Sorry, Your Vitamin C Megadose Is Basically Useless

Schools are back in session, which means the common cold is not too far behind.

To avoid a cold or cut one short, you may be tempted to stock up on supplemental drink mix-ins like Emergen-C and Airborne for supposed cold-fighting ingredients like vitamin C or zinc. But do these unregulated powders and tablets actually work?

Unless you’re a marathon runner, skier or soldier in extremely cold temperatures, extra vitamin C probably isn’t going to keep you from getting sick. And children are most likely to benefit from zinc, but their parents? Not so much.

The basics

Vitamin C, or ascorbic acid, is an essential nutrient that helps the body’s immune system, improves the body’s absorption of iron, helps metabolize protein and regenerates antioxidants in the body. Too little of it will lead to scurvy, historically considered a sailor’s disease because of the lack of access to fresh fruits and vegetables on long voyages. Too much of it can result in diarrhea, nausea, kidney stones and excess iron absorption.

Like most vitamins, the best way to consume this nutrient is via food: citrus, tomatoes, strawberries and spinach are just a few of the foods that are rich in vitamin C. Adult men should get at least 90 milligrams per day of vitamin C, while adult women should have at least 75 milligrams per day, according to the Institute of Medicine. The IOM also suggests an upper limit of 2,000 milligrams per day, lest people face the consequences listed above.

The IOM recommends that men and women get 11 milligrams and 8 milligrams, respectively, of zinc. It can be found in foods like oysters, red meat, poultry, beans, nuts and whole grains. Like vitamin C, consuming too much zinc exacts a toll on health; some nasal gels —> Read More