5-HTP is often used and recommended by physicians and laypersons alike for the management of depressive symptoms. This is because 5-hydroxytrphtophan (5-HTP) is the immediate precursor of serotonin and freely crosses the blood-brain-barrier.


It is freely synthesized into serotonin without biochemical feedback, so in theory, you can raise serotonin levels indefinitely if provided adequate 5-HTP. This often leads to a very appealing and vehemently defended assertion that depression is due to a lack of serotonin, so all that is necessary is to provide more 5-HTP. While this sounds good, it doesn’t jive with available scientific evidence.

A comprehensive literature search of 5-HTP and depression reveals that 5-HTP alone is not very effective at relieving depression. Part of the problem is that very few double-blind, placebo-controlled trials using 5-HTP and depression have been done. This can make a huge difference in how one interprets the results as the placebo effect in the management of depression usually runs between 30% and 45%. Therefore, any study without a placebo control that claims that 5-HTP helps up to 45% of the people treated could be solely from the placebo effect.

Depression Involves More Than Serotonin

In the clinical setting, we have found the depression is not exclusively caused by serotonin dysfunction. Depression may be caused by dopamine and/or norepinephrine dysfunction or a combination of serotonin and catecholamine (dopamine, norepinephrine and epinephrine) dysfunction. Once more, administration of only 5-HTP sets up conditions that facilitate the depletion of other neurotransmitters, which actually makes the underlying neurotransmitter imbalances worse.


Illustration used with permission from Marty Hinz, MD.

As illustrated above, giving only 5-HTP (or any of the amino acids listed) in an improper balance for each person can create more imbalance and dysfunction. That is why it is so important to work with a provider that has the training and experience to help you determine what combination of amino acids you need to restore proper function and eliminate your symptoms.

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5-HTP efficacy and contraindications (peer-reviewed paper and analysis)