Writing in the journal Nutrients, researchers from the Federal University of São Paulo, Brazil reported that supplementation with a combination of probiotics preserved vigor and total mood disturbance in a sample of 14 male marathon runners. Additionally, blood samples revealed that the supplement improved inflammation.
“The decrease in LPS concentration in the probiotic-supplemented group mediated the change in the pro/anti-inflammatory balance, indicating a possible immunometabolic mechanism by which the gut-brain axis impacts mood regulation after strenuous exercise,” the researchers wrote.
The new study adds to the body of evidence suggesting that strenuous exercise may be detrimental to mood and is mediated by the gut-brain axis.
Exercise and mood
The researchers noted that while studies show that exercise benefits mood in healthy and depressed individuals, recent research links strenuous exercise, such as marathon running, to impaired mood. The mechanisms involved include neurophysiological changes such as serotonin and cortisol levels, dehydration, low blood sugar and increased inflammation, they added.
Animal research suggests a U-shaped relationship between exercise load and brain health, with moderate exercise improving brain structures and very high-intensity exercise causing mental fatigue and other adverse effects.
Exhaustive exercise can also alter the microbiota profile, causing dysbiosis, worsening symptoms in digestive disorders and adversely affecting the gut-brain axis.
The researchers hypothesized that probiotics may mitigate the undesirable effect of strenuous exercise on mood, reflecting previous research indicating that probiotics improve the inflammatory response in athletes.
Study details
The double-blind, placebo-randomized study evaluated the effects of consuming either the multi-strain probiotic or placebo daily for 30 days in a group of 14 male marathon runners between the ages of 30 and 45 . The probiotic supplement contained Lactobacillus acidophilus, Lactobacillus lactis, Bifidobacterium lactis and Bifidobacterium bifidum strains.
At the end of the supplementation period, the runners participated in a marathon during which they consumed a carbohydrate drink at intervals.
The researchers assessed mood using the Brunel Mood Scale, collected blood samples before and after the marathon and profiled the participants' diets throughout the study.
Compared to placebo, the supplement preserved the vigor and total mood disturbance post marathon and improved the pro/anti-inflammatory balance indicated by the interleukin (IL)-2 to IL-4 ratio and by a reduction in lipopolysaccharides (LPS) after the marathon.
"These results deserve to be highlighted for their novelty, including the combination of probiotics, the time of supplementation, the population studied and the context of the study, which enhances our understanding of the relationship between the gut and the brain," the researchers wrote.
They called for further studies with larger sample sizes that include both sexes and research into how probiotics affect mood in other types of exercise.
Source: Nutrients 2024, 16(21), 3761
doi: 10.3390/nu16213761
“Protective effects of probiotics on runners’ mood: Immunometabolic mechanisms post-exercise.”
Authors: E. Tavares-Silva et al.