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Prebiotics and fiber-rich foods are having a major moment in health circles. But if you’ve wondered if they’re actually healthy or just hype, the science increasingly suggests they do matter—perhaps more than we ever realized.
According to 2024 research supported by the National Institute on Aging, older adults who develop a more unique, diverse gut microbiome pattern tend to be healthier and live longer than peers whose microbiome remains unchanged. The individuals with healthier microbiomes had blood tests showing lower LDL cholesterol (sometimes referred to as “bad” cholesterol), higher vitamin D levels, and more beneficial metabolites produced by gut health-supporting bacteria.
“Your gut isn’t just a digestive organ—it’s a longevity organ,” says Sumana Moole, MD, a gastroenterologist and founder of Merus Gastroenterology & Gut Health. The growing body of research connecting gut health to everything from signs of a healthy gut to disease prevention is reshaping how doctors think about aging.
What does “gut health” actually mean?
When experts talk about gut health, they’re referring to far more than your microbiome alone. “Gut health includes the microbiome—the community of bacteria and other organisms living in the digestive tract—but it goes far beyond that,” says Hau Liu, MD, MPH, chief medical officer at Cylinder Health and clinical assistant professor at NYU Grossman School of Medicine. “It refers to how well the entire gastrointestinal system functions: how you digest food, absorb nutrients, maintain a strong intestinal barrier, and regulate inflammation and immune responses.”
Thinking of your gut as “a dynamic ecosystem—microbes, host tissues, immune and nervous signaling—working together,” says Sabine Hazan, MD, a gastroenterologist and founder of ProgenaBiome, a genetic sequencing research lab.
A healthy gut shows up in everyday comfort—regular bowel movements, minimal bloating or pain, and consistent energy levels. It’s also reflected in less visible ways: a well-functioning immune system, balanced mood, and efficient metabolism. Dr. Moole adds that true gut health means “having an internal ecosystem that keeps inflammation low, supports immunity, produces vitamins and neurotransmitters, and helps your whole body run smoothly.”
How your gut can affect healthy aging
Want to know what the longest-lived people on Earth have in common? It’s strange but true: bacteria. It might seem hard to believe, but the microbes living inside these individuals have a powerful impact on healthy aging. A 2023 study published in Nature Aging analyzed gut microbiome data from nearly 1,600 people ranging in age from 20 to 117—yes, 117—including 297 people who lived until at least 100 years old.
The findings were striking: compared to other older adults, centenarians had gut microbiomes that looked surprisingly young. We’re talking higher diversity, more beneficial bacteria, and fewer of the troublemakers. Researchers studying centenarians in Japan and Italy also found the same patterns, suggesting that your gut bacteria might be keeping score on how well you’re aging.
“Gut health is deeply tied to both lifespan and healthspan—how healthy your years actually feel,” Dr. Moole explains. A well-balanced microbiome helps regulate your immune system and produce short-chain fatty acids (the good stuff your gut bacteria make when they break down fiber). These compounds have been linked to lower inflammation and protection against chronic disease. Think of your microbiome as a tiny internal pharmacy—when it’s well-stocked, it’s working for you around the clock.
On the other hand, chronic dysbiosis, defined by the Cleveland Clinic as “an imbalance in the different types of microscopic organisms living in your body,” is linked to many things that can tank your health and even shorten your lifespan, “including causing low-grade inflammation and a higher risk for conditions that shorten healthy life, like cardiovascular disease, metabolic disease, some cancers, neurodegenerative conditions and autoimmune problems,” Dr. Hazan says.
Dr. Liu says that gut health alone won’t guarantee you’ll blow out 100 candles, but it’s a meaningful piece of the puzzle. “The same habits that support a healthy gut—eating a fiber-rich, diverse diet, moving regularly, getting good sleep, and managing stress—are also some of the most powerful, proven behaviors for improving long-term health,” he says.
What is “inflammaging”?
Here’s the not-so-fun part of getting older: your microbiome tends to become less diverse and more inflammatory over time. Scientists have a name for this that combines “inflammation” with “aging”: inflammaging. And it’s linked to many of the conditions we associate with aging, including heart disease, diabetes, and cognitive decline.
The good news? It’s not inevitable. “Remarkably, people who live into their 90s and 100s tend to have high levels of protective gut bacteria and far fewer harmful species,” says Dr. Moole. “In other words, people who age well often have guts that age well.”
