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Probiotics: What You Need to Know

In recent times there has been a substantial amount of news regarding the benefits of probiotics, yet, it seems that these microorganisms are misunderstood as to what they do and how they can benefit the human body.

It is important to first define probiotics. In general terms, probiotics are known as the “good or friendly” bacteria found in the gastrointestinal tract. This “good” bacteria helps the body to break down food, use nutrients appropriately and effectively eliminate waste. It also plays a vital role in keeping the “bad” bacteria at bay. Having an overabundance of “bad” bacteria in the digestive tract creates the potential for illness and disease to thrive. Some well-known examples of bad bacteria include:

  • Streptococcus bacteria causing strep throat and cellulitis 1

  • Escherichia coli (E.coli) that can cause diarrhea, vomiting and other digestive complaints and is generally contracted through food poisoning.1

  • Streptococcus pneumoniae is the most frequent cause of ear infections 2

According to Mary Ellen Sanders of Oxford Journals, the definition of probiotics is “live microorganisms that, when administered in adequate amounts, confer a health benefit on the host.”3

Let me break this down into detail. “Live Microorganisms…” Yes, probiotics are live bacteria that are naturally occurring in the lining of the gastrointestinal tract of the human body. They are a food source that allows the ecology of the gut to work in balance, promoting health from the inside out. The most common and well understood are the Lactobacillus and Bifidobacterium groups. However, there are a variety of species and strains that provide different benefits.

For example, Lactobacillus bacteria is especially useful for the small intestine.

According to The University of Maryland, Lactobacillus acidophilus (L. acidophilus) is the most commonly used probiotic.4 However, other strains include L. bulgaricus, L. casei, and L. reuteri, Lactobacillus GG 4, just to name a few, all with varying benefits. Additionally Bifidobacterium is especially useful for the large intestine. Some examples include the most common one, Bifodobacterium longum 5, as well as B. breve, B. infantis, B. bifidum.6

Since each species and strain provides specific benefits, it is important to note that not all probiotics are created equal, even though they are often grouped together as just one unit. Therefore, it is important to know what genus, species and strain is included in a supplement that is being taken.

Next, Sanders states that probiotics should be “…administered in adequate amounts”. This is where some food manufacturers and supplements companies may fall short. Let’s compare it to something we are all familiar with: water. Everyone has likely heard by now that the human body requires 64 oz. of water each day for optimal functions. There are many foods that contain water, such as all fruits and vegetables. However, this does not mean that it is providing the “adequate amounts” needed over the course of the day and, therefore, further consumption of water is required. So what are adequate amounts of probiotics as Sanders mentioned? Research has stated that the dosing should be determined based on the strains that are efficacious for the human body. For example, Bifidobacterium infantis 35264 has been documented at 100 billion cfus (colony forming units) when being used for women with IBS.7 While Lactobacillus acidophilus NCFM, when used in conjunction with Bifodobacterium BI-07 at 15 billion cfus (colony forming units), was beneficial for children with cold and flu-like symptom reduction.8

So this might leave you wondering, “What dose do I need?” Frankly, there isn’t a clear-cut answer, as it depends on why you are using them. The gold standard for measuring the effectiveness of probiotics is 15 billion cfus. Therefore, as a clinician, I recommend this to be the minimum starting point.

Foods that contain probiotics include fermented foods like miso, sauerkraut, and pickles. A small amount of these foods should be consumed daily for optimal results. Yogurt is commonly advertised in the media to contain probiotics. They are correct in saying this, however, the largest amount of active bacteria will be found in plain, unsweetened yogurt. The sugar that is added to most yogurts on the market break down the bacteria, allowing die-off to occur, which lessens the effects of it, if not negating it completely. It is ideal to make your own yogurt, sauerkraut and pickles for the maximum amount of probiotics per serving.

