Fermented foods are the foremost subject overlooked by the modern holistic health movement. A lot of people spend insane amounts of money on acidophilus supplements without utlizing their local farmer's supply of raw milk or making homemade sauerkraut, kombucha or other cultures which typically have larger amounts of, and greater variety of, beneficial bacteria. Personally, I make my own whey and other cultures and make a point to ride my bike the 15 mile round trip every week to pick up raw fermented kefir, advertised as having 100 times the probiotic content of pasteurized yogurt, at the local farmer's market. I'm lactose intolerant and can only consume kefir because cheese and raw milk have lactose (and casein) and kefir doesn't. GTs kombucha is also a product that has been invaluable for overall detox and I buy it even though it's expensive because it has produced more tangible results than almost anything including herbal medicine. Another benefit of fermentation is that raw whey can digest sugars, meaning that you can have huge amounts of fermented fruit without it triggering an increase in blood sugar levels.
Wild Fermentation is by far the best source on this subject. I learned everything I know from visiting Sandor's off-the-grid farm, Short Mountain, for the annual Beltane celebration. Their kitchen is always full of a wide variety of fermented foods and after staying there for a month eating raw yogurt and sauerkraut I was so healthy compared to when I first showed up. Fermented foods are a miracle cure that everyone needs to know about. Unfortunately, there are mountains of paperwork aimed towards making these foods illegal and the FDA has been conducting armed raids on family farms and health food stores. Raw milk is still illegal in most states and millions of people's health is suffering because this valuable resource has been criminalized by the federal govt. So support your local hormone free dairy farmer and encourage them to produce raw ferments, if possible. I'm thinking of finding an under-the-table source because you can't sell raw whey in California, which means I have to also make cheese which I don't need or want.