* Vitamin C won’t stop a cold
No cure for the common cold has been better studied than vitamin C, which, it is claimed, helps by increasing infection-fighting white blood cells. However, more than 30 clinical trials involving more than 10,000 people have examined the effects of taking daily vitamin C and have shown that it does not prevent colds. At best, it only slightly reduces the duration of symptoms.
The only time it might help is if you’re engaged in extreme physical exercise or exposed to extreme physical cold. Several studies have shown that soldiers, skiers and marathon runners in these situations who down a daily dose of 200mg of vitamin C have the risk of a cold reduced by half