Probiotics 101: A Beginner’s Guide

Life gets difficult when your stomach or intestines aren’t healthy. Bloating and distension are terribly uncomfortable, and bowel diseases can be excruciating. When you have abdominal issues, sometimes getting through the day seems impossible.

There are plenty of products out there claiming to relieve you of these symptoms, but they rarely live up to their own hype. There is good news, though.

Over the past 20 years, doctors have thoroughly researched how bacteria known as “probiotics” can help restore your gut health.

So what are probiotics? According to the Oxford Journal’s Clinical Infectious Diseases, they are live microorganisms that offer legitimate health benefits when you take specific amounts of them.

Cindy Klinger, a California-based integrative dietician, offers further insight. “A probiotic is a bacteria or yeast that provides health benefits to the digestive tract. They provide a range of functions, including supporting a healthy gut, preventing disease, maintaining a healthy weight, and helping us absorb nutrients effectively.”

And as you’ll soon read, there are many studies which point to probiotics’ potential to restore your gut health.

But not all bacteria are considered beneficial to your gut. Many types have been linked to conditions like inflammatory bowel disease, bloating, and weight gain. Probiotics differ from this pathogenic bacteria by repopulating your gut and giving it a greater chance of becoming healthy.

In this guide, we’re going to walk you through the basics of probiotics. We’ll focus on the common uses of probiotics and the types of foods which contain them. 

Why Does a Healthy Digestive System Matter?

Your digestive system is key to good health. All the vitamins and nutrients within your food are absorbed into your body via your digestive system, and you tend to miss out on the health benefits of what you are eating if your digestion isn’t working as it should.

But your gut controls more than your nutrient intake – it plays a pivotal role in your overall health.

Daily life can become miserable if there’s an imbalance of good and bad bacteria in your gut. “If something goes wrong inside your gut, it’s not as immediately obvious as a broken arm or a twisted ankle.” Lisa Richards, a nutritionist and creator of the Candida diet, told us.

“However, the activity within your gut is actually one of the most important factors affecting your long-term health. The microorganisms that live within your gut play a hugely important role in your digestion, your immune system, and even your mood.”

Conversely, undesirable microbes can cause a host of health complications. Under certain circumstances, bad bacteria can trigger problems like bloating, gas, and other digestive issues.

That’s where probiotics come in – they help balance out the bad bacteria and can, according to many studies, be helpful in a variety of conditions related to your stomach and intestines. We’ll talk about some of those studies in a few seconds.

But before we start, we need to make a quick disclaimer. As we talk to you about the benefits of probiotics, you’ll come across some hard-to-pronounce bacteria. These aren’t interchangeable with each other. You can think of each of these bacteria as a house within the probiotics neighborhood; all the houses are in the same community, but not all the houses are the same.

What Are The Health Benefits of Probiotics?

There are plenty of reasons to consider taking probiotics. Below are a few of the biggest potential health benefits:

Reduced Risk of Antibiotic-Associated Diarrhea (AAD)

Antibiotics kill certain bacteria, and by doing so, they can upset the balance of good and bad bacteria in our gut. Diarrhea is a common side effect of this imbalance.

A Canadian study in 2011 found that taking a probiotic cocktail helped patients experience a decrease in AAD.

“Probiotics have been found to reduce AAD by 52%,” Dr. Bryan Tran, a doctor of osteopathic medicine and expert on probiotics, told us. “[They do this] by restoring and helping to maintain normal gut flora.”

Combat Constipation

More than 60 million people deal with constipation, the condition in which a person has infrequent bowel movements. We found a 2010 Polish study in which constipated adults found sweet relief after taking probiotics. Their particular brew of probiotics included Bifidobacterium lactis and Lactobacillus casei Shirota.

Lowers Your Risk and Severity of Allergic Reactions

Doctors from Finland found in 2011 that probiotic bacteria can help children with food allergies and inflammation due to allergies. While the bacteria didn’t act as a complete cure, the research is promising.

As Dr. Tran told us, “A study revealed that children who are administered probiotics at an early age reduce their chances of developing atopy (a cluster of diseases that include eczema, asthma, and allergies) by one half (46% in placebo-treated children versus 23% in probiotic-treated children. These findings were verified in follow-up and additional studies.”

» See Also: Probiotics for Kids: A Parent’s Comprehensive Guide

Effective Remedy for Inflammatory Bowel Disease

A research team from the University of California, San Francisco, confirmed in 2011 that maintaining a healthy gut through consuming probiotics can be an effective therapy/management tool for inflammatory bowel disease, a painful inflammation of the intestinal tract.

Boosts Immune System Functioning

Elie Metchnikoff, a Russian zoologist who is considered by many to be the father of probiotics, discovered in the 20th century that Bulgarian peasants were remarkably healthy for being so impoverished. The reason? They drank sour milk, which happened to be full of probiotics.

Metchnikoff later discovered that probiotics were the heroes here, as they helped to strengthen both the intestines and the immune system.

Improves Your Mood

It turns out your stomach and attitude are more connected than most of us realize. “Our immune system and our brain chemistry are among some of the most important reasons why we need to keep our digestive system healthy,” Dr. Donese Worden, a naturopathic medical doctor, told us.

“Many of our immune cells are made and instructed by our gut. That’s why we tend to get sick when we’ve had an emotional upset. On the flip side, we can become depressed if our GI is not working well because the majority of serotonin is made in the gut.” 

Dr. Krista Casazza, an associate professor at the University of Alabama at Birmingham, provided further insight. “The brain’s reward system, including mood and mental health, is wired for feedback with the gut, which is dependent on healthy flora… In health, the gut profile promotes feedback that aligns with energy balance, glucose, and lipid homeostasis, and positive mood.” 

