By Dr. Mercola

All of your feelings create physiological changes, and stress is no exception.

While under stress, your heart rate can go up, your blood pressure may rise, and blood is shunted away from your midsection, going to your arms, legs, and head for quick thinking, fighting, or fleeing.

This is meant to be a temporary response to help with survival, but when stress becomes chronic, as it is the case for millions of people reading this, it can pull the rug out from beneath your health, wreaking havoc on your gut and digestive health.

The stress response causes a number of detrimental events in your gut, including:

But that's not all.

In a very real sense you have two brains, one inside your skull and one in your gut. Interestingly, these two organs are actually created out of the same type of tissue.

During fetal development, one part turns into your central nervous system while the other develops into your enteric nervous system.

These two systems are connected via the vagus nerve, the tenth cranial nerve that runs from your brain stem down to your abdomen.

This "brain-gut axis" is what connects your two brains together, and explains why you get butterflies in your stomach when you're nervous, for example.

Likewise, stress results in alterations of your brain-gut connection, which can contribute to or directly cause numerous gastrointestinal disorders, including:

As written in the featured Journal of Physiology and Pharmacology study:

"Stress, which is defined as an acute threat to homeostasis, shows both short- and long-term effects on the functions of the gastrointestinal tract … The major effects of stress on gut physiology include:

Mast cells (MC) are important effectors of brain-gut axis that translate the stress signals into the release of a wide range of neurotransmitters and proinflammatory cytokines, which may profoundly affect the gastrointestinal physiology."

Hippocrates once said that "all diseases begin in the gut," and it's also widely known that stress is a trigger that causes multiple chronic disease processes to occur. These two health dogmas are actually intricately intertwined, as stress is detrimental to your gut health, and together stress and a damaged gut can contribute to multiple inflammatory diseases and conditions, such as:

To put it simply, chronic stress (and other negative emotions like anger,anxietyand sadness) can trigger symptoms and full-blown disease in your gut. As Harvard researchers explain:

In addition, research suggests that some people with functional GI disorders perceive pain more acutely than other people do because their brains do not properly regulate pain signals from the GI tract. Stress can make the existing pain seem even worse." Interestingly, the connection works both ways, meaning that while stress can cause gut problems, gut problems can also wreak havoc on your emotions. The Harvard researchers continue:

If you're feeling stressed, it's therefore essential to realize that not only could this affect your gut health, it could be caused by your gut health, or more specifically, your lack thereof. Increasingly, scientific evidence shows that nourishing your gut flora with the friendly bacteria with fermented foods or probiotics is extremely important for proper brain function, and that includes psychological well-being and mood control. For instance, the probiotic known as Bifidobacterium longum NCC3001 has been shown to normalize anxiety-like behavior in mice with infectious colitis.i

Research published in 2011 also demonstrated that probiotics have a direct effect on brain chemistry under normal conditions -- in such a way that can impact your feelings of anxiety or depression. In short, the probiotic Lactobacillus rhamnosus had a marked effect on GABA [an inhibitory neurotransmitter that is significantly involved in regulating many physiological and psychological processes] levels in certain brain regions and lowered the stress-induced hormone corticosterone, resulting in reduced anxiety- and depression-related behavior.2 The authors concluded:

Interestingly, neurotransmitters like serotonin are also found in your gut. In fact, the greatest concentration of serotonin, which is involved in mood control, depression and suppressing aggression, is found within your intestines, not your brain!

The Harvard HealthBeat has compiled a useful list of physical, behavioral and emotional symptoms of stress. We're all exposed to stress virtually every day, but these signs signal that stress may have become overwhelming in your life, and could be increasing your risk of related health problems:

Physical Symptoms