What are Probiotics? A Beginner’s Guide

What are Probiotics? A Beginner’s Guide

You may know that probiotics are good for you and that including them in your diet can be beneficial, but do you know exactly what probiotics are?

If you’ve ever picked up a container of yogurt, you’ve probably seen probiotic written somewhere on the label. You may know that probiotics are good for you and that including them in your diet can be beneficial, but do you know exactly what probiotics are?

In this article, we’re going to break down why these microbes are so important for your body. We’ll also go over how many of these essential bacteria you should be taking for optimal health and what to look for when you buy a probiotic supplement or take probiotic foods.

What are Probiotics?

Probiotics are microscopic bacteria that live in your gut and may support your overall health. When you think of bacteria, you might immediately think about the types of bacteria that make you sick when you leave food in the fridge for too long like E. coli or Salmonella. Even though these bad bacteria can be potentially deadly, probiotic bacteria support your digestion and immune system. There are more than 100 trillion probiotic bacteria in your gut. (1)

Here are a few of the functions of these healthy microorganisms:

  • Help optimal digestion (2)
  • Reduce gastric discomfort (2) (5)
  • Support immune function (3) (4)
  • Support healthy skin (6)
  • Improve constipation (7)

Where Do You Get Probiotics in Your Diet?

The best place to get probiotics in your diet is through fermented food. Along with preserving food longer, the fermentation process also creates the perfect environment for gut-healthy bacteria to multiply.

Here are a few common fermented foods that are extremely probiotic-dense. If you find that you have problems digesting dairy products, you may want to avoid yogurt and milk kefir. You can find kefir seeds at many organic grocery stores and ferment them yourself in water or coconut milk for a non-dairy alternative.


Foods High in Probiotics:

  • Yogurt (buy sugar-free, plain yogurt for best results)
  • Kefir
  • Kombucha
  • Kimchi
  • Miso
  • Sauerkraut  

You can also take a high-quality probiotic supplement. Probiotic supplements offer several advantages over fermented foods. Supplements generally label the specific strands of bacteria that they contain as well as list the number of active cultures.  

The History of Probiotics

The benefits of probiotics are a fairly recent discovery even though people have been consuming fermented food for thousands of years. As long ago as 10,000 years, people in the Middle East stored milk in canvas bags. When these bags were left in the sun, the milk fermented into the earliest form of yogurt. In the Far East, people in China, Korea and Japan have also been using fermentation as a way to preserve vegetables for more than 2000 years.

At the turn of the 20th century, a scientist in Bulgaria named Stamen Grigorov discovered a strand of bacteria in yogurt named later named  L. delbrueckii ssp  bulgaricus. Grigorov had a theory that the long lifespans of people in Bulgaria at the time may have been attributable to the bacteria in the yogurt they were eating.

Grigorov’s theory sat for most of the 1900s until research picked up again in the 1990s. Researchers around this time began realizing that probiotics might have benefits for boosting the immune system and enhancing digestion. (9) Since then, people have begun to become more aware of the incredible benefits of probiotics.

How many Probiotics Should You Take?

Probiotics are generally measured in colony-forming units (CFUs). Research is continually being done to determine how many CFUs one should consume in order to receive the full benefits of probiotics. Scientists haven't yet come to an ultimate conclusion, but some researchers suggest that the minimum effective dose is at least 10 million CFUs. (8)

Many supplements offer more than a billion CFUs. Quantifying probiotic bacteria in food is a little more difficult. Generally, yogurts that are labeled as probiotic have more than a billion CFUs, but the exact number they contain can depend on how it was stored, how long it was fermented, and how close to the expiration date it is.  


Including prebiotics in your diet along with fermented foods and probiotic supplements can further increase the health benefits that healthy bacteria give you. Prebiotics are carbohydrates that your body can’t break down that are found in a variety of fruits, grains, and vegetables.

Some of the best sources of prebiotics include the following: (2)

  • Seaweed
  • Cocoa
  • Apple
  • Oats
  • Barley
  • Bananas
  • Asparagus
  • Dandelion greens

If you want to optimize the number of prebiotics you get through your diet, it’s a good idea to eat a varied diet filled with fruits and vegetables. Unfortunately, many people who eat a standard Western diet rely on a handful of foods for most of their calories. In fact, it’s thought that more than 75% of the food the average person consumes comes from a mere 12 plants and five animals. (8)

Bottom Line

Probiotic bacteria help to support your digestion and immune system. If you want to benefit from probiotics, you can add more fermented foods to your diet, take a probiotic supplement, or both.  According to Stamen Grigorov, the long lifespans of the people in Bulgaria, during the 20th century, may have been attributable to the bacteria in the yogurt they were eating. Researchers suggest that in order to receive the full benefits of probiotics one should be taking, at minimum, 10 million CFUs.


This content is for informational and educational purposes only. It is not intended to provide medical advice or to take the place of medical advice or treatment from a personal physician. Readers of this content are advised to consult their doctors or qualified health professionals regarding specific health questions. Neither the author(s) nor the publisher of this content take responsibility for possible health consequences of any person or persons reading or following the information in this educational content. All readers of this content, especially those taking prescription or over-the-counter medications, should consult their physicians before beginning any nutrition, supplement or lifestyle program.



1. Hill DA, Artis D. Intestinal bacteria and the regulation of immune cell homeostasis. Annu Rev Immunol. 2010;28:623-67.


2. Carlson JL, Erickson JM, Lloyd BB, Slavin JL. Health Effects and Sources of Prebiotic Dietary Fiber. Curr Dev Nutr. 2018;2(3):nzy005.


3. FAO. What is Happening to Agrobiodiversity? http://www.fao.org/3/y5609e/y5609e02.htm


4. Yan F, Polk DB. Probiotics and immune health. Curr Opin Gastroenterol. 2011;27(6):496-501.


5. Didari T, Mozaffari S, Nikfar S, Abdollahi M. Effectiveness of probiotics in irritable bowel syndrome: Updated systematic review with meta-analysis. World J Gastroenterol. 2015;21(10):3072-84.


6. Mori N, Kano M, Masuoka N, et al. Effect of probiotic and prebiotic fermented milk on skin and intestinal conditions in healthy young female students. Biosci Microbiota Food Health. 2016;35(3):105-12.


7. Liu LW - Can J Gastroenterol (2011) Chronic constipation current treatment options.pdf


8. Sanders ME. Probiotics: definition, sources, selection, and uses. Clin Infect Dis. 2008;46 Suppl 2:S58-61.

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