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Does vitamin C really help prevent a cold?

Published by Cheryl Mussatto, MS, RD, LD on Jan 28, 2019

It’s been called “the cure for the common cold” many times over the decades but just how effective is ascorbic acid, better known as vitamin C, for keeping us from getting sick?

Vitamin C’s claim to fame was born when Nobel laureate Dr. Linus Pauling, escalated public interest stating it could prevent the common cold when taken as a supplement in large doses. Numerous studies have been conducted trying to prove if vitamin C lived up to Dr. Pauling’s assertion. Unfortunately, scientific evidence of supplement use of vitamin C being beneficial is sparse. A 2017 review looked at the validity of vitamin C preventing common colds but found that taking a vitamin C supplement on a regular basis, only slightly reduced the length and severity of a cold. Some studies have shown that supplemental vitamin C’s effectiveness during an acute illness, at best, is an 8 percent speedier recovery – meaning you’ll feel better 13 hours sooner during a typical seven-day illness.

A more convincing 2013 study did a review of 29 randomized trials with over 11,000 participants.  Researchers found that participants who took at least 200 milligrams of vitamin C daily and were extremely active such as marathon runners, skiers and Army troops practicing heavy workouts in subartic conditions, did reduce their risk of getting a cold in half.  But for the other participants who were not exercising as hard, they had no benefit from taking daily supplements of vitamin C of reducing their risk of getting a cold.

Most doctors and scientists agree that research results and data show only marginally beneficial effects from taking a vitamin C supplement in regards to reducing or preventing a cold.

Vitamin C is a unique vitamin for humans in the fact that most mammals and other animals have the ability to make vitamin C or ascorbic acid on their own.  Humans cannot make vitamin C so we must obtain it from our food choices.  We need vitamin C on a regular basis because of this fact; it’s required to help strengthens our immune system, bone structure, iron absorption and for healthy skin.

The best way for people to obtain vitamin C is by consuming rich food sources containing it. Men require at least 90 milligrams (mg) and women require at least 75 mg every day.  Vitamin C is only found in fruits and vegetables with some of the best sources including the following:

  • Orange juice – ¾ cup – 62-93 mg
  • Grapefruit juice – ¾ cup – 62-70 mg
  • Kiwifruit – 1 – 91 mg
  • Orange – 1 – 70 mg
  • Grapefruit – ½ – 38 mg
  • Strawberries – 1 cup – 85 mg
  • Tomato – 1 medium – 16 mg
  • Sweet red pepper – ½ cup – 95 mg
  • Broccoli – ½ cup cooked – 51 mg
  • Potato – 1 medium, baked – 17 mg
  • Spinach – 1 cup, raw – 8 mg

The best advice is to choose rich food sources of vitamin C each day by having a fruit or vegetable at each meal.  Besides vitamin C, these foods also provide numerous other vitamins, minerals, anti-oxidants and fiber. If you eat the recommended five servings of fruits and vegetables each day, you will get sufficient vitamin C.  And when your body is already getting the vitamin C it requires on a daily basis, your body will be much better prepared to help fight off a cold to begin with without having to resort to taking supplements.

So, while taking vitamin C when sick probably won’t hurt you, the best medicine is still fluids, rest, and time.

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Cheryl Mussatto, MS, RD, LD

Cheryl Mussatto MS, RD, LD is a registered dietitian with a master’s degree in Dietetics and Nutrition from the University of Kansas and a bachelor’s degree in Dietetics and Institutional Management from Kansas State University. She is a clinical dietitian for Cotton O’Neil Clinics in Topeka and Osage City; an adjunct professor for Allen Community College, Burlingame, KS where she teaches Basic Nutrition; and is a freelance writer and blog contributor for Dr. David Samadi, Urologic Oncologist Expert and World Renowned Robotic Surgeon in New York City. Cheryl is also the author of The Nourished Brain, The Latest Science on Food’s Power for Protecting the Brain from Alzheimers and Dementia and The Prediabetes Action Plan and Cookbook, both available on Amazon in Kindle and paperback editions.

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