Quercetin, found in a wide range of everyday foods and drinks, is attracting attention for its potential health benefits, especially in later life. What is it and how might it help you?
🕒 8 min read
You've probably consumed some quercetin today without knowing it. A plant pigment found in many fruits and vegetables, as well as the flowers, bark, stems and roots of plants, quercetin has been quietly working its magic in food and medicine for centuries.1 In the past few years its many and varied properties and biological activities have placed it high on scientists’ agenda as one of the most promising plant compounds for health.
What is quercetin?
Quercetin – Latin for oak forest2 – is one of the most abundant members of the flavonoid family,3 a large group of natural phytochemicals, responsible for the vibrant colour of many plants.
In plants, flavonoids play a key role in stress survival. In humans, they are among the many plant compounds being researched for their potential benefits for lifelong health.45
Quercetin is responsible for the colour found in the papery outer skins of brown onions. It’s used as a yellow or yellow-orange dye, especially for wool and silk.6
How does it work?
Scientists are still trying to work out exactly how quercetin behaves in the body, but research suggests there are several mechanisms of action.
Could quercetin help fight oxidative stress?
Some of the most persuasive research on quercetin revolves around its role in helping the body withstand oxidative stress, the everyday wear and tear caused by attack from unstable molecules. Indeed, lab studies suggest quercetin may be one of the most potent antioxidant flavonoids, although it’s not yet entirely clear how this may translate to humans.789
Could quercetin help calm inflammation?
Inflammation is how the body defends itself and heals from injury, irritation or infection. When it becomes chronic, as it tends to do in later life (inflammageing), immune cells release chemicals that can impact organs and tissues. Numerous studies suggest that quercetin helps dampen down some of the enzymes and other chemicals involved.10
Could quercetin help the immune system?
Quercetin has attracted interest for its potential role in helping immune cells stay resilient, although findings are mixed.
- In an early study published in 2007 of 40 trained cyclists, those who took 1000mg of quercetin a day for three weeks before and after a period of intense exercise caught significantly fewer colds and respiratory infections, compared with those who took a placebo.11
- The same researchers looked at quercetin supplementation (again 1000mg/day) in 1,000 people aged 18-85 years. In this study published in 2010 supplementation failed to reduce the number of sick days overall. However, in an intriguing – and unexpected finding – a subgroup of 325 people aged 40-plus who rated themselves physically fit took a third fewer days off sick and had milder respiratory symptoms than those who took a placebo.12
How might quercetin help as we get older?
Quercetin’s antioxidant and anti-inflammatory properties have brought it under the spotlight of scientists studying what happens in cells as we age. Both oxidative damage and inflammation are thought to be underlying drivers of ageing as is another process: cell senescence.
As we get older more of our cells stop dividing but don’t die and send out inflammatory signals that can affect other tissues. Researchers are beginning to explore whether quercetin could be used to target these senescent or ‘zombie’ cells.13
In a study reported online in 2026, 21 days of 1000 mg a day of quercetin helped support DNA repair capacity as well as to stabilise inflammation-related blood markers in a group of middle-aged men doing high-intensity interval training.
The study involved just 13 men, and hasn't yet been independently checked by other scientists, so it's hard to draw a definitive conclusion. However, it offers an intriguing glimpse into quercetin's potential to protect against DNA damage, oxidative stress and inflammation, all processes implicated in ageing.14
Could quercetin help cognition?
Quercetin's influence on brain health is under research, although human studies are sparse.15
- In a 40-week RCT published in 2022, 80 healthy adults aged 60–75 years complaining of age-related forgetfulness consumed a drink containing 110mg of quercetin. This was linked to significantly quicker reaction times compared with placebo.16
Could quercetin help ageing muscles?
Muscle mass and strength diminish with the passing years (sarcopenia), leading to a higher risk of falls and fractures. Resistance training – with weights, bands, machines, kettlebells or body weight – can help maintain muscle health as we age. Emerging research suggests quercetin might help enhance the benefits of such training.
- In a 6-week trial published in 2025, 26 older adults did resistance training while taking either 200 mg of quercetin a day or a placebo. Although both groups experienced gains in strength the quercetin group saw a noticeably bigger effect. The researchers surmise that quercetin helped muscles fire more efficiently.17
- In a 2023 review, quercetin supplementation was linked to faster recovery after intense exercise, including reduced muscle soreness and lower blood markers of muscle damage and inflammation, although studies were not confined to older people.18
Is quercetin good for the heart?