The last part of this definition is, “…confer a health benefit to the host.” We, the human body, are the host. Yes, the live bacteria (microorganism) should be providing benefits to the body. In other words, the amount of good bacteria should outweigh the bad bacteria found in the gut. Some benefits include the protection against disease-causing bacteria, stimulation of the immune system, improved digestion and the breakdown of lactose.5 Probiotics have been demonstrated to improve the intestinal barrier in Crohn’s Disease and maintain remission in Ulcerative Colitis9. Additionally, probiotics have been shown to counteract the inflammatory process in eczema and dermatitis.10

Specifically, Bifidobacterium longum has been shown to reduce symptoms (flatulence) associated to lactose intolerance11, while Lactobacillus acidophilus has been shown to be beneficial for women who suffer from reoccurring vaginal yeast infections12, to control Candida albincans13, and decrease risk factors associated to colon cancer.14

If you would like to take it one step further, the best way to reinoculate the ratio of probiotics living in your GI tract, you will need to feed the bacteria. These bacteria live on foods that contain fiber, specifically inulin, which is the non-digestible food ingredient from many sources, such as artichokes, garlic, leeks, onion, chicory, barley, flax, and oats. 15

Key things to look for when choosing a probiotic supplement:

  1. It is a food source to the body, therefore, they are most effective when taken daily to keep the GI tract populated.5, 15

  2. They should contain a mixture of Lactobacillus and Bifidobacterium 5, 15

  3. It has an expiration date to insure effectiveness.5,15

  4. It is refrigerated15. The cold keeps the bacteria inactive until you consume them.

  5. The product label guarantees the dose (cfus) at time of expiration, not the time of manufacturing.5,15

  6. Most probiotics, including Lactobacillus and Bifidobacterium, are measured in colony forming units (cfus) rather than milligrams (mg).

  7. Look for complete classification, including the genus, species and strain. Example: Lactobacillus (genus), acidophilus (species) NCFM (strain)

In conclusion, probiotics are a friendly food source that needs to be consumed on a daily basis for optimal health benefits. Consuming a small amount of fermented foods, along with supplementation, is recommended. Since there are many genus, species and strains available, it is best to speak with your healthcare professional to help you decide which one is most appropriate for your optimal health.


1.US National Library of Medicine, National Institute for Health. Bacterial Infections.

2. Leibovitz E, Greenberg D. Acute otitis media in children: current epidemiology, microbiology, clinical manifestations, and treatment. Chang Gung Med J . 2004;27(7):475-88.

3. Sanders, Mary Ellen. Probiotics: definition, sources, selection and uses. Clin Infect Dis. (2008) 46 (Supplement 2): S58-S61.doi: 10.1086/523341

4. University of Maryland Medical Center,

5.Weiss, Decker. Gastric Stable Acidophilus.

6. Takahiro Matsuki Koichi Watanabe, et al. Distribution of Bifidobacterial Species in Human Intestinal Microflora Examined with 16S rRNA-Gene-Targeted Species-Specific Primers. Appl Environ Microbiol. Oct 1999; 65(10): 4506–4512.

7. Whorwell PJ, Altringer L, Morel J, et al. Efficacy of an encapsulated probiotic Bifidobacterium infantis 35624 in women with irritable bowel syndrome. Am J Gastroenterol 2006;101:1581-90.

8. Leyer GJ, Li S, Mubasher ME, et al. Probiotic effects on cold and influenza-like symptom incidence and duration in children. Pediatrics 2009;124:e172-e179.

9. Madsen K. The use of probiotics in intestinal disease. Can J Gastroenterol.2001;15:817-22. Abstract.

10. Kalliomaki M, Salminen S, Arvilommi H, Kero P, Koshinen P, Isolauri E. Probiotics in primary prevention of atopic disease: a randomized placebo controlled trial. Lancet. 2001;357:1076-9. Abstract.

11. Jiang T, Mustapha A, Savaiano DA. Improvement of lactose digestion in humans by ingestion of unfermented milk containing Bifidobacterium longum. J Dairy Sci. 1996;79:750-757.

12. Hilton E, Isenberg HF, Alperstein P, France K, Borenstein MT. Ingestion of yogurt containing Lactobacilluys acidophilus as prophylaxis for candida vaginitis. Ann Intern med. 1992;116:353-357.

13. Hilton E, Isenberg HD, Alperstein P, France K, Borenstein MT. Ingestion of yogurt containing Lactobacillus acidophilus as prophylaxis for candidal vaginitis. Ann Intern Med.1992;116:353-357.

14. Lidbeck A, Nord CE, Gustafsson JA, Rafter J. Lactobacilli, anticarcinogenic activities and human intestinal microflora. Eur J Cancer Prev. 1992;1:341-53. Abstract.

15. Institute for Functional Medicine.

#probiotics #lactobacillus #goodbacteria #largeintestine #smallintestine #fermentedfoods

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