Possible Interaction: Serotonin and Tryptophan

“ TRP supplementation is known to increase plasma TRP levels and to influence brain 5-HT synthesis (Markus, Firk, Gerhardt, Kloek, & Smolders, 2008).”

“Reduction of the monoamine serotonin 5-HT ) via the dietary manipulation of tryptophan (acute tryptophan depletion; ATD) has been shown to induce negative cognitive biases similar to those found in depression in healthy individuals.”

“BACKGROUND Tryptophan depletion TD ) reduces brain serotonin and may induce acute depressive symptomatology, especially among those with a history of Major Depression.”

“Since tryptophan is a precursor to the neurotransmitter 5-HT and since the enzymes … in the 5-HT synthesis normally are not saturated, the decreased plasma ratio of tryptophan might cause a decrease in brain 5-HT synthesis and, thus, to an impaired function in brain 5-HT neurons.”

“Free tryptophan Trp ), which is augmented by liberated free fatty acids (FFA) from adipose tissue, can induce mental fatigue via serotonin during exercise.”

“Because brain serotonin levels depend directly on the amounts of exogenous tryptophan (TRP) available for its synthesis, amounts of TRP in the diet may be manipulated to alter the corresponding levels of serotonin.”

“ 5-HT levels were reduced by rapidly lowering plasma levels of its precursor, tryptophan ; tryptophan levels were reduced by stimulating protein synthesis with a large drink of amino acids devoid of tryptophan.”

“The amino-acid L-tryptophan is essential in the synthesis of brain serotonin , and its depletion can lead to a widespread reduction in central serotonergic activity.”

“While tryptophan may potentiate spinal 5-HT function to decrease nociceptive afference in some circumstances, there may be clinical conditions in which the use of tryptophan is contraindicated.”

“These experiments were performed to test the hypothesis that alterations in brain 5-hydroxytryptamine , brought about by dietary alterations in brain tryptophan , regulate selection of protein and carbohydrate.”