At a glance
Effects
- Antioxidant protection: Scavenges free radicals and reactive oxygen species in body fluids, protecting DNA, proteins, and lipids from oxidative damage [5][8].
- Collagen synthesis & wound healing: Acts as an essential cofactor for hydroxylation of proline in procollagen; without it, mature collagen cannot form its stable triple-helix structure [6].
- Immune support: Accumulates in neutrophils and supports leukocyte function; the body maintains near-maximal neutrophil saturation at adequate intake levels [2].
- Iron absorption enhancement: Significantly improves absorption of non-heme (plant-based) iron from the gut, beneficial in iron-deficiency anaemia [1].
- Scurvy prevention & treatment: Deficiency causes scurvy (haemorrhage, hyperkeratosis, haematological abnormalities); even small intakes (≥10 mg/day) prevent it [6].
Essential water-soluble vitamin / antioxidant micronutrient
~8–40 days at low plasma levels; ~30 min at high (gram-level) intakes [14]
Oral (tablets, capsules, powder, chewable); IV/parenteral for clinical use
Not a controlled substance; freely available OTC
2,000 mg/day (IOM); above this, GI and renal risks rise [4]
About Vitamin C (Ascorbic Acid)
Every point here is drawn from public medical and harm-reduction sources. A bracketed number after a claim — like [1]— is a reference: tap it to open the exact source it's based on (numbered list at the bottom). It is not a rating or score. Educational information, not medical advice.
Product specifics
- Est. delivery
- 3–7 business days · EU tracked
Product details as stated by the vendor (claims, not independently verified). Delivery is our standard EU estimate.
What it is
Vitamin C (ascorbic acid) is an essential, water-soluble micronutrient that humans cannot synthesise themselves and must obtain from diet or supplementation [4][2]. It is primarily used to prevent and treat deficiency (scurvy), support immune function, collagen synthesis, and wound healing, and is widely taken as a general antioxidant supplement [1][3].
How it works
Ascorbic acid works as a potent water-soluble antioxidant, donating electrons to neutralise free radicals and reactive oxygen species in aqueous environments [5]. It is an essential cofactor for enzymes that hydroxylate proline in procollagen — a step required for the triple-helix structure of mature collagen — and for the biosynthesis of carnitine and neurotransmitters [6]. It also enhances iron absorption from plant-based foods and supports normal neutrophil (immune-cell) function [1]. Plasma levels are tightly regulated by intestinal absorption, tissue transport, and renal reabsorption; absorption efficiency falls as oral doses increase [4].
Risks & side effects
Most important: At high doses, ascorbic acid increases urinary oxalate excretion and can promote oxalate crystal formation in the kidneys, with oxalate nephropathy and renal calculi reported at very high intakes [10][11]. Individuals with G6PD deficiency face an additional serious risk: high-dose vitamin C can trigger haemolytic anaemia, and this population should not use high-dose supplementation [12].
Common
Serious
- Kidney stones (oxalate renal calculi) — risk elevated at sustained high doses, especially in those predisposed [10][11]
- Haemolytic anaemia in G6PD-deficient individuals at high doses [12]
- Iron overload in people with haemochromatosis or thalassaemia — ascorbic acid substantially increases iron absorption [3]
- Interference with laboratory glucose tests (pseudohyperglycaemia) [15]
Safety & harm reduction
- G6PD deficiency — high-dose vitamin C can cause severe haemolytic anaemia [12]
- History of oxalate kidney stones — supplemental vitamin C raises urinary oxalate [10]
- Haemochromatosis or thalassaemia — vitamin C substantially increases iron absorption and may worsen iron overload [3]
- Known hypersensitivity/allergy to ascorbic acid [3]
- Severe renal failure — impaired clearance raises risk of oxalate nephropathy [10]
- Renal function (serum creatinine, urinalysis) if using high doses long-term [10]
- Serum iron / ferritin in those with iron metabolism disorders [3]
- Blood glucose should not be measured with point-of-care oxidation-based strips while on high-dose IV ascorbate — use alternative methods to avoid false readings [15]
- G6PD status should be checked before initiating high-dose therapy [16]
- Bortezomib (cancer therapy) — ascorbic acid may reduce its therapeutic effect; avoid co-administration [17]
- Deferoxamine — ascorbic acid may enhance its adverse/toxic effects [17]
- Ciclosporin (systemic) — ascorbic acid may decrease ciclosporin serum levels [17]
- Certain antibiotics (erythromycin, doxycycline, streptomycin, kanamycin, lincomycin) — ascorbic acid may reduce their activity [15]
- Bleomycin — inactivated by ascorbic acid in vitro [15]
- Non-heme iron supplements — ascorbic acid markedly increases absorption; monitor iron levels [1]
- Take oral vitamin C with or after food to minimise gastrointestinal irritation [3]
- Split high doses across the day — intestinal absorption saturates at higher single doses and excess is excreted [4]
- Smokers require an additional ~35 mg/day above the standard RDA due to increased oxidative turnover [2]
- Those predisposed to kidney stones should limit supplemental intake to below 1 g/day [4]
- Do not abruptly stop very-high-dose regimens without medical guidance [4]
Dosage context
RDA (commonly reported, not a prescription): 90 mg/day for adult men, 75 mg/day for adult women; add 35 mg/day for smokers [2]. The Tolerable Upper Intake Level (UL) set by the IOM is 2,000 mg/day for adults to avoid gastrointestinal disturbance and elevated oxalate risk [4]. Supplementation ranges typically reported are 250–1,000 mg/day; doses above ~2–5 g in a single sitting commonly cause diarrhoea [13]. High-dose IV protocols (up to several grams per day) are used in clinical research settings only, under supervision [10]. These figures are commonly cited reference intakes, not personalised prescriptions.
Sources
- 1.NIH ODS – Vitamin C (Consumer)
- 2.NIH DRI – Vitamin C (NCBI Bookshelf NBK225480)
- 3.Mayo Clinic – Vitamin C
- 4.Linus Pauling Institute – Vitamin C
- 5.ScienceDirect – Ascorbic Acid overview (antioxidant mechanisms)
- 6.StatPearls – Vitamin C (Ascorbic Acid) NBK499877
- 7.PubMed – Pharmacokinetics of vitamin C (PMID 18450228)
- 8.PubMed – Two Faces of Vitamin C (PMC7285147)
- 9.Healthline – How Much Vitamin C Should You Take?
- 10.ClinicalTrials SAP – SAFE EVICT CORONA-ALI NCT04344184 (oxalate nephropathy)
- 11.ClinicalTrials ICF – Metabolic Resuscitation NCT03422159 (oxalate crystal risk)
- 12.ClinicalTrials SAP – ACTS Trial NCT03389555 (G6PD, haemolysis, contraindications)
- 13.ClinicalTrials – Stem Cell Transplant IV Vit C NCT03613727 (GI adverse events)
- 14.PMC – Misleading Info on Vitamin C half-life (PMC1236801)
- 15.ClinicalTrials – IV Vitamin C Sepsis Lung Injury NCT03828929 (risks, interactions)
- 16.ClinicalTrials – IV Vitamin C Bladder Cancer NCT04046094 (G6PD haemolysis, oxalate)
- 17.Medicine.com – Ascorbic Acid HCP (interactions)
This information is provided for educational and harm-reduction purposes only. It is not medical advice. These substances can carry serious health risks; effects and safe use vary by individual. Consult a qualified healthcare professional before use. Legal status varies by country — it is your responsibility to know your local law. We do not encourage misuse.