Dietary tryptophan is required for the synthesis of serotonin in humans. Evidence suggests that changes to the blood level of tryptophan can alter the synthesis rates of serotonin and that this may in turn change the mood of the individual. For example, in one study researchers depleted the blood levels of tryptophan in subjects by feeding them a tryptophan restricted diet for 24 hours. The protein content of the diet was controlled by the use of an amino acid mixture that was devoid of tryptophan. The results of this feeding was that the ratio between the tryptophan in the blood and other large neutral amino acids, fell by 22 % over 6 hours. This fall in the ratio of tryptophan to other large neutral amino acids was associated with a lowering of mood. These changes were particularly evident in subjects where there was a family history of depression, suggesting that these people may have a genetic predisposition to depression by being more sensitive to changes to their blood tryptophan levels.
Eat Well, Stay Healthy, Protect Yourself
RdB
