Key Findings

  • Probiotics are “good bacteria” that can be eaten in food or supplements; they can help keep disease-causing bacteria, viruses and parasites in check.
  • The primary role of probiotics is to keep the digestive and immune systems healthy, but they also play important roles in other areas.
  •  Fermented and cultured products are rich sources of good microorganisms, but probiotic supplements may be helpful for some people.

The good stuff

Probiotics are pros at supporting good health. Their name comes from two roots, “pro” meaning “promoting,” and “biotic” meaning “life.” They promote life by making good bacteria flourish in your intestines, and the resulting gut balance makes your overall health flourish as well.

A common misconception about bacteria is that they’re nothing more than parasitic organisms that cause illness and infections. These enemies do exist, but they are outnumbered by the beneficial microorganisms. These brave warriors can be found in food, drink and supplement form, and they perform a wide range of valuable functions both inside and outside the body.

What are probiotics?

Before we get into what they do, let’s take a deeper look into what probiotics are.

Each of us has a personal microbiome, a collection of microorganisms, mainly bacteria, living in and on our bodies. Some of them have positive and some have negative effects on health. One to three percent of our weight is made up of these microscopic organisms. But because microbes are so small, the number of bacteria cells inside the body is roughly equal to the number of human cells.

Sometimes factors like aging, lifestyle, heredity and food choices result in good bacteria dying off. As a supplement, probiotics contain living bacteria and can help replenish and strengthen the ranks of these good bacteria in the intestines. The International Scientific Association for Probiotics and Prebiotics (ISAPP) describes them as “live microorganisms that, when administered in adequate amounts, confer a health benefit on the host.”

Three classes of probiotics exist, and they work together to support a healthy digestive tract. Each also has a distinct role:

  • Lactobacillus – Consisting of at least 50 different species, this group helps treat and prevent yeast infections, bacterial vaginosis, traveler’s diarrhea and other conditions like respiratory infections.
  • Bifidobacteria – More than 30 species of bifidobacteria are found in the colon and can help reduce glucose intolerance and IBS symptoms and improve blood lipids.
  • Saccharomyces boulardii – This is the only yeast probiotic, and it helps counteract the symptoms of antibiotic-associated diarrhea.

Main functions of probiotics

With a wide range of powerful functions, probiotics are a bit like superheroes. Of their various roles, supporting a healthy digestive tract and a healthy immune system are arguably two of the most important.

Many gastrointestinal conditions, such as Crohn’s disease, irritable bowel syndrome, celiac disease and urinary tract infections (UTI), can be alleviated with the help of beneficial bacteria and yeast in the digestive system. They can also be used to resolve imbalances in gut microbe populations caused by stress, lack of sleep, kidney stones or antibiotics. Probiotics can also help to strengthen the intestinal lining and alert it to approaching foreign invaders. This can help prevent viruses and other pathogens gaining a foothold in the body.

Additional benefits of probiotics include improving antioxidant levels, increasing protein and fat absorption, and promoting positive emotions by helping the gut create serotonin. They can also digest the milk sugar lactose, which can be particularly helpful for those who are lactose-intolerant.

Best sources of probiotics

Fortunately, good bacteria are easy to find. They come from a wide variety of foods, and fermented or cultured foods are particularly rich sources of beneficial bacteria.

Here are some food-based probiotic sources (in alphabetical order):

  • Aged cheeses
  • Kefir
  • Kimchi
  • Tempeh
  • Sauerkraut
  • Sour pickles
  • Soy products
  • Yogurt

If you can’t add some of these foods to your diet, then probiotic supplements may be a good option for you. Probiotics are generally safe for most people, but it’s a good idea to discuss all your supplements with your physician or a holistic practitioner like Dr. Sergey Kalitenko, to make sure they’re appropriate for you.


Probiotics can help maintain a healthy mix of friendly bacteria and yeasts in your digestive tract, which can help to keep your digestive and immune systems strong. Probiotics can be found in fermented or cultured foods, but you may need to supplement if you aren’t getting enough from your diet.