NOW Testing of St. John’s Wort Sold on Amazon Shows “Widespread Failure”

Bloomingdale, IL—NOW has shared the latest results from its industry quality testing program, which investigates unfamiliar brands sold on online in an effort to raise awareness on low-quality products in the marketplace. The focus of this round: the mood-supporting herb St. John’s Wort (Hypericum perforatum) sold on Amazon.com. NOW explained the active compounds hypericin and pseudo hypericin are responsible for the herb’s beneficial properties, and are typically standardized to 0.3% for product quality and effectiveness.

NOW reported that, aside from the NOW product, every product tested failed potency testing. Raising another concern, NOW noted that several samples contained synthetic dyes. The problem, NOW says, is that synthetic dyes are “commonly used by bad actors to make low-quality or adulterated products appear authentic.”

About NOW’s St. John’s Wort testing

NOW purchased two bottles of each St. John’s Wort supplement (including NOW product) from Amazon.com in August 2025. One bottle of each sample was tested in NOW’s in-house labs, and the other sample was sent to Alkemist Labs, which is an ISO 17025-accredited independent laboratory that specializes in botanical identification and testing.

Testing Methodology

• The active compound hypericin was quantified by High-Performance Liquid Chromatography (HPLC) using a validated reverse-phase method after irradiation with white light to ensure specificity.
• Hypericin content was expressed as the sum of hypericin and pseudo hypericin.
• High-Performance Thin Layer Chromatography (HPTLC) was performed to confirm the product identity and detect common synthetic dyes including Brilliant Blue (E133), Sunset Yellow (E110), and Tartrazine (E102). NOW explained that these dyes artificially inflate hypericin readings in less specific testing methods.

Findings

• NOW reported that, out of 22 tested brands, only the NOW product met the label claim for total hypericin and contained no synthetic dyes.
• Nine brands contained synthetic dyes.
• Five brands had no detectable hypericin; none of the gummy brands had any detectable hypericin.
• Non-standardized St. John’s Wort whole herb may have as low as 0.03% hypericin and of the six products containing the non-standardized material, all had less than this amount.

Achart detailing the brands involved and results can be accessed on NOW’s website.

NOW’s observation about the results

“We are accustomed to seeing abysmal test results in at least some of the brands we buy from Amazon for this testing program, but this time we were shocked to find that they all failed, and only NOW St. John’s Wort met the label claim for total hypericin and showed no evidence of dye adulteration,” said Katie Banaszewski, NOW Senior Director of Quality. “What stands out most to me is the strong evidence that none of these brands used fit-for-purpose testing, if they tested at all. Our in-house analytical testing, paired with Alkemist Labs’ independent verification, underscores the importance of scientifically valid methods.”

The company maintains that choosing the correct testing method for St. John’s Wort is key, explaining: “Non-specific methods, such as simple colorimetric or spectrophotometric assays, can be fooled by synthetic dyes that mimic the deep red color of hypericin. These approaches may artificially inflate potency results, making products appear compliant when they are not. In contrast, HPLC can separate and identify true hypericin compounds from adulterants, providing an accurate and reliable measure of product quality. NOW’s and Alkemist’s testing both relied on chromatographic specificity, ensuring confidence in the findings.”

Previous NOW testing includes:

NOW also has reported multiple supplements sold on Amazon impersonating the NOW brand, as well as another prominent industry supplement brand.

Opportunity for natural products retailers

NOW generally does not test health food store brands or practitioner brands, as the company says quality issues do not seem to be a major issue with those brands. In 2022, WholeFoods Magazine recognized NOW and other industry leaders for their industry self-policing efforts, naming the  Person of the Year: The Amazon.com Quality Activists. Dan Richard, VP of Global Sales and Marketing, NOW Health Group, told WholeFoods: “Stores can publish NOW’s results to let consumers know ‘buyer beware.’ They can share some of the many articles published about our testing programs in their newsletters or on social media. The low prices online are sometimes too good to be true. Local stores have many advantages that online stores can’t offer including service, in-person experience, sampling, and more. It’s not easy these days for any business, but many natural retailers still succeed by finding a worthwhile niche, providing quality health products and at a reasonable price.”