Can Low-Dose Vitamin C Help During Cold and Flu Season?

Maybe vitamin C really does help you stay healthier during cold and flu season. An older study in the Canadian Medical Association Journal (April 5, 1975;112:823–826) randomly divided 622 people into two groups. One group received a placebo and the other took 500 mg of vitamin C once a week.

If they developed cold or flu symptoms, both groups were told to increase their dose of “pills.”

  • The vitamin C group increased to 1,500 mg on the first day of illness,

  • then 1,000 mg daily for the next four days.

The people taking vitamin C spent less time sick than those on placebo, with about 25% fewer days spent indoors due to illness.

This trial was designed to test relatively low-dose vitamin C. Earlier studies using higher daily doses suggested even stronger benefits, but this one still hints that even modest vitamin C support may help shorten the course of colds.