What are probiotics, the ultimate guide


The healthy image of greek yogurt isn’t just made up of it’s nutritional benefits, such as it’s high protein and low calorie count. No, besides it’s versatility and health benefits, the fact that greek yogurt contains probiotics has played a huge role in it’s success over the past years. But what are probiotics, and what do they do? Are they just a marketing tool used to promote greek yogurt, or are they legit and can they play an important role in our overall well-being? In this ultimate guide to probiotics I’m going to explain to you what probiotics are and explore it’s possible benefits and side effects. Ready to learn about probiotics? Here we go!

What are probiotics

Probiotics didn’t really come “on the scene” until the 1990s when researchers started to wonder if these little buggers were actually good for us. They know bacteria are all over our body–both inside and out–so they knew there had to be more to these billions of bacteria than just infections and digestion. But what are probiotics, exactly? They are basically just bacteria that are beneficial to our body’s overall function. Before there’s any nose wrinkling, we need to remember that our bodies are riddled with both good and bad bacteria. Probiotics are our friends; they’re good bacteria. They’re naturally found in the body, but they’re also in different foods, mainly yogurt and fermented goods.

What do probiotics do? When we’re talking about probiotics benefits, the benefits come to light primarily when our body loses its naturally occurring good bacteria due to illness or after a round of antibiotics. Unfortunately, antibiotics don’t discriminate between the friendly and the malicious bacteria throughout our bodies, so they wipe out most bacteria throughout the body, which is where probiotics come in. Putting good bacteria in the body can also eliminate the bad bacteria that lead to infections, helping fight an array of illnesses. They’ll also work to create a balance between the good and bacteria to support a healthy immune system. Worried about side effects? Probiotics side effects are pretty minimal and are usually limited to mild gas and bloating.

When we’re doing our research, the term “prebiotics” is sure to come up. Keep in mind that these are different than probiotics. A prebiotic is a dietary fiber and usually comes in the form of powder, meaning they aren’t found in foods like probiotics are. Instead of introducing bacteria into the body, they encourage the gut’s good bacteria to grow and stay healthy. They’re helpful to people with inflammatory bowel diseases or digestive disorders.

In summary, probiotics are good bacteria, while prebiotics grow existing good bacteria. 

Probiotic benefits

Probiotics benefits are most commonly thought of in terms of supporting our digestive system. Certain yogurts are marketed specifically to help–to put it euphemistically– maintain “digestive regularity”. The best probiotic defense is in maintaining the overall health of the digestive system, yes, but it can do so much more! When the digestive system is healthy, it filters out harmful things like chemicals and various toxins while maximizing the intestines’ absorption of nutrients. They also affect the body’s immune system, giving it strength and making it more effective in fighting illness and disease. A balanced ratio of good and bad bacteria wards off allergic reactions, autoimmune disorders, and various infections. 
While we’re talking about what good these little bacteria can do for us, we should talk about what specific bacteria are giving the probiotics their power. 


Lactobacillus is the most well known bacteria. There are more than 50 types of lactobacilli, and they’re found naturally in the genital, urinary, and digestive systems. They’re also found in things like yogurt and certain dietary supplements. 

Lactobacillus gasseri has been shown to treat children quite successfully for irritable bowel syndrome. When patients were given 3 billion cells twice daily, the severity and frequency of their diarrhea episodes were significantly reduced. It’s also successful in reducing antibiotic-related diarrhea in kids. It also helps reduce the frequency and length of lung infections in young kids (1 to 6 years) who attend day care. When inserted into the vagina in capsule form, it decreases the frequency of vaginal bacterial infections. 

Lactobacillus casei given twice daily to hospitalized adults who are taking antibiotics decreases the risk of diarrhea. Small children affected with rotavirus have shown improvement in the severity of diarrhea when given lactobacillus rhamnosus. Lactobacillus plantarum has shown a swift ability to digest protein, meaning it is helpful in treating minor food allergies and regulating stomach inflammation. Babies who suffer from painful colic have shown improvement in the amount of gas when they’re put on a lactobacillus reuteri regimen. 

