Guest Post by Bastyr University Nutrition Studies Student, Amber Lagerwey

I imagine that vitamin C is probably one of the most well known of the nutrients and for good reason. Vitamin C is a powerful nutrient that has numerous complex roles in the human body, from involvement in wound healing to synthesis of neurotransmitters and hormones. However, this vitamin has earned its fame for its antioxidant affects that help maintain a healthy immune system. When it comes to colds, vitamin C is our knight in shining armor and supplementation has been touted as a way to shorten the duration of our colds. But how exactly does vitamin C work and does consuming massive doses of it really have a worthwhile effect on our colds?

Vitamin C’s antioxidant role in immune function involves its capacity to act as an electron donor.  In a series of various reactions, these transfers lead to the neutralizing of toxic products produced by immune cells when they kill pathogens, as well as regenerating other antioxidants vital for health, such as vitamin E. Vitamin C has also been shown to stimulate the production and function of white blood cells.

Maintaining a healthy vitamin C status is crucial for overall immune health and fortunately it is a nutrient that is easy to obtain from common whole foods. For example, the RDAs for men and women are 90 and 75mg, respectively. A medium size orange contains 70 mg of vitamin C; a half-cup of red bell pepper, 95mg. An overall balanced diet adequate in fruits and vegetables guarantees optimal vitamin C status for a healthy immune system. The vitamin is water-soluble and can be safely consumed by most in relatively high amounts, the safe upper limit for vitamin C being 2,000mg/day for adults. It takes a considerable amount of whole foods to reach this level but many popular supplements contain 1,000mg per capsule. With some brand’s instruction labels encouraging  “ Take as needed”, it can be easy for some to cross into amounts above this upper limit with regular over the counter use. Levels above the safe upper limit most commonly cause diarrhea, nausea, and stomach cramps.

As for supplementation after the onset of a cold? Unfortunately, there is no conclusive evidence that supports the claim that vitamin C supplementation has any effect on combating the common cold once you are already sick. With supplements costing $12 and up a box, it may be money down the drain for those who buy it after the first sniffle. We should be mindful to find ways to incorporate fruits and vegetables into our diets as a means to obtain this vital nutrient year round. Not only can we enjoy the bounties of a healthy immune system without worry of excess but we also get fiber, minerals, and other compounds that we lose when we reach for the powder over the whole food. 



 1.Smith, Jack L., and James L. Groff. “9.” Advanced Nutrition and Human Metabolism. Sareen Annora Stepnick. Gropper. Australia: Wadsworth/Cengage Learning, 2013. Print.