The chronic ingestion of diets containing different proteins produces marked variations in brain tryptophan levels and serotonin synthesis in the rat.
Level 5 - mechanism / opinion, no new human data
Animal research with no human data
PubMed 21207140 · doi:10.1007/s11064-010-0382-1
What was done
Male rats were fed diets containing 17% dry weight of one of five distinct proteins (zein, wheat gluten, soy protein, casein, or α-lactalbumin) for 9 days to test whether dietary protein composition chronically affects brain precursor levels and neurotransmitter synthesis. Brain concentrations of tryptophan, tyrosine, and leucine, as well as synthesis rates of serotonin and catecholamines, were measured.
What was found
Brain tryptophan concentrations varied up to eightfold and brain serotonin synthesis rates varied fivefold across the protein diet groups. In contrast, brain tyrosine and leucine concentrations and catecholamine synthesis rates varied much less. Exact baseline or group-specific numerical values and variance metrics were not reported in the abstract.
Why it matters
This work demonstrates that the type of dietary protein ingested chronically exerts large and persistent effects on brain tryptophan availability and serotonin synthesis in rodents.
Limits
This study was conducted exclusively in male rats and cannot directly establish human dietary effects. The abstract does not report the total sample size (n), group-specific numerical quantities, or statistical dispersion metrics.
Cited by
- supports Dietary tryptophan provided by protein serves as a precursor molecule for the synthesis of the neurotransmitter serotonin.