Multiple studies confirm that quercetin, a compound found in onions, capers and other foods, reduces blood pressure – also called hypertension.
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| Quercetin from onions and other foods has been shown to reduce blood pressure. |
Quercetin is a flavanol most prominent in onions and capers, but also found in other foods. Quercetin fights some cancers – including breast cancer.
Multiple studies confirm quercetin’s hypertension effects
A 2020 review of research found 17 different clinical studies tested nearly 900 people. The studies that found that quercetin significantly reduced both systolic and diastolic blood pressure. They were given the quercetin supplement for 8 weeks or more. The study subjects were all adults, and most of them were in their mid-40s.
The researchers combined the results of each study and found that the quercetin reduced systolic blood pressure an average of 3.09 mmHg. They also found the compound reduced diastolic blood pressure by an average of 2.86 mmHg.
Yes, the compound reduced both diastolic and systolic blood pressure by about 3 mmHg. And that is just in two months.
Quercetin also reduces cholesterol
Many of the 17 studies also tested the subjects’ cholesterol. They found that quercetin significantly reduced the subjects’ low-density cholesterol (LDL-c) and triglycerides.
The quercetin also significantly improved the subjects’ good cholesterol levels – HDL-c.
What dosages were used?
The studies utilized dosages that ranged from 30 milligrams to 1,000 milligrams. Six of the studies utilized onion peel extract capsules, and the rest used quercetin capsules or tablets.
A 2016 review of quercetin research on blood pressure separated dosage levels with effects. They found 7 studies of 587 patients. Those that used doses of more than or equal to 500 milligrams a day resulted in an average of 4.45 mmHg drop in diastolic BP and 2.98 mmHg in systolic levels.
The bottom line is that for supplemented quercetin, 500 milligrams to 1,000 milligrams has the most benefit according to the research.
Does onion-derived quercetin require less dosage?
However, quercetin from onions may require less dosage. A 2015 study from Germany’s University of Bonn tested 70 patients who were overweight and had stage 1 hypertension. This study was not included in the combined results above.
In this study, the patients were either given a placebo or 162 milligrams of quercetin per day, in the form of onion skin extract powder. The study lasted for six weeks.
The researchers found that those with hypertension who were given the quercetin had an average reduction of systolic BP by 3.9 mmHg.
How to get your quercetin
There are several ways to take quercetin. One is to consume a supplement. This will deliver a specific dose that can easily be duplicated daily.
The other is to consume quercetin in foods. One of the best is red onions. 100 grams of red onions will deliver about 40 milligrams of quercetin. That’s about half of an average-sized onion.
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| Capers have the highest amount of quercetin among foods. |
Capers by far contain the highest levels of quercetin. 100 grams of raw capers will contain 234 milligrams. Capers, a flower bud of a middle-eastern shrub, tastes quite bitter. Not for the ordinary diet.
Other common food sources include:
• Elderberries (27 milligrams per 100 grams)
• Kale (23 milligrams per 100 grams)
• Apples (19 milligrams in 100 grams of skin)
• Okra (21 milligrams per 100 grams)
• Asparagus (15 milligrams per 100 grams)
• Cranberries (15 milligrams per 100 grams)
Other foods that contain quercetin include feijoas, Aronia berries and goji berries.
Organic foods tend to contain higher levels of quercetin according to other research.
That said, it would take some discipline to accomplish the consistency of the dose required to affect blood pressure levels found in the research.
Scientific References
Huang H, Liao D, Dong Y, Pu R. Effect of quercetin supplementation on plasma lipid profiles, blood pressure, and glucose levels: a systematic review and meta-analysis. Nutr Rev. 2020 Jan 6. pii: nuz071. doi: 10.1093/nutrit/nuz071.Serban MC, Sahebkar A, Zanchetti A, Mikhailidis DP, Howard G, Antal D, Andrica F, Ahmed A, Aronow WS, Muntner P, Lip GY, Graham I, Wong N, Rysz J, Banach M; Lipid and Blood Pressure Meta‐analysis Collaboration (LBPMC) Group. Effects of Quercetin on Blood Pressure: A Systematic Review and Meta-Analysis of Randomized Controlled Trials. J Am Heart Assoc. 2016 Jul 12;5(7). pii: e002713. doi: 10.1161/JAHA.115.002713.
Brüll V, Burak C, Stoffel-Wagner B, Wolffram S, Nickenig G, Müller C, Langguth P, Alteheld B, Fimmers R, Naaf S, Zimmermann BF, Stehle P, Egert S. Effects of a quercetin-rich onion skin extract on 24 h ambulatory blood pressure and endothelial function in overweight-to-obese patients with (pre-)hypertension: a randomised double-blinded placebo-controlled cross-over trial. Br J Nutr. 2015 Oct 28;114(8):1263-77. doi: 10.1017/S0007114515002950.
Marunaka Y, Marunaka R, Sun H, Yamamoto T, Kanamura N, Inui T, Taruno A. Actions of Quercetin, a Polyphenol, on Blood Pressure. Molecules. 2017 Jan 29;22(2). pii: E209. doi: 10.3390/molecules22020209.
USDA Database for the Flavonoid Content of Selected Foods. Release 3.2 (November 2015)
Sultana B, Anwar F. Flavonols (kaempeferol, quercetin, myricetin) contents of selected fruits, vegetables and medicinal plants. Food Chem. 2008 Jun 1;108(3):879-84. doi: 10.1016/j.foodchem.2007.11.053.