NOW Tests St. John’s Wort Supplements Sold on Amazon

Continuing our mission to promote transparency and higher standards in the supplement industry, NOW recently tested 22 St. John’s Wort products purchased from Amazon in August 2025. Results revealed that all except for one (NOW) product failed potency testing, and several contained synthetic dyes used to make low-quality or adulterated products appear authentic.

We purchased two bottles of each St. John’s Wort supplement (including NOW product) to conduct internal analyses, and we partnered with Alkemist Labs, an ISO 17025-accredited independent laboratory specializing in botanical identification and testing, to ensure accuracy and transparency.

Why Test St. John’s Wort?

St. John’s Wort (Hypericum perforatum) is a popular herb used to support mood balance and emotional well-being. The key active compounds, hypericin and pseudohypericin, are responsible for its beneficial properties and are typically standardized to 0.3%. Ensuring supplements contain genuine, properly standardized extract is essential for product quality and effectiveness.

Testing Methodology 

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

Product Testing Results

• Out of 22 tested brands, only NOW 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 is reported to have as low as 0.03% hypericin, and of the six products containing the non-standardized material, all had less than this amount.

Importance of Analytical Method Selection

Choosing the correct testing method for St. John’s Wort is critical. 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.

Conclusion

Bottom line is, only NOW^® St. John’s Wort met the label claim for total hypericin and showed no evidence of dye adulteration. Our in-house analytical testing, paired with Alkemist Labs’ independent verification, underscores the importance of scientifically valid methods. NOW will continue to purchase and test products sold on major online platforms and publicly share the results to encourage higher quality standards across the supplement industry.