Prebiotics and Probiotics

Probiotic food

What are pre and probiotics?

There are millions of bacteria that live in each person's digestive system or gut. Some of these bacteria such as E.coli, Staphylococci, and Streptococci can be harmful. However, certain types of bacteria in the gut provide health benefits.

Bacteria such as Lactobacilli, Bifidobacteria, and Enterococci are good for gut health. These "good" bacteria help protect us against infections and protect against certain germs and viruses.

Pre and probiotics are substances used to reduce the "bad" bacteria and increase the "good" bacteria in the gut.

The difference between prebiotics and probiotics


Prebiotics are food ingredients that, when eaten, help the growth and function of certain "good" bacteria in the gut. These prebiotic foods contain sugars which are a food source for "good" bacteria. In this way, prebiotics promote the growth of these bacteria. Common food sources of prebiotics include onions, garlic, banana, asparagus, leeks, and Jerusalem artichokes.


Probiotics are the actual "good" bacteria themselves. Eating foods that contain probiotics improves the ratio of "good" bacteria to "bad" in the gut. Sources of probiotics are fermented foods such as kefir (fermented yogurt) and foods with added probiotics. These include acidophilus milk and yogurt. When eaten as a food supplement or as part of a natural food product, they offer benefits to gut health.

The "pros" of pre- and probiotics

Research to date has shown that prebiotics can improve constipation. Probiotics also improve lactose intolerance, antibiotic-associated diarrhea, and intestinal infections. Other possible uses for prebiotics and probiotics include reducing blood lipids (fats); improving calcium absorption; treating irritable bowel disease (IBD), irritable bowel syndrome (IBS), and traveller’s diarrhea; treating and preventing colon cancer; and preventing various infections in the gut. However, more research is needed to confirm these benefits.

There may be many benefits to pre- and probiotics. There are many different food and supplements with pre or probiotics. Talk to a registered dietitian to find out what may be beneficial to you.

Prebiotic food sources

  • artichokes
  • banana
  • garlic
  • onions
  • shallots
  • leeks
  • asparagus
  • energy-boosting products with added "good" bacteria

Probiotic food sources

  • fermented milk products
  • Liberty Kefir or Elwest Kefir
  • yogurts with added probiotics are common (check the label)
  • fermented soy products
  • tempeh
  • supplements
  • Bio-K+

Key Points

  • Pre and pro biotics promote the growth of healthy bacteria in the gut
  • Pro biotics come from fermented foods and supplements
  • Prebiotics come in fruits and vegetables and in supplements

Cristina Cicco, RD


Marteau P, Seksik P, Jian R.   (2002)  Probiotics and intestinal health effects: a clinical perspective.  British Journal of Nutrition, 88, Suppl. 1, S51-S57.

Saavedra JM, Tschernai A. (2002)   Human studies with probiotics and prebiotics: clinical implications.  British Journal of Nutrition, 87, Suppl. 2, S241-S246.

Marteau P, Boutron-Ruault MC.   (2002)  Nutritional advantages of probiotics and prebiotics.  British Journal of Nutrition, 87, Suppl. 2, S153-S157.

Manning TS, Gibson GR.   (2004)  Prebiotics.  Best Practice & Research Clinical Gastroenterology, 18(2), 287-298.

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