Quercetin is an antioxidant that is the most abundant flavonoid in most people’s diets. It is especially abundant in onions, apples and tea.
What does quercetin do?
As a powerful antioxidant, quercetin helps to suppress inflammation. It also activates a gene, SIRT1, which regulates cell metabolism to improve energy production, exercise tolerance, glucose control and weight maintenance.
Blood pressure: Although research is in its early stages, this antioxidant appears to have beneficial effects on blood pressure through its ability to stimulate sodium excretion.[i]
Diabetes: It has beneficial effects on glucose control through multiple actions that reduce intestinal glucose absorption and improve insulin secretion and sensitivity, as well as improving glucose use in muscles.[ii]
Immunity: It may support immunity through its anti-inflammatory, antioxidant and nerve protecting actions. Several recent studies suggest quercetin may improve symptoms associated with rheumatoid arthritis, inflammatory bowel disease, multiple sclerosis, and systemic lupus erythematosus.[iii]
Exercise endurance: The results from 11 studies found that endurance athletes who took quercetin supplements provided a statistically significant benefit in human endurance exercise capacity and exercise performance although the effect was small.[iv]
Exercise-induced respiratory infections: Taking quercetin daily for 3 weeks before, during 3 days of prolonged, intense cycling, and for two weeks afterwards reduced the number of upper respiratory infections reported compared with placebo (1 infection among 20 athletes taking quercetin versus 9 among 20 athletes taking placebo).[v]
Who’s deficient?
Many of the beneficial effects associated with the Mediterranean diet are related to its high quercetin content. If you eat few fruit and vegetables, however, you are likely to have low intake.
Where we can get it?
You’ll find it in plant foods such as capers, red grapes (and wine), red onions, black plums, kidney beans, berries, green tea, apples and members of the cabbage family. It is also an active ingredient of many herbal medicines such as Ginkgo biloba and St John’s Wort.
How to boost your intake
Follow a Mediterranean-style diet that includes quercetin rich foods.
Supplements
It is included in many modern supplements and is often combined with green tea for elite athletes and with black elderberry to support immunity. Try Healthspan Elite Quercetin with Green Tea, 90 Capsules, £29.99.
A typical dose is 50mg to 1000mg per day.
What to avoid
As usual, if you have a medical condition seek advice before taking any supplements.
A to Z of vitamins and minerals is a guide by Dr Sarah Brewer who is the Medical Director at wellbeing brand Healthspan and Rob Hobson who is a Registered Nutritionist.
[i] https://pubmed.ncbi.nlm.nih.gov/28146071/
[ii] https://pubmed.ncbi.nlm.nih.gov/27633685/
[iii] https://pubmed.ncbi.nlm.nih.gov/34248976/
[iv] https://pubmed.ncbi.nlm.nih.gov/21606866/
[v] https://pubmed.ncbi.nlm.nih.gov/17805089/
About the Author / Sarah Brewer
Dr Sarah Brewer is a regular contributor to 50connect, she qualified from Cambridge University with degrees in Natural Sciences, Medicine and Surgery. After working in general practice, she went on to achieve her master’s degree in nutritional medicine from the University of Surrey. As well as being a licensed doctor, Sarah is now also a Registered Nutritionist, Registered Nutritional Therapist and an award winning health writer. Dr Brewer writes widely on all aspects of health and nutrition, including complementary medicine and the safe use of herbal remedies and vitamin supplements. She has written over 50 popular self-help books, is the Editor of YourWellness magazine, and a regular contributor to national newspapers and key women’s publications. Sarah is married with three children and lives in the Channel Islands.
