Probiotics can do more than improve your gut health. They also may indirectly enhance your brain. The gut has been called a second brain because it produces many of the same neurotransmitters as the brain does, like serotonin, dopamine, and gamma-aminobutyric acid, all of which play a key role in regulating mood that includes the feeling of stress and anxiety. It is estimated that 90% of serotonin is made in the digestive tract.
What are Stress and Anxiety?
Stress is a normal reaction to everyday pressures, but can become unhealthy when it upsets your day-to-day functioning. Stress involves changes that affect nearly every system of the body, influencing how people feel and behave. Stress can be defined as any type of change that causes physical, emotional, or psychological strain. Stress is your body’s response to anything that requires attention or action. Everyone experiences stress to some degree. The way you respond to stress, however, makes a big difference to your overall well-being.
Anxiety is an emotion characterized by feelings of tension, worried thoughts, and physical changes like increased blood pressure. It is not the same as fear, but they are often used interchangeably. Anxiety is considered a future-oriented, long-acting response broadly focused on a diffuse threat, whereas fear is an appropriate, present-oriented, and short-lived response to an identifiable and specific threat.
Brain and Gut Connection
The brain and gut send signals to each other through the vagus nerve, which is part of our central nervous system. This communication not only regulates stress response and anxiousness, but the gut even makes and then sends neurotransmitters such as serotonin and dopamine along the vagus nerve to the brain. If the gut microbiome is unhealthy then this communication system may not work well and you may have increased levels of anxiety.
How do Probiotics Help Reduce Stress and Anxiety?
Certain probiotic strains appear to exert a positive influence on our mood. These strains of friendly bacteria are sometimes referred to as psychobiotics. Specific probiotic strains that have been researched for their effects on stress and anxiety include:
- Bifidobacterium longum 1714
- Lactobacillus acidophilus Rosell-52 and Bifidobacterium longum Rosell-175
- Lactobacillus casei Shirota
Firstly, certain probiotics can produce neurotransmitters in the gut or impact the body’s ability to produce neurotransmitters, including GABA (Gamma-Aminobutyric Acid), serotonin, and dopamine. Neurotransmitters are chemical messengers responsible for transmitting information within our nervous system. These substances are secreted within the gut where they influence nerve cell signaling which affects the information transmitted to our brain. This directly affects our brain chemistry and function, subsequently altering our behavior and mood.
Serotonin is sometimes referred to as our happy or feel-good chemical as it lifts our mood. Certain types of pharmaceutical anti-depressants target serotonin signaling in the brain as a means of combatting depression. If serotonin is our happy chemical, then GABA is our chill or relaxation chemical. It is responsible for a state of calm and GABA signaling is often disturbed in those who suffer from anxiety. Approximately 90% of our serotonin is produced in the gut, and our gut microbes play an important role in its production. This is one connection between gut health and mood.
The second way in which ‘psychobiotics’ can influence our state of mind is via their impact on the hypothalamic-pituitary-adrenal axis (HPA axis). The HPA axis makes up the body’s stress response system and orchestrates our hormonal response to physical or psychological stress. When dysfunction occurs in the HPA axis, our daily rhythmic production of cortisol and other stress hormones become disrupted which can result in feeling stressed, altered mood, and disrupted sleep.
Scientists are still some way off from understanding the full impact of different strains of probiotic bacteria on our moods. Research is ongoing in this area, but it will most likely be quite some time before we are equipped with a list of the best strains of probiotics to support mental well-being.