For a bad cold or the flu, for instance, Dr. Cathcart might recommend that someone take 2 to 12 grams of ascorbic acid every 15 minutes until they reach bowel tolerance. The time frame varies from person to person, but tolerance could occur within four to eight hours, Dr. Cathcart says. For a condition like severe mononucleosis, he says, one woman was able to tolerate 200 grams of ascorbic acid before she reached bowel tolerance. When you reach that point, Dr. Cathcart says, generally, your symptoms quickly vanish. How long you need to take high amounts to keep your symptoms at bay depends on many variables and could range from a few days to months.
Some people take several grams a day indefinitely.
While there is some research to indicate that taking additional vitamin C can help shorten the duration of a cold, there is little evidence to support the use of large amounts for illnesses such as mononucleosis, hepatitis, cancer, or AIDS, says Balz Frei, Ph.D., professor of biochemistry and biophysics and director of the Linus Pauling Institute at Oregon State University in Corvallis. I m not saying that it doesn t work or that the theory behind this isn t sound. I m saying that there is currently not enough scientific evidence to conclude that megadoses of vitamin C provide health benefits beyond those of more moderate doses of the vitamin, he says. As for everyday, or anti-aging, use of vitamin C, Dr. Cathcart believes that the amount an individual needs is based on their own free radical load. If you have a chronic illness or inflammation, if you ve abused your body with alcohol or smoking, or if you look old for your age, you probably can use more than someone who s healthier, he says.