Probiotics 101: What are they? And which are the best?

Probiotics may have been gaining popularity in recent years—but believe it or not, probiotics have been around since the early 19th and 20th centuries in some fashion or another. In those times, biologists found bacteria and yeast were used in the fermentation process and linked them to positive health outcomes. 

In 1994, the Dietary Supplement Health and Education Act (which allowed dietary supplements to be regulated differently than prescription medications) was implemented by the United States Food and Drug Administration (FDA). This meant less rigorous standards for supplements—including probiotics. As a result, probiotics could be sold over the counter, which allowed consumers to purchase them more easily.

What are probiotics?

Probiotics are live microorganisms, including yeast and bacteria, that aid in digestive health. They are beneficial because they restore and balance the gut flora (or microbiome), which in turn improves gut health. While bacteria or excessive yeast might call infections to mind, not all bacteria is bad for humans. You have a significant amount of good bacteria in your gut (more specifically in the intestines and digestive tract) that is essential for keeping you healthy and processing the food you eat. In fact, microorganisms like bacteria outnumber human cells  in your body 10 to one. 

“Probiotics, in essence, are the good bacteria in our gut microbiota,” says Jenna-Ann Del Borrello, a registered dietitian in New York City. “They can be found in many fermented foods such as kimchi, certain cheeses, and yogurt as well as in pill or powder form.“

Probiotics often try to mimic or copy the natural beneficial bacteria in the human gut. While probiotics have many different bacteria species or strains, the two most common bacteria strains found in probiotics include: Lactobacillus and Bifidobacterium.

Probiotic products include dietary supplements or foods with natural probiotics (like fermented foods such as kimchi and sauerkraut) or added probiotics such as Activia yogurt. As pills or capsules, probiotics can be purchased over the counter or with a prescription.

Probiotics should not be confused with prebiotics, which are a type of dietary fiber the bacteria in the gut feed on. 

What do probiotics do?

There are many benefits of probiotics, but most notably, they are used to treat GI health conditions as they help balance out the good and bad bacteria in the gut. Probiotics can:

• Play a role in the synthesis of some vitamins, including vitamins B and K.
• Produce short-chain fatty acids (SCFAs), which help regulate T-cells.T-cells strengthen the immune system and act as anti-inflammatories. 
• Improve symptoms of inflammatory bowel disease (IBS), Crohn’s disease, and ulcerative colitis.
• Reduce oral candidiasis and yeast infections by promoting healthy pH balances
• Combat obesity and improve weight loss (though further research is needed in this area).
• Treat a variety of diarrheas and GI issues, such as infectious diarrhea, clostridium difficile, and pouchitis.  
• Improve skin conditions like atopic dermatitis (eczema).
• Help soften stool and potentially help with constipation, though they do not increase the number of bowel movements. 

There is a lot of speculation over the effectiveness of probiotics because there is limited research. For example, systematic reviews have shown little to no beneficial effects of probiotics on the common cold and urinary tract infections. This is because probiotics come in so many varieties with many different strains, and it’s yet to be seen if all variations of a particular strand would produce the same benefits. 

For example, if a specific kind of Lactobacillus helps prevent an illness, that doesn’t necessarily mean that another kind of Lactobacillus would have the same effect. This complicates research as it would be difficult to test all the possible strands of bacteria and their effectiveness in supporting the digestive system.

What is the best probiotic?

It is hard to say what the best probiotic is because the effects of probiotics are different for each person. Everyone has their own unique gut flora, so the probiotic that works best for you depends on the microbiome in your gut. There are up to 500 species of bacteria found within our large intestines. 

For those wanting to treat irritable bowel syndrome and acute dermatitis, the most commonly used probiotic strains typically include Lactobacillus sp., Bifidobacterium sp., Streptococcus thermophilus, and Saccharomyces boulardii.

Overall, the most popular and best-researched strains of probiotics include: Bifidobacterium, Lactobacillus, and Saccharomyces. It is important to note that most probiotic products and supplements contain multiple strains of live bacteria. 

While probiotic supplements and probiotic foods have both been found to have health benefits, probiotic foods have been found to be more effective carriers of probiotics. Overall, more research and clinical trials are needed to determine which strains are most effective and for what.

8 probiotic foods

While some foods have added probiotics, a “probiotic food” is a food that naturally contains it. These are some of the most naturally probiotic-rich foods.

1. Yogurt 

Perhaps the most well-known of all probiotic foods, yogurt is a fermented dairy product. It typically includes bacterial cultures of Lactobacillus bulgaricus and Streptococcus thermophilus. Bifidobacteria is another common bacteria found in most dairy products. Some research speculates there may be additional health benefits of eating yogurt with fruit, which is high in prebiotics.

2. Kefir

Kefir, a fermented milk drink, originated from Eastern Europe. As well as antifungal and antibacterial properties from the probiotics, kefir may have anticancer properties. Kefir is often safe for those with lactose intolerance.  

3. Sauerkraut

Sauerkraut is a fermented food made from cabbage, with roots all the way back to the 4th Century. The probiotics found in sauerkraut are anti-inflammatory, but don’t eat too much: Consistent, large quantities of sauerkraut can lead to diarrhea.  

4. Kombucha

Originating in Northern China, kombucha is a fermented tea product. Kombucha is high in acetic acid and lactic acid bacteria, and has been found to have antimicrobial properties. However, more studies are needed to fully understand the effects of Kombucha on the human microbiome.  

5. Kimchi

Originating from Korea, kimchi is a popular fermented cabbage and radish dish. Kimchi contains many helpful bacteria, such as the Lactobacillus bacteria. One study found kimchi to be good for colon health as it decreases toxic enzyme activity.

6. Fermented soybean products

There are a variety of fermented soybean products that are high in beneficial probiotics, including tempeh, natto, and miso. As an added bonus, some research hypothesizes that compounds lignans and isoflavonoids in soybeans help prevent cancer. 

7. Traditional buttermilk 

Traditional buttermilk contains probiotics. Keep in mind this is different from cultured buttermilk, which is found in most stores and doesn’t contain probiotics. Traditional buttermilk contains Lactococcus lactis, which has unique properties that are said to work well with newborns. One study found that buttermilk helped decrease the severity of necrotizing enterocolitis (an infection in the intestine) in rabbits. 

8. Pickles

Some pickles do contain probiotics, but any made with vinegar don’t. There are brands which do contain live probiotics and recipes to make your own. Pickles can also help increase your intake of antioxidants. 

Is it okay to take a probiotic every day?

Since probiotics are typically sold as supplements and not drugs, the FDA does not have to regulate the health claims. However, research shows that daily use of probiotics is safe. 

“While there are usually not many side effects associated with using a probiotic, people may feel occasional bloating/gas or differences in bowel movements when they first start taking a probiotic,” Del Borrello says. “It usually goes away with time.”

It is also important to get the correct dosage of probiotics for full effectiveness. Probiotic dosages are given in “colony-forming units” or CFUs. Children are recommended to take 5-10 billion CFUs a day and adults are recommended to take 10-20 billion CFUs per day. 

When starting probiotics, it is possible that you will develop loose stool for the first few days. Because probiotics are “live” bacteria, it is important to check the sell by date on the supplement.

Who should not take probiotics?

It’s important to talk to a healthcare professional when adding supplements to your diet. It is especially important for people with cancer and immune deficiencies to consult with their healthcare provider before taking probiotics. Otherwise, most people can safely take probiotics.