THE BASICS: Your digestive tract contains more than 500 different types of bacteria and an estimated 100 trillion individual bacteria, most of which are beneficial. In fact, you have 10 times more bacteria in your gastrointestinal tract than you have cells in your entire body. Probiotic supplements contain some of these bacterial species and can provide many health benefits.

ALIAS: The term probiotics is a general one. The names of specific intestinal bacteria can be confusing because there are so many different types. For example, lactobacillus refers to a genus of bacteria that consists of many species, including L. acidophilus,
L. rhamnosus, and L. casei. Some species, such as L. casei, have subspecies, such as L. casei GG. There’s more—all bacteria have two names, such as Bifidobacteria bifidum; the first represents the genus, and the second identifies the species. The names are usually abbreviated, such as B. bifidum.

HOW PROBIOTICS WORK: Intestinal bacteria contribute to our health in numerous ways, and probiotic supplements support these functions. They help us digest food and also make small amounts of some vitamins. They protect against infectious bacteria, in large part by crowding them out. Intestinal bacteria secrete peptides (protein-like substances) that help maintain our immune activity and defenses against a wide range of threats.

HEALTH BENEFITS: Probiotics have many different health benefits.

• Antibiotic-related diarrhea. At one time or another, nearly everyone takes antibiotic drugs to fight bacterial infections. However, antibiotics kill both pathogens and friendly intestinal bacteria. The consequence is what doctors call a “microbial vacuum,” which is sometimes filled by opportunistic disease-causing bacteria, such as Clostridium difficile. C. diff, as it is commonly known, can lead to a secondary infection and diarrhea.
  
  Probiotic supplements are essential for fighting C. diff and restoring normal gut health. Start taking probiotics with antibiotics—the probiotics will not interfere with antibiotics, but they will lessen their undesirable effects. It’s important to continue taking probiotic supplements for at least a month after stopping antibiotics. The reason is that the “dysbiosis” caused by antibiotics can linger for years and set the stage for local and systemic candida yeast infections. Consider a probiotic supplement containing L. casei GG, B. lactis, or S. thermophilus.
• Infectious diarrhea. So-called stomach flus and cases of food poisoning are often caused by infectious bacteria. Probiotics can help in infants, children, and adults because these good bacteria secrete their own types of antibiotics, which fight infection-causing germs. In an analysis of nine studies, Cornelius W. Van Niel, MD, of the University of Washington, Seattle, found that treatments with lactobacillus probiotics led to faster recovery from gastrointestinal tract infections.
• Irritable bowel syndrome. Pathogenic bacteria can cause inflammation, damage the gut wall, and may even contribute to irritable bowel syndrome, food allergies, gluten intolerance, and the use of antibiotics. Probiotics containing L. plantarum can help control irritable bowel syndrome and reduce symptoms such as abdominal pain, bloating, constipation, and flatulence.
• Vaginal infections. Candida albicans, a type of yeast, can cause both vaginal and systemic infections. Probiotics containing a different type of yeast, Saccharomyces boulardii, can often eliminate vaginitis and candida infections. Probiotic capsules, live-culture yogurt, and even probiotic suppositories have yielded benefits, according to several studies. In addition, several species of bacterial probiotics, including L. acidophilus, L. rhamnosus, and L. fermentum can help control candida infections.

BACKGROUND CHECK: Almost every cultural group eats probiotic foods. Germans eat sauerkraut, Japanese enjoy miso and natto, and Koreans eat kimchee. There’s also live-culture yogurt and kefir.

GLEANINGS: A recent study in the journal Nature found that probiotics typical of those in the guts of people reduced the risk of type 1 (insulin-dependent) diabetes in laboratory mice. Animals without gut bacteria were far more likely to develop type 1 diabetes.

HEADS UP: Gerhard Pulverer, MD, of the University of Cologne, Germany, discovered that specific types of intestinal bacteria secrete peptides that help maintain normal immunity. Ironically, antibiotics can disrupt the activity of these beneficial bacteria, but probiotics can reactivate production of many different immune compounds that fight infections and might even protect against colon and breast cancers.

WHAT YOU SHOULD TAKE: Probiotic supplements may contain one or several species of beneficial bacteria. Product potency—that is, the number of bacteria per capsule—is based on the day of manufacture. Opt for fresh products and keep them refrigerated to maintain potency. Take probiotics at the end of a meal to buffer the bacteria-killing effect of stomach acid.

There are so many high-quality brands of probiotics available; a few of our favorites: Essential Formulas Dr. Ohhira’s Probiotics 12 Plus, Jarrow Formulas Jarrow-Dophilus EPS, Rainbow Light ProbioActive 1B, Udo’s Choice Super Bifido Plus Probiotic, Natren Healthy Trinity, and Enzymatic Therapy Acidophilus Pearls.