Passion flower might just sound like the type of flower to send your loved one on Valentine's Day - but it's not that kind of passion flower. It actually got its name from Christian missionaries who drew parallels between the flower and the "passion" or "crucifixion" of Christ.
According to the legend, the ten petals reminded the missionaries of ten of the disciples fleeing the garden (leaving out the Judas, the traitor, and John, who stayed with Mary at the cross), the tendrils reminded them of the whip, the leaves reminded them of the lance, etc.
So, all things being considered, probably not a great choice as a romantic gesture.
Nowadays, passion flower products are very popular in the health and wellness niche. While passion flower is used for a wide range of health benefits, it is probably best known to help people relax and sleep. Is this just another urban myth or a potent natural remedy?
What is Passion Flower?
Passion flower is also known as passiflora, apricot vine or corona de viste. In Brazil, passion flower is known as "maracuya" where it is a popular drink.
As mentioned above, it is one of the most commonly prescribed phytomedicines today.
There are over 400 species of passionflower. The plant is native to North, Central and South America.
It has blue-white petals and fruits called "mayhop."
From a therapeutic perspective, the vines, leaves, seeds and roots are used in herbal medicine and contain flavanoids, alkaloids, saponins, carotenoids, vitamins, oils, minerals fiber (1).
Over 1000 passionflower products are available for sale on Amazon and include dried herbs, teas, liquid, tinctures and tablets. A 100mg capsule of passion flower extract costs about $0.10.
Is There Any Research?
There are only 650 publications including 15 clinical trials on passiflora. To put this into context, there are over 20,000 publications on melatonin (a competitor to passiflora for sleep hygiene) including over 1000 clinical trials.
Does Passion Flower Help Reduce Anxiety?
A 2007 Cochrane review looked at the evidence base for using passionflower for anxiety. They cast a very wide net and included studies on panic disorders, obsessive-compulsive disorders, post-traumatic disorder, agarophobia, and social phobia. They even contacted the manufacturers of passiflora for any in-house data (2).
Despite this, they identified only two studies with 198 study participants. Yes, two studies with 198 study participants.
The first study comes from Iran and had 36 participants with a generalized anxiety disorder. They compared passiflora with the benzodiazepine, oxazalam, over a four week trial period (3). This study found an improvement in job performance in favor of passiflora but not at the level of statistical significance.
The second study comes from Japan and had 162 study participants. They compared moxazolam to passiflora over a 4 week study period (4) This study showed a lower rate of drowsiness with passiflora compared to benzodiazipines but again not at the level of statistical significance.
The meta-analysis noted that the key limitation of their overview was the fact that the two papers did not include a direct comparison between passiflora and antidepressants which is a real issue considering the fact that antidepressants are now commonly used for treating anxiety.
Sorry, but I have to add my own little commentary. Surely, the real problem here is the fact that a multi-million dollar industry has been built up around passionflower and we have data from less than 200 people over 4 weeks which failed to show that it works anyway?
Ever open-minded, let's look to see what else has been published since this 2007 review.
A 2013 study from Iran looked at the effect of passiflora in people undergoing periodontal treatment (5). To be fair, dental treatments can certainly induce fear in the bravest of people which makes this a very valid and practical study.
A total of 63 subjects who were scheduled to undergo periodontal treatment were randomized to either passiflora drops, placebo drops or no intervention. The study showed a statistically significant difference in the anxiety levels before and after the Passion flower administration in the passion flower group and also between the passion flower group and the other two groups.
In 2017, German investigators studied the effect of passiflora on nervous restlessness’ over 12 weeks (6). They found statistically significant improvements in quality of life, restless exhaustion, sleep disturbance
A 2007 meta-analysis failed to show any benefit of passiflora in anxiety. Since then, a couple of clinical studies suggest that passiflora helps reduce anxiety. Either way, there is no convincing evidence to support the multi-million dollar passiflora anti-anxiety industry.
Does Passion Flower Reduce ADHD symptoms?
A systematic review of herbal medicine for ADHD identified 9 randomized trials which included 464 patients (7). Only randomized controlled trials with children (0-18years) suffering from ADHD were included in this review. The German reviewers found 'low evidence for passiflora in ADHD' and concluded that they 'could not make any concrete recommendations'.
As this review took place in 2017, I think we can take that as the final word on the subject for now.
No concrete recommendations can be made about passiflora and ADHD at this time.
Does Passion Flower Reduce the Effects of Menopause?
There is one human clinical trial on passion flower in the menopause. This study looked at the effect of an Italian commercial nutraceutical containing passiflora, quercetin, and resveratrol in 60 perimenopausal women (8).
The study team did not work for the company that makes the commercial nutraceutical and were independent investigators. At the end of 6 months of follow up, statistically significant improvements were noted in quality of life and sexual function.
It is impossible to attribute the improvements to passiflora as opposed to the other ingredients in the herbal blend.
There is very limited data to support any claims that passiflora helps reduce menopausal symptoms.
