This publication describes prebiotics and probiotics and their health benefits.
Julie A. Albrecht, Extension Food Safety Specialist
Probiotics are live microorganisms that when administered in adequate amounts provide a beneficial health effect in humans.
The idea of food with microorganisms purposely added to the food seems startling since there is an emphasis on omitting microorganisms that cause food-borne illness from food.
Where did the idea of probiotics come from?
Probiotics have a long history. The Old Testament suggested that Abraham lived long and healthy because of consuming sour milk (it contains live microorganisms). In the 20th century, Russian scientist Elie Metchnikoff suggested Bulgarian peasants lived long and healthy lives because they consumed yogurt containing live bacteria.
Are mircoorganisms harmful?
Many bacteria are not harmful to us. In fact, our bodies carry about 100,000,000,000,000 (1x1012) bacteria, mostly in our colon. They live and grow there and help strengthen our immune system. There are, however, harmful bacteria that cause infections, even disease. Probiotic bacteria are “good bacteria” that may help fight off harmful bacteria in our gastrointestinal (GI) tract.
Are probiotics “safe?”
In general, probiotic bacteria are comprised of Lactobacillus and Bifidobacterium species. Probiotics are safe; they are deemed GRAS (generally recognized as safe) status by the Federal Food and Drug Administration.
Do foods with added probiotics have active, living microorganisms?
Some probiotics are active and some are inactive in food products. Non-active probiotic bacteria are manufactured as dried bacteria that are stable and dormant. They will grow only when they reach the moist environment in the body. On the other hand, active probiotic bacteria are cultured in some food products such as yogurt.
What are the benefits of consuming probiotics?
Benefits of consuming probiotics are:
- Reduce allergy conditions
Exposing children to microbes before 6 years old may help the immune system tolerate allergens in later life.
- Reduce cancer risk
Rats fed fermented milk have a lower incidence of chemically induced tumors. One human study demonstrated that the group with bladder cancer consuming a probiotic had a longer recurrence-free period than the control bladder cancer group.
- Reduce diarrhea incidence
A paper in a 2002 Journal of Pediatrics concluded that Lactobacillus is safe and effective as a treatment for children with acute infectious diarrhea.
- Reduces the risk of stomach ulcers
Helicobacter pylori is the bacteria that causes stomach ulcers. Probiotics can reduce the metabolic activity of H. pylori bacteria and decrease the side effects of the antibiotic used to eradicate this bacteria.
- Relieve symptoms of Irritable Bowel Syndrome, with symptoms of diarrhea, gas, bloating, abdominal pain, cramps and/or constipation.
- Reduce hypertension
Fermented milk contains gamma-amino butyric acid which may decrease systolic blood pressure 10 to 20 mm Hg.
- Strengthen immune system
Animal and some human studies have demonstrated that probiotics (yogurt or lactic acid bacteria) enhance the level of certain immunoreactive cells like lymphocytes. Probiotics also enhance regulation of immune factors like cytokines and immunoglobulins.
- Reduce kidney stone incidence
High levels of oxalate are associated with a higher risk for kidney stones. Patients fed probiotics demonstrated less oxalate in their fecal excretion, suggesting probiotic bacteria may reduce oxalate absorption.
- Good for the lactose intolerant
Lactose intolerant individuals can consume fermented dairy products with fewer symptoms. Yogurt helps digestion because the lactic acid bacteria in yogurt break down lactose (milk sugar) before reaching the intestines.
- Treat vaginosis
Lactobacilli dominate a healthy vagina, and a lack of this microorganism is a risk factor for vaginosis. Positive effects have been reported when strains of Lactobacilli in yogurt were given to women with vaginosis.
- Staying healthy
Studies have demonstrated even healthy people can benefit from consuming probiotics. Results of these studies show a reduce incidence of cold, infections, and absences from work and day care centers.
Finding probiotic products
Probiotics have a long history associated with fermented dairy products. Common products are yogurt and some types of milk (cultured milk, acidophilus milk). Other examples of foods containing probiotics are miso, tempeh, sauerkraut, sourdough bread, salami, and some juices and soy beverages. Probiotics can be purchased in supplemental (tablet) form as well.
A prebiotic is a nondigestible food ingredient that beneficially affects the host by selectively stimulating growth of beneficial bacteria in the colon.
What are benefits of consuming foods with prebiotic compound?
A research study confirmed that specific prebiotics (such as non-digestible oligosaccharides) enhance calcium absorption. Two preliminary studies suggest that prebiotics improve the human immune system and resistance against infections. Prebiotics also may help inhibit the growth of lesions in the GI tract and reduce the risk factors involved in colorectal diseases.
Are there any side effects from consuming prebiotics?
People who consume prebiotics may experience flatulence, stomach cramps, and discomfort in the GI tract, due to the gas released from fermenting prebiotics. However, the symptoms reported are very mild and usually occur when high amounts of prebiotics are consumed, such as 14 to 15 grams per day.
How may prebiotic products be identified?
Read the ingredient label for these terms: inulin, fructooligosaccarides (FOS), polydextrose, arabinogalactan, lactulose, or lactitol.
What foods have prebiotics?
Prebiotic compounds, such as inulin, are naturally found in a wide variety of foods like whole grains, onions, bananas, garlic, honey, leeks, and artichokes.
Food manufacturers may add prebiotic ingredients in fortified foods, beverages, dietary supplements, and some processed foods. When prebiotic ingredients are added to foods, they increase the fiber content of the product.
The author would like to thank Adeline Lum, a student in UNL’s Undergraduate Creative Activities and Research Experiences program, for developing content for this publication.
Visit the University of Nebraska–Lincoln Extension Publications Web site for more publications.
Index: Food & Nutrition
Issued July 2008