Your digestive system is a sophisticated boundary between you and the outside world. It allows you to break down and absorb all the nutrients you need from food while making sure toxins, poisons, dangerous bacteria, and viruses stay out.
Though these functions of the digestive system have been obvious to humans for centuries, it is only very recently that science has begun to understand how they really work, how complex their regulation is, and how far-reaching their effects on human health are.
Why is Gut Health So Important?
The majority of the progress in this field of research has come from advancements in technology. This allowed scientists to study the over one trillion bacteria that live in the human intestine. These bacteria are commonly referred to as gut microbiota or gut flora.
Understanding how they interact with intestinal cells has led to a remarkable shift in understanding not only how the digestive system works, but also how your digestive system affects the health of the rest of your body. Based on the current studies, we will explore seven reasons your gut health is important.
Contrary to the common-sense notion that what you eat determines what nutrients are available to your body, evidence now shows that it is your gut that ultimately determines the amounts of vitamins, minerals, and fuel that enter in your body.
Much of this shift in understanding has come from studies not looking at the intestines themselves, but at the gut microbiota. We now know that these bacteria play a fundamental role in determining which nutrients are available to the intestines and how well the available nutrients are absorbed.
Multiple studies show that your gut health helps prevent nutrient deficiencies by:
- Producing vitamins directly in the intestines for you to absorb, including vitamin K and the B-vitamins
- Producing fuel for the cells lining the intestines, to keep them absorbing nutrients at full capacity
- Communicating with the cells lining the intestines when and when not to grow and divide, and to keep the lining of the wall at the right thickness for optimal nutrient absorption
Studies also show that gut bacteria are able to break down normally non-digestible components of food into molecules that the body can use for fuel. Fascinatingly, some species of gut bacteria are better at converting non-digestible food to fuel than others. This means that, depending on the species of bacteria living in your intestines, you extract a different number of calories from the food you eat.
Studies indicate that individuals with an unhealthy gut microbiota absorb hundreds of calories more than people with a healthy one, from the same exact meal. Such studies indicate that having good gut health can help you maintain a healthy energy balance and avoid weight gain.
Having good gut health can promote regular bowel movements. Strong, healthy muscles in the walls of the intestines are able to contract more efficiently, pushing food through the intestines more quickly.
A healthy gut microbiota has also been shown to help coordinate the contractions of the intestinal walls, helping move food through the gut at a healthy rate.
Regular bowel movements are vital to protecting your overall health. Not only do they prevent the pain and bloating associated with constipation, they dramatically reduce your risk of developing two serious conditions:
- Hernias. Straining to pass the hard, dry stools caused by irregular bowel movements puts you at serious risk for developing a hernia. A hernia occurs when an intestine or other organ pushes through the wall of your abdomen or diaphragm. This is not only debilitatingly painful but may also become life-threatening.
- Cancer. Though occasional constipation likely has little effect, having irregular bowel movements for extended periods of time puts you at greater risk for certain types of cancer. This is because bowel movements are responsible for removing toxins and digestive fluids from your body, which can promote cancer.
Perhaps the most important cancer-causing molecules that build up in your intestines if you are constipated are bile acids. While you are supposed to have moderate amounts of bile acids in your intestines to help digest and absorb fat, high concentrations can damage your DNA, promoting cancer. Many studies show that when bile acids build up in the digestive tract, they can promote throat, stomach or intestinal cancer.
Additionally, if bile acids aren’t removed from the gut quickly enough, through regular bowel movements, they can be absorbed by the intestines and build up in the bloodstream as well. From there, they can promote cancer anywhere in the body, such as in the breasts or the pancreas.
It may not surprise you to learn that gut health affects the way your digestive tract wards off infections. Healthy intestines and gut microbiota perform complementary functions that prevent dangerous bacteria from getting into the wall of the intestines.
A healthy top layer of intestinal cells creates a physical barrier, keeping the dangerous bacteria out of the walls of the intestines. When the gut microbiota is healthy, it naturally kills off dangerous bacteria in the area by:
- Consuming nutrients that dangerous bacteria need to survive
- Producing natural acids to make the content of the intestines too acidic for infectious bacteria to survive
- Stimulating intestinal cells to produce natural antibiotics
Since the gut microbiota never comes into contact with bacteria living anywhere but the intestines, scientists were surprised to discover that a healthy gut microbiota also helps kill off infections in the rest of the body.
We now know that this effect is mediated by the ability of healthy gut microbes to boost the function of the entire immune system. Multiple studies have shown that a healthy gut microbiota increases the total number of white blood cells available to surveil your body for intruders.
Moreover, recent studies show that healthy gut bacteria also increase the ability of immune cells to kill their targets. A greater number of deadlier white blood cells provides a serious boost in immune function! In fact, evidence suggests that a healthy gut microbiota can increase your ability to fight off everything from a simple sinus infection or yeast infection to a life-threatening infection, like pneumonia.
A healthy gut microbiota may even boost your immune system enough to make vaccinations from your doctor more effective. Vaccines work by introducing a part of a dangerous bacteria or virus to your immune system so that it can recognize the whole bacteria or virus if it comes across it later.
