In its latest round of testing products that it purchases online, supplement company NOW revealed serious quality issues while investigating 30 resveratrol supplements available through Amazon.
 
“’Buyer beware’ certainly applies to resveratrol, as we found significant problems with most products tested,” said Dan Richard, VP of sales and marketing at NOW Health Group. “Once again, NOW will share this information with Amazon directly and with the FDA, in hopes of further action.”
 
Resveratrol is a polyphenol typically found in grapes, red wine, peanuts, and herbs, and are available in cis-resveratrol and trans-resveratrol varieties. Trans-resveratrol is more bioavailable and easier for the body to absorb. The most common natural resveratrol comes from Japanese knotweed extract, where it can reach 50-98% concentrations. Natural resveratrol also contains trace levels of other antioxidants, while synthesized resveratrol is isolated chemically and doesn’t contain other antioxidants.
 
NOW bought two bottles of each product from 30 brands, including NOW, on Amazon. Even before testing, most products seemed suspicious due to inflated potencies and mislabeling on the front label panels.
 
NOW completed in-house testing and sent an unopened bottle of each brand to Alkemist Labs. Both NOW and Alkemist performed high-performance liquid chromatography (HPLC) testing. High-performance liquid chromatography with ultraviolet light detection is the correct method for measuring trans-resveratrol in a sample.
 
NOW found that 20 of the 30 brands tested had what they considered to be confusing or dishonest labeling for resveratrol. 21 brands tested were below labeled potency, with 17 brands containing less than 10% of claimed potency. Many brands displayed a higher potency number on the front panel and in Amazon search terms, and then had mismatched numbers on the side panel, according to NOW.
 
For instance, aSquared Nutrition Resveratrol Ultra Strength and NasaBe’Ahava Resveratrol 1000 mg each claimed to contain 1,000 mg of resveratrol on the front panel. However, they only provided an 8% potency yield per two capsules, resulting in just 40 mg of resveratrol per capsule. Although aSquared Nutrition’s test results indicated a higher amount than 40 mg, the initial claim remains deceptive, NOW said. Notably, aSquared Nutrition’s products have failed NOW’s tests 12 out of 12 times.
 
Meanwhile, Purify Life Resveratrol Gummies claimed “1500 mg per serving” on the front panel, but only 10 mg of resveratrol in a 150:1 extract in the supplement facts panel.
 
The front panel of the July 69 brand indicates that it contains 600 mg of resveratrol per serving. However, the side panel lists the ingredients as “resveratrol blend 600 mg” and includes additional complicated information such as “Japanese Knotweed (10% Trans-Resveratrol) (Polygonum cuspidatum) (root), Japanese Knotweed (50% Trans-Resveratrol) (Polygonum cuspidatum) (root)” in very small font size. This labeling might be confusing for people trying to understand what these percentages and what these ingredients mean.
 
The side panel of Dr. Martin’s Nutrition Resveratrol listed “Trasn-Resveratrol Complex” as 920 mg per two capsules, combined with nine other fruits and herbs. “The side panel has an extremely small font size and is barely legible,” NOW reported. “The high claimed potency, unknown brand, and misleading labeling led us to include this product in testing.”


 


Both labs also used high-performance thin-layer chromatography (HPTLC) to test if Japanese knotweed was the source of resveratrol, comparing samples with verified Japanese knotweed reference material to assess similarities. This testing was carried out at Alkemist Labs, and most of the samples contained resveratrol extract with a purity of over 98%, at which point testing couldn’t confirm the botanical source.
 
“The results further substantiate the fact that the market is saturated with unscrupulous companies that make false claims,” Richard said. “Consumers should be cautious when buying from lesser-known brands and opt for trusted, honest, and transparent brands.”