What is quercetin and why take it?

by Hannah de Gruchy October 23, 2022

What is quercetin and why take it

A healthy diet is balanced with a rich intake of lean proteins, wholegrains, and small amounts of healthy fats. Proteins, carbohydrates, and fats are known as macronutrients and provide both calories and energy.

The micronutrients are vitamins, minerals, and phytochemicals (naturally occurring plant chemicals such as antioxidants). Whilst the micronutrients provide no calories or energy, they each perform numerous essential roles within the body to support our overall wellbeing.

One group of micronutrients, called flavonoids, are important antioxidant compounds that help to support a healthy body and keep damaging free radicals at manageable levels.

There are various types of flavonoids, one of which is a group of compounds called flavanols. Quercetin is an important flavanol in many different foods and a powerful antioxidant.

Quercetin fast facts

  • Quercetin is an important antioxidant that belongs to a group of compounds called flavanols.
  • Antioxidants help to neutralise the damaging effects of free radicals and oxidative stress.
  • Quercetin is found in a variety of foods, including fruits, vegetables, and grains.
  • Supplements provide a safe way to increase quercetin intake for most people.
  • Quercetin supplements can be made more bioavailable if taken with other compounds such as bromelain.

What is quercetin and how does it work?

Quercetin belongs to the group of antioxidant flavonoids called flavanols. It’s a naturally occurring pigment found in various fruits, vegetables and grains and is one of the most common antioxidants in the diet.

Antioxidants work to neutralise free radicals. Free radicals are unstable molecules of oxygen that have lost an electron. They then move around the body searching for regular oxygen molecules to ‘steal’ an electron from, setting off a cascade of new free radicals and so on. Antioxidants donate electrons to free radicals, helping to stabilise them.

Quercetin molecule

During this process, if there are insufficient antioxidants in the body to donate their electrons, free radicals can cause damage to our fatty tissues, proteins, and DNA. If this damage is left unchecked, it can lead to oxidative stress, a condition that can be a precursor to premature ageing and chronic lifestyle diseases such as type 2 diabetes, high blood pressure, atherosclerosis (hardening of the blood vessels) and heart disease.

Free radicals are introduced into the body because of a poor diet high in saturated fat, salt and sugar, smoking, excessive alcohol consumption, stress and breathing in toxins and environmental pollutants. They’re also a consequence of normal biological functions, such as breathing and digestion, so they cannot be avoided altogether.

The good news is, if we consume a diet rich in antioxidants that mop up free radicals by selflessly donating electrons, we can strike a good balance between free radicals and antioxidants.

Quercetin is a potent antioxidant that helps to neutralise free radicals and reduce the risk of oxidative stress and degenerative diseases. Foods that are rich in quercetin should therefore form a large part of our diets.

What foods contain quercetin?

Quercetin is found in a wide variety of different food and drinks including: apples, berries, nuts, red wine and green tea. A healthy, balanced diet rich in these foods (with a sensible approach to caffeine and alcohol intake) will help to provide a plentiful supply of quercetin and other antioxidants.

What are the benefits of taking quercetin supplements?

Happy ladies

Since quercetin is a powerful antioxidant, taking a quercetin supplement can help to protect the body from the consequences of free radical damage. Quercetin capsules and tablets can support the work of the antioxidants in the diet, further protecting the body from oxidative stress and chronic disease.

As well as protecting against free radical damage, quercetin can help to protect the body from chronic inflammation. Some level of inflammation is healthy, it’s part of the normal immune response that protects us from potential invading pathogens and foreign bodies.

But if inflammation is allowed to become chronic, due to a poor diet, stress or illness, the body can become more at risk of chronic diseases such as type 2 diabetes and heart disease.

It’s now also known that free radicals can lead to increased inflammatory response. Studies show that quercetin can reduce the markers of inflammation in the human body. Therefore, supplementing the diet with quercetin may provide extra protection against both free radical damage and chronic inflammation.

