What if millions of tiny beings lining your digestive tract were controlling much more than the direction of your food? A walk through your local health food store quickly shows the extent to which misinformation and confusion around gut health abound — you see hundreds of choices for prebiotics, probiotics, fermented foods and more claiming to help protect you from cancer, depression and everything in between. But do they work? And is the gut really that powerful?
The elusive and mysterious study of the microbiome (the bacteria and other microorganisms that live in our bodies) and the potential powers our gut health holds, is one area doctors still have much to learn about ― even those who study it every day. Experts themselves say they have just scratched the surface in their understanding of how gut health affects the rest of the body and mind.
Ashkan Farhadi, a gastroenterologist at MemorialCare Orange Coast Medical Center and director of MemorialCare Medical Group’s Digestive Disease Project in Fountain Valley, California, cautions against focusing on any one study or company that claims make conclusions about gut health.
“Unfortunately, our understanding of their importance and function is lagging way behind what is advertised in the media. For example, we are dealing with a whole spectrum of species of germ in the gut but only have antibiotics that kill almost all germs indiscriminately,” he said, adding that it’s really not surprising that even experts in the field even have “no idea” about the importance and function of germs.
Here are a few areas they are hoping to learn more about in a growing body of evidence that gut health may be key to overall health.
How rapidly the balance in our gut can change
Can we give our gut health a “makeover” in just a day, rather than a whole year of eating differently? Possibly, Farhadi said, noting that experts are working to understand the dynamic nature of the microbiome.
“With one full day of a specific diet, it can change. With putting someone through stress, the germs’ composition could change,” he said.
The fact that gut bacteria can change so quickly is what makes it hard to pin down, but that also gives experts hope that controlling these changes can improve other medical conditions.
The impact of gut health on weight
Experts are also trying to understand more about the connection between gut bacteria and weight. For example, one study published in September looked at stool and blood samples of people who had lost weight (and controlled for factors like age, sex and body mass index). Researchers found a connection between the person’s microbiome and weight loss. Specifically, the microbiomes of the weight-loss group seemed to have an increased number of genes that sped up the growth of beneficial gut bacteria.
Therefore, the study authors concluded, diet alone might not be the only factor contributing to weight loss. “Your gut microbiome can help or cause resistance to weight loss and this opens up the possibility to try to alter the gut microbiome to impact weight loss,” lead study author Christian Diener, a scientist at the Institute for Systems Biology in Seattle, said in a statement.
Other studies have also pointed to the microbiome’s impact on weight loss. Rudolph Bedford, a gastroenterologist at Providence Saint John’s Health Center in Santa Monica, California, said this doesn’t mean that focusing solely on gut health will lead to weight changes. But he does believe it plays some role ― especially when it comes to weight-related illnesses like diabetes.
“[Our microbiome] may help in controlling blood sugar, and may affect the risk of you developing diabetes,” he said.
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Could our gut play a role in an overactive immune system?
The connection to autoimmune diseases
The triggers of autoimmune diseases can feel just as mysterious as the microbiome, and researchers are exploring how they might be linked.
Farhadi said the microbiome plays an important role in immune function. When there is stress in the body, it makes the intestines more permeable, giving bacteria more access to the immune system. This can alert the body that germs are nearby and activate an immune response. Scientists know this much. But it may go further than that.
“What if this is exaggerated? What if this turns into a vehicle that your immune system picks up and starts fighting itself, in autoimmune disease? Like Crohn’s disease, like inflammatory bowel disease, rheumatoid arthritis … maybe this is a mechanism for the mechanism to go haywire … for function to start not behaving.”
This is why he isn’t surprised that diseases such as rheumatoid arthritis are treated in part with probiotics. “We kind of crudely know that the gut and autoimmune processes can have some connection. … We want to work on that front.”
How gut health can shift mental health
Gut health experts are also studying how the microbiome can affect mental well-being.
“We don’t know much, but we have some evidence,” Farhadi said of the connection between gut health and mental health. “There are a lot of studies on the role of bacteria in depression, our moods, our confidence, and other studies that show when we go through stress, the composition of bacteria changes.”
Bedford said bacteria in the gut can produce chemicals and even serotonin, the feel-good hormone that helps stabilize mood. He said people with various psychological disorders can have different species of bacteria in their gut compared with others who don’t.
There’s more to learn, and much we don’t know: “We have trillions and trillions and trillions of bacteria,” Bedford said. “And only because we use so many antibiotics, so many processed foods now ― all of which affect the microbiome ― we are finding more and more things that occur when that microbiome is altered.”
In the meantime, here’s what to do to improve gut health
While we wait for answers on how the human body works (Bedford joked that we should call back in 10 years), experts are sure about a few positive gut-health moves you can make now:
Only use antibiotics when they are absolutely medically necessary Eat a wide variety of fruits, vegetables and whole grains Choose probiotics that contain Lactobacillus and Bifidobacteria. Don’t fall for claims on labels like, “contains 50 billion bacteria.” (Bedford said to remember you have trillions in your gut — “50 billion is a grain of sand on the beach.”) Get plenty of fiber in your diet by eating foods like legumes, beans and broccoli, among others. Eat fermented foods, which include yogurt, sauerkraut and kefir.