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Not All Quercetin Supplements Contain What They Claim, ConsumerLab Tests Reveal
White Plains, New York, April 1, 2019 — Quercetin is a flavonoid found in foods such as onions, kale and apples. Sold as a supplement, quercetin is promoted to help with a range of conditions including prostatitis, asthma, and rheumatoid arthritis, as well as blood sugar control. But do quercetin supplements really work, and if so, which products contain what they claim and provide the best quality and value?

To find out, ConsumerLab carefully reviewed the clinical evidence for quercetin, and purchased and tested popular quercetin supplements sold in the U.S., including capsules, a powder, and a liquid. The tests revealed that two products contained 12% to 14% less quercetin than listed on their labels. The cost for a 500 mg dose of quercetin from the products ranged from just 11 cents to as much as $1.17.

Among products found to contain their claimed amounts of quercetin, ConsumerLab selected its Top Picks based on quality and cost to help consumers find the best quercetin supplement.

The results are available online now in ConsumerLab's new Quercetin Supplements Review, which includes test results and comparisons. Products covered in the report are: Quercetin Dihydrate, MRM Quercetin, Natrol Quercetin Complex Immune Health, Ultra Quercetin 650 mg, Solaray Quercetin, Solgar Quercetin Complex and Source Naturals NutraDrops Quercetin. Six of the products were selected for testing by ConsumerLab and one other underwent the same testing through CL's voluntary Quality Certification Program.

The review also summarizes the clinical evidence for and against quercetin, information about the different forms of quercetin -- including "free form" quercetin, quercetin dihydrate and iso-quercitrin, dosage, potential quercetin side effects, and drug interactions. It also explains what to look for on quercetin labels and how to maximize absorption of quercetin.

Founded in 1999, is a leading provider of consumer information and independent evaluations of products that affect health and nutrition. Membership to is available online and provides immediate access to reviews of more than 1,300 products from over 500 brands. The company is privately held and based in New York. It has no ownership from, or interest in, companies that manufacture, distribute, or sell consumer products.

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