How much vitamin C should I take a day?
Also, should I take vitamin C daily?
For most people, taking vitamin C supplements in the recommended amounts is also safe. The RDA or recommended daily allowance is 90 mg for men and 75 mg for women. High doses of vitamin C (greater than 2000 milligrams per day for adults) may cause kidney stones, nausea, and diarrhea.
Keeping this in consideration, how much vitamin C can the body absorb at one time?
While small doses (under 200 mg) are completely absorbed, only a fraction of a single large dose of ascorbic acid can be absorbed at one time (500 mg or more). Spacing the doses out will increase the overall absorption. You can take vitamin C every few hours, but it becomes a difficult practice to keep up.
Very high doses of vitamin C are known to cause gastric discomfort and diarrhea, and this is the basis for the current upper tolerable daily intake limit of 2,000 mg for adults. More limited, but concerning, evidence suggests problems with daily doses of just 500 to 1,000 mg of vitamin C.