National Suicide Prevention Lifeline: 1-800-273-8255
St. John’s wort is known by the scientific name Hypericum perforatum L. and is a member of the Hypericaceae family. The plant is listed as a noxious weed in nine U.S. states and is considered a livestock-poisoning plant, but its extract is sold as an herbal supplement for depression and not currently regulated by the Food and Drug Administration (FDA). Research on the plant is relatively unknown.
Facts about St. John’s Wort
Hypericum plants are native to Northern Africa, parts of Asia, and Europe. The plant has been naturalized to Japan, Australia, South America, the West Indies, and parts of North America, including Hawaii. The plants are usually collected when flowering because the distinctive yellow flower is considered the most advantageous portion of the plant.
St. John’s wort supplements are found in many forms, such as teas, pills, and capsules, and for many indications, the most well-known being depression. The active chemicals in the extract are hypericin and hyperforin.
Studies of the Effect of Hypericum Extract on Depression
In 1997, a Swedish study looking at 25 controlled trials found that treating depression with a low dose of extract improved the moods of 61 percent of patients, and high doses (2.7 mg) improved 75 percent of patients. They also found that side effects were mild and less frequent than with other antidepressants (study abstract translation available here).
More recent studies have found that the possible mechanism of action may involve the serotonin, dopamine, and adrenaline pathways, but it seems to have only a weak effect on monoamine oxidase A and B activity, the assumed pathway 15 to 20 years ago. The GABAergic pathway has also been shown to be affected, and there is some indication that it exerts genetic control over the stress axis.
There are still many questions about the exact mechanisms of Hypericum in treating depression, but there does appear to be evidence that it works, both anecdotal and clinical. There is a need for more comparative studies with highly prescribed antidepressants, such as fluoxetine, in order to bring this supplement under regulation and make it safely available to the patients. One review even suggested it be used in the treatment of clinical depression.
Side Effects of St John’s Wort Supplements
There are a few effects that must be noted for this herbal supplement:
- Photosensitivity – The molecular reactions of hypericin causes increased sensitivity to UV light. There are also concerns about the effect this may have on the retina, and blindness is a possibility for those who take high doses of the extract for long periods of time and are exposed to sunlight.
- Drug-drug interactions – Hypericin interferes with antibiotics, antiviral medications, and birth control.
- No regulation and heavy metal poisoning – Because herbal and dietary supplements are not regulated, there have been many cases of heavy metal poisoning due to negligence during manufacturing. This is not a side effect of the plant itself, but a call for more strict production regulation.