St. John’s Wort in Focus: Only 1 in 22 Products Meets Its Label Claims

A recent investigation by NOW Foods and Alkemist Labs reveals significant quality issues in St. John’s Wort preparations (Hypericum perforatum) sold through online platforms.

Of 22 products tested, only one met its declared hypericin content. In several samples, no hypericin could be detected at all. Synthetic dyes including Brilliant Blue and Tartrazine were also identified, presumably used to mimic the natural plant colour and influence analytical results.

Adulteration Is Becoming More Strategic

The findings point to a clear market trend:

Adulteration is no longer random — it is increasingly targeted at analytical testing methods.

This pushes conventional quality control approaches to their limits.

Why a Single Marker Is Not Enough

Hypericin is frequently used as the primary marker for St. John’s Wort. Relying on this parameter alone, however, does not reflect the complexity of the plant.

St. John’s Wort contains a wide range of bioactive constituents, including:

• Naphthodianthrones (e.g. hypericin, pseudohypericin)
• Phloroglucinols (e.g. hyperforin)
• Flavonoids and biflavonoids

A reliable assessment of quality and authenticity therefore requires the combined analysis of multiple compounds and their ratios to one another.

Implications for Quality Control

The growing complexity of adulteration calls for a change in approach:

• Multi-compound strategies instead of single markers
• Combination of modern analytical methods (e.g. HPTLC, HPLC, LC-MS)
• Use of qualified reference standards

Only in this way can natural variability be reliably distinguished from deliberate adulteration.

Conclusion

The findings make one thing clear:

The quality of herbal products cannot be reduced to a single measurement.

Reliable assessment requires a deep understanding of phytochemical complexity and analytical strategies that reflect this reality.

[1] NOW Tests of St. John’s Wort Products from Amazon Show Widespread Quality Failings – Nutraceuticals World