Probiotics and Prebiotics

More than 400 types of microorganisms are in your gastrointestinal tract. Some of these microorganisms are healthy and others are unhealthy. The healthy bacteria in your gut help digest food. They also synthesize some vitamins and essential fatty acids.

Probiotics are live microbes that can benefit your health by allowing the healthy bacteria in your gastrointestinal (GI) tract to thrive while inhibiting or destroying toxins released by other bacteria. While the research on the positive effects of prebiotics and probiotics is promising, many unknowns still exist, including what bacteria work best with each condition, what dose is needed to have an effect, and whether or not probiotic foods and/or supplements lose their effectiveness over time.

Benefits of probiotics
Scientists still are learning how and why probiotics work. Some of the potential benefits include:

• Synthesizing vitamins (particularly the B vitamins)


• Boosting your immune system by producing antibodies for certain viruses


• Decreasing allergies (particularly in regard to skin reactions, such as dermatitis or eczema)


• Decreasing the risk of developing dental caries


• Speeding recovery from bacterial vaginosis


• Reducing the problems associated with inflammatory bowel disease (particularly related to pouchitis or ulcerative colitis) and irritable bowel syndrome


• Helping people with lactose intolerance digest dairy products more easily


• Reducing symptoms of  diarrhea associated with antibiotic usage or acute illness

Foods containing probiotics
Pasteurization kills probiotics, but many fermented-food manufacturers add them back into the food. Fermented foods and dairy products are the two most common sources. Strict labeling guidelines do not exist for probiotic-containing foods at this time. The dose needed for probiotics varies widely, depended on type and formulation.

The following foods contain probiotics: 

• Yogurt


• Cottage cheese


• Buttermilk


• Kefir


• Soy sauce


• Miso


• Tempeh


• Fresh sauerkraut

Benefits of prebiotics
Prebiotics are nondigestible substances that feed the probiotics, helping them to thrive in the GI tract. Not all probiotics consumed will survive, so it is important to consume prebiotics with probiotics.

Prebiotics release short-chain fatty acids, which decrease the pH of the colon and, thereby, enhance mineral absorption, particularly calcium, iron, and magnesium, possibly decreasing the risk of osteoporosis development. This decrease in pH also leads to the decreased survival of some pathogenic bacteria. Prebiotics may decrease cholesterol levels and also reduce the risk of colon cancer. Some forms of prebiotics aid in the relief of constipation. Different strains of prebiotics provide different health benefits. 

Foods containing prebiotics

• Chicory root


• Jerusalem artichoke


• Wheat


• Barley


• Rye


• Flax


• Oatmeal


• Onion


• Garlic


• Leeks


• Legumes


• Asparagus


• Leafy greens


• Berries


• Bananas


• Honey

Best sources of probiotics or prebiotics*
Use this chart to identify the best sources of probiotics or prebiotics for a variety of conditions:

*Adapted from Douglas and Kane and the American Gastroenterological Association

Resistant starch
Resistant starch helps to feed probiotics, similar to prebiotics. Resistant starch is found in cooked starchy products, such as hot cereals and unripe fruit, such as bananas that are still firm to the touch. On food labels, resistant starch is referred to as starch, modified food starch, cornstarch, or maltodextrin. 

Probiotic and prebiotic supplements
Only live microorganisms are classified as probiotics. Avoid any that are not live.

Prebiotics are consumed in different ways, including:

• Sprinkled on food


• Stirred into liquid


• Taken in capsule form


• Purchased in prebiotic-fortified foods and beverages, such as sports drinks 

Safety
Individuals who are immunocompromised, have compromised gut integrity, or who have allergies or intolerances to foods containing probiotics or prebiotics should only use these products under the advisement of a doctor. Otherwise, they appear safe for human consumption.

References and recommended readings

American Gastroenterological Association. Probiotics: what they are and what they can do for you. Available at: http://www.gastro.org/patient-center/diet-medications/probiotics. Accessed October 21, 2012.

Douglas LC, Sanders ME. Probiotics and prebiotics in dietetics practice. J Am Diet Assoc. 2008;108:510-521.

International Food Information Council Foundation. Functional foods fact sheet: probiotics and prebiotics. Available at: http://www.foodinsight.org/Resources/Detail.aspx?topic=Functional_Foods_Fact_Sheet_Probiotics_and_Prebiotics. Accessed October 21, 2012.

National Center for Complementary and Alternative Research. Oral probiotics: an introduction. Available at:
http://nccam.nih.gov/health/probiotics/introduction.htm. Accessed October 21, 2012.

Roberfroid M, Gibson GR, Hoyles L, et al. Prebiotic effects: metabolic and health benefits. Br J Nutr. 2010;104:S1-S63.

Sanders ME, Heimbach JT, Pot B, et al. Health claim substantiation for probiotic and prebiotic products. Gut Microbes [serial online]. 2011;2:127-133. Available at: http://www.landesbioscience.com/journals/gutmicrobes/Sanders-GMIC2-3.pdf. Accessed August 2, 2012.

World Gastroenterology Organisation. World Gastroenterology Organisation Practice Guidelines: probiotics and prebiotics. Available at: http://www.worldgastroenterology.org/assets/downloads/en/pdf/guidelines/19_probiotics_prebiotics.pdf. Accessed October 21, 2012.

Review Date 10/12
G-0719