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Vitamin C Does Not Cure Colds, Evidence Shows Limited Benefits
Linus Pauling was a famous scientist who won two Nobel Prizes.
In 1970, he wrote that taking lots of vitamin C could help prevent colds.
Many people began buying more vitamin C because of this idea.
Later scientists examined the evidence more carefully.
They found that vitamin C does not stop most people from catching colds.
Taking it regularly may make severe symptoms slightly shorter or less intense.
Taking vitamin C only after symptoms begin does not appear to help.
Very large doses can cause problems such as stomach upset and kidney stones, so people should ask a doctor before taking them.
Linus Pauling’s 1970 book promoted high-dose vitamin C to prevent colds.
Later reviews criticized Pauling’s analysis for mathematical errors and reliance on weak trials.
Research finds vitamin C does not reduce the general population’s risk of catching colds.
Regular supplementation may reduce severe symptoms by about 8%-15%, but not mild-symptom duration.
Adults are advised to avoid continually exceeding 1,000mg daily without medical guidance because of possible side effects.
- Who
- Linus Pauling, later researchers, and people taking vitamin C supplements.
- What
- A review of evidence showing that high-dose vitamin C does not prevent colds and offers only small benefits for severe symptoms.
- Where
- The claims originated in Pauling’s work in the United States, while the cited studies included research involving people in places such as the Swiss Alps; guidance discussed includes Australia and the United States.
- When
- Pauling published his book in 1970; relevant meta-analyses were published in 2013 and 2023.
- Why
- Pauling’s claims helped popularize vitamin C for cold prevention, but later research found his interpretation overstated the benefits.
Pauling’s High-Dose Claim
Later Scientific Evidence
Cold prevention
Pauling’s High-Dose Claim
Linus Pauling argued that high doses of vitamin C could help prevent colds.
Later Scientific Evidence
Later research found no evidence that vitamin C reduces the general population’s risk of catching a cold.
Symptom benefits
Pauling’s High-Dose Claim
Pauling’s interpretation suggested broad health and cold-related benefits from high-dose vitamin C.
Later Scientific Evidence
Meta-analyses found only small reductions in severe symptom duration or severity, with no benefit when supplementation began after symptoms appeared.
Dose and safety
Pauling’s High-Dose Claim
Pauling recommended roughly 1,000-2,000mg daily for good health, with even more to prevent colds.
Later Scientific Evidence
The article says this is much higher than Australia’s 45mg recommended daily intake, and continual doses above 1,000mg may increase adverse effects.
Key facts
- Pauling’s recommendation
- About 1,000-2,000mg of vitamin C daily, and more to prevent a cold.
- 2023 meta-analysis
- Ten placebo-controlled trials involving 2,736 healthy adults, children, and athletes.
- Severe symptoms
- Regular vitamin C use was associated with a 15% reduction in severe symptoms in the 2023 analysis.
- 2013 meta-analysis
- Around 200mg daily did not reduce colds in the general population, though fewer colds occurred among athletes and army personnel.
- Australian recommended intake
- Adults over 19 are advised to consume 45mg daily.
- Upper-limit guidance
- Australian guidance refers to recommendations not exceeding 1,000mg daily for adults; the United States sets an upper limit of 2,000mg.
- Potential adverse effects
- High doses can cause gastrointestinal problems, increased oxalate excretion, increased iron absorption, and interactions with some treatments and medicines.
Sources
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