Probiotics: the gut brain connection
By Dr. Madhavi Gupta, M.D.
Your intestinal microbiome is a collection of bacteria, yeasts, and viruses that live in your gut and do an enormous amount of work to keep you healthy. Among the many things your microbiome does are manufacturing vitamins (Vitamin D and Vitamin K), detoxifying environmental toxins, and helping our digestion and immune systems.
This vast gut ecosystem includes over 100 trillion bacteria! That’s about 10 times the number of cells in your body. That makes you about 90% bacteria and 10% human. The gut microbiome has a profound effect on your immune system. It’s estimated that the digestive system contains over 70% of your immunity. Two of the most prominent types of friendly bacteria are those belonging to the Lactobacillus and Bifidobacterium groups. One of the primary functions of friendly bacteria is to produce anti-inflammatory cytokines and down-regulate pro-inflammatory cytokines like TNF-alpha and IL-6. Pro-inflammatory chemicals can cause stress, negative immune responses, inflammation, and more. They can also lower levels of brain-derived neurotrophic factor (BDNF), which helps protect nerve cells.
In a study published in the American Journal of Clinical Nutrition, researchers found that oral administration of Lactobacillus plantarum daily for 6 weeks significantly decreased both markers of oxidative stress (37% reduction) and inflammation (42% decrease) in healthy men and women (1).
A growing body of evidence has shown two-way signaling between the gut & the brain. This includes multiple neuro and endocrine signal mechanisms. Changes to the gut microbiome affect brain health.
The feel-good neurotransmitter serotonin is also made in the gut. Many medications, not just antibiotics, can negatively alter your gut microbiome. Certain antivirals, antipsychotics, and chemotherapy drugs also had “antibiotic-like” side effects according to new research published in Nature (2).
Building and maintaining the proper amount of beneficial bacteria (e.g., probiotics) is crucial for a number of reasons. Once in the gut, probiotics are free to colonize and spread their health-boosting functions, which include:
- Helps make serotonin
- Helps promote better digestion
- Supports a healthy gut-brain connection
- Supports healthy regularity
- Supports immunity
Again, we return to the importance of that “second brain” - that is the gut. There is a growing body of research suggesting the gut-brain axis’ significance in brain health and performance. With that in mind, it’s a very good idea to consume 1- 2 servings of probiotic-rich foods daily, including the following traditionally fermented options:
- Dairy with live, active cultures (e.g., yogurt, kefir)
- Fermented vegetables (e.g., pickles, sauerkraut, kimchi)
- Tempeh, miso, soy sauce
- Kombucha tea
- Probiotic supplements
Probiotics supplements are particularly beneficial, especially if they are in a delayed-release capsule. The delayed-release capsule allows the probiotic bacteria to bypass the stomach, where most of them are killed in the harsh stomach acid. The capsule travels to the small intestines, where the bacteria are released and can do their important work.