I have always heard about armies marching on their stomachs and know first hand of the moral-boosting effects of good food. But, it runs deeper than that. Food and the bacteria that lives inside of us also effects the way that we think and feel. Before all of the psyche-majors start protesting, hear me out.

There are neurons in your digestive system as well as your brain. And the digestive system is constantly sending stomach sensations to the brain. This is why we get “gut reactions” and “butterflies in the stomach.” The brain is affecting substances within the gut and vice versa.

For instance, serotonin, which influences mood, sleep, depression and aggression, is more concentrated in the gut than the brain. Something like 5-10% is stored in the brain and the remaining 90-95% is in your intestines. (This might explain the problems of antidepressants raising serotonin in your brain and not your intestines). Even though both the brain and intestines produce serotonin separately from each other, their nerve pathways remain open. This means that a healthy digestive tract promotes a happy brain. So, happy stomach helps a healthy mind.

Now, get a load of where the healthy bacteria come in.

A study at the University of Toronto, School of Medicine and Department of Nutritional Sciences demonstrated the affects of beneficial bacteria on humans with Chronic Fatigue Syndrome (CFS). 39 people with CFS were randomly given either 24 billion Colony Forming Units (CFU) of Lactobacillus casei strain Shirota (LcS) or a placebo over two months.

After two months, the people taking the Lcs probiotics showed a marked decrease in anxiety, including better sleep and less dizziness, appetite changes and shortness of breath.

A similar study, this time involving mice, was reported in the December 2011 Journal of Neurogastroenterology and Motility. In this experiment the probiotic Bifidobacterium longum, was found to reduce anxiety behavior in mice with colitis. Better bacteria meant happier mice.

You only have to look at some of the healthier cultures that stay lean, strong and reasonably sane. What do they eat? Both fresh and fermented foods. The Japanese natto (fermented soybean), the Korean kimchi, the European sauerkraut and European and Mongolian yogurt or kefir. Even Captain Cook fed his sailors sauerkraut and saw a significant drop in scurvy.

Here are a few things that you can do to get the benefits of brain-enhancing, fat-reducing intestinal flora:

1. Reduce all white sugar. This means even artificial sweeteners. A 2008 study at Duke University found that rats fed Splenda had a significant reduction of good bacteria in their in their digestive tract.

2. Eat fermented foods. They are good-tasting and cheap. Many ethnic stores have kimchi, Japanese natto, East Indian Dahi and sauerkraut and are much cheaper than the main supermarkets. Learn to make your own.

3. Avoid sweeteners. This means eat only plain yogurt or kefir.

4. Use probiotics. I find that the Greens-type of probiotics work well for me. (I have no commercial connection with any of the brand names.)

So, cut back on the Prozac and get your intestinal bacteria upgraded and in shape. You can feel better all round and even lose weight in the process.