Does Passion Flower Help Lower Blood Pressure and Insulin Levels?
Piceatannol is a phytochemical present in passion fruit seeds and is chemically related to resveratrol (the healthy part of grapes and wine).
Blood pressure is divided into systolic and diastolic blood pressure. Systolic is the bigger number and diastolic is the smaller number. Say your blood pressure is 110/70, then the systolic blood pressure is 110 and the diastolic blood pressure is 70.
Systolic blood pressure is measured when the heart is beating, while diastolic blood pressure is measured between heartbeats. Systolic blood pressure is more relevant clinically.
Brazilian investigators who studied the effects of passiflora in patients undergoing dental extraction included blood pressure in the list of parameters that they measured (5).
They found statistically significant differences in diastolic blood pressure in the passiflora arm of the study. As mentioned above, systolic blood pressure is more important and so reductions in diastolic blood pressure are not too exciting.
Japanese investigators conducted a randomized, placebo-controlled study in 39 subjects, including 19 overweight adults and 20 normal-weight individuals (9). Subjects were randomized to either piceatannol from passionflower (20 mg/day) or placebo capsules for eight weeks.
Piceatannol supplementation resulted in statistically significant improvements in metabolic health, including insulin sensitivity, blood pressure and heart rate in overweight men. The passionflower derivative had no effect on metabolic health in non-overweight individuals.
Putting all this together, we can see that passiflora reduced blood pressure in overweight individuals but not normal-weight individuals. It also reduced diastolic blood pressure but not systolic blood pressure in adults undergoing dental procedures.
Considering the fact that these confusing results are based on data from 79 people, I think we cannot conclude anything much about passiflora for BP at this stage.
Equally, passiflora extract improved insulin sensitivity in overweight individuals but not normal-weight individuals in a small study which makes it very hard to draw any conclusions about this.
Does Passion Flower Reduce Inflammation?
Brazilian investigators found that passiflora extract reduced inflammatory markers including white blood cells, myeloperoxidase, nitric oxide, TNFalpha and IL-1beta levels in a mouse pleurisy model (chest infection) (10). All very interesting, but on the grounds that my pet mouse does not have pleurisy, let's switch to human studies.
The Japanese study that looked at metabolic health also captured data on inflammation (9). Inflammation was assessed by measuring C-reactive protein, interleukin-6, diacron reactive oxygen metabolite, and biological antioxidant potential at baseline and after 8 weeks of placebo or piceatannol supplementation. Piceatannol had no effect on inflammation in this study.
Passiflora had no effect on inflammation in one human clinical study.
Does Passion Flower Improve Your Sleep?
Japanese researchers compared the effects of chamomile with passiflora in sleep disturbed rats. The study showed that chamomile, but not passiflora, significantly decreased sleep latency. Sleep latency is the time it takes to fall asleep (11).
Mexican investigators administered passiflora into the abdomen of six adult male rats and recorded a statistically significant increase in total sleep time and especially slow-wave sleep (12).
Again, my pet rats will be delighted with this news but I am a doctor, not a vet.
Australian investigators studied the effect of either passiflora tea versus placebo in forty-one participants who had mild sleep disturbances (13). Following a wash-out period of one week, the study participants received the other treatment. Passiflora resulted in statistically significant improvements in sleep quality in the study participants.
Clinical and pre-clinical data support a role for passiflora in sleep hygiene. However, there are no studies looking at people with severe sleep disturbances or long term effects of passiflora on sleep.
Is Passion Flower and its Extract Safe?
Overall, passiflora has a good safety profile (but it has to be said that we are not drowning in data).
Passiflora has sedative effects and as such care should be taken in people who operate machinery, drive or when taken by people who drink alcohol.
Passiflora should also be avoided in people taking monoamine oxidase inhibitor (MAOI) antidepressant medication as there is a risk of significant drug-herb interactions.
Passiflora can cause uterine contractions and should be avoided in pregnancy as there is a risk of miscarriage.
As passiflora can lower diastolic blood pressure, care should be taken in people with low blood pressure or people taking BP-lowering medications.
As with many other herbal products, passiflora should be avoided in people who are taking blood-thinning medication.
Australian physicians reported the clinical history of a 34-year-old woman who was admitted to hospital severe nausea, vomiting, drowsiness and a heart rhythm disturbance following self-administration of Passiflora incarnata L., at recommended doses (14). The heart rhythm disturbance was life-threatening and she required cardiac monitoring.
The most scientific recommendations for passiflora are based on the short-term use of passiflora for mild sleep disturbances. There is insufficient evidence to recommend it for longterm use or for moderate to severe sleep disturbances.
The available data on passiflora in anxiety is really inadequate to make any recommendations.
The most remarkable thing about passion flower is the fact that a multimillion-dollar industry has spawned from just 15 clinical trials and it is not even as if all of these trials are amazingly positive.
I don't think that I will be adding this one to my shopping cart (unless maybe if my pet mouse gets pleurisy).