What is the recommended dosage for Vitamin C?

General: 75-90 mg/day; Acute Illness: 1,000-2,000 mg/day; Immune Support: 200-1,000 mg/day

What are the side effects of Vitamin C?

Potential side effects include: Gastrointestinal distress (nausea, diarrhea, cramps) at high doses, Increased risk of kidney stones in susceptible individuals, Interference with certain lab tests (glucose, occult blood), Iron overload risk in hemochromatosis patients.

What is vitamin C and how does it support the immune system?

Vitamin C (ascorbic acid) is a water-soluble antioxidant that supports multiple immune functions, including epithelial barrier integrity, neutrophil chemotaxis, phagocytosis, and lymphocyte proliferation. It is one of the most extensively studied nutrients for immune health.

What dosage of vitamin C has been studied for immune support?

Clinical trials have used vitamin C at doses of 200 mg to 2,000 mg per day for immune outcomes. Meta-analyses suggest that regular supplementation of 200 mg or more per day may reduce cold duration by approximately 8% in adults. The Tolerable Upper Intake Level is 2,000 mg per day.

What are the potential side effects of vitamin C supplementation?

High doses (above 2,000 mg per day) may cause gastrointestinal distress, diarrhea, and nausea. Individuals with a history of kidney stones should exercise caution, as excess vitamin C is metabolized to oxalate. Vitamin C also enhances non-heme iron absorption.

Vitamin C

vitamin

Also known as: Ascorbic Acid, L-Ascorbic Acid

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About

Vitamin C (ascorbic acid) is a water-soluble essential nutrient and potent antioxidant that serves as a critical cofactor for immune cell function. It enhances neutrophil chemotaxis, lymphocyte proliferation, and natural killer cell activity while supporting epithelial barrier integrity. Regular supplementation may help reduce the duration and severity of common colds.

How It Works

Essential cofactor for immune cell function; enhances neutrophil chemotaxis, lymphocyte proliferation, and natural killer cell activity while supporting epithelial barrier integrity.

Evidence For Conditions

Condition	Grade	Studies	Participants
Upper Respiratory Tract Infections	B	30	10000	View →
Exercise-Induced Immune Suppression	B	5	600	View →

Side Effects

Gastrointestinal distress (nausea, diarrhea, cramps) at high doses
Increased risk of kidney stones in susceptible individuals
Interference with certain lab tests (glucose, occult blood)
Iron overload risk in hemochromatosis patients

Drug & Supplement Interactions

Enhances non-heme iron absorption (beneficial or harmful depending on iron status)
High doses may reduce effectiveness of certain chemotherapy agents
May interfere with anticoagulant therapy (warfarin) at high doses
Aluminum-containing antacids (increased aluminum absorption)

Always inform your healthcare provider about all supplements you take.

Related Ingredients

Vitamin A Vitamin B6 Vitamin D Vitamin E

Quick Facts

Dosage: General: 75-90 mg/day; Acute_Illness: 1,000-2,000 mg/day; Immune_Support: 200-1,000 mg/day
Forms: capsule tablet powder chewable liquid
Natural Sources: Oranges, Red bell peppers, Kiwi, Strawberries, Broccoli, Kale
Upper Limit: 2,000 mg/day
Best Time: With meals; divide doses >500 mg for better absorption

Evidence Summary

Upper Respiratory Tract Infections B

Exercise-Induced Immune Suppression B

FDA Disclaimer: These statements have not been evaluated by the Food and Drug Administration. The products and information on this website are not intended to diagnose, treat, cure, or prevent any disease. The evidence grades presented are based on our analysis of published peer-reviewed research and do not constitute medical advice. Always consult your healthcare provider before starting any supplement regimen.