This is still a terribly new study, but intestinal flora may someday be a key element to a long and healthy life, and avoiding infections, both that cause acute problems, and those that may cause long term problems.
Nothing like getting a poop transplant.
I’ve been doing a lot of studying in this regard lately and as a result have added many fermented foods to my diet in the past few months.
Home made kombucha, sour pickles, fremented radishes, lemons and kefir made with raw whole milk. Fermented homemade mayo, sour cream, cream cheese. Getting ready to try saurkraut, preserving with just salt, water and time.
You need to introduce these types of foods slowly though as they are detoxifying and aging folks particularly will probably need to adjust slowly.
Think about preserving food and how they must have done it worldwide prior to refrigeration.