Vitamin C
Ascorbic Acid (Vitamin C)
Ascorbic acid (Vitamin C) is an essential water-soluble vitamin that humans cannot synthesize endogenously and must obtain through diet or supplementation. It is primarily used to prevent and treat scurvy, support immune function, enhance iron absorption, and act as a potent antioxidant. At higher doses, it is also used therapeutically for immune support during illness, collagen synthesis promotion, and cardiovascular health.
Mechanism of Action
Vitamin C functions as a cofactor for prolyl and lysyl hydroxylases, enzymes essential for collagen cross-linking and connective tissue integrity. It acts as a primary water-soluble antioxidant, donating electrons to neutralize reactive oxygen species and regenerating other antioxidants like vitamin E. It also stimulates immune function by supporting neutrophil chemotaxis and phagocytosis, enhancing lymphocyte proliferation, and facilitating non-heme iron absorption in the gastrointestinal tract via reduction of ferric to ferrous iron.
Evidence by Health Goal(18 goals)
Dosing Protocols
With meals to reduce gastrointestinal irritation
RDA is 75-90mg/day for healthy adults; 500-1000mg daily is a common maintenance dose for antioxidant and immune support. Doses above 2000mg/day (the tolerable upper limit) significantly increase risk of GI distress and kidney stones. Buffered or liposomal forms improve tolerability at higher doses.
Administered in clinical or IV infusion setting
Cycle: Short-term protocols of 4-8 weeks; ongoing as clinically directed
High-dose intravenous vitamin C (IVC) is used in integrative oncology and severe immune support contexts. Must be administered by a qualified healthcare provider. Baseline G6PD testing is recommended before high-dose IV protocols due to risk of hemolytic anemia in G6PD-deficient individuals.
Applied to cleansed skin in the morning before sunscreen
L-ascorbic acid serums are used for collagen stimulation, hyperpigmentation reduction, and photoprotection. Formulations must be at low pH (below 3.5) for effective skin penetration. Oxidation of the product (yellowing) significantly reduces efficacy.
Safety & Side Effects
Vitamin C has an excellent safety profile at standard dietary and supplemental doses up to 2000mg/day; it is non-toxic and well-tolerated by most healthy adults. However, chronic mega-dosing above 2000mg/day increases risk of kidney stones and GI complications, and high-dose IV administration carries specific risks in those with G6PD deficiency, renal impairment, or iron overload conditions.
Possible Side Effects
- !Gastrointestinal discomfort, bloating, and cramping at doses above 1000mg
- !Osmotic diarrhea at or above bowel tolerance threshold (typically 2000-5000mg/day)
- !Nausea and heartburn, particularly with acidic ascorbic acid forms on an empty stomach
- !Kidney stone formation (calcium oxalate) with chronic high-dose supplementation in predisposed individuals
- !Transient headache with rapid high-dose intravenous infusion
- !Hemolytic anemia in individuals with G6PD deficiency receiving high-dose IV vitamin C
- !Rebound scurvy upon abrupt discontinuation of very high chronic doses due to upregulated catabolism
Interactions
- -May enhance iron absorption - use caution in individuals with hemochromatosis or iron overload disorders
- -High-dose vitamin C may interfere with certain chemotherapy agents (e.g., bortezomib) - consult oncologist before use
- -Can falsely lower blood glucose readings on some glucometer systems, potentially masking hypoglycemia in diabetics
- -May increase absorption and toxicity risk of aluminum-containing antacids when taken concurrently
- -Combined use with estrogen-containing oral contraceptives may slightly increase estrogen bioavailability
Cost & Where to Buy
Standard oral supplementation (500-1000mg/day) costs as little as $5-10/month for bulk ascorbic acid powder or generic tablets. Premium liposomal vitamin C formulations range from $25-40/month. IV vitamin C administered clinically can cost $75-200 per infusion session and is not reflected in these retail estimates.
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