Rosie Brogan (RB): How does St John's Wort (SJW) work to improve low mood?

Sophie Tesoriero (ST): It is not known how SJWworks. One theory is that it increases the brain's content of serotonin and may work in a similar way to SRI (serotonin reuptake inhibitor) drugs such as Prozac: the supplement may keep serotonin in the synapse where this neurotransmitter is needed to work.

SJW may also increase the level in synapses of other lesser known neurotransmitters such as acetylcholine, dopamine, gamma aminobutric acid (GABA) and norepinephrine.

• Acetylcholine is a neurotransmitter for the the parasympathetic nervous system which helps us to ‘rest and digest’. It also helps maintain sleep.
• Dopamine influences mood and may contribute to the feeling of euphoria.
• GABA inhibits nerve impulses associated with anxiety from reaching the motor centres of the brain.
• While insufficient norepinephrine production results in poor mood and increased feelings of apathy

RB: Who are the best candidates to benefit from its effects (in terms of symptoms, age and health status)?

ST: People with mild to moderate feelings of low mood will benefit from SJW. However it is also showing promising results in people with more pressing low mood.

RB: Are there people/groups that are less suited to taking St John's Wort?

ST: It was previously thought that SJW was only modestly better than the placebo effect in cases of serious low mood.

However in 2009 an overview of 13 clinical trials showed that there was no difference between SJW and SSRIs when it comes to treating more serious incidents of low mood.

RB: Can it safely be taken long-term (say, for more than two weeks)?

ST: It takes two to four weeks for SJW to take action. And for the best effect, SJW should be taken for longer than four weeks.

It is best to check in with a health professional for long term monitoring.

RB: I've read that SJW can block the absorption of iron, which may impact upon energy levels. Is this true?

ST: This concern arose due to the presence of tannins in SJW.

Tannins found in regular tea were linked to increased risk of anaemia. However this effect has not been proven with St John's Wort (as a tea or herb) - so the concern is only a theoretical one.

JP: Are there any common drug interactions or side effects that users should be aware of?

ST: SJW may decrease the activity of certain medications. Some are common, others less so - but they’re important by virtue of the risk that an interaction entails.

Common medications that interact with SJW (consult your healthcare professional before use if you are taking any of the following):

• warfarin
• oral contraceptives (birth control pills)
• cyclosporine
• tacrolimus (immunosuppressant)
• protease inhibitors or reverse transcriptase inhibitors (antiviral drugs)
• methadone
• amitriptyline
• midazolam (benzodiazepine antidepressants)
• simvastatin cholesterol medication)
• atorvastatin
• verapamil
• nifedipine
• omeprazole
• voriconazole
• irinotecan or imatinib(anti-neoplastic-cancer medication).
• prescription antidepressants (tricyclics or SSRIs)
• digoxin (cardiac failure, arrythmias)

SJW can increase the action of the hepatic P450 enzyme system, which may decrease the efficacy of these medications.

Although this effect is less likely, SJW may also reduce the action of fexofenadine (an antihistamine).

Also be cautious if you suffer from mania bipolar disease or if you are on drugs which cause photosensitisation.

Reference available upon request

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Comments

I gave up smoking 15 days ago, I am feeling a bit anxious at times, the chemist recomended St John's Wort. How will this help, & is there anything else I can do to help the feelings of stress? Lynne, posted 30+ days ago. Report Abuse

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