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The benefits of probiotics and prebiotics have not been scientifically proven. Research in the area is ongoing, but studies have been limited and results inconsistent. Additional research is needed to confirm any claimed health benefits.

Probiotics and prebiotics can help balance bacterial levels within the intestines. They may increase the amount of helpful bacteria and reduce amounts of harmful bacteria, which can aid digestion and absorption of nutrients, and may protect against certain gastrointestinal problems. Probiotics and prebiotics may be especially helpful in stabilizing bacterial levels after the use of antibiotics (which can kill both harmful and beneficial bacteria present in the intestines).  

Probiotics are believed to have an effect on the following symptoms, conditions or diseases:

• Diarrhea. Probiotics may help prevent the accumulation of infectious bacteria that can cause diarrhea. Their activity in the intestines may also slow the digestive process, helping to alleviate diarrhea associated with a variety of conditions (e.g., irritable bowel syndrome, Crohn’s disease). Probiotics have been studied the most for their possible use in helping alleviate diarrhea.
  
  
• Vaginal infections, bacterial vaginosis. The use of probiotics is believed to help alleviate symptoms of these conditions, although it has not been sufficiently studied.
  
  
• Lactose intolerance. The ability of probiotics to convert the lactose in dairy products to lactic acid may be helpful for people who are unable to digest lactose. Research regarding the effects of probiotics on lactose intolerance has provided conflicting results. More information is needed before conclusions can be reached.

Prebiotics may aid in the absorption of certain minerals (e.g., calcium, magnesium, zinc, iron), thus helping to improve bone mineralization. In addition, prebiotics act as a type of soluble fiber in the intestines, which can aid digestion. Some experts believe prebiotics may potentially offer health benefits against diseases such as cardiovascular disease and type 2 diabetes, as well as gastrointestinal diseases.

Some studies have indicated that prebiotics may boost immune system development in infants, possibly helping to prevent certain allergies. Human breast milk contains prebiotics, and some studies have indicated that breastfed babies have higher levels of beneficial bacterial in their intestines, which may help protect them against certain types of infections (e.g., rotavirus).

Another study found evidence that adding prebiotics to infant formula may lower a baby’s risk of eczema.

Meanwhile, researchers in Australia discovered that giving a baby probiotics may reduce the risk of necrotizing enterocolitis, an infection that sometimes kills the lining of the bowel in premature babies. And researchers in California are examining whether or not the use of probiotics helps delay or prevent asthma in children.

However, caution is generally advised regarding use of prebiotics and probiotics in newborns. Parents are encouraged to consult their child’s pediatrician before supplementing a child’s diet with probiotics or prebiotics.