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Key points
- The gut is called "the second brain" because it is wired similarly to the brain, with neurons and neurotransmitters.
- Nutrition, medications, and alcohol can all change your gut microbiome health.
- A balanced gut microbiome can help reduce anxiety and depression and improve the immune system.
- Sleep keeps your gut bacteria healthy, and an imbalanced microbiome can disrupt sleep.
A recent review of research in Frontiers in Neuroscience examines the relationship between the bacteria living in your gut and psychological issues including mood and anxiety disorders. Here are 8 key takeaways on the link between the gut microbiota and brain axis and its role in brain disorders.
1. Microorganisms in the gut outnumber human cells in the gut by 10 to 1.
Scientists have estimated that the number of microorganisms that live in the intestine outweighs human cells at a ratio of 10 to 1. The intestine has a community of microbes or "microbiota" of between 1,000 to 1,500 bacterial species that changes and evolves over time. Optimally, the gut is both diverse and abundant in microbes, with a balance of five types of bacteria: Firmicutes (80 percent), Bacteroidetes (17 percent), Actinobacteria (3 percent), Proteobacteria (1 percent), and Verrucomicrobioa (0.1 percent). When the gut microbiome is healthily balanced, it is in a state of "eubiosis."
2. Your gut is called the "second brain" because it has such an important role in brain-based disorders like anxiety and depression.
The gut has its own nervous system called the "enteric nervous system" which communicates in the same way as your brain and central nervous system—with neurons and neurotransmitters. Every microorganism has a different effect on the enteric nervous system. The vagus nerve, which is influenced by stress, is also connected with the intestinal cell system—this has led researchers to believe it may be an important link between the brain and gut or "brain-gut axis." Certain types of gut bacteria produce neurotransmitters like serotonin, dopamine, norepinephrine and GABA which can enter the bloodstream and affect brain function.
3. Changing what you eat can improve your gut microbiome in as little as 3 days.
What you eat plays a very important role in maintaining and developing a healthy and balanced gut microbiome. The microbiome will change according to what you eat in as little as 3 days. When the composition and diversity of the gut microbiome becomes imbalanced, the problem is called gut "dysbiosis." Restrictive fad diets can reduce the diversity of the bacteria living in the gut. Intermittent fasting can inadvertently lead to the selective overgrowth of certain species of bacteria.
4. Particular strains of bacteria have been linked with reducing anxiety and depression.
Two classic examples of bacteria that has been show to reduce anxiety include Lactobacillus rhamnosus and Bifidobacterium longum NCC30001. In animal studies, a probiotic mix of Lactobacillus rhamnosus and Lactobacillus helveticus reduced symptoms of depression and anxiety.
5. Sleep and your gut microbiome are interconnected. Good sleep keeps your gut microbiome healthy. Overgrowth of certain bacteria can lead to interrupted sleep and disrupted circadian rhythms.
Both fragmented and disrupted sleep as well as not getting enough sleep have been associated with gut dysbiosis. Overgrowth of specific gut bacteria can also lead to metabolites that disrupt sleep and the circadian rhythm. Probiotic supplementation has been found to improve sleep quality.
6. Drinking excess alcohol negatively impacts your gut microbiome and can lead to a "leaky" gut.
Research studies have shown that drinking alcohol changes the bacteria living in your gut. Drinking alcohol can lead to increased inflammation in the gut as well as making the gut lining more "leaky" or permeable. Drinking too much alcohol over time can lead to the overgrowth of certain bacteria and gut dysbiosis.
7. Taking medications like antibiotics changes your gut microbiome.
When you take antibiotics to treat infections, this will lead to helpful "good" bacteria in your gut being targeted as well. Reestablishing your microbiome after an antibiotic treatment can be helpful using probiotics as well as diverse foods.
8. Your microbiome is essential for a healthy immune system.
Studies of "germ-free" animals have shown that not having any microbes in the gut actually leads to problems with the immune system. Dysbiosis has been linked to health issues including obesity, type 2 diabetes mellitus, hypertension, and many types of inflammatory bowel diseases, such as irritable bowel syndrome.
A healthy gut microbiome is essential to both your psychological and physical health.
Marlynn Wei, MD, PLLC Copyright © 2021
