The gut microbiome is composed of trillions of microorganisms, with the highest concentration and diversity found in the large intestine (colon). It is the foundation for overall health. A healthy gut microbiome supports immune function (80% of it is in there), digestion, and nutrient absorption. It is easy to influence, and has quick results: Changes to the gut microbiome can occur within days or weeks, leading to noticeable improvements in energy, digestion, and mood. It is cost-effective: Incorporating gut-friendly foods and habits can be budget-friendly. The primary food source for it is dietary fiber. All plants have fiber, and only plants have fiber. The American Gut Project launched in 2012 as part of the Earth Microbiome Project analyzed over 15,000 microbiome samples from more than 11,000 participants across 42 countries. The most notable finding is the "30+ plant rule", which says individuals who consumed 30+ different types of plant-based foods per week had more diverse gut microbes. Since changing to a *mostly* whole-food plant-based diet (Flexitarian) in January 2022, as an 88 year old male,I quickly (as noted above) have come to feel the best in my life, as far as my memory recalls. On my 3-month checkup with the doc a few days ago, he said my blood work was that of a 40 year old. The gut-care plant-based part of my diet (Flexitarian) is mostly from three excellent web based pre-prepared meal vendors...15-30 plant ingredients in each meal, and many different ones to select from...goleafside.com, daily-harvest.com, and plantstrong.com. *Minimal* preparation, great tasting, virtually no cleanup. I get two meals out of each package...cost $4-$6. As noted above, it is fiber that is the main source in building up the gut microbiome. The many foods, which can tear it down are: Antibiotics...indiscriminately kill both harmful and beneficial bacteria. Even a single course can have long-lasting effects, with some individuals experiencing persistent changes for months or even years. Sugary foods and drinks Ultra-processed foods Artificial sweeteners Fried foods Red meat and high-fat animal products Refined grains Alcohol Salty foods Dairy products (especially for those with lactose intolerance A gut microbiome in a state of dysbiosis (out of balance) is where you don't want to be. A way to tell if you're in balance without getting a stool sample test is to check-out the Bristol Stool Chart. It is the standard medical reference used for digestive/bowel problems. You want to be Type 3-4. Here's the chart... https://i0.wp.com/post.medicalnewst...x1394-english-body-952x1024.jpg?w=1155&h=2929
I think you will find the subject has been discussed here. @Yvonne Smith is a big advocate, as are others.
If you want to take a deeper dive into the Gut Microbiome, get to know Dr. Will Bulsiewicz, website theplantfedgut.com. Check out the 6-minute video below...I just found it today. What he talks about is what I learned 3 years ago, mostly from him, and started me on GM friendly eating, which changed my life! (I read his book "Fiber Fueled".) If you really want to get into it, here's one on Poo...2 hours.