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You know the feeling of butterflies in your stomach? Or that hollow feeling when you get called into the boss’s office?
I get that feeling every time before I step on the stage before giving a speech to a live audience.
It’s a natural reaction.
The truth is your brain has a direct effect on the stomach and vice versa.
This link is so powerful that your mental or emotional issues could be the cause of your stomach problems. Or you can flip the script and your stomach or intestinal problems can actually be the cause of your brain fog, stress, anxiety or depression.
This is known as the gut-brain connection.
And mastering it through the millions of microbes in your gut can be the key you're missing to controlling your emotions and mental energy.
HOW THE GUT-BRAIN AXIS (AKA CONNECTION) WORKS
Most people believe that the brain is the single most important organ that controls our every feeling, thought, and action in the human body.
But in recent years scientists have discovered the brain in your head might not be the only one you have...
It turns out your gut is home to millions of neurons that can make many of the same neurotransmitters and enzymes as the neurons in your brain.
When you get butterflies in your stomach, or feel strong emotions like excitement or fear, that sensation comes from the link between the brain and the gut.
This link is made in part by the Vagus nerve (the physical link between gut and brain), but it's also made by the billions of microbes in your small intestine.
Your gut bacteria, or microbiome, is estimated to weigh in at around 3 pounds -- the same size as a human brain. Hundreds of strains of organisms and bacteria make up this diverse "rainforest."
A constant biochemical balancing act is happening at all times along the Gut-Brain axis. This balance influences our central nervous system, our immune system, our hormones, and more.
I mentioned the gut-brain connection is still in its infancy. Just think, one of the leading organizations called The Human Microbiome Project was established just one decade ago in 2008! 
We still have so much to learn about the Gut-Brain Connection, but already know that the gut-brain axis is directly involved in:
- Development of the central nervous system and hormonal system in newborns
- Regulation of immune response
- Production of essential vitamins and hormones
- Control of cholesterol and glucose levels
- Production of neurotransmitters - substances responsible for communication between neurons. It is in involved in the production of serotonin, also known as the “happy hormone”. Some species produce GABA which is the main neurotransmitter responsible for inhibiting excitability of neurons.
- Production of chemicals responsible for growth and repair of neurons
Disruption of the microbiome is being associated with allergies; autoimmune diseases, such as arthritis and irritable bowel syndrome; metabolic disorders, including diabetes; as well as mental disorders.
The chronic inflammation associated with high levels of physical or mental stress has also been associated with the gut microbiome.
That's because high levels of stress increase the permeability of the gut which allows bacterial toxins to enter the blood stream – also known as leaky gut syndrome.
For decades we were dead set on fighting bacteria, but it turns out that these microbes, in the correct balance, are vital to our health and well-being.
WHY PROBIOTICS ARE NECESSARY FOR BRAIN HEALTH
By now I think you realize that there is a strong connection between your brain heath and your gut microbiome.
The correct diversity and composition of the microbiome is important to ensure that it works as it should. When it is out of balance it can be corrected through diet and probiotics to maintain health as well as prevent or treat disease.
Probiotics were defined by an expert group of the United Nations and the World Health Organization as “live microorganisms which when administered in adequate amounts confer a health beneﬁt on the host”. 
Probiotic use began in the 1980s where they were used to treat gut issues like diarrhea (especially after antibiotic use), bloating, constipation, irritable bowel syndrome.
But now we know that gut health isn't just limited to GI function and intestinal comfort.
The balance of your microbiome plays a direct role in how well your brain works, how you feel emotionally, and how you're able to handle stress on a daily basis.
Research has even shown that replenishing your gut with beneficial probiotics can help manage more serious mental conditions like depression, autism, schizophrenia and Alzheimer’s. 
For example, let's take a look at this recent scientific study.
PROBIOTICS IMPROVES COGNITION IN ALZHEIMER'S PATIENTS
Probiotic use was shown to significantly improve the memory and thinking of elderly persons with Alzheimer’s.
The study, published in 2016, used 60 patients with Alzheimer’s and divided them randomly into experimental and a control groups. They completed a standard mini-mental status test (MMST). Their metabolic status was assessed through basic blood tests for cholesterol, oxidative stress and markers of inflammation.
The experimental group was treated with a fermented, probiotic dairy product and the patients in the control group were given milk.
After 12 weeks the MMST scores of people who consumed the probiotic dairy product improved significantly from 8.7 to 10.6, and their metabolic health markers also significantly improved. 
Considering that this was a randomized, double-blind, controlled, these are some impressive results we can only hope to replicate in future studies.
GREATER THINGS TO COME
I believe that we are extremely close to unlocking the code of the microbiome.
Studies are coming out every year showing how crucial a healthy gut is to optimizing mental and physical health.
It's an incredibly complex subject, but when it comes to mastering the gut-brain axis for enhancing brain health and performance, a healthy gut is a sure indicator of a better-working brain.
We'll need a lot more large-scale studies before we will fully understand all the benefits of probiotics for the brain.
In the meantime the above study has demonstrated that mental status can be improved with the right probiotics.
The relationship between the gut and the brain might be one of the most important links for human health. And if we start thinking about our microbiome as a true "second brain" in the body, the all we have to do is nurture those healthy gut bugs and provide the right probiotics the gut needs to thrive and support optimal health.