Dear Dietitian: Cold and flu

Dear Readers,

As we await our vaccination date for COVID-19, the thought of coming down with a cold almost seems harmless. Yet, the common cold is responsible for 150 million missed workdays each year in the United States. Many of us will head to the nutrition supplement aisle in an attempt to ward off these nasty viruses, but do these supplements really work? We investigated four of them, and this is what we found:

• Elderberry-  In a study of 312 air travelers, those using elderberry had an average of a 2-day shorter duration of the cold and experienced fewer symptoms (1). More extensive studies are needed to confirm these results. Remember, several studies are needed before scientific value can be determined.

• Vitamin C- In a meta-analysis involving more than 11,000 participants, 200 mg of vitamin C daily did not reduce the risk of getting a cold for the general population. However, the same dosage did reduce the length of the illness by about one day (2). The supplement must be taken every day to obtain this benefit, not only when you realize you are getting a cold.

• Zinc- In a review on zinc and the common cold, researchers found that when taken within 24 hours of symptom onset, zinc reduced a cold by about one day, and the severity of symptoms was also reduced (3). It is important to note that excessive amounts of zinc can cause copper deficiency, anemia, and damage to the nervous system. Furthermore, in 2014 the FDA warned against the use of zinc nasal sprays due to permanent loss of smell in more than one hundred people. The tolerable upper limit of zinc is 40 mg per day for adults, less for those under the age of eighteen.

• Echinacea- While echinacea has been shown to stimulate immune cell production, studies are mixed when it comes to preventing the common cold and the severity of its symptoms. Overall, echinacea may shorten the life of a cold by half a day and may slightly reduce its severity (4).

Given the modest effect of dietary supplements on preventing the common cold, the best defense may be good old-fashioned self-care: Eat right; get plenty of sleep; exercise regularly; and wash your hands frequently.

Until next time, be healthy!

Dear Dietitian

References • E. Tirlongo, S.S. Wee, R.A. Lea. Elderberry Supplementation Reduces Cold Duration and Symptoms in Air-Travellers: A Randomized, Double-Blind Placebo-Controlled Clinical Trial. Nutrients. 2016 April 8(4): 182. • H. Hemila, E. Chalker. Vitamin C for preventing and treating the common cold. Cochrane Database Syst Rev 2013 Jan 31 (1): CD000980. • P. Skerrett. • B.A. Bauer. Echinacea: is it effective for the common cold? (Feb 2020) Disclaimer: The information in this column is intended for educational purposes and is not a substitute for medical advice. Talk to your doctor before beginning any dietary supplement regimen.  Leanne McCrate, aka Dear Dietitian, is an award-winning dietitian based in Missouri. Her mission is to educate consumers on sound, scientifically-based nutrition. Do you have a nutrition question? Email her today at Dear Dietitian does not endorse any products, health programs, or diet plans.

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