Serotonin is a critical neurotransmitter for mood health. It is synthesized from its precursors tryptophan and 5-hydroxytryptamine (5-HTP). Due to its role in serotonin synthesis, 5-HTP may be a supportive molecule for mood health, sleep quality, and age-related brain support.

As an example of the bi-directional nature of the gut-brain axis, 5-HTP is produced by certain microbes found in the gut microbiome. An animal study reported significantly decreased tryptophan and 5-HTP levels in depressed mouse models, along with decreased levels of hippocampal serotonin and evidence of imbalanced gut microbiota, particularly levels of certain strains of Lactobacillus. 

Probiotics found in fermented foods have been studied for their potential impact on the gut-brain axis and neurotransmitter homeostasis. Certain strains of Lactobacillus found in fermented foods have been shown to help increase colonic and serum 5-HTP levels, thus helping modulate serotonin levels. In addition, some Bifidobacterium strains have also been identified as 5-HTP synthesizers. Animal studies have associated these strains as potentially supportive of both gut microbial balance and mood health. 

Evidence suggests that the inflammatory response may play a role in the pathophysiology of certain mood disorders. Recent animal studies have correlated improvements in depression-like behavior and the inflammatory response with probiotic administration. One study reported that in the presence of Lactobacillus helveticus and Bifidobacterium breve, there were increases in serotonin and decreases in tumor necrosis factor-α levels. 

Because 5-HTP is also a precursor for melatonin production, it may help support certain aspects of sleep quality. It has been shown in animal studies to help support sleep duration, decrease sleep latency time, and help promote rapid eye movement (REM)-stage sleep. In a double-blind, placebo-controlled, crossover clinical trial, older adults with neurodegenerative symptoms and depression received 50 mg of 5-HTP daily for 4 weeks. Study results indicated improvements in the total percentage of REM-stage sleep and improvements in scores related to mood health. 

Multiple clinical studies have been conducted to investigate 5-HTP’s potential role in maintaining mood health. A systematic review and meta-analysis explored the potential efficacy of oral supplementation with 5-HTP and reported improvements in scores related to mood health. However, more studies need to be conducted, particularly in larger populations and with standardized treatment amounts. 

While more research is needed, evidence suggests that 5-HTP may help support certain aspects of mood health and sleep quality. In addition, probiotics, including common strains found in fermented foods, may promote the synthesis of bioactive brain-supportive molecules like 5-HTP. Examples of fermented foods include yogurt, kimchi, kefir, miso, and sauerkraut. 

By Dr. C. Ambrose, ND, MAT