Evidence supporting the use of: St. John's Wort
For the body system: Serotonin

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Synopsis

Source of validity: Scientific
Rating (out of 5): 4

St. John's Wort (Hypericum perforatum) is primarily used for its potential to support mood and emotional well-being, which is closely linked to the serotonin system in the brain. Scientific evidence indicates that St. John's Wort can be effective in the treatment of mild to moderate depression, a condition associated with dysregulation of serotonin and other neurotransmitters. Multiple meta-analyses and systematic reviews (e.g., Linde et al., 2008, Cochrane Review) have found that standardized extracts of St. John's Wort are superior to placebo and similarly effective as standard antidepressants, with fewer side effects in many cases.

The mechanism of action is not fully understood, but research suggests that compounds in St. John's Wort, such as hypericin and hyperforin, inhibit the reuptake of serotonin, dopamine, and norepinephrine, thereby increasing their availability in synaptic clefts—similar to the action of several pharmaceutical antidepressants. Because of this, St. John's Wort is considered to act on the serotonin system, among others.

However, its use is not without risks: St. John's Wort is known to interact with many medications by inducing cytochrome P450 enzymes, potentially reducing the efficacy of oral contraceptives, anticoagulants, and other drugs. While evidence supports its use in mild to moderate depression, it is not recommended for severe depression or bipolar disorder without medical supervision. Overall, scientific validation for its effect on the serotonin system and mood disorders is strong compared to many herbal remedies.

More about St. John's Wort
More about Serotonin

Other body systems supported by St. John's Wort

Brain
Nerves
Serotonin
Specific Neurotransmitters