Researchers from Kirin Holdings Company, Limited, in Japan, conducted a randomized, double-blind, placebo-controlled clinical trial to evaluate β-lactolin’s effects on mood in healthy adults using mood assessments, quality of life (QOL) questionnaires and salivary stress markers.
The continued search for natural mood-boosting and stress-relief solutions responds to increasing concerns surrounding mental health in today's society. According to a 2019 World Health Organization report, 970 million people worldwide suffer from mental disorders, the most common of which are depressive and anxiety disorders.
Systematic reviews of the available evidence suggest that specific dietary patterns may help prevent mental disorders, and one recent meta-analysis found that fermented dairy products reduce depression risk.
Fermentation releases compounds like fatty acids and peptides with psychiatric benefits. For example, certain milk-derived peptides have shown anxiolytic and antidepressant effects similar to diazepam in preclinical studies, though clinical evidence is limited.
The current study, published in Scientific Reports, builds on Kirin research that identified that tryptophan–tyrosine-related peptides, including β-lactolin, from whey protein improves psychiatric function in rats. Clinical trials have also shown that β-lactolin supplementation improves memory, attention and executive functions in middle-aged and older adults.
Study details
The researchers recruited 60 healthy adults between the ages of 45 and 64 who had relatively low psychological health. They were randomly assigned to receive either whey peptide (with 1.6 mg/day of β-lactolin) or a placebo for six weeks.
The β-lactolin group showed significant improvements in trait anxiety and subjective stress compared to the placebo group and scored higher on vitality and mental health measures of QOL.
The results suggest that β-lactolin supplementation reduces anxiety and stress and improves psychological well-being, potentially linked to immune responses observed in saliva.
The researchers measured salivary stress markers and found that while cortisol and α-amylase levels did not change, β-lactolin maintained higher salivary IgA levels.
They suggested that findings indicate a potential link between IgA levels and improved mood and stress relief.
Changes in the gut microbiome, particularly the Actinobacteria phylum and Bifidobacterium genus, were also observed, possibly influencing mood via gut-brain interactions, the authors hypothesized.
They reported that baseline mood states correlated with salivary linoleic acid metabolites and prostaglandins (PGs) and found that certain salivary PGs and linoleic acid metabolites were positively correlated with anxiety and stress, supporting a possible new, noninvasive way to assess mental health disturbances.
Subgroup analysis revealed that individuals between the ages of 45 and 54 experienced significant stress reduction and decreased salivary PGD2 and PGF2α levels, suggesting that β-lactolin's anti-inflammatory effects may contribute to these improvements.
In contrast, participants between the ages of 55 and 64 showed increased fecal short-chain fatty acids (SCFAs) and changes in Bacteroides abundance, pointing to an age-related variation in β-lactolin's effects.
The researchers suggested that gut-brain interactions or immunological pathways might also be involved, noting that increased cerebral blood flow in the dorsolateral prefrontal cortex, as seen in previous studies, may contribute to anxiety and stress improvements.
The study called for future research to explore mechanisms involving dopamine and cerebral blood flow.
Source: Sci Rep 14, 23444 (2024)
doi: 10.1038/s41598-024-73780-3
“Supplementation with whey peptide rich in β-lactolin improves trait anxiety and subjective stress in healthy adults: a randomized, double-blind, placebo-controlled study.”
Authors: Ayabe, T. et. al