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How does the gut-brain axis support mental clarity and alertness?

Probiotics for students to increase mental alertness

Probiotics can do more than support digestion, general health and wellbeing.  Specific strains can also enhance brain health and support mental alertness too. It is well established now that the gut and brain are connected, a fascinating partnership referred to as the gut-brain axis. While the brain can influence digestive activity, the gut can play a part in brain function and emotional wellbeing. This may be of particular interest to students and anyone else who relies on optimal cognitive function for learning, memory and information retention.

How does the gut-brain axis support mental clarity and alertness? 

The gut is sometimes known as the body’s ‘second brain’ since it can produce the same neurotransmitters as the brain does, including serotonin, dopamine and GABA (gamma-aminobutyric acid).1 These play a key role in brain function and how we think and feel. 90% of the body’s serotonin is actually produced in the gut not the brain.2 The gut microbiome is responsible for producing these gut neurotransmitters, or chemical messengers, many of which are involved in the process of learning. For example, serotonin helps regulate mood, sleep patterns, appetite and pain, dopamine plays a part in learning, concentration, memory, sleep, mood and motivation and GABA regulates brain activity to assist with concentration, irritability and sleep.3 Research has shown that taking specific probiotics, including Lactobacillus rhamnosus has been associated with improved cognitive performance in some people.4

How else can probiotics benefit students?

There is no doubt that the life of a student can often be a stressful one with exams, deadlines and thinking about the future. While a little stress can help you rise to the challenge, persistent stress can affect sleep, motivation and academic performance. Interestingly, gut bacteria have been shown to support a healthy stress response and reduce cortisol levels. This is particularly apparent with the probiotic strain Lactobacillus plantarum 299v. In a study of young students under examination stress, Lactobacillus plantarum 299v was shown to prohibit increased levels of the stress marker cortisol during the examination period.5 In another study, a multispecies probiotic was found to buffer against the detrimental effects of stress on cognition and improved working memory.6 Working memory is a crucial part of learning and is the part of short-term memory that allows you to retain information for a brief period while you’re doing something else.

What do I look for in a probiotic to support brain function and mental alertness?

To support mental focus, recall and clarity, emotional wellbeing and a healthy stress response, while you’re studying, it is important to look for a probiotic supplement that has the right strains at the right dose. Not all probiotics are created equal, especially when it comes to brain health. Lactobacillus rhamnosus (LGG®) and Lactobacillus plantarum 299v are two key probiotic strains that may help the gut brain axis connection for students, aiding with stress resilience and cognitive function.


  1. Strandwitz P 2018, ‘Neurotransmitter modulation by the gut microbiota’. Brain research, 1693, Pt B, pp 128-133
  2. Yano JM at al 2015, ‘Indigenous bacteria from the gut microbiota regulate host serotonin biosynthesis,’ Cell. Vol 161, no 2, pp 264-276
  3. Cleveland Clinic, 2022, Neurotransmitters, viewed 6 January 2023, <>
  4. Sanborn V et al, 2020, ‘Randomized Clinical Trial Examining the Impact of Lactobacillus rhamnosus GG Probiotic Supplementation on Cognitive Functioning in Middle-aged and Older Adults’, Neuropsychiatr Dis Treat, vol 16, pp 2765-2777
  5. Andersson H et al, 2016, ‘Oral administration of Lactobacillus plantarum 299v reduces cortisol levels in human saliva during examination induced stress: a randomized double-blind, controlled trial, Int J Microbiol
  6. Papalini S et al 2019, ‘Stress matters: Randomized controlled trial on the effect of probiotics on neurocognition’, Neurobiology of stress, vol 10 
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