Researchers of a study investigated the impact of habitual tryptophan intake on mood symptoms and the influence of genetic risk variants on depression in 63,277 individuals from the UK Biobank. Researchers found that a high dietary tryptophan-to-large amino acids ratio (TLR) provided a modest protective effect against depression. Genetic analysis revealed that specific serotonin and kynurenine pathway genes were associated with depression in the low TLR group but not in the high TLR group.

The study also identified significant associations at the pathway level for both serotonin and kynurenine pathways in individuals with low dietary TLR, highlighting the importance of diet in modulating genetic risk for depression. These findings suggest a distinct genetic risk profile for depression based on habitual dietary TLR, supporting the serotonin hypothesis of depression and emphasizing the need for personalized dietary interventions. Understanding the roles of serotonin and kynurenine pathways in the context of diet could lead to targeted prevention and treatment strategies for mood disorders in genetically vulnerable individuals.

Reference: Bruncsics B, Hullam G, Bolgar B, et al. Genetic risk of depression is different in subgroups of dietary ratio of tryptophan to large neutral amino acids. Sci Rep. 2023;13(1):4976. doi: 10.1038/s41598-023-31495-x.