Gary Emmett, head of hospital pediatrics at Jefferson University Hospital, wrote this for the "Healthy Kids" blog.

New studies suggest that an "alternative medicine" product - probiotics, a.k.a. good or normal germs - may be our best choice for infantile colic.

About 10 percent of newborns can be colicky: crying and acting as if they are in severe pain. This occurs especially in the first 12 weeks of life, and no effective treatment has been found up to now.

A recent study in JAMA Pediatrics showed that giving daily normal bacteria or probiotics for the first 12 weeks of life - in this case, Lactobacillus reuteri, similar to the "live culture" in yogurt - markedly reduced the pain, writhing, gas, and other signs of infantile colic. This large study of almost 600 babies, where neither parents nor doctors knew which babies were getting the good bacteria or the placebo, found that that crying time per day was cut almost in half (39 minutes versus 71 minutes), spitting up was almost cut in half (2.9 times daily versus 4.6 times daily), and the infants had slightly more bowel movements.

Bacteria can help us thrive. Or it prospers at our expense. Each of us has about 10 times more bacterial cells than human cells in our bodies. Microbiology teachers love to tell students that each human is 91 percent bacterial by number of cells.

About 500 species of bacteria live in us. They help and hurt us in many ways:

If you transplant the gut bacteria of a skinny mouse into a fat one, the porkier fellow will lose a lot of weight. So our gut flora may play a role in helping us absorb our food or making us fat.

When we get an antibiotic to treat a serious infection, the drug can cause yeast infections, overgrowth of other fungi, and diarrhea. All these occur because the antibiotic killed not only the "bad" bacteria, but also the good strains protecting our gut.

Clostridium difficile infection, a sometimes-fatal side effect of antibiotics, is especially dangerous in older, debilitated patients. It can be treated by doing a fecal transplant from a healthy individual. (Yes, this means taking the stool of a healthy person and placing it in the colon of an ill person.)

Using a daily high-dose probiotic can, in some adults, calm irritable bowel syndrome with its alternation of constipation and diarrhea and its bellyaches, seemingly by "normalizing" our gut flora.

The germs on our skin and the mucous membranes of the nose and throat keep bad bacteria such as MRSA from colonizing us. Although washing is good in general, over-washing with antibacterial soaps can strip away our normal protective bacteria on the skin and make us more susceptible to infection.

So bacteria can play a significant role in our health. Doctors do not know what causes gastrointestinal disorders such as colic or irritable bowel syndrome, but many suspect that these involve our gut bacteria. This JAMA Pediatrics study seems to agree, at least in newborns. There are now probiotic supplements for infants meant for colic. Check with your pediatrician before giving such a product to your child. More work is needed to give us insights into the relationship between colic and gut bacteria.