Independent testing program reveals subpar quality of dietary supplements sold on Amazon

An internal testing program conducted by NOW Foods has revealed a lapse in oversight of quality of a range of supplement products from lesser-known brands and sold on Amazon—by both the online retail giant and regulators.

“Vitamins should help people’s health and not do any harm,” Dan Richard, VP of global sales and marketing at NOW Foods, said. “We’ve seen low potencies, fraudulent labeling, high microbial contamination, high heavy metal levels, and beef gelatin capsules mislabeled as vegetarian capsules. Each of these is a problem.”

NOW Foods started testing products sold on Amazon in 2017, after the company noticed its position on the online platform declining—while brands with no or low brand recognition were climbing in popularity, Richard remarked.

Coenzyme Q10 (CoQ10) 400 milligrams (mg) in dry capsules, specifically, stood out.

“From my experience in trying to get this same potency in dry capsules, I knew that CoQ10 is too sticky to encapsulate on high-speed machines,” he explained. “When I looked at the prices, which were ‘too good to be true,’ I asked our lab to test these and see if the products were legit. As I suspected, they were not.”

NOW first tested four different CoQ10 products each from two “suspect” brands for potency, Richard said.

“All failed badly,” he shared.

Since its inaugural test, NOW Foods has independently purchased and tested 175 supplement products from lesser-known brands and sold on Amazon for potency and quality across a range of product categories: acetyl-l-carnitine, alpha lipoic acid, CoQ10, curcumin, Ginkgo biloba, glutathione, magnesium glycinate, quercetin, phosphatidylserine (PS) and SAMe (S-adenosyl-L-methionine).

The findings have revealed significant quality issues, including products that consistently fall below requirements for potency, and products that contain high levels of heavy metals or are adulterated with synthetic ingredients.

“We picked brands that were unknown to myself and outside the natural products channel,” Richard said. “Virtually all of these brands were sold almost entirely on Amazon alone.”

NOW did not test natural food or practitioner brands, which the company expected to be full potency and properly labeled, Richard said.

Quality: Lesser-known supplement brands on Amazon consistently fall short

One round of testing of PS products purchased on Amazon in 2020—43 sample products purchased from 15 brands, including three products from NOW Foods—revealed the vast majority, 36 samples, failed potency requirements. A whopping 17 of the failed products contained less than 10% of the labeled value.

NOW’s PS products and two other samples were acceptable per cGMPs (current good manufacturing practices), which require a minimum 100% potency when tested against label claim amounts.

The products were tested by NOW’s in-house labs and by a third-party laboratory, Eurofins.

Similarly, NOW’s test of curcumin/turmeric products purchased on Amazon in 2021 revealed more than half of the products tested failed either for potency, containing synthetic curcuminoids or high levels of heavy metals, or using gelatin capsules when the product was labeled as using vegetarian capsules. The testing comprised 23 product brands, as well as two NOW products.

What’s worse, Richard noted, are the deceptive practices some brands are taking to gain traction in Amazon’s supplement channel, which garners more supplement sales than any other retailer, including brick-and-mortar giants like Walmart and CVS.

Among the curcumin/turmeric products tested by NOW were products labeled “Turmeric Curcumin 1,650 mg” on the front panel. However, the supplement facts panel revealed the products contained 1,500 mg “turmeric root” and only a small amount of turmeric extract, equal to less than 10% “turmeric 95% standardized extract.”

Most consumers don’t know the difference between turmeric, turmeric extract, curcumin extract and standardized 95% extract, Richard said of the findings.

“What really bugs me is the dishonesty,” he continued. “I can understand how some small brands trust contract manufacturers and end up unintentionally selling bogus products. It seems worse to me when someone is intentionally cheating consumers, whether it’s with potency, labeling or vegetarian capsule deception.”

Similar deceptive labeling practices were found among PS, quercetin, CoQ10 and magnesium glycinate products.

Importantly, not all of NOW’s test results of various market segments showed widespread quality concerns. Testing of a crop of 19 glutathione brands in 2021 found only three of the 19 brands didn’t contain the potency claimed on the label, and two brands tested above Prop 65 levels for lead.

In light of the “otherwise dismal results,” Richard called the glutathione findings “baffling.”

“I’m still baffled that about 75% of the [glutathione] brands tested contained at least 90% of potency,” he said.