The probiotic acidophilus (lactobacillus acidophilus) is probably the most commonly utilized strain in the lactobacilli family. Most drug stores, no matter how small, carry an acidophilus probiotic in the form of an acidophilus pills or powders. Acidophilus benefits include reducing the frequency of bacterial infections in immunocompromised patients and lowering the negative side effects of lactose intolerance. 


This type of bacteria has a cute nickname among scientists. It’s an anaerobic bacteria, meaning it will die when it’s given oxygen. Because of this, they’re known as “shy” bacterium. Unlike a lot of other bacteria, however, they can survive the hostile stomach environment and withstand stomach acid. Remember this when the store carries expensive “enteric coated” capsules. The bifidus family of bacteria doesn’t need extra coatings to survive the journey to the colon; they can do that all on their own! 

When products are labeled with certain strains of this family like bifidus actiregularis, bifidobacterium lactis, and bifidobacterium longum, know that they’re just marketing names made by a certain brand of yogurt marketed for “digestive health and regularity”. They’re not any different than the bifidus bacterium found in supplements. 

Saccharomyces boulardii

Instead of a bacteria, this little guy is a yeast, a type of fungus. While it used to be thought that it was a very unique species of yeast, it’s actually just a strain of the quite common Saccharomyces cerevisiae (baker’s yeast). It’s most commonly used for preventing and treating diarrhea. It’s especially effective in treating infectious diarrhea types like rotavirus, traveler’s diarrhea, and diarrhea in people who are tube fed. It can also be used to treat irritable bowel syndrome, Crohn’s disease, Lyme disease, and bacterial overgrowth in people afflicted with short bowel syndrome. 

Streptococcus thermophiles

This is one of the starter strains of bacteria used to create yogurt! It has a host of researched and proven benefits, so we should love this happy little guy! It improves digestion and helps reduce the symptoms in diseases like IBS, ulcerative colitis, and leaky gut. It also helps strengthen the immune system. It’s been shown to prevent and help fight respiratory infections, decrease the symptoms of AIDS, and fight dangerous Clostridium infections. It’s also been shown to decrease infant colic symptoms and improve good bacteria flora in infants who aren’t breastfed. 

Enterococcus faecium

Naturally occurring in the intestine, it has since been used in dietary supplements for the past 25 years. It’s particularly effective in inhibiting the growth of dangerous food-borne bacteria like listeria. 


Leuconostoc has been shown to have anti-tumor effects when taken regularly in higher doses. Lab rats have shown to have decreased tumor growth rates when they are regularly dosed with these bacteria. 

Probiotics and weight loss

Yeah, yeah, digestive health, immune support. Those are all great things! But come on, let’s be real. When someone tells us that we can lose weight with the simple addition of something to our diet, we’re gonna jump right on that. Research, thankfully, is backing up the claim that these happy bacteria can help us shed those pounds keeping us from confidently wearing leggings as pants. 
A study published by the British Journal of Nutrition has shown how effective probiotics for weight loss are. In the study, 125 overweight men and women were given a 12 week diet geared to lose weight, plus another 12 week maintenance period. Half of them were given placebo pills and the others were given probiotic pills. The women who took the actual pills lost an average 9.7 pounds, while the women on the placebos only lost 5.7 pounds. During the maintenance period, the placebo takers maintained a steady weight while the other half continued to lose weight. Tests showed that women taking the pills had less obesity-related bacteria in their body. As for the men? The probiotic pills didn’t have much of an effect on them. 

Why do these supplements help people lose weight? The authors of the study believe that they help make the walls of the intestine less permeable, meaning there are less molecules contributing to diseases like obesity and type 2 diabetes that are able to enter the bloodstream. Of course, a probiotic isn’t responsible for weight loss; they have to be taken in conjunction with a healthy diet and plenty of exercise. 

