What can I say, I am fascinated. Here's another post on that topic.
It all leads back to things I read elsewhere. Everything in your body starts in your gut..... no, really! (I'll post more on that later. It's very interesting!)
"Gut bacteria is closely tied to early brain development and subsequent behavior. Probiotics have also been found to influence the activity of hundreds of your genes, helping them to express in a positive, disease-fighting manner.
There are signs that psychiatric problems might be caused by lack of natural microorganisms in soil, food, and the gut. Quite simply, modern society may have gotten too sanitized and pasteurized for our own good.
Fermented foods have been traditional staples in most cultures, but modern food manufacturing, with its focus on killing ALL bacteria in the name of food safety, has eliminated most of these foods. You can still find traditionally fermented foods like natto or kefir, but they're not the dietary staples they once used to be, and many people don't like them when trying them out for the first time in adulthood.
When you deprive your child of all this bacteria, her immune system—which is her primary defense system against inflammation—actually gets weaker, not stronger. And higher levels of inflammation are not only a hallmark of heart disease and diabetes, but also of depression.
A healthy ratio of good to bad gut bacteria is essential for psychological health, disease resistance, digesting and absorbing food and carbohydrates and vitamins, and preventing allergies.
What kills your gut bacteria?
Antibiotics, chlorinated water, antibacterial soap, agricultural chemicals, and pollution are leading factors.
It's almost impossible to avoid them all so do what you can, and also "reseed" the good bacteria in your gut by taking a high-quality probiotic supplement or eating fermented foods.
Why? 80 percent of your immune system is actually located in your gut!
What the heck are fermented foods?
Fermented foods are still the best route to optimal digestive health, as long as you eat the traditionally made, unpasteurized versions. Healthy choices include lassi (an Indian yoghurt drink, traditionally enjoyed before dinner), fermented milk such as kefir, various pickled fermentations of cabbage, turnips, eggplant, cucumbers, onions, squash and carrots, and natto (fermented soy).
If you do not eat fermented foods, taking a high quality probiotic supplement is definitely recommended.
Edited to add:
Here's the other book excerpt.(Click the picture below to read all 6 pages)