A healthy microbiota boosts the ability of white blood cells to find and memorize these pieces, improving how well the vaccine can protect you. This has been proven for specific vaccines, such as the flu vaccine, but future studies may show that this effect is common for most vaccines.
Systemic inflammation describes a state where the immune system produces the chemicals it uses to fight an infection, even though there is none.
This can occur for many reasons, but one of the most common is having molecules in your blood that are usually there when you do have an infection, such as lots of cholesterol or sugar. If your immune cells see these molecules in your blood, but cannot find an actual infection, they become confused and start just releasing infection-fighting chemicals into your bloodstream.
Unfortunately, these chemicals can also damage your healthy cells if released in this unregulated way. Over long periods of time, damage to your healthy cells from these chemicals can lead to many of our most common chronic diseases, including:
There is convincing evidence that a healthy gut keeps immune cells from producing these chemicals when they are not needed. Good gut bacteria produce specific kinds of sugar complexes that can enter the intestinal wall and activate a group of white blood cells called Tregcells. Activated Treg cells send calming signals to the rest of the immune system, turning off the white blood cells producing the damaging chemicals.
An autoimmune disease is a condition where your immune system recognizes a normal molecule in your body as dangerous and begins attacking and killing any cell that contains it.
Scientists believe many autoimmune diseases develop when the immune system encounters a foreign molecule that happens to be very similar to one naturally found in your body. When the immune system begins destroying the bacteria or virus that brought the foreign molecule into your body, your healthy cells get caught in the cross-fire.
It has been established that your gut health plays a role in many autoimmune diseases, including:
- Crohn’s disease
- Ulcerative colitis
- Rheumatoid arthritis
- Type 1 diabetes
- Multiple sclerosis
Scientists believe that this is because good gut health minimizes the number of foreign molecules the intestinal immune cells come into contact with. The fewer foreign bodies the immune system sees, the less likely it is that one of them will happen to look like a structure in your body.
If you already have an autoimmune disease, a healthy gut may still be helpful for you. Evidence suggests that a healthy gut, specifically a healthy gut microbiota, can alleviate the symptoms of an autoimmune disease.
This is due to the ability of healthy gut microbes to activate the Treg cells mentioned above. Treg cells can turn off immune cells that are attacking your own cells, helping slow down the damage to your tissues and organs.
Now, let’s talk about how your gut health plays a crucial role in keeping your heart healthy. Studies indicate that a healthy gut can influence four of the most important risk factors for developing heart disease: high cholesterol, chronic inflammation, high blood pressure, and unhealthy trimethylamine (TMA) concentrations.
- High cholesterol. Elevated levels of cholesterol in the blood are the number one risk factor for developing cardiovascular disease. A healthy gut doesn’t absorb as much cholesterol out of the diet, lowering blood cholesterol levels.
- Chronic inflammation. The evidence clearly shows that chronic inflammation promotes cardiovascular disease. As mentioned above, a healthy gut helps prevent chronic inflammation.
- High blood pressure. A healthy gut can help lower your blood pressure. Scientists think this is due, at least in part, to effects of so-called short-chain fatty acids (SCFAs). These small molecules are made as byproducts when healthy gut bacteria break down fiber for their own energy needs. SCFAs have been shown to be able to increase the diameter of blood vessels and alter the hormonal function of the kidneys (which are the primary organs responsible for regulating blood pressure).
- TMA concentrations. Trimethylamine (TMA) is a product formed by some harmful gut bacteria when they break down choline, a natural nutrient found in many plant and animal foods. TMA can be absorbed through the intestines and enter the bloodstream. Unfortunately, TMA directly damages the walls of your heart arteries, making you more susceptible to developing heart disease. A healthy gut microbiota contains no harmful bacteria that produce TMA.
Together, these effects of gut health may have the power to drastically reduce your risk of developing heart disease.
The final, and perhaps most unexpected benefit of a healthy gut is a healthy brain. There is now overwhelming evidence that a healthy gut protects against many mental conditions, including:
Scientists still know little about the mechanisms coupling gut health to mental health. One of the most promising theories is that SCFAs made by healthy gut microbes are able to send signals to the brain improving your mood and cognition.
We know that some SCFAs are able to directly activate the parasympathetic nervous system. This is a branch of the autonomic nervous system, which controls body functions you are unaware of – breathing, heart rate, body temperature.
Changes in parasympathetic signals to the brain can change hormone levels in the brain to regulate functions like appetite. Further research is being conducted to determine if a similar mechanism may be able to regulate mood and cognition as well.
Take Away Message
Recent scientific studies into the nature of the gut and the gut microbiota have revolutionized our understanding of how they work, and how they interact with the rest of the human body.
We now know that having a healthy gut benefits nearly every aspect of your health. Having good gut health can help protect you from everything from nutrient deficiencies and constipation to obesity, diabetes, autoimmune diseases, infections, heart disease, depression, anxiety, and cancer.