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Low serotonin levels are associated with various types of depression. Indeed drugs such
as SSRI’s and tricyclic anti-depressants work by inhibiting the breakdown of serotonin
in the gaps between brain cells (synapses). As a precursor of serotonin several studies
have shown 5-HTP to be an effective way to increase serotonin levels and therefore to
be helpful in patients with depression.

D-L-Phenylalanine (DLPA)
Researchers have found that 10-15 percent of depressed patients have low plasma
levels of phenylalanine. Two double-blind comparative studies reported that
phenylalanine was as effective as the antidepressant medication Imipramine.
Phenylalanine is a precursor to the mood elevating compound dopamine (which is
found to be low in some depressed patients). It also enhances other mood enhancing
chemicals such as PEA and endorphins. DLPA is converted into tyrosine before
eventually becoming dopamine and tyrosine may be preferred in some cases – see

Tyrosine is a precursor to the mood elevating compound dopamine. A number of
studies conducted in the 1970’s demonstrated tyrosine’s ability to lessen symptoms of
depression. The most impressive results were seen when tyrosine and 5-
hydroxytryptophan were combined. DLPA is a precursor of tyrosine and may be
preferable to tyrosine in some cases – see above.

Rhodiola (Rhodiola rosea)
Rhodiola’s active compounds enhance the transport of serotonin precursors
(tryptophan and 5-HTP) into the brain, leading to a significant increase in brain
serotonin activity. Rhodiola has also been shown to reduce the degradation of moodelevating
neurotransmitters. As stress accelerates the depletion of mood-boosting
neurotransmitters, the adaptogenic (anti-stress) effects of rhodiola may be additionally

St John’s Wort (Hypericum perforatum)
Research has shown that St John’s Wort can relieve mild to moderate depression,
anxiety and related sleep disturbances. Although early in vitro research suggested that
the primary mechanism of action was due to an MAO inhibiting effect of the
compound hypericin, recent evidence suggests that the mechanism appears to be a reuptake
inhibiting effect on serotonin, dopamine and noradrenaline (primarily
associated with the compound hyperforin).

B Vitamins
Various B vitamins play a major role in maintaining proper brain chemistry,
particularly relating to the activity and metabolism of neurotransmitters. Deficiencies
in certain B vitamins are common in depression with B6 and folic acid being of
particular note. For example, in studies up to 35% of depressed patients have been
found to be folic acid deficient. B vitamins work synergistically so it is important to
ensure adequate intake of all the B complex vitamins.

Omega 3 Fatty Acids
Cholesterol lowering diets appear to increase the incidence of depression, which is
possibly a result of decreased omega 3 intake impacting on DHA levels in the brain. If
this highly unsaturated omega-3 fatty acid, which is an essential part of the neuronal
cell membranes, is replaced by an omega-6 fatty acid, changes in the membrane
properties may occur, which increase the vulnerability to depression. In studies higher
consumption of omega 3 fatty acids correlates with a decreased incidence of

Depression Summary
Nutrient/Herb Typical intake range
5-HTP1 100 – 300mg per day (away from food)
DLPA2 500 – 1000mg per day (away from food)
L-Tyrosine3 500 – 1000mg per day (away from food)
Rhodiola rosea4 250 – 750mg per day
St John’s Wort (0.3% hypericin)5 300 – 600mg per day
B-Complex As per manufacturer’s directions
Omega 3 fatty acids6 1000 – 3000mg fish oil or equivalent per day


Environmental toxins
Allergens (e.g. wheat, dairy)
Trans/hydrogenated fats
Refined and processed foods

Oily fish
Nuts and seeds
Green leafy vegetables
Vegetarian protein sources
Whole foods

Lifestyle Factors
Take regular gentle exercise
Consider light therapy if depression is associated with low light levels (SAD)
Consider counselling
Reduce impact of stress - support adrenal function if necessary
Identify potential food allergies – these are common in depression

1. May increase risk of scleroderma-like symptoms in susceptible individuals. May cause serotonin
syndrome if combined with antidepressant drugs that increase serotonin levels – avoid concurrent
use. Best avoided by pregnant women and nursing mothers.
2. Combined use with antipsychotic drugs may increase the risk of developing tardive dyskinesia.
Phenylalanine may cause hypertension if taken with MAOI’s. PKU sufferers should avoid. Should
be avoided by pregnant women and nursing mothers.
3. Not to be used with MAO inhibitor drugs without the consent of a qualified medical health
practitioner. Should be avoided by pregnant women and nursing mothers and those with
4. Do not use during pregnancy or lactation. Concurrent use with anti-depressant medication under
medical supervision only.
5. May cause photosensitivity (increased sensitivity to ultraviolet light), especially with regular use
of high doses. Avoid using St. John’s Wort anti-depressant drugs.
6. Do not take in conjunction with anticoagulant medication.