Gut Bacteria Benefits: How to Improve Digestive Health - Dr. Axe

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Gut Bacteria Benefits: How to Improve Digestive Health From Within


Gut bacteria - Dr. Axe

A lot of someone’s health can be traced to the gut — specifically gut bacteria.

In the 1670s, scientist Antony van Leeuwenhoek first discovered the complex world of bacteria. At the time, he defined it as “free-living and parasitic microscopic protists, sperm cells, blood cells, microscopic nematodes and rotifers,” according to the University of California Museum of Paleontology.

Fast-forward to today (some 350-plus years later), and bacterial microbes are still at the forefront of medical research. This includes the trillions that live inside our guts and communicate directly with neurons in our brains. This incredible finding is known as the gut-brain connection.

Globally, millions of dollars are invested in gut research annually. These studies are geared toward uncovering more about how the human “microbiome” works.

Improving patients’ gut bacteria continues to prove to be an important consideration in neuroscience, diabetes and cardiovascular disease prevention. It’s even important in tackling obesity, and that’s not all.


What other conditions are greatly influenced by one’s gut bacteria? As you’ll learn, among the many are inflammatory bowel diseases (IBD), depression, anxiety, autoimmune disorders and symptoms of ADHD.

The World of Bacteria Living in Your Gut

The human microbiome, or microbiota, is essentially the bacterial ecosystem living within our bodies, mostly within our guts. The intestinal microbiota is made up of trillions of microorganisms, most of which are bacterial and not harmful to our health.

Scientists have recognized for more than 100 years that bacteria in the gut are constantly communicating with neurons in the brain, earning the microbiome the nickname ” the second brain.”

Not only do most gut bacteria not sicken us, but they are actually beneficial, vital to our health and play numerous roles. Factors such as genetics, age, sex and diet continually influence the composition and profile of an individual’s microbiota. That means no two people’s gut bacteria are quite the same.

What do our gut bacteria do exactly, and how? Roles of gut bacteria include:

  • Helping produce hormones, like serotonin, for example
  • Aiding in the extraction of energy (calories) and nutrients, including vitamins, minerals, amino acids, fatty acids and antioxidants
  • Managing our appetite and body weight
  • Digesting fiber, which helps form stool
  • Controlling our moods, motivation and cognitive health
  • Preventing us from catching colds and viruses
  • Helping repair damaged tissues and injuries
  • Much, much more

One of the most important things that “good bacteria” (also known as probiotics) living in the microbiota do is contribute to our immune systems. This protects us against pathogen colonization and invasion of harmful microbes that enter the body every single day.

So where do things wrong? Alterations in the microbiota (often called dysbiosis) can result for many reasons. Some of the most common are:

  • exposure to various environmental pollutants and toxins
  • consuming a poor diet lacking anti-inflammatory foods
  • using toxic medications and over-the-counter drugs
  • smoking cigarettes
  • high amounts of stress
  • exposure to harmful pathogens from other people who are sick

Gut Bacteria Benefits

“Poor gut health” might bring to mind intestinal and digestive disorders — including inflammatory bowel disease, irritable bowel syndrome (IBS) and celiac disease symptoms — but these are far from the only problems tied to dysbiosis. Studies show that dysbiosis of the gut microbiota is associated numerous disorders that affect us internally.

Some of these include altered hormone production, which might not always be obvious, and also externally (affecting us in more apparent ways, such as changing the appearance of our skin and body weight).

A lack of healthy gut bacteria is now tied to the onset of conditions like:

  • Food allergies
  • Asthma
  • Diabetes
  • Arthritis
  • Fibromyalgia
  • Eczema and psoriasis
  • Poor recovery from seizures, spinal cord injuries or a stroke
  • Metabolic syndrome and cardiovascular diseases (currently the number one cause of death in many industrialized nations).

Autoimmune Diseases

Recently much more has been uncovered about how bacterial species residing within the mucus layer of the colon have the ability to directly communicate with host cells in the immune system. This relationship can influence whether or not the immune system remains at homeostasis or triggers inflammatory mechanisms that destroy the body’s own healthy tissue and cells.

Autoimmune disease symptoms — including diseases like multiple sclerosis, type 1 diabetes and rheumatoid arthritis — all have links to dysbiosis. In fact, we now know that pathogens entering the body through toxins and a poor diet have the potential to cause microbial disruption. This can trigger both local and systemic inflammation.

This inflammation then creates a vicious cycle because it alters the composition of the gut/microbiota, reduces the barrier that the gut naturally has with the rest of the body, decreases nutrient absorption, increases permeability (also called leaky gut) and causes numerous symptoms tied to autoimmunity. These symptoms can include skin reactions, indigestion, mood-related problems, joint pain and fatigue.

Although we have more to learn about probiotics’ effects on autoimmunity, research suggests that acquiring bacterial strains, including Lactobacillus casei shirota, can have positive effects on controlling inflammatory reactions.


A 2013 article published in the journal Cerebrum states:


The gut-brain axis—an imaginary line between the brain and the gut—is one of the new frontiers of neuroscience. Microbiota in our gut, sometimes referred to as the “second genome” or the “second brain,” may influence our mood in ways that scientists are just now beginning to understand. Unlike with inherited genes, it may be possible to reshape, or even to cultivate, this second genome. As research evolves from mice to people, further understanding of microbiota’s relationship to the human brain could have significant mental health implications.

Our brains contain billions of neurons, and these have a close working relationship with the trillions of “good” and “bad’ bacteria alive in the gut. Bacteria seem to be instrumental in how our brains develop, how we behave, our capabilities of handling stress and how we respond to treatments for mood-related issues, like depression and anxiety.

