When you consider ways to stay healthy as cold and flu season approaches, consuming live bacteria may not be at the top of your list. But not all bacteria are bad for you. In fact, “good” bacteria found in food and dietary supplements may help you ward off illness this winter and throughout the year. The supplements are called probiotics. “Probiotics have been shown to secrete protective substances which turn on the immune system and prevent pathogens from taking hold and creating major disease,” says Dr. Allan Walker, director of the Division of Nutrition at Harvard Medical School and a world-renowned expert in the probiotics field.
The bacteria balance
Your lower gastrointestinal tract is home to 100 trillion microbes, most of which help digest food, fight harmful bacteria, and regulate your immune system. Such helpful microbes are “good bacteria.” An imbalance of the good and bad bugs in your gut can make you sick. For example, germ-killing antibiotics may disrupt the balance, leading to diseases that cause diarrhea. Imbalances may also lead to certain autoimmune diseases and allergies.
Probiotics to the rescue
You can help restore the bacteria balance by beefing up your inventory of good bugs with probiotics. They are live colonies of good bacteria found in dietary supplements and in foods. The most commonly used species (among a potential 3,000 or so) are in the Lactobacillus and the Bifidobacterium families. These are routinely used to treat a variety of gastrointestinal conditions, vaginal and urinary tract infections, and oral health problems. Dr. Walker says there’s also evidence that probiotics as a supplement can reduce the number of colds you’ll have in a year.
Intestinal Wall Ecosystem
Side effects and dosing
Probiotics are generally thought to be safe, and Dr. Walker says they have no side effects. People who have an immune deficiency or who are being treated for cancer should not use probiotics.
Foods that contain probiotics include yogurt, a fermented dairy drink called kefir, and fermented vegetables such as pickles and sauerkraut. Dr. Walker says foods may be effective for treatment, but at this time, we only have evidence showing that dietary supplements are effective. Perhaps the strongest evidence is in treating diseases caused by bad gut bacteria that lead to severe diarrhea. “When these good organisms coat the surface of the colon, then bad bacteria are blocked from attaching to and invading the wall of the colon. It’s like a physical barrier,” says Dr. Walker.
Supplements usually contain freeze-dried bacteria that warm up and come to life in your digestive system. You can find them in most drugstores and supermarkets, as capsules or tablets to swallow and loose powder to sprinkle on food. You’ll want a product that’s labeled for viability through the end of shelf life, not at the time of manufacture.
Dosages vary by product, so no general dosing recommendation can be made. However, common dosages for adults range from 5 to 10 billion colony-forming units per day, in a single daily dose, with or without food.