg/day reached 71 umol/L, which the authors read as evidence that 'it is possible to achieve saturating vitamin C concentrations through the diet and/or supplementation.' Where it is not, deficiency follows: Russian adult males 9 umol/L mean with 79% deficiency and 90% hypovitaminosis C; Mexican schoolchildren 24-28 umol/L with 23% deficiency on 44 mg/day; US NHANES 2003/2004 8.4% deficient. The authors attribute the split to intake - 'differences in dietary intakes between high-income countries and LMIC likely playing a major role' - and note that 'Many staple foods, particularly those that are grain-based, contain negligible vitamin C.' HONEST BOUNDARY: the endpoint measured throughout is biochemical, not clinical scurvy. Scurvy appears only as the introduction's cited premise and as one cited Afghan outbreak (6.3% prevalence at the end of winter), so this source supports the claim via a validated surrogate plus one clinical series, not a direct diet-to-scurvy test. GRADE CONTEXT: illustrative selection by the authors' own description, no protocol or risk-of-bias assessment, much of the underlying survey data >=20 years old, MDPI venue - hence evidence_role: review and quality moderate, which stand. No external funding; no declared conflicts. |
| Hemilä H, Chalker E 2026 · Br J Nutr | observational | supports | low | Commentary in the British Journal of Nutrition's 'Horizons in Nutritional Science' section (JATS article-type='review-article') arguing that the UK's 1991 recommendation of 40 mg/d is not evidence-based. Direction as asserted is supportive of this claim - the authors' quarrel is that 10 and 40 mg/d are too LOW, not that dietary vitamin C is unnecessary - and they restate the depletion finding, that 'nearly all individuals who received no more than 1 mg/d for 3–6 months from a specially vitamin C-depleted but otherwise adequate diet developed mild clinical signs of scurvy', adding that 'In the Sheffield study, 40 % (4/10) of vitamin C-deprived participants suffered from severe health events caused by the deprivation'. But the paper collects nothing: the scurvy content is the 1953 Sheffield experiment (n=20) at second hand, and the paper's own analysis measures respiratory-infection outcomes against baseline intake in eight previously published trials, 'is 3367 (median 176), in contrast to just twenty participants in the influential Sheffield study on vitamin C deprivation'. That trial set is openly one-directional - 'One potential limitation of this commentary is our focus on trials reporting positive outcomes.' - and the supporting reviews are the first author's own. Zero weight as evidence_role: review; the underlying Sheffield evidence should be counted on its own source, not through this restatement. |
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