Whether it is yogurt that makes you go or pills with active cultures, companies claim that these beneficial bacteria help regulate digestion, boost the immune system and even reduce lactose intolerance. But, do we really need this stuff? Well, yes and no.
The human body is home to some 100 trillion bacteria -- that's 10 times the number of cells in the human body -- and among them are hundreds of strains of good bacteria. Most people enjoy a healthy colony of helpful microorganisms in their digestive tract, renewed through foods like cheese, yogurt, bananas and sauerkraut.
"There should be more than 550 kinds (of good intestinal flora) in our gut totaling about 6 pounds," says Nancy Parlette, a certified digestive health specialist with the Loomis Institute. "They feed off the fiber in our foods and are a huge part of our immune system."
It's a naturally occurring symbiotic relationship. These beneficial bacteria aid in digestion by fermenting unused nutrients. They also destroy harmful bacteria, bolster the immune system and produce vitamins like biotin and vitamin K -- and we're not the only species that rely on microflora for proper health.
Cows, for example, get the bulk of their nutrients from the microbes in their four-chambered stomachs rather than from the food they eat directly. The bacteria ferment and digest cellulose in plants, and the cow absorbs the nutrient-rich byproducts. They also absorb the microbes themselves as they die off, which supply additional protein and energy.
Green iguanas, too, rely on microorganisms to break down the fibrous plant material that comprises the bulk of their diet -- and the species has developed a rather unsavory strategy to seed their systems. Babies frequently nibble on the excrement of adult iguanas, which contains enough of the beneficial bacteria to jump-start a colony.
Thankfully, humans have more palatable options for bolstering good bacteria. Of late, grocery shelves are packed with all manner of foods and supplements intended to replenish our digestive systems. Over time, a poor diet, stress and the use of certain medications can kill off beneficial bacteria in the gut.
"We either starve them to death by not eating anything with fiber or we kill them off by taking all the pills or treatments like antibiotics, antacids, steroids, chemotherapy and radiation," Parlette explains.
Medical research has shown a strong correlation between healthy, active colonies of microflora and healthy bodies -- there is even evidence to suggest that a daily probiotic supplement can alleviate chronic conditions like irritable bowel syndrome, Crohn's disease and lactose intolerance. Research also shows a possible link between probiotics and a reduced risk of colon cancer, obesity, urinary tract infections, tooth decay, skin problems and allergies.
"Probiotics have not classically been proven to help in many of the disorders of digestion. There have been no classic studies which compare them against a placebo with a measurable endpoint that proves probiotics are better than a placebo," says Dr. Jorge E. Rodriguez, author of "The Acid Reflux Solution" and a frequent guest on the TV shows "The Doctors," "Good Morning America" and "The View."
"That being said, there are many meta analysis that show that probiotics may help treat H. pylori ulcers, diarrhea due to antibiotics, colon cancer and irritable bowel syndrome," Rodriguez says. "I tell my patients to go ahead and take them along with accepted, proven medical therapy. It can't hurt."
Different strains of probiotics offer different benefits, so be sure to read the label carefully when choosing a supplement or supplemented food. The packaging should include the types of bacteria included and define the potency by billions of cells, which will determine how much you need to consume to reap the benefits.
Parlette recommends a multi-strain, daily probiotic supplement that contains both lactobacillus for the small intestine and bifidobacterium for the large intestine. For daily maintenance, choose a regimen that contains 20-50 billion cells.
Supplements typically offer more bacteria for the buck than supplemented foods like yogurt, cheese and cereal. The fine print in one yogurt commercial, for example, states that it must be eaten three times a day to get the full benefits, while most supplements found in the vitamin aisle pack all you need into one small pill.
To get the most out of the supplements, cut back on sugar and white flour, which feed the harmful bacteria, Parlette says. Instead, focus on a diet rich in fruits, vegetables, whole grains and legumes, which contain the fiber to feed the beneficial bacteria.
Also, eat plenty of naturally probiotic-rich foods like cottage cheese, bananas, artichokes, pickles, sourdough bread and miso soup.