Microbiome: What It Is and What It Does

First, let’s define our terms: your microbiome is the collective term for all the bacteria that populate your gut—all 100 trillion of them. Even though your microbiome is not technically “you,” it’s so important to your body’s function that it’s been characterized as another organ.

Your microbiome acts like an army, protecting you against foreign invaders (pathogenic bacteria, parasites, etc). It also helps to educate your immune system about the difference between friend and foe, making it very important to mitigate against and prevent allergies and autoimmunity.

Your Gut: Another Brain?

About 80% of your serotonin is produced in your gut, so it’s not terribly surprising that gut inflammation and leaky gut syndrome can affect your mood. I’ll certainly attest that a large percentage of my patients with increased intestinal permeability also suffer from either depression or a certain type of “overthinking” anxiety—the perfectionistic, overanalyzing kind characteristic of too little serotonin (and therefore, too much dopamine).

Since leaky gut pretty much means you’ve got an imbalance in good gut flora, at least indirectly it makes sense that there would be a connection between mood and a healthy microbiome.

But there’s now evidence that prebiotics (the food for the probiotics, or good bacteria in your gut) can directly affect your mood, decreasing anxiety and depression and modulating the stress response.

Prebiotics and Your Stress Response

This study was conducted with 45 healthy patients between 18 and 45, and they were given either a prebiotic or a placebo each day. At the end of three weeks, volunteers were given a task to assess psychological bias toward optimism or pessimism, and salivary cortisol levels were sampled.

Test subjects who ingested the prebiotics were significantly more positive, and had lower salivary cortisol than did the test subjects who ingested the placebo.

What this means: cortisol isn’t bad, but you want to have neither too little nor too much. Too much is considered an early stage of adrenal fatigue, characterized by irritability, as well as high blood sugar (tending toward metabolic syndrome and diabetes), weight gain especially in the trunk area, recurrent infections – since your immune system is suppressed, and insomnia.  Too much cortisol also inhibits the conversion of inactive to active thyroid hormone, which can lead to hypothyroidism.

Bottom Line:

If you suffer from anxiety or depression, even if you don’t also have any gut symptoms, make sure you keep your microbiome healthy. Some steps you can take:

  • Avoid eating processed junk foods. Choose real foods whenever possible, and eat plenty of raw foods. This will help to replenish the microbiome.
  • Unless you eat a whole lot of fermented foods and avoid agriculture industry animal products and antibiotics, you almost certainly need a daily probiotic. Choose one that’s 10-20 billion organisms daily, and (pending more research on specific microorganisms), for most Westerners the ratio should be about half from the bifidobacillus family, and half from the lactobacillus family.

If you’d like to try a good probiotic that meets the criteria listed above, this is one of my favorites.