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How’d you first hear about probiotics? In a candid conversation with a friend about constipation or diarrhea? Maybe you saw a video on social media about good gut health and how probiotic supplements can help. Either way, you likely have questions. What are they, and more importantly, does the science support the claims? Let’s unpack it, starting at the very top.

What Are Probiotics?

Probiotics are live microorganisms such as bacteria and yeasts. Trillions of microbes help support bodily functions and overall health. The good news is that most of the bacteria are harmless. Only a small number of “bad” bacteria in the body causes disease. Probiotics are an example of the “good” ones. 

Lactobacillus acidophilous is the most common type. It’s found naturally in your gut, mouth, lungs, and urinary tract. It also naturally occurs in yogurt and fermented foods like pickles, sauerkraut and kimchi. You can get Lactobacillus acidophilous from dietary supplements, too. 

How Do Probiotics Supplements Work?

The main job of a probiotic dietary supplement is to help restore balance to your gut microbiome. A microbiome is the collection of microbes -- bacteria, fungi, and viruses -- that naturally live in your body. When that balance gets thrown off, it could possibly lead to:

  • Heartburn 
  • Bloating 
  • Constipation 
  • Diarrhea 
  • Other gastrointestinal conditions like inflammatory bowel disease (IBD) and irritable bowel syndrome (IBS)

Things that can mess up your microbiome include:

  • Poor diets with too much saturated fat 
  • Certain medications and antibiotics 
  • Illness from a virus 
  • Stress 

Researchers are still learning about how probiotics work. But research suggests they help with: 

  • Acne and eczema
  • Cavities and gum disease
  • Vaginal and urinary tract infections
  • Diarrhea triggered by antibiotics

It’s important to note all probiotics aren’t the same. Some strains, such as Saccharomyces boulardii, can help with diarrhea. Others, like lactobacillus, may help you better digest lactose if you’re intolerant. 

And probiotic supplements aren’t regulated by the FDA. So it’s a good idea to ask your doctor which probiotics might work best for you or if you should even take them. 

What Does the Science Say?

There are smaller published studies that suggest probiotics in food and dietary supplements may boost immunity and ease symptoms of IBS or traveler’s diarrhea. But these positive effects are modest, especially if you’re already relatively healthy. In fact, there are some cases where taking probiotics to reverse the effects of antibiotics or for your overall health could affect the natural balance of your microbiome and trigger other issues. 

Some researchers think your gut health also affects:

  • Mood and pain tolerance
  • Mental sharpness and fatigue
  • Inflammation and your immune response
  • Metabolism, blood sugar, and fat storage

The most reliable way to feed your gut microbiome is by eating a healthy mix of vegetables, nuts, beans, and whole grains.

What Are Possible Side Effects?

Although probiotic supplements are generally safe for most people, you might have mild side effects, especially the first few days after you start taking them. These include:

  • Stomach upset 
  • Bloating 
  • Gas 
  • Diarrhea

They might also trigger an allergic reaction. If this happens, stop taking the supplements and talk to your doctor. 

Show Sources

Photo Credit: iStock/Getty Images


National Center for Complimentary and Integrative Health: “Probiotics: What You Need to Know”

National Institutes of Health: “Probiotics: Fact Sheet for Healthcare Professionals.” 

National Institute of Environmental Health Sciences: “Microbiome.” 

Integrative Medicine: A Clinician’s Journal: Part 1: “The Human Gut Microbiome in Health and Disease.”

Harvard Health Publishing: “Should You Take Probiotics” “Signs of Poor Gut Health.”