"Vitamin C is extremely popular. It's by far the most popular vitamin," says Lucky's Doug Green.
Now scientists are unlocking a whole new potential for vitamin C: it's ability to prevent illness by fighting stress.
New research at the University of Alabama subjected rats to stressful situations causing their stress hormone levels to rise. When scientists fed the rats megadoses of vitamin C their production of stress hormones was reduced.
"The animals that were stressed and not given C had triple the blood levels of the stress hormones," says researcher P. Samuel Campbell.
But what does that mean for stress in people? Not much, says Dr. Mark Levine of the National Institutes of Health. It's still to early to tell exactly how this might translate into human models, and people could never take a quantity of vitamin C comparable to that given to the rats.
"It's quite possible vitamin C will have effects in the adrenal gland and on stress," says Levine. "But I think based on this study you can't say that now in humans."
In both animals and people, the adrenal gland reacts to stress by releasing hormones that trigger the "fight or flight" response and suppress the immune system.
Campbell said he thinks that our prehistoric tropical ancestors probably ate large amounts of vitamin C in a diet rich in fruits. If that is the case, people may really need far more than the government recommended daily allowance of 60 milligrams a day to stay healthy.
Dr. Levine also believes current recommendations are too low and remains cautiously optimistic about the study's results. He admits the many benefits of vitamin C have yet to be tapped.
The government's guidelines on how much vitamin C to take are currently being debated and new ones are expected by the end of the year.