What type of vitamin C (ascorbic acid) is best for supplementation?

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Last updated: June 16, 2025View editorial policy

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From the Guidelines

For vitamin C supplementation, sodium ascorbate or calcium ascorbate (buffered forms) are generally best for most people, especially those with sensitive stomachs, as they cause fewer digestive issues while providing the same benefits. These forms are less acidic than pure ascorbic acid, making them a better option for individuals with stomach sensitivity issues 1. A typical daily dose ranges from 500-1000mg for general health maintenance, though up to 2000mg daily is considered safe for most adults, as supported by the tolerable upper intake level of 2,000 mg/day for vitamin C 1.

Some key points to consider when choosing a vitamin C supplement include:

  • Opting for products free from unnecessary fillers, artificial colors, and preservatives
  • Considering liposomal vitamin C for enhanced absorption, although it may be more expensive
  • Taking vitamin C supplements in divided doses throughout the day for optimal absorption, as the body can only absorb limited amounts at one time
  • Consulting a healthcare provider before supplementing if you have certain medical conditions like hemochromatosis, kidney disease, or a history of oxalate kidney stones, as vitamin C can affect these conditions

It's also important to note that high-dose vitamin C therapy has been investigated in conditions of septic shock and has shown potential benefits in reducing mortality and preventing the occurrence of multiple organ failure 1. However, for general health maintenance, the recommended daily dose of 500-1000mg is sufficient, and sodium ascorbate or calcium ascorbate remain the best options for most people due to their reduced acidity and digestive benefits.

From the FDA Drug Label

ASCOR is vitamin C indicated for the short term (up to 1 week) treatment of scurvy in adult and pediatric patients age 5 months and older for whom oral administration is not possible, insufficient or contraindicated.

The FDA drug label does not answer the question.

From the Research

Types of Vitamin C

There are various forms of vitamin C, but the most common one used for supplementation is ascorbic acid.

Ascorbic Acid Supplementation

  • The optimum intake of ascorbic acid for adults lies between 250 mg day(-1) and a much higher value, 5000 mg day(-1) or more, as proposed by 2.
  • A method of utilizing vitamin C in amounts just short of the doses which produce diarrhea is described as titrating to bowel tolerance, which can ameliorate the acute symptoms of many diseases 3.
  • Supplementation with ascorbic acid, 500 mg twice daily for two weeks, increased ascorbic acid concentrations in plasma, gastric juice, and gastrointestinal mucosa 4.
  • In surgical patients, much higher doses than the recommended daily allowance or doses recommended in parenteral nutrition guidelines are needed to normalize plasma vitamin C concentration, with more than 500 mg/day of vitamin C required in uncomplicated surgical patients 5.
  • High-dose vitamin C administration has been shown to improve hemodynamics, end-organ function, and may improve survival in critically ill patients 6.

Forms of Vitamin C

  • Ascorbic acid is the most commonly used form of vitamin C for supplementation.
  • Other forms of vitamin C, such as sodium ascorbate or calcium ascorbate, may be used in specific situations, but the evidence for their use is limited.
  • The choice of vitamin C form may depend on individual factors, such as gastrointestinal tolerance or specific health conditions.

References

Guideline

Guideline Directed Topic Overview

Dr.Oracle Medical Advisory Board & Editors, 2025

Research

Are recommended daily allowances for vitamin C adequate?

Proceedings of the National Academy of Sciences of the United States of America, 1974

Research

Vitamin C requirement in surgical patients.

Current opinion in clinical nutrition and metabolic care, 2010

Research

Vitamin C in the critically ill - indications and controversies.

World journal of critical care medicine, 2018

Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.

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