Probiotics side effects

Generally speaking, the potential side effects of probiotics are fairly minimal. Side effects can vary depending on the age, gender, and overall health of the person taking the supplements, but studies have shown that they are quite safe for most people. 

Probiotics for women

There are a variety of female-specific disorders that a probiotic can treat. They’re particularly useful for treating yeast infections caused by antibiotic use and bacterial infections in the vagina. Side effects for regular use are usually limited to bloating or gas. Some women complain of slight stomach upset on high doses. 

Probiotics for men

Like women, men will notice little to no side effects from probiotic use and are restricted to minor GI upset and bloating. 

Probiotics for children

Probiotics are considered safe in children as long as they aren’t suffering from weakened immune systems or taking drugs to prevent an organ transplant rejection. 

Probiotics for babies

Probiotics for babies can be quite effective at relieving the discomfort associated with infant colic and many companies make specific baby probiotics. There are also studies shown that probiotics can prevent deadly bacterial infections in premature babies. Side effects of probiotics in babies are usually relegated to bloating or flatulence. 

Natural probiotics versus probiotic supplements

As with everything in life, we can get things naturally or we can get them in a bottle. When it comes to choosing our happy bacteria ingestion, there’s a slight difference in natural and synthetic probiotics. 

Natural probiotics

Don’t worry. If you’re looking for probiotic foods, you’re not going to be eating anything weird. Have you fallen in love with thick, creamy, tangy Greek yogurt? Are you just wanting me to cut to the chase and answer “does Greek yogurt have probiotics?”? Yes, it does! Just beware of the labels. Does all yogurt have probiotics? Not all yogurts are created equal; some yogurts are filled with nothing but sugar. Look for labels that say “live and active cultures” for maximum benefits. 

Kombucha isn’t everyone’s cup of (fermented) tea, but if you like the taste, you’ll find it a sufficient replacement for soda because it’s fizzy and lightly sweetened. It’s been fermented with bacteria and yeast, meaning it’s completely loaded with probiotics. It’s great for naturally fighting yeast infections. Kefir, a mix between milk and yogurt, is a drink with the consistency of a thin milkshake. It’s naturally filled with the good stuff and can be purchased flavored or just poured over granola or fruit. Kimchi, a Korean pickled cabbage, is also chock full of probiotics, as well as vitamins and calcium. 

Probiotics supplements

Probiotic supplements are rising in popularity. Sometimes we need a big dose of friendly bacteria, especially after a heavy round of antibiotics. If this is the case, the best way to get those is through supplements. These come in a variety of forms: pills, powders, and tablets to name a few. Most brands contain the important bacteria, particularly saccharomyces boulardii and acidophilus, the holy grail of the probiotic world. 

Capsules and tablets are often coated in enteric coatings to protect the bacteria until it can get into the gut. Probiotic pills are usually made with controlled-release technology to keep the bacteria safe from the hostile stomach environment while slowly releasing the bacteria throughout the entire digestive tract. Probiotic tablets are usually preferred because the powders usually die in the stomach and don’t have the chance to reach the intestines where they’re really needed. 


All in all, probiotics can do a lot for our bodies, and they’re so much more than a healthy side benefit of greek yogurt. These good little bacteria can balance out our bodies. From improving our immune system, maximizing out the body’s nutritional absorption and helping you lose weight. All with minimal side effects.

If you have a fairy tale with probiotic benefits that you’d like to share or if you have any questions, feel free to leave a comment below!

What are probiotics, the ultimate guide was last modified on January 4th, 2016 by Elizabeth Wallace of Greek yogurt paradise

Elizabeth Wallace

Hey there, I’m Elizabeth! It’s so nice to meet you. A bit about me: I’m a big fan of eating healthy, and I love greek yogurt! This blog is where I share my recipes, thoughts and much more. Have fun!


  1. Actually there are different types of bifidobacterium….not necessarily just marketing names..there’s bifidobacterium lactis, longus…etc etc although I get what you’re trying to say, some companies do make up names for marketing like Activis yogurt did but I just wanted to point out there are indeed different types/strains of bifidobacterium.

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