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- Probiotics are "good" bacteria living in our gut that help digest food and boost the immune system.
- Probiotics can also naturally be found in foods like kimchi, miso soup, and sourdough bread.
- Benefits of probiotic supplements include improving mood, IBS symptoms, and cardiovascular health.
- Visit Insider's Health Reference library for more advice.
Not all bacteria are bad. In fact, trillions of microorganisms, including yeasts and bacteria, live in your gut, making up what doctors call the gut microbiome. These microorganisms help your body keep certain systems running like digestion or our immune responses.
Probiotics – live microbes mostly found in the large intestine – have become popular supplements as of late. But, research is still emerging on how they can help certain conditions.
Here's a breakdown of what probiotics are, how they may improve your health, and how to take them.
What are probiotics?
Probiotics are a combination of live bacteria or yeast that are naturally present in our bodies. Taking probiotics can help increase the amount of "good" bacteria that support your immune system.
You can buy probiotics as over-the-counter supplements. They are also found in certain foods, including:
- Yogurt
- Kefir
- Cottage cheese
- Sourdough bread
There are thousands of different types or strains of probiotics for purchase, says Heather Finley, DCN, a registered dietitian with her own private practice focusing on gut health. Though, for the majority of these, there's limited or no research on whether, or not, they can improve gut health.
The strains that have been the most widely studied include Lactobacillus, Bifidobacterium, and Saccharomyces boulardii.
Researchers are still exploring the various ways probiotics may help the body, but here are some of the benefits they've found:
1. Treat antibiotic-related digestive issues
Antibiotics may disrupt the balance of good and bad bacteria in the gut. This can cause unpleasant symptoms like:
- Diarrhea
- Abdominal pain
- Gas
- Nausea
Taking probiotics while on antibiotics can help restore good bacteria in the gut and relieve some of these symptoms, says Stacie Stephenson, a certified nutrition specialist and board member of the American Nutrition Association.
In fact, a large 2010 review found the Saccharomyces boulardii probiotic strain prevented antibiotic-related diarrhea in 84% of patients.
2. May treat IBS symptoms
IBS, a condition affecting the large intestine, can cause abdominal discomfort, diarrhea, constipation, bloating, and gas. Doctors aren't yet sure what causes IBS, but some research indicates an overgrowth of bad bacteria in the gut may be to blame.
The probiotic strains Lactobacillus plantarum and Bifidobacterium infanti may help reduce some of the symptoms affiliated with IBS, but the research so far is mixed.
A 2015 review found probiotics effectively reduced symptoms of IBS. In three of the trials, people with IBS who took probiotics for four weeks saw an improvement in the frequency and severity of their abdominal pain, bloating, and gas compared to the placebo.
However, a 2019 review found mixed results with seven studies indicating probiotics improved IBS symptoms and four reporting no significant improvement over placebo.
If you have IBS and want to try probiotics, talk with your doctor who can recommend specific types and doses.
3. May ease depression and anxiety
While probiotics alone aren't enough to treat depression and anxiety, some research indicates they may improve symptoms more than a placebo. While it's unclear why there are a couple of potential reasons:
- Probiotics reduce inflammation, which has been linked to depression, Stephenson says.
- The large intestine generates many of the same neurotransmitters responsible for mood in the brain, including serotonin. In fact, an estimated 90% of the body's serotonin is made in the gut. This may be why some studies have found a link between a healthy microbiome and mood regulation.
4. May improve cardiovascular health
A 2016 review found probiotics may offer several cardiovascular benefits, including lowering blood pressure. Meanwhile, a 2017 review examining the effects of probiotics on cholesterol found the strains Lactobacillus reuteri and Lactobacillus plantarum significantly reduced low-density lipoprotein (LDL) levels - aka the "bad" kind of cholesterol.
"Multiple studies have also shown that the state of the microbiome plays a role in the development of heart disease," Stephenson says. "So it makes sense that anything that improves microbial balance could act as a preventive for heart disease. However, we need more research into the particulars, such as which strains are most beneficial for which purposes."
Probiotic side effects
A healthy person is not likely to experience any side effects from taking probiotics. However, someone already experiencing gastrointestinal issues may experience:
- Upset stomach
- Diarrhea
- Gas
- Bloating
How to take probiotics
You can get probiotics as a supplement or in certain foods. The benefit to eating probiotic-rich foods is that it can also help you meet your recommended daily intake of vitamins and minerals, Finley says.
However, if you wish to take a particular probiotic strain for a specific condition, it may be easier to use supplements, Finley says.
Insider's takeaway
Research is still emerging on how probiotics may help certain conditions, but some studies indicate they may prevent antibiotic-related side effects or improve IBS symptoms.
However, if you are healthy there's no clear evidence that consuming probiotics - particularly supplements - will have an effect on your microbiome. Though many probiotic foods contain key vitamins and minerals and are, therefore, part of a healthy diet.