There is also evidence that quercetin may help to reduce the markers of ageing in skin cells, although more human studies are needed.

Supplementing with quercetin

Although quercetin is found in many different foods, many people choose to supplement their diet and support their bodies with quercetin capsules and powders.

Types of quercetin

Pineapple and citruses

Quercetin is available as a supplement on its own, or with other active ingredients. When taken on its own, however, the body may struggle to absorb it, due to its low ‘bioavailability’. For this reason, quercetin supplements are available with added active ingredients such as bromelain.

Bromelain is a digestive enzyme that breaks down the proteins in our diet, ready for absorption. It’s found in a high concentration for instance in pineapples.

When taken alongside quercetin, it helps to increase the level of quercetin that’s absorbed by the body. Bromelain also has an anti-inflammatory effect on the body, further supporting the work of quercetin in reducing inflammation and the risk of chronic inflammatory diseases.

Vitamin C also helps to increase the bioavailability of quercetin and is therefore another beneficial addition to quercetin supplements.

We recommend taking Quercetin with both bromelain and vitamin C to help ensure maximum bioavailability and effectiveness.

How much quercetin should I take a day?

Consuming a healthy and balanced diet rich in fruits, vegetables and whole grains will provide enough quercetin to meet our daily needs.

However, some people choose to supplement their diet with quercetin to provide extra antioxidant support, usually in the form of quercetin with added ingredients such as bromelain.

There is no official recommended daily intake for quercetin, but a daily serving size of between 500mg and 1,000mg is considered beneficial.

When should I take quercetin?

Like most vitamin supplements that can be taken daily, it’s generally accepted as safe to take quercetin every day. As with many supplements, taking quercetin with food is recommended. So ideally the best time to take it is with your breakfast or evening meal.

How long does quercetin take to work?

As with any food supplement, it may take up to three months of taking a quercetin supplement daily before you notice any significant benefits.

Are there any side effects to taking quercetin?

There are no known serious side effects to taking a daily quercetin supplement. However, some people find that taking a large daily serving size of 1,000mg or more can cause upset stomachs and headaches.

If you have a sensitive stomach or you’re at all concerned, start by taking a lower serving size and gradually increasing it if you notice no side effects.

Who shouldn’t take quercetin?

Although quercetin-rich foods are safe for pregnant and breastfeeding women, there isn’t yet enough evidence to confirm that quercetin supplements are also safe. Therefore, if you’re actively trying to become pregnant or you’re pregnant or breastfeeding, avoid taking quercetin for the duration.

Quercetin supplements may also interfere with certain medications including some antibiotics and some medications that manage high blood pressure. If you’re concerned, speak to your GP or pharmacist.

How to choose a good quality quercetin supplement

Quercetin complex with bromelain – G&G

Good quality nutritional supplements contain high-quality ingredients and are researched for their effectiveness and safety. They contain only the necessary ingredients, and no artificial fillers or binders.

At for the Ageless, we provide only the highest quality supplements that contain ingredients that have been ethically sourced, manufactured in the UK where possible, contain zero toxins or fillers and have been personally tested by us.

Quercetin Complex with Bromelain from G&G Vitamins meets all our strict criteria as well as being free from gluten, soya, and lactose and suitable for vegans and vegetarians and anyone following a Kosher diet.

They contain quercetin - known for its antioxidant and anti-inflammatory properties - and bromelain, which helps to keep inflammation at healthy levels. The addition of vitamin C provides immune system support and, along with bromelain, helps to ensure good absorption. These supplements also contain vitamin B5, which supports a healthy immune system.

Take one to three capsules per day with food for at least three months as part of a healthy diet and lifestyle. After this time, you may notice significant benefits to your overall well-being. These quercetin capsules are then safe to take daily for as long as you require them.

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Hannah de Gruchy
Hannah de Gruchy


Health and wellness author and biologist specialised in sustainability, nutrition and eco-living.

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