By Nicoletta Lanese
March 10, 2020
Vitamin C, also known as ascorbic acid, became known as an immune-boosting supernutrient after two-time Nobel Prize winner Linus Pauling touted the substance’s supposed benefits in a series of books, Live Science previously reported. Pauling claimed that taking large doses of vitamin C could not only prevent the common cold, but also help thwart more severe illnesses like cancer and heart disease.
Since Pauling published his books, in the 1970s, his bolder claims have not stood up to scientific scrutiny. However, recent research does suggest that vitamin C supplements reduce the duration of colds in the general population, according to a 2013 review of several dozen studies.
The review found that vitamin C supplements taken during a cold can reduce the duration of the illness by 8% in adults and 14% in children. Practically, that means that supplementing vitamin C can shorten the duration of a cold by about one day. Participants in each study supplemented vitamin C for varying periods, but generally, the daily dose was at least 200 milligrams.
Several of the reviewed studies included people under intense physical stress, including marathon runners and soldiers training in the Arctic. Among these individuals, those who took vitamin C were about half as likely to catch a cold as those who did not take such supplements. But in the general population, the supplements did not prevent the common cold.
Likewise, no evidence suggests that vitamin C supplements can help prevent COVID-19, Dr. William Schaffner, a professor of preventive medicine and infectious diseases at Vanderbilt University Medical Center in Tennessee, told New York Times Parenting.
“If there’s going to be an advantage, it’s going to be very modest,” Schaffner said.
Some scientists are testing if vitamin C could alleviate symptoms and improve outcomes for patients with COVID-19 — if given in a high enough dose. Researchers at Zhongnan Hospital of Wuhan University launched a clinical trial with 140 patients in February to test whether ultrahigh doses of vitamin C, delivered intravenously, could treat the viral infection more effectively than a placebo. The test group will receive infusions twice a day for seven days, with each infusion containing 12g of vitamin C. (The daily recommendation for an adult man is only 90mg.)
The trial will be completed in September, and no results are yet available, according to ClinicalTrials.gov. In the meantime, Chinese scientists have launched dozens of other clinical trials as well, testing everything from antivirals to antibody therapies to traditional Chinese medicines.