Cheese is one of the very few commercial foods you'll be able to find live (fermentation) bacteria living in, but even then many cheeses won't because the producers save expense by pasteurizing instead of more closely monitoring cheeses to make sure they don't develop molds.
But, there are a few companies who do sell high-quality raw fermented foods, like Real Pickles up here in New England. You'll be able to find healthy bacteria on organic farm-bought produce as well; sauerkraut can be made easily by putting some sliced cabbage in a jar with salt, pounding it down, topping off the jar with water, and capping it for a week.
This is already sold. It's called humility, but you'll have to import it if you live in the US.
You're right, but note that most store-bought sourdough breads are barely sourdough at all; they're mostly just flavored but don't undergo the traditional fermentation process which takes too long for bread corporations more interested in moving stock. Roman legions actually survived largely off of long-fermented sourdough bread.
As a medical student who has been closely reviewing probiotic research, I would like everyone to know that research is extremely important.
Perhaps it will be the greatest breakthrough in medicine of the 21st century. This angle is one of the primary reasons that the 'calories in=calories out' theory doesn't function as a successful principle for people trying to lose weight and keep it off. I recommend looking into the GAPS diet for anyone suffering auto-immune problems, since auto-immune disorders are all primarily caused by dysregulation of the digestive system.
Some ideas on the yogurt study (also being an opportunity to explain some of the nuances):
there is an incredible breadth of biodiversity in the gut, and yogurt only typically contains one or two strains, in this case it looks like one.
gut bacteria number in the trillions, so a short-term regime of any probiotic food or supplement won't necessarily provide its benefits quickly. A significant amount of the benefit is also delivered in the chelating and detoxifying properties of healthy bacteria, which can over time remove harmful toxins built up in intestinal bile; a significant build-up may take years to fully flush though, and other health problems may still still inhibit it.
other things in the diet will impact bacterial growth just as much as the addition of yogurt. Foods high in sugar could very easily be inhibiting the multiplication of the yogurt's probiotic bacteria (after being ingested) by encouraging the growth of competing bacteria associated with negative health. Food eaten then also becomes the basis for the bacteria's food, so a poor quality diet could sabotage the probiotics.
the quality of the yogurt which the probiotic was added to will impact the growth of bacteria tremendously. The pasteurization process itself makes the yogurt less healthful and can create an environment less conducive to probiotic multiplication.
no distinction is made whether the stress can be considered 'justified' or not; it would be undesireable to be less stressful in a situation where stress is justified and helpful. The study also seems not to account for variance in difficulty of course load, since students may have signed up for classes with intuitive knowledge of the additional stress received through their usual gut bacteria.
there are also a variety of standard practices in preventing contamination, which I assume the group carried out
What is the mechanism by which Warren Buffet creates wealth by himself? If you're talking about investing, couldn't a good supercomputer hypothetically do the same job for free? Anyways, Buffet doesn't do all of his own investments: most capitalists don't. They engage in joint ventures and mutual funds. Their only "contribution" to these is being the owner of investment funds (an arbitrary title when removed from historical context). Buffet does contribute to society but not (through some divine justice) proportionate to the compensation he is allotted.
Consider if Warren Buffet's teachers had not taught him to do math and he hadn't had the opportunity to do anything he did. What if his local librarian wasn't able to help him find books on investment, if he hadn't happened upon mentors who could teach him business, if he had been born poor and had to work minimum wage from a young age. Now consider if there are other potential Warren Buffets who would thrive as much as him given the opportunity but actually DO experience such setbacks.
Anyways, to assume that private investment is a social imperative is not friendly to reality. China right now has a totalitarian government which controls investments (including closely regulating foreign investment), and its economy has been exploding for decades as a result of infrastructure investment. There are plenty of models in-between China and the US which also function fine.
In the United States, we consistently overestimate the contribution of private industry in developing our infrastructure. Cars are only possible because of roads, telephones were only possible because of telephone wires, the internet & technology revolution were only possible because of massive Cold War defense department spending (the ARPANET was the prototype for the internet). It is not an exaggeration to say that the public has a far greater stake in private business than it realizes. In some cases, the privatization of public research can justifiably be seen as a transfer of wealth from taxpayers towards the fortunes of big business investors. http://en.wikipedia.org/wiki/ARPANET
In regards to Hume's interesting contributions to the question, I stumbled across this video a while back which I think will be interesting: http://www.youtube.com/watch?v=BVZG0G-jnAM (don't let the title throw you off; there is content within it).
You might not think the economic value was so low if you had children in school, were going to have children, were a child yourself, had significant health expenses, had a criminal record, were poor, or are going to get old eventually.
Economic value pays for the cultural value.
No, my claim is literal. The role of the discipline 'psychology' has shifted over time away from what we now consider 'sociology' and towards an individualistic approach to mental health. The assumption didn't used to be that mental problems were profoundly unique to the individual, but now mainstream psychology does not take into account the sociological factors which affect mental health in all situations.
Some sources to elaborate the transformation of the discipline are historiologists & sociologists like Immanuel Wallerstein and Michel Foucault, but there are plenty of non-mainstream psychologists who still practice holistic psychology like Helene Shulman & Mary Watkins.