Research shows that gut bacteria plays a significant role in everything, from mental health to physical well-being.

You've heard it before, "you are what you eat." Well, science is increasingly confirming that this adage holds true, especially when it comes to the impact of our gut microbiome on our overall health. 

From the very young to the old, from pregnancy to Alzheimer's to cancer, your gut health plays an important role in your overall health.

"There is a natural abundance of the good and the bad bacteria there living together," USF Institute for Microbiomes Neurosurgeon Hariom Yadav said.

New research out of Harvard found that gut bacteria produces a hormone called Allopregnanolone. This hormone is made naturally by the body during pregnancy.

Low levels are linked to postpartum depression and other mental health issues including cognitive decline, depression and anxiety.

Altered gut bacteria may also play a more important role as we age.

"The bad guys grow much faster than the good guys. The microbiome is very different in the people who are a high risk of developing dementia," Yadav said.

A new study from Washington University School of Medicine suggests that gut bacteria may play a role in the early stages of Alzheimer's disease.

"Our hope is by offering or correcting the microbiome abnormalities early enough will delay or prevent the cognitive decline or dementia progress," Yadav said.

But our microbiomes are not all bad, they can also help in the fight against cancer, as researchers at UT Southwestern Medical center learned.

New research is also showing the imbalance of good and bad gut bacteria caused by eating too many processed foods.

Sugar and alcohol may also contribute to several inflammatory conditions such as heart disease, arthritis, lupus and inflammatory bowel disease.