It’s been found that in stressful situations, the microbiota profile may actually change itself, shifting how different bacteria interact with one another. The gut-brain relationship basically comes down to how the immune system alters the nervous system.

A 2011 study published in the journal Nature showed that feeding healthy mice probiotics helped decrease anxiety-like and depressive-like behaviors compared to control mice. It also showed that activation of neurons in the hypothalamus (part of the emotional/fear center of the brain) were greater when mice were fed infectious bacteria that cause a destructive immune response.

Obesity and Weight Gain

Each year, the U.S. population spends more money on diets than the amount needed to feed all the hungry people in the rest of the world. We’ve all gotten the message by now that we should be eating less and moving more.

Less talked about? The need to take care of our gut health in order to manage our appetites, hormones and energy expenditure.

What does gut bacteria have to do with obesity, you might be wondering? Although the underlying mechanisms are still not entirely clear, obesity is known to be associated with chronic low-grade inflammation and hormonal changes that lead us to overeat:

  • Research suggests overeating and obesity might be tied to reductions in certain beneficial bacteria that populate a healthy microbiome. Certain studies have found that some obese individuals have higher levels of two major classes of bacteria — bacteroides and firmicutes. These can cause increases in inflammatory metabolic endotoxins, plus decreased mucus lining the intestinal wall and therefore more gut permeability.
  • The gut microbiota also contributes to retention of fat mass, and certain bacterial gut changes have been shown to reduce leptin sensitivity (meaning we feel satisfied less easily).
  • A study published in Endocrinology showed that, additionally, dysbiosis might result in reduced expression of obesity-suppressing neuropeptides proglucagons in the brainstem.

In studies using mice, researchers have found that introducing gut bacterial flora from obese mice into normal-sized mice results in increased obesity even with reduced calorie intake. The opposite also seems to be true: Introducing bacterial flora from lean mice into obese mice can help promote weight loss and appetite regulation.

Neurological and Spinal Cord Injuries

Researchers at Ohio State University found that disruption of the microbial community seems to hinder recovery from neurological damage and spinal cord injuries due to prolonged inflammation in mice.

Previous studies showed that spinal cord injuries in mice caused migration of gut bacteria into other tissues of the body and activation of pro-inflammatory immune cells. Mice that experienced the largest changes in their gut bacteria tended to recover most poorly from their injuries, especially if they were treated with antibiotics to further disrupt gut bacteria levels.

Fortunately, the opposite has also been shown to be true: When injured mice are given daily doses of probiotics to restore levels of healthy gut bacteria, they experience less symptoms related to spinal damage and regain more control over movement and daily functions.

Irritable Bowel Disease (IBD)

IBD is a term used to describe hard-to-treat disorders that cause bloody diarrhea, abdominal pain, cramping, and sometimes malnutrition and weight loss. Although treating IBD can be complicated and sometimes require various types of intervention, probiotics seem to help manage IBD symptoms (especially severe diarrhea) in many patients and can help with reversal of inflammation in the digestive tract.

Studies suggest that bacterial strains and a combination formula might be most effective in IBD treatment. If you haven’t been diagnosed with IBD but still have occasional digestive problems, such as diarrhea, bacterial strains including Saccharomyces boulardii and Lactobacillus GG can likely help.

How to Improve Gut Bacteria

Even if you don’t necessarily suffer from one of the disorders or diseases mentioned above, you can still benefit from improving gut health. Considering the average person eating a “westernized/American diet” doesn’t ordinarily consume many probiotic foods (plus likely lacks at least several nutrients key to gut health, including prebiotics and fiber), most of us can afford to make some dietary and lifestyle changes.

What are common signs of gut bacteria imbalance? These can include:

  • Frequent digestive issues, like bloating, gas, acid reflux, constipation and diarrhea (especially if stool ever appears bloody or causes unexplained weight loss)
  • Acne, mild skin rashes and other signs of skin inflammation
  • Frequently getting colds, viruses and other “common” illnesses
  • Stuffy nose, respiratory infections and trouble breathing
  • Low energy levels and fatigue
  • Achy joints and muscular pains

Here are simple steps you can take now to start improving gut bacteria:

  • Consume probiotic foods, such as yogurt, kefir, cultured veggies and kombucha. Also consider taking a high-quality probiotic supplement.
  • Avoid common allergen foods, which can make poor gut health even worse. These include conventional dairy, shellfish, peanuts, soy and gluten products. Processed/packaged foods, fried foods and too much added sugar might also worsen gut health (not to mention cause other issues), so work on reducing these as well.
  • Eat plenty of fiber and prebiotics, which help probiotics in the gut thrive.
  • Quit smoking, and reduce alcohol intake to moderate levels.
  • To avoid dangers of antibiotics, only take them when absolutely necessary. Antibiotics can wipe out both good and bad bacteria in the gut.
  • Vary your protein intake. It’s been found that high consumption of animal products and very high-protein diets might contribute to carcinogenic metabolites forming in the microbiota that alter immunity. Rather than making meat, eggs or cheese the center of all your meals, try to focus on variety and eating more plant foods for protein, like soaked beans, nuts, seeds and legumes.
  • Reduce toxin exposure in your home by using natural cleaning products. The same goes for beauty or skin care products. Try switching to natural skin care ingredients like coconut oil, which don’t contain harsh chemicals. Avoid antibacterial soaps, too.
  • Exercise, and manage stress to keep inflammation levels low.
  • Introduce traditional gut-friendly foods into your diet, like bone broth, a great source of collagen, which helps rebuild the gut lining and prevent permeability.

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