What are probiotics?

Probiotics are microorganisms, such as bacteria or yeast, that can be beneficial to your health. Some types of these microorganisms live in your body – in your intestines, for example. Probiotics are also found in food, such as some kinds of yogurt. They're also available as dietary supplements, and some baby formulas even have added probiotics.

Some adults take probiotic supplements to help with digestive problems. Probiotics may also have benefits for infants, such as easing colic and treating diarrhea.

But there isn't scientific evidence to support all the claims made in favor of probiotics. Before giving your baby a probiotic supplement or probiotic-enhanced formula, talk to your child's doctor and do a little research.

Read on to find out how probiotics work and what the evidence shows about their benefits and safety.

How do probiotics work?

Your body hosts trillions of microorganisms, mostly bacteria, that are collectively known as your microbiome. Some types are considered harmful and others helpful, but ideally they coexist in balance with one another. When the balance is disturbed, resulting in too many "bad" bacteria, it can lead to diarrhea or other health problems.

Certain illnesses can upset the balance of bacteria in your intestines. So can taking antibiotics, which wipes out both good and bad bacteria. The body usually restores this balance on its own over time. But studies show that taking probiotics can sometimes help speed up this process and may prevent or ease certain symptoms.

How can probiotics help babies?

Probiotics may help infants with:

  • Diarrhea: There's strong evidence that certain probiotics can help treat diarrhea caused by infection or antibiotics. One study showed that giving babies certain probiotics as soon as they started having diarrhea caused by a stomach virus shortened the course of illness by one day. There's not as much evidence that probiotics can prevent diarrhea in babies.
  • Colic: The cause of colic is unknown, but some experts believe that it may be related to gas-producing bacteria and low numbers of a certain type of bacteria in a baby's intestinal tract. Probiotics may reduce colic symptoms by tipping the balance in favor of good bacteria in the intestines. One study found that colicky, breastfed babies given a probiotic supplement cried for a shorter period of time each day than untreated infants within one week of starting the treatment. However, more studies are needed to confirm this effect.
  • Eczema: In another study, researchers gave probiotics to women with a history of eczema in their last months of pregnancy. They breastfed their babies and gave them probiotics for six months. By age 4 years, kids who received this treatment were almost half as likely to have eczema than those who didn't. However, other studies found no benefit.

What about prebiotics?

Prebiotics are substances found in certain foods (mostly fruits and vegetables) that function as food for gut bacteria, stimulating their growth. Prebiotics are also sold as dietary supplements and can be found in some baby formulas.

Not much research has been done on prebiotics. In one study, infants were given prebiotic supplements in formula during the first six months of life. After 2 years, the infants given the prebiotics were less likely to have a type of skin allergy called atopic dermatitis. But other studies haven't found any benefit to prebiotic supplements.

How can I tell what kind of probiotics could help my baby?

Talk to your baby's health care provider. She'll first examine him to rule out a more serious illness and make sure that it would be safe for him to take probiotics. This is especially important if your child has a compromised immune system.

If you decide to give probiotics a try, your child's doctor may be able to recommend a brand that contains the right bacterial strains to meet your baby's needs. For example, research suggests that Bifidobacterium breve and Bifidobacterium longum can help manage colic. Bifidobacterium lactis, Lactobacillus reuteri, and Lactobacillus rhamnosus (known as LGG) may help treat diarrhea.

Dosage is another consideration. For infants and children, studies show that a dosage between 5 and 10 billion colony-forming units (CFUs) per day is sufficient to establish enough good bacteria.

How do I give my baby probiotics?

Probiotic supplements come in many forms, including liquid drops and powder that can be mixed into breast milk, water, or formula. However, keep in mind that the U.S. Food and Drug Administration (FDA) doesn't regulate supplements, so it's often difficult to know exactly what you're getting. (See our article on buying supplements for guidance.)

You can also put probiotic drops directly into your baby's mouth. If you're breastfeeding, you can even put the drops on your breast right before you nurse him. Or you can add them to a bottle of formula or breast milk. Just don't heat the bottle over 100 degrees F or you'll risk destroying the microorganisms.

You can also buy formula containing probiotics. Unlike the supplements described above, these products are regulated by the FDA and have been approved as safe. But that doesn't mean there is evidence in support of any health claims. And as with the drops mentioned above, you'll destroy the probiotics if you heat the formula too much.

Are there foods containing probiotics that I can give my baby?

Some foods contain probiotics, although there haven't been any studies done that demonstrate health effects for babies. Still, it can't hurt to try them.

Yogurt is a great source of probiotics. Most babies can start eating yogurt as soon as they start eating solids – around 4 to 6 months. Look for products that contain "live" or "active" cultures, which means the organisms have not been destroyed by heat during processing. Choose plain, unsweetened yogurt to avoid added sugar. 

Other foods that naturally contain probiotics:

  • Kefir, a type of fermented milk drink (like yogurt)
  • Miso (fermented soybean paste)
  • Tempeh (another fermented soy product)
  • Aged cheeses, like cheddar or blue cheese

If you have questions about starting your baby on these foods, talk to your health care provider. BabyCenter also offers these tips for introducing your baby to new foods.

Learn more:

Probiotics for children