Right now, your digestive system is teeming with bacteria, fungi, viruses and even parasites — they’re all part of the gut microbiome, which plays a bigger role in your health than you might imagine.
It may sound a bit alarming that trillions of microorganisms call your gut home if you’ve grown up thinking that all germs are bad. However, there are some “good” ones that actually protect your body from illness and disease.
Mahmoud Ghannoum, a researcher on the microbiome and professor in the department of pathology at Case Western Reserve University, tells Yahoo Life that the gut thrives on a variety of microbial species. If one type of bacteria cannot do its job, another species can step in and help out. Ghannoum compares the diversity of the gut microbiome to a diverse human society. Each element has its own role to play, but everyone works together to keep society moving forward.
A less diverse microbiome, or dysbiosis, can cause an imbalance between “good” and “bad” bacteria. When there’s more “bad” bacteria, your body is more prone to infection and disease. “The gut is becoming a central part of how we manage our health,” Ghannoum says. “If science keeps going in this direction, the way we practice medicine will be better, because we will have more preventative treatment, such as preventing certain diseases just by adjusting your microbiome.”
Here’s what you need to know about the effects of an unhealthy gut on your health, and how to keep both you and your gut microbes happy and healthy.
Why is it important to take care of your gut health?
The gut microbiome has many functions. It’s involved in:
Helping with digestion
Maintaining good brain health
Protecting against dangerous pathogens
Producing essential vitamins and nutrients
Helping with drug metabolism
Scientists have recently shed more light on how gut bacteria play a role in fighting chronic disease. A 2018 study published in the journal Urology found that men with prostate cancer were more likely to have an excess of a bacterial species called Bacteroides massiliensis than those who did not contract the disease.
Gut bacteria can also influence the success of cancer treatments. A 2022 study found that patients with melanoma who responded well to treatment were more likely to have the Lachnospiraceae species. Meanwhile, cancer treatment was found to be less effective in people with high amounts of the Streptococcaceae species.
Some gut microbes influence metabolism and inflammation. When there is a gut microbiome imbalance caused by an unhealthy diet and antibiotics, research suggests it could contribute to increased body weight.
Research also suggests that having less diverse microbiota in the gut may impair the immune response in the brain, contributing to an increased risk of inflammation and neurodegenerative disorders. Ghannoum adds that when the gut-brain connection changes because of a gut imbalance, it increases the risk for neurological conditions including Alzheimer’s disease, autism, multiple sclerosis, stroke and Parkinson’s disease.
What are the signs of an unhealthy gut?
Because the gut microbiome is involved in multiple bodily processes, an unhealthy gut can manifest in a variety of symptoms. Ghannoum says people often experience gastrointestinal symptoms such as:
Chronic abdominal pain
Other less obvious signs are changes in your behavior. A 2019 study suggests changes in gut bacteria can influence unhealthy food cravings, a person’s reaction to stress, and increase the risk of depression.
Nowadays, you can purchase tests using fecal samples to profile your gut bacteria in order to evaluate whether or not your gut is healthy. Dr. Arik Alper, a pediatric gastroenterologist and assistant professor of pediatrics at Yale School of Medicine, tells Yahoo Life that there is no official method of checking a healthy gut and recommends a certain skepticism of such tests.
How do you maintain a healthy gut?
Experts say there are several ways you can protect your gut health. Here's how:
No. 1: Eat more fruits, vegetables and fiber in general
One way to supercharge your gut is by changing what you eat. Gut microbes need nutrients to survive, and a healthy diet is a major component in shaping the microbiome. A 2019 review suggests that eating foods high in animal meat, saturated fat, sugar and salt increase the number of “bad” bacteria and harm the growth of “good” bacteria.
On the flip side, eating leafy greens, plants high in protein (like tofu or beans) and foods rich in omega-3 (such as salmon, oysters, flaxseed and walnuts) is linked to the production of “good” bacteria. Ghannoum also recommends consuming foods rich in fiber (such as oats, lentils, popcorn and chia seeds) because they are a substantial food source for gut microbes.
No. 2: Avoid restrictive diets
Alper says that it’s not only about what you eat but also what you avoid eating. Restrictive eating, cutting out certain food groups, means you’re limiting access to potential fuel for your microbes, which can lead to a less diverse gut microbiome.
“I would be cautious about making abrupt and unnecessary changes to your diet,” warns Alper. He points out that some people, for example, avoid eating gluten. Unless you’re allergic or have celiac disease, he argues that there is no advantage for your microbiome in staying on a gluten-free diet, especially because most gluten-free products are less nutritious, low in fiber and high in saturated fat.
Additionally, abruptly switching to a gluten-free diet can upset the gut and cause the death of gut microbes that rely on gluten to survive. “By limiting your diet, you're actually decreasing the diversity of your gut microbe composition,” Alper says. “But if you expand your nutrition and eat a little of everything, you're promoting the growth of different gut microbes.”
No. 3: Don’t put all your hope on probiotics
Probiotic supplements are a popular option marketed to boost gut health. However, experts say you should not depend on them to solve all your gut problems. “Probiotics would never change your gut microbiome,” says Alper. That’s because there are trillions of gut microbes in your gastrointestinal tract. “Do you think that if you take a probiotic, which is 0.001% of your total gut microbiome composition, that this will change something?” he says.
Alper also points out that many of the microbes in probiotics probably don’t survive the acidity of the stomach. Additionally, he says the existing gut microbes are not going to let the “new microbe on the block” dominate your GI tract. That said, it doesn’t mean all probiotics are necessarily bad or pointless. Ghannoum says taking probiotics is “better than nothing.” Just don’t expect it to change your entire gut microbiome diversity.
No. 4: Eat foods rich in prebiotics
Prebiotics serve as fuel for gut microbes. Certain vegetables are rich in prebiotics, specifically garlic, onions and beans. Ghannoum says high-fiber foods also contain prebiotics that can “shift the microbiome to become more balanced.”
A 2018 review on prebiotics' impact on the gut suggests that they help promote the growth of good bacteria, such as those that reduce inflammation and promote metabolism or weight loss. Another benefit is increasing gut bacteria that improve immune response and absorb better minerals, such as calcium to avoid bone fractures.
No. 5: Avoid using antibiotics when possible
Antibiotics help to get rid of infection-causing bacteria, but in return, can cause collateral damage, wiping out a number of good bacteria living in the gut. Even one course of antibiotics taken in infancy can substantially reduce gut diversity, allowing fungi to expand and reproduce.
“If you’re exposed to antibiotics even once, the gut remembers,” says Alper. “All of those can decrease the diversity of the gut microbiome.” It can take a while for your gut to recover after exposure to antibiotics. A 2022 study showed that a single course of antibiotics could disrupt patients' microbiomes for six months.
Using antibiotics also risks creating bacterial strains that are resistant to antibiotics, and the research suggests that antibiotic-resistant bacteria can cause infections that are difficult to treat. One example is the growth of C. difficile, which damages the gut and causes antibiotic-resistant diarrhea.
Alper says the bottom line is not to rush into taking antibiotics unless absolutely necessary or if there’s an effective alternative treatment.
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