Constant exhaustion. That annoying zit cluster on your forehead that won’t fade no matter how many pimple patches you apply. The blues that bring you down even when you’re having fun with friends. While you might not think these issues have any connection to one another—let alone, to your health—they could actually have a common cause: a poor gut microbiome.
First, a brief refresher: Your gut microbiome is the trillions-strong collection of bacteria and other microbes that live in your digestive tract. Within it, there are “more organisms than there are cells in our body,” Vincci Tsui, RD, a certified intuitive eating counselor based in Canada, tells SELF, emphasizing its sheer scale. Because of the gut microbiome’s location, you might assume that it only affects, well, your digestion. But an imbalance—too few beneficial bacteria or too many harmful ones—could actually show up in ways that you might not expect.
“Our gut microbiome is something that’s been a hot topic in nutrition and health research for the past decade, and I think we’ve still only scratched the surface of what we know,” Tsui says. “But one thing that we do know is that our gut microbiome can affect things beyond just gut health.” In fact, it’s “like a major body organ,” Robert Burk, MD, a professor of microbiology and immunology and of epidemiology and population health at Albert Einstein College of Medicine, tells SELF. Digestive woes like constipation and diarrhea might be fairly obvious indicators that something is off, but there are plenty of others that are less self-evident—including the seven below.
The top subtle signs of an unhealthy gut microbiome
Here are some health issues that you might not have realized can be a symptom of dysbiosis, the technical term for an out-of-whack GI ecosystem.
You’re battling breakouts (or other skin issues)
You’ve probably heard of the gut-brain axis—the complex network of nerves that connects your gut and brain and exchanges signals between the two—but what about the gut-skin axis? “Sometimes, inflammation [induced by poor microbiome health] can show up in terms of skin-related issues,” Tsui says. Not only can those issues take the form of conditions like acne, dandruff, atopic dermatitis, seborrheic dermatitis, psoriasis, eczema, rosacea, and alopecia, they can also manifest as severely as skin cancer. In the case of eczema, for example, a decline in beneficial Lactobacillus and Bifidobacteria bacteria can make flare-ups worse.
Your weight is fluctuating for no apparent reason
Poor gut microbiome health can really mess with your metabolism, which can lead to weight changes. “Your gut microbiome helps influence satiety, when and how much you eat, and how well you process nutrients,” Alice Cheng, MD, PhD, a University of Chicago gastroenterologist and research scientist specializing in the gut microbiome, tells SELF. “Our ability to process sugar, glucose, and fats may be affected.” Depending on how your body responds, that could manifest as either shedding or putting on pounds. Dr. Cheng says these metabolic shifts could also affect related biomarkers like blood sugar, blood pressure, cholesterol, and triglycerides, or even your risk for health conditions like obesity, type 2 diabetes, and heart disease.
You toss and turn at night
“Your gut microbiome does a lot of things that can help or hurt with regulating circadian rhythms,” Orlando “Landon” DeLeon, PhD, a research assistant professor at the University of Chicago Pritzker School of Medicine, tells SELF, and “your clock can get shifted” if the microbial balance is off-kilter. Most of the body’s serotonin—a neurotransmitter that affects mood and sleep—is actually produced in the gut, so an imbalance can disrupt that process, triggering insomnia , making it difficult to stay asleep, or creating other sleep disturbances.
You often feel fatigued
On a separate but related note, feeling consistently tired and drained no matter how much sleep or rest you notch can also be a red flag for poor gut microbiome health, according to Tsui. Infection by the bacterium H. pylori is one potential mechanism: By attacking your stomach lining and the first stretch of your small intestine, it can cause dysbiosis and impair your ability to absorb iron, a mineral critical for energy.
Your mood is (unexplainably) down
Perhaps the best example of the gut-brain axis at work is its impact on your mood. Because “our gut communicates with our brain,” Tsui says, poor gut microbiome health can manifest as mood changes “[centered] around anxiety and depression.” Research has even uncovered associations between generalized anxiety disorder and major depressive disorder (MDD) and changes in a range of intestinal bacteria. Studies have consistently found that Eggerthella is increased and Faecalibacterium and Coprococcus are decreased in MDD patients, for example.
You have trouble focusing
Your mood isn’t the only thing that can take a hit if your gut microbiome is impaired—your cognition can, too. While there don’t appear to be too many studies examining the relationship between brain fog and poor microbiome health specifically, “some people find that difficulty concentrating might be a part of that,” Tsui says.
You’re getting sick frequently
“The gut microbiome is critical for priming our immune system,” Dr. Burk says. In turn, researchers have observed “that people who tend to get sick more often” have poorer microbiome health, Tsui explains. Meaning: If you catch bugs on a regular basis, especially compared to other people around you, “that could potentially be a sign of that kind of [negative] shift in the microbiome.”
Because the science on gut health is evolving rapidly, experts often aren’t always completely sure how poor microbiome health can bring about these issues. In some cases, the link may actually be a matter of correlation rather than causation: “Some of these associations first came about” through studies on specific populations (say, those diagnosed with depression or other mental health issues), when researchers noticed a difference between the microbiomes of their subjects and a control group, Tsui says. One review found that more than half of people who had irritable bowel syndrome also had chronic fatigue; one study found that people with rosacea were significantly more likely to have small intestinal bacterial overgrowth (SIBO) and that eradication of SIBO nearly eliminated the rosacea symptoms; similarly, another study found that the psoriasis drug ustekinumab was effective against Crohn’s disease. Whether causation or correlation, one thing’s for sure: There is a link.
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