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The Lowdown on Probiotics and Prebiotics

posted Apr 17, 2018, 1:01 PM by Tracy Ducker, MS, RDN

Our gastrointestinal tract contains more than 400 types of microorganisms. Some of these microorganisms are healthy and others are unhealthy. The healthy bacteria in your gut help to digest food, and synthesize some vitamins and essential fatty acids. Probiotics are live microbes that help to improve the balance of our gut flora.  There are also prebiotics, which are different, but just as important. Prebiotics are nondigestible substances (like fiber) that feed the probiotics, helping them to thrive in the gastrointestinal tract. Not all probiotics consumed will survive; it is important to consume prebiotics with probiotics. 


As stated above, probiotics are living microorganisms that are beneficial for gut health which research has shown can affect overall health. There are many different species of probiotic bacteria and within these species are different strains that have different effects in our bodies. Some probiotics work well alone and others work better in combinations. Scientists are still studying all the of health benefits probiotics. So, you may ask yourself, if there are already "good bacteria" in the gut why do I need more? The reason is that our gut flora is constantly changing, from the foods we eat, to medications we take (like antibiotics), to illness. Consuming more foods rich in probiotics and prebiotics can help keep the "good" bacteria at high levels. Probiotics are found in fermented foods naturally and are also added to some foods and beverages. There are three main groups that have been studied the most, Lactobacillus and Bidifobacterium and Streptococcus and one yeast variety, Saccharomyces boulardii.

Probiotics have been shown to boost the immune system, alleviate diarrhea from infections and from antibiotics, reduce anxiety and depression, decrease allergic reactions in children, decrease inflammation, and even be used as a treatment for irritable bowel syndrome and ulcerative colitis. It is important to speak with a registered dietitian or health care provider to decide on the appropriate amount and combination of probiotics to determine what will work best for you.

             Probiotic                                                                            Food Sources

 Lactobacillus acidophilus Dairy and  non-dairy yogurt, lassie, kefir, miso, tempeh
 Lactobacillus  helveticus Dairy and non-dairy yogurt, kefir, Italian and Swiss cheese
 Lactobacillus delbrueckii subsp. bulgaricus Dairy and non-dairy yogurt, kefir
 Lactobacillus reuteri Fermented vegetables, dairy foods
 Lactobacillus rhamnosus GG Dairy and non-dairy yogurt, kefir, kombucha, sparkling probiotic drinks
 Lactobacillus casei Kvass, Dairy and non-dairy yogurt, lassi, probiotic dairy drink, kefir
 Streptococcus thermophiles Dairy and non-dairy yogurt, kefir,  lassi, cow’s milk  probiotic beverage
 Bifidobacterium longum Dairy yogurt, kefir
 Bifidobacterium bifidum Dairy and non-dairy yogurt, kefir
 Bifidobacterium  infantis Yogurt, kefir, buttermilk, miso, tempeh, pickles, kimchi, cured meats, some wines/vinegars, sauerkraut, sourdough bread
 Saccharomyces boulardii kombucha

Chart from: Ellis, E.L. the Potential of Probiotics. Food and Nutrition. March/April 2018:19-20


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 of the "bad" bacteria. Prebiotics may decrease cholesterol levels and reduce the risk of colon cancer, as well. 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

While there are many supplements available it is best to try to consume as many foods as possible containing prebiotics and probiotics.

Probiotics as Supplements

Probiotics can also be found as supplements. However, supplements are not FDA regulated and therefore it is important to read the labels and research the manufacturer. Here are some tips if you decide to purchase probiotic supplements:

· Read the label to find the probiotic group, species, strain and the number microorganisms or colony forming units (CFU).
· Buy only from reputable companies that have been around. They are more likely to have studied and tested their product more.
· Be cautious of the internet. Be sure you are familiar with company, there are many people who will sell fake products, or take your money and run.

Increasing Probiotics and Prebiotics in your diet  

Probiotics and prebiotics are found in many foods you probably already eat. Be sure to eat a variety of these foods daily and if you decide along with your health care provider to include a probiotic supplement make sure they contain live cultures. Look for "contains live active cultures" on the label. Be sure you are taking or consuming the right type of probiotic for the benefit you want to achieve.

Note: Probiotics and prebiotics are generally safe, however they are NOT recommended if you have a severly compromised immune system or acute pancreatitis. Check with your health care provider first.

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