Had digestive problems for years and did a lot of research. This is my take on what the microbiome needs in order to sustain a functioning ecosystem.

my take is it has to be majority carbohydrate. over 50% of diet should be carbs. eating too much protein/fats blocks off oxygen to the cells. i'd like to get your opinion/research. disagree with me if you must, just looking for more info.

Fruits:
Grapes in particular, lemons, olives, cucumbers, berries etc.

Vegetables:
-Onions, leafy greens, mushrooms.
-Lettuce is probably the healthiest food I can think of.

Proteins:
-mainly fish (only good source of omega 3's), some grass fed mammals (beef/lamb/sheep)
-I don't think humans should eat poultry (they're birds, can't think any good reason to eat a bird)

Nuts:
-I don't think this is food for humans.

Grains:
-should be rarely eaten, often inflammatory, contains mould etc .