Digestive diseases and disorders are more prevalent these days.

In fact, recent studies show more people have celiac disease or inflammatory bowel disease now than 50 years ago. What’s more, scientists have confirmed it’s not just due to improved methods of diagnosis. So why are these digestive problems on the rise?

No clear cause has emerged, but one leading theory is the hygiene hypothesis. In the quest to eliminate bacteria from our lives (think about all of the hand sanitizer and anti-bacterial soap on the market), our immune systems may be underdeveloped. So now, when the immune system encounters a safe food—take gluten, for example—it can mistakenly attack it as a foreign invader.

The widespread fear of bad germs means our digestive tracts also house fewer healthy bacteria.

One main function of these good bugs is to provide a protective barrier, preventing true invaders from leaking through the digestive tract into the body.

The Microbiome in a Healthy Gut

Together, the beneficial bacteria and fungi that live in our gut are called the microbiome. In 2008, The National Institutes of Health (NIH) launched the Human Microbiome Project (HMP), which mapped out the microbiomes of healthy volunteers. Through this research, we are learning how certain gut bacteria influence mood and behavior, may improve blood pressure, and can potentially reduce childhood allergies. Some gut microbes can actually regulate weight gain, so current studies are investigating how the microbiome influences obesity.

The gut is similar to a rainforest in its diversity as well as its fragility. Despite not knowing exactly what a healthy microbiome looks like, we do know that a microbiome with more diversity is better able to cope with stressors, such as illness and disease. A major shift in an individual’s microbiome can throw off the whole ecosystem. An imbalance in the microbiome, called dysbiosis, can result in chronic inflammation in the body. Obesity, cardiovascular disease, diabetes, and possibly Alzheimer’s disease have all been linked to chronic inflammation.

The Gut-Brain Connection

The intestinal tract is also home to the enteric nervous system (ENS), the operating center for the digestive system. The same neurotransmitters in the brain are also found in the intestinal tract. The ENS can work independently, or in conjunction with the brain. You may have already experienced how the brain can cause digestive upset. For example, you receive devastating news and you immediately feel nauseous or have diarrhea. Now we know the gut can in turn upset the brain. This connection is known as the gut-brain axis. So if you or someone you know is experiencing digestive issues, what can you do?