Eases Acute Gastroenteritis (AGE) in Kids

AGE is a nasty little bug that tends to affect children. It causes lots of diarrhea and can lead to dehydration. In 2014, a team of scientists from Europe discovered giving kids probiotic treatments can reduce the intensity and duration of AGE.

»Related: Can Probiotics Help You Lose Weight?

What Are the Best Ways to Take Probiotics?

Now that we’ve walked you through an overview of probiotics, we want to give you some practical advice on how to get these helpful little organisms into your body. Below is a short list of five kinds of products that contain probiotics.

Keep in mind that, while there are plenty of studies which praise probiotics, most experts haven’t reached a conclusion about how much probiotic-friendly foods you should eat.

We spoke with Katherine Zeratsky, a nutritionist at Mayo Clinic, who brought up a good point: most adults can add to their diet foods and supplements rich in probiotics without a big risk of side effects. As always, make sure you check with your doctor first before starting a new diet regimen.


Kefir is one of those foods you see and don’t think much about because you don’t really know what it is.

Kefir originates in the Caucasus Mountains (Russia, Turkey and that part of the world). It’s made by mixing kefir grains with milk. The result is a tangy liquid that might remind you of drinkable plain yogurt.

This unique sipper has a healthy dose of Saccharomyces, a bacteria known to reduce or prevent diarrhea as well as a reputation for easing the effects of IBD and some symptoms of ulcerative colitis.

Those who struggle to tolerate lactose products may benefit the most from kefir.

“The main benefits of kefir is countering lactose intolerance, improving digestion and gut health, and countering allergies. Kefir is generally easier tolerated than other products such as yogurt,” said Bart Wolbers, a health and wellness researcher.


Of all the items on this list of probiotic-packed foods, yogurt is probably the most familiar. It’s a popular breakfast food that has benefitted from an increased interest in probiotics.

“Yogurt may improve your immune system and counter allergies,” Wolbers said. “[Other] possible benefits (that are not yet scientifically proven) include lowering inflammation, countering arthritis, and preventing cancer.”

Yogurts are made from various bacteria, but two of the popular ones are Streptococcus thermophilous and Lactobacilli.


There’s a lot of scientific evidence for the usefulness of probiotics for your digestive system. Lactobacillus acidophilus is a frequent ingredient in supplements, and often it’s packaged as a stand-alone supplement called “acidophilus.”

Supplements can contain multiple probiotics, so if you ever want to cross-reference the scientifically proven benefits of an ingredient, use this helpful chart from the National Institutes of Health.

Sour Milk

As we mentioned earlier, the Russian zoologist and father of probiotics Elie Metchnikoff discovered that Bulgarian peasants unknowingly boosted their immune systems by drinking sour milk.

We don’t recommend searching for sour milk at your local supermarket because you probably won’t find it. However, there are baking recipes which use sour milk as an ingredient and plenty of information online about how to make sour milk. Again, this is a smart option if you struggle to tolerate regular milk products.


Kimchee is a staple of Korean cuisine. It’s a fermented, spicy mixture of several different vegetables including cabbage. It’s a cult favorite and, because it's fermented, it is full of helpful bacteria.

Most of the bacteria that have been found in kimchee are in the Lactobacillus family, which has a long list of benefits for the digestive system.

However, there are some reasons for caution when eating fermented cabbage. “Kimchi may increase stomach cancer risk, in part because of the high levels of sodium available in the product (due to salt being added for fermentation),” Wolbers told us. 

Don’t Forget Prebiotics

As important as probiotics are on their own, you will boost their benefits further by ensuring your diet contains prebiotics as well. By Medical News Today’s definition, prebiotics are a form of fiber that humans can’t digest, but that serve as food for probiotics.

Klinger shared with us why prebiotics are important.

“Including prebiotics in your diet (dandelion greens, jicama, onions, and raw Jerusalem artichokes, for instance) can help feed the probiotics, another great way to support gut health and encourage your probiotics to flourish,” she said.

Our View: Is It Time to Add Probiotics to You Diet?

There is a significant amount of research available through studies and via the experts with whom we spoke that points to the fact that probiotics are helpful for gut health and a variety of conditions.

Research and experts indicate that probiotics can help with digestion, constipation, various allergic reactions and can even improve your mood.

What’s also nice about these good bacteria is that you can get them a variety of different ways, whether it’s fermented dairy products like kefir and yogurt, fermented vegetables like kimchi or using probiotic supplements or probiotic-enhanced foods.

If you want to take the next step in your understanding of probiotics, take a few minutes to read through our guide about when you should take probiotics and if they are safe.

In the article, we talk about the types of people who can benefit from probiotics, five different situations in which they can help, if you should take them with alcohol as well as what the reported side effects are.

Also, we include the expertise of two probiotics specialists: Dr. Krista Casazza, whom we talked with for this article, as well as Dr. Andrea Arikawa, an associate professor of nutrition and dietetics at the University of North Florida.

Editor’s note: This article was originally written by J.R. Duren and published on Dec 4, 2015. It has been revised and updated by Lydia Noyes on May 31, 2019.

Lydia Noyes

Lydia Noyes is a health, wellness, and lifestyle reporter who focuses on ways to live a healthier, more sustainable life. She is a member of the Association of Health Care Journalists. She received a bachelor’s in Environmental Studies from Calvin College and her writing work has been featured in Mother Earth News Magazine, Natural Living Ideas, and dozens of other websites, including her personal site FirstRootsFarm.

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