Good and bad bacteria

Illustration: Peter Arkle

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Check Your Bug Type
Between 300 and 500 species of bacteria live in your digestive tract. Some are beneficial bacteria that process indigestible carbohydrates, extract nutrients, and protect against disease; some are harmful bacteria associated with a range of health problems, from autoimmune disorders to gastric cancer. One way to promote the good bugs is by feeding them fiberlike substances called prebiotics. (See below for examples.) But ten years from now, we will have a much more detailed understanding of intestinal ecology: Your doctor may be able to tell you which bacteria species you lack and which prebiotics you should eat to boost the population of those species. Achieving the right mix of microbes might help with weight loss, immunity, and digestive problems; studies also indicate that certain prebiotics can minimize inflammation, increase calcium absorption, improve bone density, and help kill cancer cells in the colon.

What You Can Do Today
Start incorporating more prebiotics into your diet now. They occur naturally in a variety of plants, including onions, asparagus, artichokes, garlic, chicory, and bananas. You can also cultivate more good bugs in your gut by eating probiotics—live bacteria in yogurt and fermented foods. If you've recently suffered a serious illness (especially one that required antibiotics), it's worth trying probiotic supplements to restore balance to your intestines. Look for reputable brands of flora such as Lactobacillus acidophilus or rhamnosus GG and Bifidobacterium bifidum.