According to experts at Brown University, a few key suggestions to avoid inflammaging include:
- Eat an anti-inflammatory diet
- Quit smoking
- Stay active
- See your doctor regularly
Your gut is also running a behind-the-scenes communication network with your brain. Meena Malhotra, MD, founder of Heal n Cure Medical Wellness and Anti-Aging Center in Glenview, Illinois, explains that the gut functions as a neuroendocrine system—a fancy way of saying it produces chemical messengers that influence how you think and feel.
Adds Dr. Malhotra: “Neurotransmitters are small peptides or hormones through which the brain talks to the body. They are all made in the gut, influenced by the microbiome.”
So that “gut feeling” you get? It’s more literal than you might think. What’s happening in your digestive system can shape your mood, stress response, and mental clarity—all factors that influence how well you age.
The truth about probiotics
Why bother with eating extra nutrients through veggies or fruit if you can get powerful probiotics in a pill? There are three main issues with that approach, Dr. Hazan says. First, she states that most probiotics, when tested in a lab, do not have the bacterial strains they claim they do—and because probiotics are not regulated by the U.S. Food and Drug Administration (FDA), it’s hard to know what you’re getting.
The second issue, she says, “is that even if it does contain bacteria, the probiotic is dead in the capsule or dies on its way to the colon due to stomach acid,” so it’s not doing you a lot of good. Lastly, everyone’s gut reacts differently to probiotics and they may not permanently engraft in your gut. This doesn’t mean all probiotics are useless, but you’ll get the best bang for your buck getting them the old-fashioned way, through food.
“Diet is the single most powerful day-to-day determinant of microbial composition,” Dr. Hazan says. “Fibers and prebiotic foods feed beneficial microbes that fight inflammation while fermented foods can increase microbial diversity and beneficial metabolites.”
If you do decide to go the supplement route, Dr. Liu says that probiotics may help some people—just be sure to work closely with your healthcare provider for personalized recommendations, especially if you’re taking antibiotics or other medications that can affect gut bacteria.
Top expert tips for better gut health
The experts agree: When it comes to supporting your microbiome, food is the most powerful daily tool available. “A fiber-rich, minimally-processed, plant-rich diet, such as the Mediterranean diet, has strong evidence for improving long-term health and supporting a healthy microbiome,” Dr. Liu says.
Aim for 25 to 30 grams of fiber per day from a variety of sources—fruits, vegetables, whole grains, beans, and nuts. Fermented foods such as yogurt, kefir, kimchi, and sauerkraut can provide beneficial bacteria. However, Dr. Moole notes that “not everyone responds the same way” to probiotics—your baseline microbiome determines whether a specific probiotic works for you.
At the same time, you should limit added sugars and ultra-processed foods, Dr. Hazan adds.
Beyond diet, the experts recommend syncing your eating with your body’s natural rhythms. “Your gut has a clock,” Dr. Moole explains. “Eat at regular times, avoid late-night meals, and get seven to nine hours of sleep to keep your digestive system in sync.” Exercise also plays a role—physical activity increases beneficial bacteria and helps create anti-inflammatory compounds.
And don’t underestimate the importance of managing stress and mental health. “The gut and brain talk constantly. Stress reduction (therapy, mindfulness, social connection) supports both mood and gut function,” Dr. Hazan says. “Treating mental health proactively can indirectly improve gut health, and vice versa.”
The bottom line
Your gut is pulling a lot more weight than it gets credit for. Beyond digestion, it’s influencing your immune system, brain function, inflammation levels, and quite possibly how many healthy years you have ahead. Scientists are still piecing together exactly how the microbiome shapes aging, but the research is pretty clear on one thing: a diverse, well-fed gut seems to be a common thread among people who age well.
But you don’t need a complicated protocol to support your microbiome. The same advice your doctor gives for overall health—eat plenty of plants and fiber, move your body, manage stress, and prioritize sleep—happens to be exactly what your gut bacteria want too. “Think of it this way,” Dr. Moole says. “Every meal is a message to your microbiome about how you want it to behave.” So that salad you had for lunch? Your gut got the memo.
Of course, we’re all working with different bacterial communities. If you’re curious about probiotics, specific dietary changes, or other gut-focused strategies, talk to your healthcare provider about what might make sense for you.
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