A Dr. Mercola article on importance of healthy gut flora

http://articles.mercola.com/sites/articles/archive/2011/10/22/this-supplement-can-actually-make-you-happy.aspx?e_cid=20111022_DNL_art_3


What Interferes With Healthy Gut Bacteria?

It's important to understand that your gut bacteria are an active and integrated part of your body, and as such are heavily dependent on your diet and vulnerable to your lifestyle. If you consume a lot of processed foods and sweetened drinks, for instance, your gut bacteria are likely going to be severely compromised because processed foods in general will destroy healthy microflora and sugars of all kinds feed bad bacteria and yeast.

Your gut bacteria are also very sensitive to:

Antibiotics
Chlorinated water
Antibacterial soap
Agricultural chemicals
Pollution
Because of these latter items, to which virtually all of us are exposed at least occasionally, it's generally a good idea to "reseed" the good bacteria in your gut by taking a high-quality probiotic supplement or eating fermented foods.

How to Optimize Your Gut Flora

An estimated 80 percent of your immune system is also located in your gut, so reseeding your gut with healthy bacteria is important not just for psychological health but for your overall physical health as well. A robust immune system is your number one defense against ALL disease, from the common cold to cancer. In light of this, here are my recommendations for optimizing your gut bacteria.

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 grass fed organic milk such as kefir, various pickled fermentations of cabbage, turnips, eggplant, cucumbers, onions, squash and carrots, and natto (fermented soy).

If you regularly eat fermented foods such as these that, again, have not been pasteurized (pasteurization kills the naturally occurring probiotics), your healthy gut bacteria will thrive.
Probiotic supplement. Although I'm not a major proponent of taking many supplements (as I believe the majority of your nutrients need to come from food), probiotics are definitely an exception. I have used many different brands over the past 15 years and there are many good ones out there. I also spent a long time researching and developing my own, called Complete Probiotics, in which I incorporated everything I have learned about this important tool over the years.

If you do not eat fermented foods, taking a high quality probiotic supplement is definitely recommended.