So what can probiotics help you with?
Each of us has more than 1,000 different types of bacteria that live in our digestive tracts, helping us to break down food and absorb nutrients. But when we take antibiotics — medicine that is designed to kill destructive, illness-causing bacteria — the drugs can also kill the healthy intestinal flora that helps us digest. About 30 percent of the patients who take antibiotics report suffering from diarrhea or some other form of gastrointestinal distress, according to the recent JAMA study on probiotics and antibiotic-associated diarrhea. As a result, doctors commonly prescribe taking probiotics to “repopulate" the digestive tract with healthful bacteria. The study found that it was a viable solution for many.
But probiotics can also help with other types of digestive issues. Research has shown that probiotics can be helpful for people with irritable bowel syndrome, or IBS — a hard-to-treat condition that can have a range of intestinal symptoms, such as abdominal pain, cramps, bloating, diarrhea and constipation. In one study, female IBS patients experienced some alleviation of symptoms like abdominal pain and irregularity when they were given a supplement of the bacterial strain, Bifidobacterium infantis.
Even for those without an urgent problem, probiotics can help with overall digestive management. Challa argues in his book, Probiotics For Dummies, that good bacteria help “crowd out" bad bacteria. That's because the intestine is lined with adherence sites where bacteria latches on. If the sites are populated with good-for-you microbes, there's no place for a harmful bacterium to latch on.
Probiotics make a nice compliment to antibiotics among people who suffer from urinary tract infections, according to the research.
What's more, there's emerging evidence that regular probiotics can help prevent bad bacteria from invading the urinary tract by maintaining a population of healthy bacteria on the tract's adherence sites.
Infections of the urinary tract are extremely common, especially in women. Most infections disappear with antibiotics, but about 30 to 40 percent might return, according to literature from the University of Maryland Medical Center.
Allergy research is still preliminary, but at least one large, high quality study found a relationship between women taking probiotics during pregnancy and a 30 percent reduction in the instance of childhood eczema (an early sign of allergies) in their infants.
Researchers selected women who had a history of seasonal allergies — or whose partners had histories of allergies. The infants who received probiotics in-vitro also had 50 percent higher levels of tissue inflammation, which is thought to trigger the immune system and reduce allergy incidence.
Just like the digestive tract, the vagina relies on a precarious balance of good and bad bacteria. When that balance is off, it can result in one of two very common, though thoroughly uncomfortable infections: bacterial vaginosis and yeast infections. In fact, bacterial vaginosis can actually lead to a yeast infection.
Some small studies have found that L. acidophilius can help prevent infection, manage an already active one or support antibiotics as a treatment, though it's worth noting that the probiotics were taken as vaginal suppositories, rather than orally in food.
Probiotics may also have a special role in maternal health, as pregnant women are particularly susceptible to vaginal infections. And bacterial vaginosis has been indicated as a contributing factor to pre-term labor, making probiotics a potential boon for fetal health.
Surprisingly, one of the main functions of healthful bacteria is to stimulate immune response.
Maintaining good intestinal flora, a person can also help to maintain a healthy immune system. And that has real world effects: for example, in one small study of students, those who were given a fermented dairy drink (instead of milk) displayed increased production from lymphocytes — a marker of immune response.
In 2006, Stanford University researchers found that obese people had different gut bacteria than normal-weighted people — a first indication that gut flora plays a role in overall weight.
Some preliminary research shows that probiotics can help obese people who have received weight loss surgery to maintain weight loss. And in a study of post-partum women who were trying to lose abdomnial fat, the addition of lactobacillusand bifidobacterium capsules helped reduce waist circumference.
It's still unclear how probiotics play a role in weight loss — and there is some controversy about how significant the probiotics-associated weight loss is.
But as long as the probiotics source is low-calorie and healthful, itself, it is an innocuous method to attempt.