Passion flowers put to the test in Passion Week
The Irish Times
Health Supplement, p. 13
7 April 2009
DOES IT WORK? Passion flowers for anxiety and insomnia
PASSION FLOWERS have a unique, complex and beautiful flower structure. This led to them being named for the Passion of Christ when Spanish missionaries to South America first encountered them in the 15th century.
The corona in the middle of the flower represents the crown of thorns. Three styles project from the flower and are said to resemble the three nails, with five stamens for the wounds (two hands, two legs and the lance). The 10 petals represent the 10 faithful apostles, excluding Peter the denier and Judas the betrayer. Many of the flowers are white and blue, colours that traditionally represent purity and heaven. Upon finding the flowers, the Spanish explorers believed their mission was blessed by Christ.
About 500 passion flower species are known, mostly vines that grow throughout North, Central and South America. Many are cultivated for their fabulous flowers. The species used medicinally is named Passiflora incarnata, which is different to the species used to make passion fruit juice. Just as the Passion of Christ is ultimately to bring a spirit of peace and contentment, passion flower extracts are used to relieve anxiety and help with insomnia.
A large number of different compounds have been isolated from passion flower extracts. A group of substances called harman alkaloids stimulate the central nervous system (CNS) in the same way as a group of older antidepressant pharmaceuticals called MAO inhibitors. These are no longer widely used because of the availability of antidepressants with few complications. Other constituents in passion flower extracts cause sedation in animal models. Passion flower extracts are approved for use in Germany to treat “nervousness”.
A Cochrane Library review of the research found only two controlled trials of passion flower extract for generalised anxiety. Both studies were small and compared a passion flower extract against benzodiazepines (Valium-type drugs).
Both studies found that people improved to the same degree when taking the passion flower extract or the pharmaceuticals. The results either mean that the two treatments were equally effective, or that the groups were too small to detect if one treatment was better than the other.
In the past, passion flower was approved in the US as an over-the-counter sleep aid. It was taken off the market when it was noted that no controlled trials had demonstrated that it was effective. Studies of its effectiveness for insomnia have still not been published. A small number of other human trials have examined herbal remedies containing passion flowers along with several other herbs. Such combination products often include German chamomile, hops, kava, skullcap and valerian. All these herbs have a reputation for causing sedation, making it impossible to know which, if any, of the herbs may be beneficial.
Passion flower itself is relatively safe. However, some people appear to be particularly sensitive to its constituents, and can become dizzy or confused. Larger doses have led to nausea and vomiting, and prolonged drowsiness. Probably the largest concern with passion flower extracts is their combination with other medications. Taking passion flower along with any prescription medication or other herbal remedy for anxiety, depression or insomnia could lead to additive effects. Women who are pregnant should not take passion flower as it has been found to stimulate the uterus in animals.
Passion flower extracts have been used for centuries by people with mild anxiety or difficulty sleeping. Studies of the many constituents in the extracts show that they have sedative properties. Most of the research has been conducted in animals, but some evidence is starting to emerge from human trials. Overall, these extracts may have a mild, beneficial effect.