|Article by Ann Walker|
Laboratory studies on the plant are numerous and support these traditional uses and mechanistic studies have pointed to the action of this herb operating through modulation of the GABA (gamma-amino butyric acid) neurotransmitter system in the brain, but the jury is still out. Although the compounds present in passiflora have been identified, no single compound has yet been found to account for its physiological action. Hence, it is likely that two or more compounds work in synergy, as we have found to be the case for several other herbs.
Small-scale clinical studies have, in the past, supported the use of passiflora for anxiety, but now a Brazilian study (PMID: 27918731) has compared the anxiety levels of volunteers taking a single dose of either passiflora (260 mg of extract) or a benzodiazepine drug called midazolam (15 mg) before wisdom tooth extraction. The study was randomised, double-blind and cross-over in design. Each of forty volunteers had two extractions – one tooth on one side of the jaw with a dose of passiflora given beforehand and, on a separate occasion, a tooth on the other side of the jaw, with the drug given beforehand. [A cross-over design using two interventions on the same volunteer like this is regarded as superior to using only one intervention per person, because the volunteer acts as their own control, giving more strength to the study.]
Over 70% of the volunteers said that they felt calm or only a little anxious under both protocols – indicating that the effect of passiflora was equivalent to the drug. However, whilst using passiflora there was no significant interference with memory, whilst 20% of volunteers reported no recollection at all whilst on the drug.
While more rigorous clinical trials to assess the traditional use of passiflora would be very welcome, the herb remains an effective non-addictive sedative that does not cause drowsiness. Fortunately, quality extracts of passiflora are freely available in herbal products which carry a THR (Traditional Herbal Registration) and further information on these THR products containing passiflora can be found on the BHMA website to ensure safety of use.
PMID = PubMed identifier
Ann Walker PhD FCPP MNIMH RNutr
Course Director DHM