the key to getting more butyrate in your life is to eat keto bread. that bread is made of flours like almond flour or coconut flour or any of a dozen different flours that the stomach and small intestine can’t digest. the flours are all digested in the large intestine and bowls by the bugs. keto bread is basically bug food. bugs make the butyrate and other short chain fatty acids that the body needs.
There’s a growing body of evidence that US diet just doesn’t include enough bug food.
Butyrate can be found in the following products Jerusalem artichokes, chicory root and jicama. Also you can buy a product called ,pre-biotin prebiotic, its load it with inulin from chicory root. $30.00 Amazon
I do agree that keto bread/tortillas are a good way to get forms of soluble fiber/resistant starch. Also, inulin, with daily amounts of 20 grams or less, is good.
Green bananas and cold baked potatoes also have other resistant starch forms.
Cellulose is not a good fermentable starch.
Items with “Modified Wheat Starch,” which includes keto breads, should be okay.