Quality oversight: Amazon ups requirements, shirks enforcement

NOW’s testing of glutathione products sold on Amazon was conducted in 2021—not long after Amazon’s 2020 policy revamp dictating quality requirements for supplements sold on its platform.

The updated policy requires supplement brands to maintain three pieces of documentation to sell their products on the e-commerce site: a certificate of analysis (CoA) from an ISO/IEC 17025-accredited laboratory for each supplement; product images; and a letter of guarantee from the product manufacturer, including an assurance that the supplement is produced under FDA’s cGMPs incorporated in 21 CFR Part 111.

While Amazon’s move toward tighter requirements for supplements quality was largely applauded by industry, concerns remain that oversight by the online retailer is lacking.

Since its first round of testing CoQ10 products in 2017, NOW Foods has tested CoQ10 products purchased on Amazon, including a number of the same brands, three additional times: in 2018, 2020 and 2022.

In the 2020 survey of 10 brands, testing conducted internally by NOW Foods revealed five of the brands had less than 20% potency. None of the brands achieved 100% potency as required by cGMPs. In 2022, testing conducted internally by NOW Foods and Eurofins showed seven out of eight brands had less than 30% of the potency claimed on the label.

aSquared, Healthy Way, NasaBe'Ahava and We Like Vitamins had less than 35% potency in both 2020 and 2022. As of the date this article was published, none of these brands had responded to requests for comment.

The potency results, according to Richard, are an indication that quality issues are still at large on Amazon.

“The same brands that tested low in 2017 are still being sold today,” he said. “One brand, aSquared, actually tested low for CoQ10 in 2017, 2018, 2020 and 2022. Every test we did, it failed by more than 50%!”

Yet, aSquared is still available on Amazon.

Before publishing its early findings, NOW shared the results with Amazon, Richard said. Amazon confirmed receipt of the analytical test results, which included the initial CoQ10 findings, according to email correspondence between Amazon and NOW Foods in 2017 and obtained by Natural Products Insider.

Since then, NOW has shared nearly all of the findings with Amazon and yet has received no feedback from the e-commerce giant, according to Richard.

Amazon declined to confirm whether it’s taken action against the brands identified by NOW’s findings.

“It is amazing how these brands can do this for five years (so far) and not get busted or sued or shut down,” Richard said.

He said NOW Foods also shared some of its recent findings with FDA, but the company hasn’t received feedback or inquiry from the agency.

An FDA spokesperson declined to confirm whether the agency has been in contact with Amazon or any of the brands identified by NOW’s findings, citing policy that prohibits FDA from discussing firm-specific communication with third parties.

The agency, the spokesperson explained, uses a variety of surveillance activities and “carefully reviews product complaints and adverse event reports” to monitor the compliance of dietary supplement products.

“If the FDA determines that a product labeled as a dietary supplement is unsafe or otherwise violates the law, the agency takes action as appropriate, based on public health priorities and available resources,” the spokesperson said.

Quality implications: Low prices, at a high cost

Many of the lesser-known supplement products tested by NOW Foods claimed to offer quality on par with high-quality counterparts, but at a fraction of the price.

For example, the top-selling brands of PS products on Amazon were offering prices that averaged 70% below NOW’s prices. CoQ10 products tested by NOW, too, touted “too-good-to-be-true” prices, Richard said.

This has potentially serious implications for the broader industry, Richard warned.

“When cheating brands win sales, quality brands, of course, lose and market prices are set falsely too low, making it a challenge to maintain market share with a quality product,” he said. “So the brands committed to selling quality products take a financial hit, and consumers are cheated of both their money and the health benefits they think they are getting.”

This is especially true for certain product categories, such as CoQ10, which consumers lean on for support with specific health concerns.

“Some items like CoQ10 400 mg are taken for serious heart health [needs] and could lead to major health problems potentially avoided if they had taken a legitimate product,” Richard explained.

He called on Amazon and FDA to shut down brands that are cutting corners on quality and to “enforce when products are mislabeled.”

Until then, Richard suspected low-quality brands will continue to thrive on Amazon.

“Unfortunately, the track record of cheating brands, Amazon’s ineffective quality program and FDA inaction each lead to the conclusion that cheating will continue,” he stated.