Norma asked on another thread, I thought I would split to here:
I would be interested in hearing the health benefits of using natural preferments.
I'm not sure about other types of natural preferments, but sourdough has the following health benefits (as I understand it). I would suspect that most of them are true for other types of natural preferments as well.
1. Sourdough is a symbiotic culture of natural yeast species and lactobacillus (or lactic-acid-producing) bacteria. Many of the lactobacillus species commonly found in sourdough cultures are considered "probiotics" i.e. healthy gut flora. Now, with most uses of sourdough (bread, pizza) the yeast & bacteria will all be dead by the time you ingest it, so it has no probiotic effect. But, if you ever taste your starter, or make pancakes (mine are often pretty soft on the inside) you might
be getting some probiotics.
2. Increased mineral absorption. Because there are so many different species of organisms involved in the fermentation, sourdough does a much better job of pre-digesting, and humans can absorb a lot more of the nutrients. For example, the bacteria in sourdough break down phytic acid in wheat which prevents mineral absorption. Because of this sourdough bread is actually a good source of iron.
3. Similar to above, sourdough also does a much better job of breaking down gliadin (the component of gluten that causes problems in people with gluten sensitivity) than commercial yeast. While fully gluten intolerant people (celiac disease) still can't have wheat-based sourdough, it may be okay for those with a minor sensitivity. And my opinion is that eating sourdough in place of commercially-yeasted bread, will make you less likely to developer gluten sensitivity later in life.
4. Sourdough products have much lower glycemic index (I've heard 68 for white sourdough compared to 100 for regular white bread). This is especially important for diabetics, but probably matters for everyone (give your poor pancreas a rest!). See here for a scientific study: http://www.uoguelph.ca/news/2008/07/sourdough_bread.html
Some of the above benefits can probably also be realized by using longer fermentation times with commercial yeast, like we see in many of the pizza recipes on this forum. (It's kind of neat that the reception of "better taste" with long fermentation goes hand in hand with health benefits.) But, I would guess that sourdough still has a big advantage over commercial yeast, because of the lactobacillus bacteria, and having multiple varieties of yeast, it can do a more thorough job of fermentation.
Cheers, and sorry if it sounds like I'm on a high horse!