WHAT THEY ARE
Probiotics are beneficial bacteria that live in the intestines. Our systems start to absorb them naturally just days after we're born. "They manufacture nutrients our bodies need—vitamin B12, for example—and can suppress the growth of harmful bacteria that make us ill," says Merrell.
WHAT THEY DO
A basic course of antibiotics can kill off good bacteria with the bad. "Probiotics 'reset' your system and get you back to a healthy state," Merrell says. Probiotic supplements repopulate the natural ecosystem of bacteria already living in our bodies, improving the functioning of the digestive system—where 70 percent of the immune system resides.
WHAT THEY TREAT
Probiotics can help improve irritable-bowel syndrome, diarrhea, constipation, and general digestive issues. Some people opt to ease specific ailments by taking probiotics for a short period; people with chronic problems can take them on a long-term basis.
HOW TO CHOOSE ONE
Ask your doctor before introducing anything new to your or your child's system. In addition to our product suggestions at right, Merrell recommends sites like Medline.com and Pubmed.com to check out research on different strains and brands.
FAQ
Still have questions? Dr. Merrel was kind enough to answer our editors' many queries on the benefits of probiotic supplements:
When disguising probiotics in food, does it matter if the food is hot or cold? And do they have a taste?
Bacterial probiotics are usually tasteless and odorless. If anything, on their own they may have a slightly milky taste. If you're mixing them into food, it's best to use cold food, or at least cool. High heat can kill the probiotic cultures.
Are probiotics safe to take on a regular basis? Can you "overdose," or otherwise take too many?
Well, you can overdo anything—even water! Not everyone finds that all probiotics agree with his or her system, and there are many subspecies of beneficial bacteria. That said, generally they cause few to no side effects, and for most people, they are completely safe.
People with severe milk allergies obviously need to make sure that the probiotics are not milk based. The packages tell you which ones are dairy-free.
People with chronically inflamed bowels have a major break in the lining of the intestine, and theoretically things they ingest can leak into their bloodstream. There's some question about whether that can give these patients an infection. A healthy person can take them, no big deal, but somebody who is truly ill should get the advice of a health-care provider before they try them.
What kills your natural probiotics, and is there anything you can do to help your naturally occurring intestinal flora thrive?
Antibiotics, especially, can kill off our natural defenses. I recommend that, along with probiotic supplements, people use prebiotics, which are nutrients that promote growth of beneficial bacteria and inhibit growth of pathologic ones. Some people feel prebiotics are even more important than probiotics! But they do sometimes have one side effect, which, while safe, can be alarming: lots of gas. It's usually fairly odorless and not everyone gets it, but start with small doses to be safe. Traditional dietary sources of prebiotics include soybeans, inulin sources (such as Jerusalem artichokes or jicama) and raw oats.
If you just stop taking antibiotics, will probiotics eventually regrow themselves, so you don't need to take them in pill form?
Most probiotics (including the entire acidophilus family) are not the same ones naturally present in the bowel. They do not "colonize" (i.e., self-replicate forever), as do those that are present in our systems since birth. Almost all probiotic supplements must be taken regularly to continue to thrive in the intestines.
Sometimes my son gets constipated. I want to give him probiotic yogurts to help with digestion, but you're not supposed to eat dairy when constipated, correct?
Calcium is constipating, but not necessarily all dairy is—other than cheese, which really can be. A little yogurt should be fine.
I heard that I should change my brand of probiotics every few months or so. Do probiotics lose effectiveness after you have been taking them for a while?
No, that's not true. But because there is no quality control in the marketplace, the key is to get the right brand—one that is (a) reliable and (b) of the right species (i.e., bifidophilus, especially for kids, or acidophilus.) An enteric coating may also help protect the probotics against your stomach acids.
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