There's a complex ecosystem deep inside your gut, home to trillions of bacteria armed with the power to help – or harm – you.
Kathleen Pender knew her gut was trying to tell her something. She just wasn’t sure what it was.
The 23-year-old Minneapolis woman had recently returned from a stay in Ghana, where she took antibiotics to treat a bout of food poisoning. Back in Minnesota, she soon developed severe, chronic diarrhea and abdominal pain.
A gut analysis performed by her doctor revealed the source of her problem: She was very low on “good bacteria.”
Trillions of microscopic bacteria live inside our intestinal tract, forming an elaborate network now believed to play a major role in combating disease, affecting metabolism and weight and even regulating mood.
The bacteria swimming around in our stomachs have the power to help or harm us, depending on how we treat them, explained Dr. Greg Plotnikoff, a physician at the Penny George Institute for Health and Healing in Minneapolis and author of “Trust Your Gut,” a book about how to deal with digestive problems.
“The gut is much more of a garden than a gutter,” he said. “Our mission is to be good gardeners.”
But scientists have only begun to understand the complicated ecosystem in our stomachs. Like the human genome and the brain before it, new technology is allowing medical experts to look inside our guts like never before. The National Institutes of Health funded a $173 million project in 2008 to map the “human microbiome.”
The Human Genome Project was complicated — after a decade of work, scientists were able to identify all the genes present in humans. But the microbes in our intestines are much more complex. These tiny organisms have 100 times more genes than we do.
“They are an integral part of our body,” said Dr. Alexander Khoruts, a gastroenterologist at the University of Minnesota. “They do all kinds of things in physiology and we’re just starting to understand this.”
Friends with benefits
Our bodies are covered — inside and out — with bacteria.
Some bacteria are out to hurt us, causing infections. Good bacteria, however, serve as bouncers that keep the bad ones in check.
For the most part, gut bacteria have a mutually beneficial relationship with their human hosts, explained Khoruts. “We give them a home and they, in turn, help digest foods.”
The foods we eat are broken down by enzymes produced by the bacteria. But many doctors say the kinds of food we eat can promote or stifle a diverse bacteria ecosystem in our guts.
For example, refined sugars are digested quickly in the small intestine and never reach the lower intestine, so the bacteria living there do not get fed.
“When the food industry processes foods for us, and predigests it for us and infuses it with simple metabolites like fructose and sugar, there’s nothing left for bacteria to do,” Khoruts said. “It’s all absorbed early on in the intestinal tract.”
Starved, the bacteria then either die or turn hostile, upsetting the balance of good and bad microbes. Doctors think that imbalance can leave us vulnerable to certain diseases.
Complex carbohydrates such as leafy vegetables and whole grains do not break down easily without help from bacteria in the lower gut. By consuming certain foods, we can help maintain a rich gut bacteria ecosystem, Plotnikoff said.