Research suggests that quercetin may influence heart and circulatory health as well as metabolic health – meaning how well the body processes and uses energy from food – as measured by blood glucose, blood pressure, blood fats and waist size.
Its benefits may derive from its potential to influence the elasticity of blood vessels as well as its antioxidant and anti-inflammatory properties.19
- A 2016 review and meta-analysis of seven randomized controlled trials (RCTs) involving 587 people, published in the Journal of the American Heart Association found quercetin supplementation lowered blood pressure, especially at doses of 500mg a day or more.20
- A 2022 meta-analysis of ten RCTs involving 841 people found that quercetin lowered systolic blood pressure (the top figure on the blood pressure reading) in people with normal blood pressure and lowered diastolic blood pressure (the bottom figure) in those with high blood pressure.21
- In a small 12-week trial of overweight men and women published in 2016 a quercetin-rich onion extract (100mg/day) was linked to a reduction in body weight and percentage of body fat, an effect not seen in the placebo group.22
- A 2011 trial in 92 male smokers revealed lower total and ‘bad’ LDL cholesterol, along with reductions in blood pressure and blood glucose in those who took a quercetin-rich onion extract (100mg/day), for 10 weeks.23
What foods are high in quercetin?
Quercetin is found in a wide range of fruit, vegetables and herbs, although amounts vary. Capers are among the most concentrated sources weight for weight,24 with red onions, leafy greens, berries and herbs such as dill and oregano also contributing significant amounts, although of course we tend to eat the latter in much smaller quantities than onions or greens.25
Natural food sources include:
Could I benefit from a supplement?
While a healthy varied diet is always the best place to start – and has other benefits such as fibre together with a slew of other nutrients and plant compounds that work synergistically – a supplement could be worth considering if:
- You find it difficult to eat a wide range of fresh fruit and vegetables regularly, for whatever reason
- Your diet is lacking in quercetin-rich foods such as onions, leafy greens, apples or berries
- You want a more consistent daily intake than diet alone usually provides.
The amount of quercetin we get from a typical Western diet is estimated at 0–30mg,26 whereas in studies doses tend to fall anywhere between 100 mg and 1000 mg a day.
With so many products out there it can be hard to know which to go for. It pays to bear in mind that:
Quercetin comes attached to different glucose molecules and forms designed for better bioavailability so it’s important to choose carefully.
You may see quercetin combined with resveratrol and other plant compounds or nutrients in supplements, based on the idea that they may work together more effectively than on their own.27
When considering a supplement look for one made to Good Manufacturing Practice (GMP) standard. This helps ensure that products are manufactured to recognised quality standards. Find out more about what to look for when buying supplements.28
Interested to explore quercetin alongside other researched longevity-linked ingredients? Healthspan’s longevity range, including Age Synergex, which brings together several researched plant compounds and other nutrients could be worth a look.
How can you get the most from quercetin?
Quercetin is poorly absorbed on its own, but you can help optimise its benefits by:29
Pairing with fat… consuming quercetin-rich foods or taking your supplement alongside a source of dietary fat e.g. avocado or olive oil appears to roughly double how much is absorbed.
Considering how you cook… frying onions rather than boiling or steaming has been shown to increase quercetin content so, provided you don’t make too much of a habit of it, getting out the frying pan is no bad thing.
How long before I might experience benefits?
As with any supplement it can take time to experience benefits. The studies cited above range from six weeks to 40 weeks. Incidentally there’s no best time of day to take quercetin, although as suggested healthy fats may aid absorption.
Most of the research uses daily dosing so if you do decide to try a supplement taking it every day with food is likely to be your best bet. Always follow the instructions on the label and check with your doctor or pharmacist if you’re at all unsure.
Can anyone take quercetin?
Quercetin is usually considered safe and well tolerated with reported side effects tending to be mild. Think the occasional headache, upset tummy or tingling in the arms and legs at higher doses. In studies using doses of around 500 mg twice daily for up to 12 weeks there have been few problems.
Check with your doctor or pharmacist first if you:
- Are taking blood thinners such as warfarin30
- Are taking antibiotics or other prescribed medications31
- Have kidney disease or other existing medical condition32
- Are pregnant or breastfeeding
The bottom line
Scientific interest in quercetin continues to grow, and the evidence so far is encouraging, although more research is needed. The five pillars of healthy ageing – regular movement, healthy nutrition, sleep, stress management and social connection – remain key to a long, healthy life.33
But, whether or not you choose to add a supplement to your regime, the science around quercetin is a reminder that some of the most valuable compounds for health are to be found in your veg box.
