Thinking about becoming a pescatarian? What you should know about the pescatarian diet
Let’s not call it cancer
Chair exercises for seniors: Boosting strength, flexibility, and stamina
Why all the buzz about inflammation — and just how bad is it?
Chronic kidney disease: What to know about this common, serious condition
Beyond the usual suspects for healthy resolutions
COVID tests: Do at-home tests work on newer variants?
A liquid biopsy for metastatic prostate cancer
One way to combat loneliness? Strengthen relationships you already have
Feel like you should be drinking less? Start here
Trillions of microbes — bacteria, viruses, fungi — call your gut home. They do more than just help you digest food. They fight harmful pathogens; make vitamin K and other important chemicals; affect the way medications work; and may influence your immune system, heart health, and cancer risk. It also appears gut microbes may play a role in healthy aging and longevity. The genes of all your gut microbes are collectively called the gut microbiome.
In a study published online Feb. 18, 2021, by Nature Metabolism, scientists observed that older adults whose mix of gut microbes changed the most over time lived longer than those people with less change in their gut microbiome.
The study didn’t prove that an eclectic microbiome directly caused people to live longer. However, such a microbiome was also associated with lower cholesterol levels, faster walking speeds, and higher levels of beneficial blood chemicals — all factors that lengthen the life span.
How do you make your gut microbiome more diverse and achieve health benefits? It mainly comes down to lifestyle factors. Indeed, one of the reasons that a healthy lifestyle may protect your health is through the impact of your lifestyle on your microbiome.
Eating the right foods is one of the best ways. Your gut microbes like to eat, too, and their favorite foods are the ones that are healthiest for us: fruits, vegetables (especially dark, leafy greens), legumes (beans, peas), and whole grains (quinoa, whole wheat, brown rice). “Those foods contain fiber. Our bodies don’t break down fiber for food; fiber passes through to the gut and microbes feed on it. It gives them a good environment to grow,” explains April Pawluk, strategic program manager at the Harvard Chan Microbiome in Public Health Center.
But when you eat an unhealthy diet with lots of processed, fatty, sugary foods, it makes it harder for helpful microbes to survive. “In the absence of diversity-promoting nutrients like fiber in our diets, the genes of our gut microbiome can produce chemicals that could increase our risk for developing different diseases,” Pawluk says.
Exercising appears to promote gut microbiome diversity, but the way it works is a matter of speculation, Pawluk says. Several ways are plausible. “It could be that exercise changes the rate at which material moves through the intestines. Or perhaps exercise reduces inflammation in the gut. Or exercise might alter our appetite, and alter the way that our bodies process the food we eat. All of these could affect the microbiome environment,” Pawluk says.
Dogs are always tracking things in from outside — like dirt, grass, and insects — exposing their human families to more microbes. That might help counteract the effect of a modern world on the microbiome.
“Over the past century, there’s been a decrease in the diversity of the human microbiome, possibly because of sanitation and modern medicine,” Pawluk says. “Studies looking at young children growing up in a house with a pet show their microbiome becomes more diverse and they have less risk of allergies. We don’t know if this helps older adults, but it wouldn’t hurt.”
Cigarettes contain lots of chemicals and toxins that are harmful to the whole body, including your gut and its residents. “Smoking can kill some microbes and decrease microbe diversity. Smoking also puts physical stress on the body, including microbes. And when microbes are under stress, they change their function; they sense that they’re in a bad situation and in some cases attack each other — or us. That can cause imbalance in the gut microbiome,” Pawluk says.
One last suggestion that may affect the gut microbiome is to ingest colonies of “good” bacteria known as probiotics, which come in pills or powders or occur naturally in fermented foods (such as yogurt, kefir, and sauerkraut). “The intention is to boost the amount of beneficial bacteria in the gut,” Pawluk says. “If you’ve recently taken antibiotics, which kill both harmful and beneficial bacteria, probiotics may help re-establish a diverse microbiome. The thing is, if you already have a diverse gut microbiome, adding more of one species probably isn’t going to promote any significant change.”
But Pawluk says there’s no evidence probiotics are harmful, especially when they come from food. And there are many reasons why you might want to eat healthy probiotic-rich foods like yogurt, which has lots of calcium, or try any of the lifestyle habits we’ve laid out here. They all benefit health in numerous ways.
Image: © wmaster890/Getty Images
Heidi Godman, Executive Editor, Harvard Health Letter
As a service to our readers, Harvard Health Publishing provides access to our library of archived content. Please note the date of last review or update on all articles.
No content on this site, regardless of date, should ever be used as a substitute for direct medical advice from your doctor or other qualified clinician.
Thinking about becoming a pescatarian? What you should know about the pescatarian diet
Let’s not call it cancer
Chair exercises for seniors: Boosting strength, flexibility, and stamina
Why all the buzz about inflammation — and just how bad is it?
Chronic kidney disease: What to know about this common, serious condition
Beyond the usual suspects for healthy resolutions
COVID tests: Do at-home tests work on newer variants?
A liquid biopsy for metastatic prostate cancer
One way to combat loneliness? Strengthen relationships you already have
Feel like you should be drinking less? Start here
Staying Healthy
Diseases & Conditions
Diseases & Conditions
You might also be interested in…
When your digestive system is running smoothly, you tend not to think about it. Once trouble begins, your gut — like a squeaky wheel — suddenly demands your attention. This Special Health Report, The Sensitive Gut, covers the major sources of gastrointestinal distress: irritable bowel syndrome, gastric reflux, upset stomach, constipation, diarrhea, and excess gas. It also includes a special Bonus Section describing how emotional stress and anxiety can cause gastrointestinal distress.
Get the latest in health news delivered to your inbox!
© 2025 Harvard Health Publishing® of The President and Fellows of Harvard College
Do not sell my personal information | Privacy Policy and Terms of Use
Thanks for visiting. Don’t miss your FREE gift.
The Best Diets for Cognitive Fitness, is yours absolutely FREE when you sign up to receive Health Alerts from Harvard Medical School
Sign up to get tips for living a healthy lifestyle, with ways to fight inflammation and improve cognitive health, plus the latest advances in preventative medicine, diet and exercise, pain relief, blood pressure and cholesterol management, and more.
Health Alerts from Harvard Medical School
Get helpful tips and guidance for everything from fighting inflammation to finding the best diets for weight loss…from exercises to build a stronger core to advice on treating cataracts. PLUS, the latest news on medical advances and breakthroughs from Harvard Medical School experts.
BONUS! Sign up now and
get a FREE copy of the
Best Diets for Cognitive Fitness
Stay on top of latest health news from Harvard Medical School.
Plus, get a FREE copy of the Best Diets for Cognitive Fitness.
Stay on top of latest health news from Harvard Medical School.
Plus, get a FREE copy of the Best Diets for Cognitive Fitness.