In a 2011 review of studies of people who'd recently gotten sick, researchers looked at those who'd started taking zinc and compared them with those who just took a placebo. The ones on zinc had shorter colds and less severe symptoms.
Zinc is a trace element that the cells of our immune system rely on to function. Not getting enough zinc (Harvard Medical School researchers recommend 15-25 mg of zinc per day) can affect the functioning of our T-cells and other immune cells. But it's also important not to get too much: an excess of the supplement may actually interfere with the immune system's functioning and have the opposite of the intended result.
The vitamin C hype - which started with a suggestion made by chemist Linus Pauling in the 1970s and has peaked with supplements like Airborne and Emergen-C touting its benefits along grocery store shelves - is just that: hype.
Study after study has shown that vitamin C does little to nothing to prevent the common cold.
A 2013 review of 29 trials which involved more than 11,300 people, for example, found "no consistent effect of vitamin C ... on the duration or severity of colds." The only place the authors observed some benefits of vitamin C supplementation was in marathon runners, skiers, and soldiers on "subarctic exercise" - and even in those small populations, the observed effect was small. According to the study authors, "The failure of vitamin C supplementation to reduce the incidence of colds in the general population indicates that routine vitamin C supplementation is not justified."
Plus, megadoses of 2,000 milligrams or more may actually raise your risk of painful kidney stones.
So instead of chugging fizzy drinks loaded with vitamin C, stick to getting the nutrient from food. Strawberries and many other fruits and veggies are a great source. And if you aren't getting enough zinc in your diet, try a zinc supplement. Chickpeas, kidney beans, mushrooms, crab, and chicken are all rich in zinc, and lozenges like Cold-Eeze can also help boost your intake.