Quercetin & Vitamin C - Two Powerful Nutrients for Immune Strength

Quercetin & Vitamin C - Two Powerful Nutrients for Immune Strength

More than ever before, we understand the value of a strong immune system. The importance of getting the right nutrients in a daily regimen to prevent and fight viral infections, bronchial congestion, and allergic reactions can’t be overstated. And one of the strongest nutrient combinations I can recommend is quercetin and vitamin C.


While quercetin may not be quite as well-known as other immune strengthening ingredients, it is more common than you might think. Quercetin is a flavonoid polyphenol compound found in apples, grapes, onions, tea, and various herbs. There’s no doubt that a diet rich in quercetin containing foods can help you stay healthy, but there’s also plenty of research that backs up quercetin as a natural medicine for fighting viral infections.

In fact, scientific studies show that pretreatment with quercetin is the best way to stop viruses from replicating, and it effectively blocked H1N1 (swine flu) within 48 hours. Other in vitro work found that quercetin inhibited replication of rhinovirus, the virus responsible for the common cold, within 24 hours. Other laboratory research has found that quercetin reduces bronchial inflammation and moderates the immune response to prevent it from going into overdrive. It is considered a valuable natural antiviral in cases of influenza A virus and can help stop many others as well.

In fact, researchers in Italy, one of the nations with an early (and especially deadly) outbreak of Covid-19, have proposed that both quercetin and vitamin C be used as synergistic nutrients for preventing and treating the virus.


Unfortunately, many of the drugs used to treat allergies are unhealthy and cause unpleasant side effects, including insomnia, brain fog, fatigue, dizziness, nausea, increased heart rate and blood pressure, and difficulty with urination. Long-term use of certain allergy medications called anticholinergic drugs are associated with a dramatically increased risk for dementia.

Fortunately, an ever-growing body of scientific and laboratory research shows that quercetin may provide a safer, yet still effective, answer. Because of the actions of quercetin on histamine and its ability to reduce bronchial and sinus congestion, quercetin can reduce the body’s reactivity to allergens and make asthma symptoms less severe.

Quercetin inhibits mast cell and eosinophil activation, relaxes the trachea, and reduces inflammatory compounds in cells that line the inside of the lungs. Some researchers believe quercetin could easily become a natural bronchodilator medicine for treating chronic obstructive pulmonary disease (COPD) and asthma. Scientific study on cells from COPD patients have found that there is also potential for quercetin to make the conventional medicine for COPD more effective when patients develop resistance to them. Quercetin’s ability to balance inflammatory and immune cytokine activity means it can be a valuable ally in treating autoimmune conditions, too.


Quercetin has powerful effects on oxidative stress and inflammation. A randomized, double-blind clinical study found that a combination of quercetin and vitamin C was more effective in reducing C-reactive protein levels and the inflammatory marker IL-6, than either nutrient used alone. The individuals in this study were non-professional athletes who, in the course of their workouts, typically generated a lot of potential free radical and inflammatory damage. As to why both nutrients worked better together than they did separately, one answer may be in the way that vitamin C regenerates quercetin. Once quercetin becomes oxidized during its work in the body, it splits into metabolites which can be recycled as quercetin and prevent free radical damage once again. This is one way that vitamin C can help make quercetin more bioactive.


For all its potential power, quercetin is not easily absorbed. It needs a boost. That’s why I prefer quercetin combined with gamma-cyclodextrin, which gives the fat soluble nutrient the absorption qualities of a water-soluble one. In fact, gamma-cyclodextrin has proven its worth in helping other fat soluble nutrients absorb better. In the case of CoQ10, it’s been shown to improve absorption by as much as 800 percent.


I’ve already mentioned how vitamin C may help reboot quercetin levels in the body, but of course it has incredible value far beyond that.

Some of the reasons that vitamin C is considered so essential to your immune system is that aside from its antioxidant value in preventing free radical damage that can deplete your natural defenses—it also supports aspects of what are called your innate and your adaptive immune systems.


Vitamin C touches on almost every aspect of immune function, strengthening the response of protective T-cells, antibodies, and other natural defenders that respond to viruses and bacteria. Your innate immune system also includes specialized white blood cells that can respond to any threats from pathogens like viruses and bacteria.

Your adaptive immune system is what helps your body develop immunity to a specific bacteria or virus after exposure or illness.

The adaptive immune system includes T-cells, antibodies, and white blood cells that recognize invaders that survive your innate immune system, and either bolster your immune strength as a result, or destroy the infected cells so that they move out of your body altogether.

Vitamin C contributes to both of these immune “operating systems” and covers a broad range of activities. It acts as a fuel that helps your immune system protect you against microbes and various reactive oxygen species that damage and stress your cells, especially when your resistance is compromised.


A healthy and responsive immune defense depends on many things: restorative sleep, proper diet, and low stress levels. But it can be easily strengthened with convenient and consistent levels of daily nutrients. I think a combination of quercetin and vitamin C is the best. Consider adding them to your regimen today, and keep your immune system well-nourished for the days ahead.

For immune strength, I recommend using Vitamin C (as ascorbic acid) and Quercetin [from Japanese pagoda tree (Sophora japonica) flower buds].

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