| Food and Nutrition Q&A: | |
by Chelsy Leslie, RD, from the April 2004 newsletter
Most of the time, when we think of bacteria, we think of harmful germs. There are a lot of media messages about antibiotics and antibiotic soaps, but not much talk about the positive aspects of bacteria. There are between 400-500 different species of bacteria that live in our gastrointestinal (GI) tract. They play an essential role in our health. They help to break down food, produce certain vitamins, protect against harmful bacteria, and stimulate the immune system.
Although both disease-causing bacteria and beneficial bacteria can be found in the GI tract, generally there is a balance between the two. When there is an imbalance, problems such as diarrhea, constipation, and other more serious intestinal problems can result. Harmful bacteria can also cause damage to the intestine and promote disease.
Probiotics and prebiotics have been used to help the healthy bacteria stay in control. They are being investigated to help with irritable bowel syndrome, lactose intolerance, immune function, urinary tract infections, yeast infections, and cancer prevention. Probiotics literally mean “for life.” Probiotics are foods or supplements that contain beneficial microorganisms that can help improve the bacterial balance in the GI tract. The most common forms of probiotics include Lactobacillus and bifidobacteria. Yogurt is the main food source of probiotics. Some doctors advise their patients to eat yogurt or drink acidophilus milk after they have been on antibiotic therapy for a while to reestablish good bacteria in the GI tract. Other fermented products like tempeh, miso, sauerkraut, kefir, and kimchee can provide some beneficial bacteria. However, the potency and number of live organisms in commercial probiotic products varies widely.
Probiotic supplements are also available. However, the amount and types of bacteria needed to produce beneficial effects is still not known. It appears that probiotics are generally safe and well tolerated by humans even at high dosages. The supplements have to be in a form that can survive the acidity of the stomach. Probiotics in food, especially dairy products, seem to survive the harsh environment of the stomach better. Careful processing and storage is important because probiotics are affected by light, heat, oxygen, and moisture. Some products may not even have any live bacteria when you actually take them and some only have half of what they claim. Yogurt probably has the most reliable reported levels of probiotics due to its short shelf life and because it is refrigerated. Supplements should be kept in a cool, dry place with minimal exposure to light and air.
Prebiotics are non-digestible food products that stimulate the growth of friendly bacteria. Fructo-oligosaccharides (FOS) are one type of prebiotic that acts similar to fiber in the body. The advantage that prebiotics have over probiotics is they are stable and can be put into almost any food product. Food sources of FOS include honey, beer, onion, asparagus, rye, barley, Jerusalem artichoke, banana, maple sugar, oats, and Chinese chives.
More research needs to be done on probiotics and prebiotics to determine how they can be used and how much is needed to maintain or improve the balance of bacteria in the GI tract. Researchers will also examine synbiotics, the combination of probiotics and prebiotics. This will definitely be a topic you will hear more about in the future … so stay tuned!
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