Massively. Changing diet is about the only realistic way to elicit long-term changes in the microbiome. Even taking probiotics doesn't last very long.
There's a lot of questionable microbiome science that hasn't been replicated. You can find a lot of studies that say something changes the microbiome, but it's almost always a single short-term observational study on a small group of people.
Realistically, increasing vegetable intake and reducing processed food intake are the easiest knobs you can turn to adjust the microbiome. A lot of people reach for supplements or imagine extreme measures like fecal transplants, but the practical solution is to simply buy some snacking vegetables every time you go to the store and eat them throughout the day.
What is your definition of processed food? Are potatoes processed because they are cleaned? Is chicken breast processed because the chicken is plucked? Is vinegar processed because it has undergone a chemical transformation via fermentation? Are potato chips processed because they are sliced potatoes fried in oil? Are fried plantains processed because they are sliced plantains fried in oil?
I do not mean to come across as antagonistic, I just haven't been able to find a line that everyone agrees with and felt it was useful to demonstrate that by asking a bunch of questions.
> What is your definition of processed food? Are potatoes processed because they are cleaned? Is chicken breast processed because the chicken is plucked? Is vinegar processed because it has undergone a chemical transformation via fermentation? Are potato chips processed because they are sliced potatoes fried in oil? Are fried plantains processed because they are sliced plantains fried in oil?
In practice, for the vast majority, it doesn't matter where the line is drawn.
Simply moving your diet as close as possible to unprocessed food (read: minimal steps between organism and ingestion) is the goal.
Nobody seems to agree, but the best I've been able to find is that every step counts and the level of invasiveness does too. So a plucked chicken is one thing, but a plucked, chlorine rinsed, freeze dried, ground up, centrifuged, glued, rehydrated, salted, etc. is another
FWIW: I avoid added sugar (sweeteners), empty calories.
eg Pre-made spaghetti sauce has sugar, so I make my own. Can of costco tomato sauce, garlic, italian herbs, garlic, oil, garlic, pinch of salt & pepper. Then I add some garlic.
eg I use plain greek yogurt in my smoothies. Flavored yogurt means added sugar. I can add my own flavors.
In my house, we make a distinction between "snacks" (food in-between meals) and "treats". I mosdef crave potato chips, doughnuts, cake, candy, etc. To better moderate, I don't keep any of those "empty" calories at home.
YMMV. IIRC, type-2 diabetics use artificial sweeteners. I'm not a doctor and can't guess what's best for anyone else.
My personal definition is that if you can stack the food you buy, it has been processed. It’s a subjective definition, and there might be dozens of counterexamples, but it feels true to me.
There's a lot of questionable microbiome science that hasn't been replicated. You can find a lot of studies that say something changes the microbiome, but it's almost always a single short-term observational study on a small group of people.
Realistically, increasing vegetable intake and reducing processed food intake are the easiest knobs you can turn to adjust the microbiome. A lot of people reach for supplements or imagine extreme measures like fecal transplants, but the practical solution is to simply buy some snacking vegetables every time you go to the store and eat them throughout the day.