NOW’s potency testing finds only one St. John’s Wort supplement passed

Natural product manufacturer NOW released results from its latest testing of products sold on Amazon, and described a widespread failure of potency testing for St. John’s Wort (Hypericum perforatum) products.¹ Out of 22 products tested, only NOW’s St. John’s Wort passed the potency testing, a November 5, 2025, press release explains. The tests also revealed synthetic dyes in nine products.

St. John’s Wort is typically used for mood and emotional balance and support.

How the potency testing was conducted

As the press release from NOW explains, in August 2025, the company purchased two bottles of each of the selected 22 St. John’s Wort products from Amazon.com, testing one sample using their in-house testing laboratory and tseting the other with the ISO 17025-accredited Alkemist Labs.

The active compounds in the herb are hypericin and pseudo hypericin, usually standardized to 0.3%. A validated reverse-phase High-Performance Liquid Chromatography (HPLC) method was used to quantify the hypericin in the products, after irradiation with white light was used to ensure specificity. Total hypericin content was reported as the sum of hypericin and pseudo hypericin.

Results: hypericin and synthetic dyes

The tests revealed that hypericin was not detected in five of the brands (including all of the gummy brands). Six products containing the non-standardized St. John’s Wort whole herb had less than 0.03% hypericin. Detected using High-Performance Thin Layer Chromatography (HPTLC), the dyes in some of the products included Brilliant Blue (E133), Sunset Yellow (E110), and Tartrazine (E102).

“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,” stated 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 testing confirmed that only the St. John’s Wort veg capsules from NOW met the claims on its label for hypericin content (300 mg/0.3% hypericin). It also did not contain synthetic dyes. As NOW explained, certain nonspecific testing methods can misrepresent synthetic dyes, leading to artificially inflated potency results.

NOW’s ongoing product testing program

NOW has previously undertaken testing of multiple brands and products over the past several years. Recently, in its twentieth round of product testing, the company tested 25 Methyl B-12 (a form of vitamin B12) brands sold on Amazon, finding that several brands did not meet label claims, though fewer failings were identified than in past rounds of testing.²

Similar to the potency testing of St. John’s Wort products, NOW collected two bottles of 25 samples of the products from Amazon in January 2025, including two products from NOW, and tested them in-house and with a third part laboratory.

The results were shared with Amazon and the Food and Drug Administration, the news release adds.

NOW’s women’s wellness campaign

In May 2025, during Women’s Health Month, NOW launched a "Be You, NOW" campaign to promote tips on wellbeing and support health routines for women of any age.³ Four female voices in the wellness space offered their perspectives: Olympic medalist and sprinter Gabby Thomas; Peloton instructor Emma Lovewell; celebrity yoga, Pilates, and meditation expert Kristin McGee; and Registered Dietitian Nutritionist DJ Blatner. Profiles, videos, and recipes were included.

References

1. NOW. NOW Tests of St John’s Wort Sold on Amazon Shows Widespread Failure, Indicating Use of Incorrect Test Methods and Low Quality. November 5, 2025.
2. NOW. NOW’s Testing of Methyl B-12 Brands on Amazon. https://www.nowfoods.com/healthy-living/articles/nows-testing-methyl-b-12-brands-amazon (accessed 2025-11-07).
3. McEvoy, E. Women’s health and wellness campaign launched by NOW. May 2, 2025. https://www.nutritionaloutlook.com/view/women-s-health-and-wellness-campaign-launched-by-now (accessed 2025-11-07).