Prebiotics and Probiotics

Your gut is home to trillions of bacteria!  This little bacterial universe is called your gut microbiota. It can weigh over four pounds! Your microbiota is like another type of fingerprint – it is completely individual to you. We each have a unique combination of over 1,000 different types of microbes. Unlike a fingerprint however, your microbiota changes, depending on your environment and your diet. It is affected by every meal that you eat. And, the composition of your microbiota can have major implications for your health!  (1,2,3)

Good microbes (bacteria) help with:

  • Digestion and absorption of nutrients
  • Your immune system – they help prevent allergies, infection and disease
  • Controlling bad bacteria, which can cause diarrhea, bloating, bad breath, depression, brain fog, fatigue and irritability

A long-term microbe imbalance (too many bad microbes) can lead to serious diseases, such as: colon and liver cancers, diabetes, obesity, irritable-bowel syndrome, celiac disease and arthritis.

You can boost your good microbes with:

Probiotics  – These beneficial bacteria help to keep your digestive system in balance and functioning well. (4)

Probiotics can be found in fermented foods, such as:

  • Yogurt and kefir – fermented dairy products (non-dairy yogurts work too!)
  • Tempeh and miso – fermented soybean products
  • Sauerkraut, kimchi, fresh sour dill pickles – fermented vegetables.  Look for fresh/refrigerated varieties, which contain live/active cultures.

Prebiotics – These nondigestible carbohydrates act as fertilizer or food for probiotics. When probiotics and prebiotics are combined, they work together synergistically.

Prebiotics are typically found in fruits, vegetables, whole-grains, beans/legumes, nuts and seeds.  Some especially high prebiotic foods are: bananas, honey, onions, garlic, leeks, asparagus, artichokes, soybeans and whole-wheat foods. (5)

Supplements – There are many varieties of probiotic and prebiotic supplements available in powder and capsule forms and even in fortified foods. Talk to your doctor or dietitian if you are interested in trying these.

Exercise – Research has also shown that exercise may improve the diversity/composition of your gut bacteria. (3)


Processed sugars and starches, which feed the bad bugs

Gut microbiota is a very exciting area of research right now!  And we still have a lot to learn in this area. The National Institutes of Health recently launched its Human Microbiome Project, with more than $100 million supporting research on the health effects of gut bacteria, so stay tuned! Cutting edge research is working on analyzing individual microbiomes to predict disease and individualize treatments. (12)

“Let food be thy medicine and medicine be thy food.” -Hippocrates


  1. Gut Microbiota Info. Gut Microbiota for Health website. Accessed Oct 28, 2016.  
  2. WGO Handbook on Gut Microbes. World Gastroenterology Organisation.  2014.
  3. Whiteman H.  The gut microbiome: how does it affect our health. Medical News Today website. March 11, 2015.
  4. Weil A.  Supplements & Remedies: Probiotics. Dr. Weil website. Accessed Oct 28, 2016.
  5. Brown-Riggs C. The Gut Microbiota — Is It a Novel Contributor to the Obesity and Diabetes Epidemics? Today’s Dietitian. 2014;16(11):22.
  6. US Probiotics Home. California Dairy Research Foundation website. Accessed Oct 28, 2016.
  7. 7 Must Eat Fermented Foods For a Healthy Gut. Eating Well website. Accessed Oct 28, 2016.
  8. Zeratsky K. Do I need to include probiotics and prebiotics in my diet? Mayo Clinic website. Accessed Oct 28, 2016.
  9. The Benefits of Probiotics. Harvard Health Publications website. Accessed Oct 29, 2016.
  10. International Scientific Association for Prebiotics and Probiotics website. Accessed Oct 28, 2016.
  11. Baumler MD. Gut Bacteria. Today’s Dietitian. 2013;15(6):46.


The Canadian Digestive Health Foundation has some great videos on gut health and microbiota.

More on Prebiotics and Probiotics

The International Scientific Association of Probiotics and Prebiotics defines a prebiotic as “a selectively fermented ingredient that results in specific changes, in the composition and/or activity of the gastrointestinal microbiota, thus conferring benefit(s) upon host health.” (5)

Jen Kim, RDN

About Jen Kim, RDN

Jennifer is a Registered Dietitian Nutritionist (RDN). She completed her Bachelor's of Science degree at the University of Illinois, and holds a Master's Degree in Business Administration (MBA) from San Diego State University. Jennifer also has a Certification in Adult Weight Management. She has worked in hospitals as a Clinical Dietitian, done obesity research and worked as a Corporate Dietitian for a national weight loss company. Jennifer is passionate about helping people live healthier lives. She believes in a balanced approach to nutrition - where all foods can fit - centered around a natural, plant-based diet. Jen lives in San Diego with her husband and two boys - where she enjoys playing soccer and tennis, hiking, playing on the beach, playing board games and shooting pool.

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