How much vitamin c when sick
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Optimal Vitamin C Dosage When Sick: Insights from Research
Introduction to Vitamin C and Illness
Vitamin C, also known as ascorbic acid, is a vital nutrient that plays a crucial role in immune function. Its potential benefits during illness, particularly in reducing the severity and duration of symptoms, have been widely studied. This article synthesizes findings from multiple research studies to provide guidance on the optimal dosage of vitamin C when sick.
Low to Moderate Doses of Vitamin C
Daily Maintenance and Therapeutic Doses
Research indicates that even relatively low doses of vitamin C can be beneficial during illness. A study involving 622 volunteers found that a maintenance dose of 500 mg once weekly, combined with a therapeutic dose of 1500 mg on the first day of illness and 1000 mg for the next four days, resulted in less severe illness compared to a placebo group. Participants in the vitamin C groups experienced approximately 25% fewer days spent indoors due to illness.
Prophylactic and Therapeutic Regimens
Another study with 2349 volunteers assessed the effects of larger doses of vitamin C. The study included various regimens, such as daily doses of 0.25, 1, or 2 grams, and therapeutic doses of 4 or 8 grams on the first day of illness. The combination regimen (1 gram daily and 4 grams on the first day of illness) showed a greater reduction in the severity of illness, although the differences were not statistically significant compared to placebo groups.
High Doses of Vitamin C
Intravenous Administration in Critical Illness
In critically ill patients, particularly those with sepsis, high doses of intravenous vitamin C have been explored. Studies have administered doses ranging from 6 grams per day to mega-doses of 50-100 grams per day. While some studies suggest that high doses may be associated with decreased mortality, the certainty of these findings remains low .
Pharmacokinetics and Safety
A study on the pharmacokinetics of vitamin C in critically ill patients found that a dose of 2 grams per day resulted in normal plasma concentrations, while a 10 grams per day dose led to supranormal levels and increased oxalate excretion, which could pose a risk of metabolic alkalosis. Another study recommended a minimal supplementation of 3 grams per day intravenously to restore normal serum values in critically ill patients.
Recommended Dietary Allowance and Safe Dosages
General Population
For the general population, a study on healthy volunteers suggested that the current recommended dietary allowance (RDA) of 60 mg per day should be increased to 200 mg per day to achieve optimal plasma saturation. Doses above 400 mg per day showed no additional benefits and were associated with increased urinary excretion. Another study recommended an RDA of 90 mg per day for young women based on similar findings.
During Acute Illness
During acute illness, larger doses of vitamin C may be beneficial. The evidence suggests that doses up to 1000 mg per day are safe and can help reduce the severity of symptoms. However, doses above this threshold do not provide additional benefits and may lead to increased excretion and potential side effects .
Conclusion
The optimal dosage of vitamin C when sick varies depending on the severity of the illness and the individual's health status. For mild to moderate illness, a therapeutic dose of up to 1000 mg per day is generally safe and effective. In critically ill patients, particularly those with sepsis, higher doses administered intravenously may be beneficial, but the evidence is not conclusive, and further research is needed. Always consult with a healthcare provider before starting high-dose vitamin C therapy.
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