A lot of companies that sell probiotics have made claims regarding the health benefits of these products. The market has exploded as people turn to them based on these claims. But how much scientific evidence is there regarding how probiotics can promote gastrointestinal health? While a lot of research indicates that supplements can deliver on a lot of those promises, there is much work to be done before other claims can be substantiated.
What are Probiotics?
In a nutshell, probiotics are living microorganisms that mainly reside in the “gut,” the portion of the body that comprises the gastrointestinal tract. There has been an increased amount of interest in probiotics in recent years, and a great deal of research has been devoted to exploring their impact on the body.
Probiotics are found in abundance in certain types of foods, such as sauerkraut and yogurt. But unless you want to eat these foods exclusively, you need to get your probiotics in different ways. Most health food stores carry probiotic supplements, which typically come in capsule or powder form. A lot of manufacturers also sell drinks that provide probiotic benefits.
The main function of a probiotic is to make sure that there are enough beneficial bacteria in the gut to offset the harmful ones that reside in this portion of the body. If there are too many harmful bacteria, that can lead to serious health issues.
Different Strains of Probiotic Bacteria
There have been some concerns voiced by health organizations that some probiotics are mislabeled, leading people to believe that they provide health benefits when they really don’t.1 Some manufacturers put certain types of bacteria into their products that haven’t been proven to boost digestive health.2 When purchasing probiotics, look for ones that contain the Lactobacillus and Bifidobacterium strains in particular, because research shows they have beneficial effects.
You should also make sure that the products you buy are actually able to deliver beneficial bacteria to the gut. For example, some probiotic capsules are unable to survive their passage through the digestive tract because they can’t resist acids in the stomach. If they can’t reach their destination intact, the beneficial bacteria die before they can proliferate in the intestines.
Manufacturers claim that probiotics can boost the immune system and also help to alleviate problems such as diarrhea and allergies. Let’s take a closer look as to what the science says.
Immune System Health
A common claim is that probiotics can strengthen the immune system and help the body better defend itself against many types of health issues. While research does suggest some benefits, it’s unclear exactly how probiotics promote immune system health.3 Data suggest that the beneficial bacteria in probiotic products enhance the ability of cells to attack harmful substances that attempt to invade the body.4 Studies also indicate that probiotic bacteria help to stimulate protective mucus within the gut, and also inhibit the release of substances that can cause inflammation.5 More research is needed to determine the mechanisms by which probiotics help to reduce inflammation, and whether they can be tailored for specific applications.
The science appears to definitely meet the hype when it comes to the ability of probiotics to help reduce the occurrence of diarrhea.6 The Lactobacillus rhamnosus GG, Bifidobacterium lactis BB-12, and Lactobacillus reuteri SD222 are particularly effective in not only helping to reduce symptoms of diarrhea in children, but to prevent them as well. 7 One study involved an examination of the role the L. rhamnosus GG bacterium played in reducing the hospital stays of small children who were suffering from severe diarrhea. The study found that the bacterium helped reduce the duration of symptoms and also helped shorten hospital stays.8 This preventive effect was observed in malnourished children between the ages of 18-29 months, as well as in children who were not breastfed.
Again, the mechanism through which probiotics can help with diarrhea symptoms is not totally understood. The best guess so far is that probiotics help block certain receptors in the digestive tract, inhibiting the ability of the viruses that cause diarrhea to invade the body.9 But even if the exact mechanism isn’t known, there is enough evidence to suggest that using probiotics in conjunction with rehydration therapy could be very effective in treating rotavirus diarrhea, which can be fatal to infants.10
Scientific evidence suggests that the way that a child’s gut bacteria develop can have a substantial impact on whether or not that child will develop allergies.11 As certain harmful bacteria strains (the Ureaplasma urealyticum and Staphylococci strains, in particular) colonize in a developing gastrointestinal tract, the chances of allergy development increase. Studies show that when probiotics are used during pregnancy, they can reduce the chances that a newborn will be “atopic,” or predisposed to certain allergic conditions, such as asthma or hay fever.
One particular study involving pregnant women was conducted over a four-week period right before birth. During that time, one group of women received probiotics containing the L. rhamnosus bacterium. The bacterium was then given to their newborns. The other participants, as well as their babies, were given placebos. The babies who were part of the treatment group showed a substantial reduction in atopic indications.12 Follow-up studies conducted four years later showed that the probiotic effects lasted beyond infancy.
The Bottom Line
There is a substantial body of scientific evidence that suggests many of the claims made by the manufacturers of probiotic products are valid, especially products that contain certain types of beneficial bacteria. But the jury is largely still out regarding the benefits of other strains that are commonly used in probiotics.
As with any type of supplement, it is very important that you talk to your doctor before you start taking probiotics. There are some instances where using supplements could worsen symptoms associated with certain conditions, so make sure your doctor says it will be safe. And it’s also important to remember that even though probiotics provide substantial benefits, they aren’t a panacea. You still need to exercise regularly and follow a healthy diet.