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29.01.2022

High-dose quercetin protects against colds - if you're 40+ and fit

If you are no longer very young but still fit, then supplementing with a high dose of quercetin may reduce the chance that common cold viruses make you ill. This is apparent from a somewhat older study, which in this dark age has become even more interesting for some of our readers than it already was.

Study
Biologists at Appalachian State University, who by the way belonged to David Nieman's research group, divided just over a thousand average Americans aged 18-85 into 3 groups. One group received a placebo every day for 12 weeks, and subjects in the other two groups received a low- or high-dose quercetin supplement every day, respectively.

The researchers used a combination of quercetin, vitamin C and niacin.

Vitamin C and niacin would increase the bioavailability of quercetin, according to manufacturer of the supplements the researchers used. The subjects in the 'low-dose' experimental group took 500 milligrams of quercetin, 500 milligrams of vitamin C and 20 milligrams of niacin daily, the subjects in the other experimental group took 1000 milligrams of quercetin, 1000 milligrams of vitamin C and 40 milligrams of niacin on a daily basis.

During the 12 weeks that the experiment lasted, the researchers recorded how many days the subjects had a cold and how serious the symptoms were. To put it in medical jargon, the researchers looked at symptoms of upper respiratory tract infection.

Using questionnaires, the researchers determined the subjects' weight, fitness, education level and quality of diet.

Results
At first glance, the quercetin supplement did nothing at all. The subjects in the placebo group caught a cold just as often and just as severe as in the supplementation group. But when the researchers looked more closely at their data, they found that a specific group did respond positively to the supplement: fit people over 40.

In this group, supplementation with one gram of quercetin per day reduced the number of cold days as well as the severity of the infection by about a third.

The researchers do not understand how this is possible. Fit people catch a cold less often than non-fit people. Why would the protective effects of quercetin manifest themselves in this low-risk group in particular?

Speculation
We ourselves, unimpeded by a great deal of relevant expertise, have an undoubtedly wild idea. Fit people are fit thanks to a lifestyle with lots of exercise. Exercise is good for literally everything, but after intense exercise sessions, the immune system is less alert to viruses for a short period of time.

Quercetin can mitigate this effect. The studies on which we base this bold statement are at the bottom of this page.

Sponsor
The study, which was published in 2010, was funded by Coca-Cola and Quercegen Pharma. As far as quercetin is concerned, Quercegen Pharma is active as Quercis. Quercis is a subsidiary of Quercegen. [quercis.com]

Source:
Pharmacol Res. 2010 Sep;62(3):237-42.

More:
Does quercetin take the sting out of covid? 12.08.2021
Covid patients recover faster with quercetin phytosome supplementation 09.08.2021
Quercetin makes zinc a better corona protector 26.07.2021

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Immune System
Quercetin

Quercetin sabotages influenza virus In test tubes, quercetin, a flavonoid found in many plant foods, makes it difficult for influenza A viruses to infect cells.	Animal study | Quercetin helps prevent virus infection after strenuous exercise We found a somewhat older animal study by scientists at the University of South Carolina that substantiates the virus-inhibiting effect of quercetin - and reveals how you can increase the virus-inhibiting effect of quercetin.	Quercetin protects athletes from colds and flu Quercetin may reduce the risk of virus infections in real people, especially if they train intensively.