Did you know that there are billions of tiny organisms living in your small and large intestines, and that some actually help your body digest and use the nutrients in food? If you've ever heard people talk about eating yogurt or taking pro-biotics, they're trying to populate their gut with the 'good' kind of bacteria in an effort to keep other less desirable organisms (like yeast) at bay

.One recent study on intestinal bacteria found that we can basically be divided into three distinct types of bacterial makeup - kind of like blood types. Just like you might have O- or AB+ blood, the composition of your gut flora will likely match one of three types, or enterotypes as the researchers call them. This research is still somewhat limited but in the future may lead explanations as to why some people have certain cravings more than others, like a sweet-tooth for example, or why different people respond to certain foods or drugs differently.

New research is also shedding light on another function of these intestinal bacteria. A recent article in Scientific American reported on a study that shows that the bacteria in the digestive tracts of mice actually influences their brain development and mood. Mice with less intestinal flora were found to have less anxiety and higher levels of neurotransmitters like dopamine and seratonin.

It remains to be seen what either of these studies mean for humans, but the fact that these bacteria are an important part of our body ecology is clear. Imbalances of these bacteria can be part of the cause of many conditions, ranging from eczema to allergies to irritable bowel disease.

So how do you keep a healthy balance of intestinal flora? Imbalances are most often caused by use of antibiotics, stress, and poor diet, especially a diet high in sugar and sulfites and low in fiber. If you do have to take antibiotics for an infection, or if you're going through a particularly stressful period, try to supplement with yogurt or pro-biotic supplements, and stick to a diet low in sugar and high in fibrous vegetables to promote the return of healthy flora.