December 2012
The term probiotic means “for life” and is currently used to name friendly bacteria associated with beneficial effects for humans and animals. In fact, the Food and Agriculture Organization of the United Nations and the World Health Organization define probiotics as “live microorganisms which when administered in adequate amounts confer a health benefit on the host.”1 Several probiotic species, mainly those of the lactobacilli and bifidobacteria genus, are used singly or in combination in dietary supplements and functional foods.
This article will discuss the specific health applications of probiotics. However, before addressing the health applications, it’s important to describe the definitions of additional key terms associated with the category of probiotics.
Prebiotics and Postbiotics
A prebiotic is generally a long-chain, non-digested carbohydrate classified as a fiber that ferments in the digestive tract and preferentially or selectively feeds friendly bacteria.2 Examples of prebiotics include inulin, fructooligosaccharides, mannan oligosaccharides and arabinogalactans.
Three criteria are required for a dietary component to be a prebiotic:3
1. It must resist host digestion, absorption and adsorption processes
2. It must be fermented by the microflora colonizing the gastrointestinal tract
3. It must stimulate the growth and/or activity of friendly bacteria
Postbiotics are the metabolic products of probiotics. Specific strains of a probiotic species are referred to as postbiotics (e.g., Lactobacillus paracasei B21060, L. rhamnosus GG).4 Nevertheless, in the popular lexicon, postbiotics are still generally referred to as probiotics.
Supplements or Yogurt?
The question has often been posed as to whether there is a difference in obtaining probiotics from supplements or from food products such as yogurt. In fact, both have their advantages and disadvantages.
Foods that contain probiotics, including yogurt, sour cream, kefir, sauerkraut, kombucha (fermented) tea and fermented soy (miso, tempeh) generally focus on one or two strains. If you want multiple species and strains, you’re not likely to find them in these foods. Plus, the food may or may not provide a clinically relevant dose of the strain(s) it does contain.
Since most brands do not indicate the probiotic dosage on the product, it is generally not a simple task to make that determination. On the upside, research suggests that brands of yogurt tested did indeed provide viable probiotic content.5
By contrast, probiotic supplements are available as single strain products, as well as products with multiple species and strains. In addition, probiotic supplements generally provide specific doses of each species/strain on the product label, so you can easily determine whether or not you are getting a clinically relevant dose.
In addition, some research suggests that the consumption of certain probiotic strains commonly found in supplements may have more of a therapeutic effect than consuming a yogurt drink that does not contain that same strain.6 Unfortunately, some brands of probiotics tested did not contain what their labels claim,7-8 so it is always important to choose probiotic products from trustworthy companies.
Understanding the Different Forms
Probiotic supplements are available as liquids, freeze-dried powders, capsules (containing freeze-dried powder) and beads. The liquids generally contain live bacteria. They must also contain a source of nutrition for the bacteria to feed upon.
Consequently, there is a built-in issue of storage and shelf-life that can be short for some live products. Furthermore, competition for nutrition between bacterial strains within the same live product is another important consideration. In addition, liquid probiotics all require refrigeration.
Powders consist of probiotics that have been freeze-dried under low temperature and pressure in order to remove water without damaging the delicate structure of the cell or organism itself. This puts the probiotic bacteria in a state of suspended animation well suited to long-term storage. In fact, research has demonstrated that various freeze-drying methods are able to successfully keep the probiotic bacteria stable.9
Once moisture becomes available again to the bacteria (such as when they are ingested) they rehydrate. Subsequently, a proportion of the bacteria will go on to function and divide again as they did before being freeze-dried. Once this happens, research has also demonstrated the rehydrated probiotics are able to effectively provide their respective benefits.10-11 Whether or not refrigeration is required for probiotics is dependent upon the actual strains, some of which are heat and shelf stable and some of which are not.
There are two types of probiotic beads. One is microencapsulated probiotic beads.
Microencapsulation is a technology of packaging active materials in miniature sealed capsules that can release their contents at controlled rates under the influences of specific conditions. With regard to probiotics, the purpose is to enhance their viability during processing, and also for their targeted delivery in the gastrointestinal tract.12 While microencapsulation certainly has value, this process is probably unnecessary where hardy, stable probiotic strains are concerned.
The other type of probiotic beads is a softgel capsule shaped like a rounded bead. The claim to fame for these products is that enclosure in the softgel beads is supposed to protect the probiotic bacteria from the acidic environment of the stomach. While the softgels may or may not do this, there is a serious question as to whether or not the probiotic will survive the softgel encapsulation process, due to the high temperature used to keep the gelatin in a liquid state prior to forming the actual softgel. In conversations with a softgel manufacturer, I was informed that, in their experience, analytical testing found that probiotic bacteria did not remain viable after softgel encapsulation.
A Probiotic Deficiency
Since probiotics are not nutrients, they are often not thought of in regard to being deficient in the human body. Nevertheless, some inflammatory conditions of the gut are thought to be caused, at least in part, by “a relative deficiency of bifidobacteria.”13
Furthermore, there are a range of adverse effects when probiotics are present in insufficient quantities. One example of this is small intestine bacterial growth syndrome, a condition associated with the increase in pathogens. This occurs, in part, due to the fact that there are insufficient numbers of friendly, probiotic organisms to inhibit the spread of the harmful, pathogenic organisms.
The result is an increase in chronic diarrhea, as well as more bacteria and toxins finding their way from the intestine to the blood, as well as intestinal absorption disorders causing vitamin B12-deficiency anemia, low levels of various vitamins and protein deficiency. A major strategy for decontamination of the small intestine in this instance is the use of probiotics (both after antibiotics and independently), which suppress pathogens, improve digestion and ease diarrhea.14-15 The effectiveness of probiotics in correcting some of the previously mentioned nutrient deficiencies has also been seen in research where vitamin B12 and folate deficiencies were corrected in children who took Lactobacillus acidophilus.16
Lactobacillus and Bifidobacterium
Lactobacilli and bifidobacteria are two of the most common probiotic genera. Lactobacilli refer to a genus of lactic acid- producing, friendly bacteria17-18 that make up many of the 400 normal probiotic species in the human body.19-22, 17 The most important of these are probably L. acidophilus, L. rhamnosus, L. casei and L. plantarum.
The bifidobacteria genus normally colonizes in the human colon23-24 and, like lactobacillus species, also produces lactic acid. These probiotics appear to be the most important organisms in the intestine in helping to create a microbial barrier to infection. Specifically, bifidobacteria produce antimicrobial substances that are effective against many harmful bacteria.23, 25
Clinical Use of Probiotics
In addition to the prevention and treatment of probiotics deficiency, probiotics have also been used in treating a wide range of disorders, and there is strong evidence for their efficacy in some clinical scenarios. In fact, probiotics are now widely used in many countries by consumers and in clinical practice.26
A significant amount of research has been conducted regarding the different probiotics strains, and the value that these individual strains have for human health. Following is a table that identifies which probiotic species have been studied for specific applications to human health.27-30
A Note on Potency
It is inevitable that a certain percentage of probiotic bacteria will be destroyed by gastric acids.
That’s why it’s important to consume a probiotic formulated with survivability in mind. Many marketers claim that a relatively high dose is necessary (5 to 10 billion cells or colony forming units, CFUs) to assure that an adequate quantity of these microorganisms will make it through to the intestinal tract intact to provide their benefits. However, the bottom line is that it’s more advantageous to ensure the good bacteria survive to begin with rather than rely on taking high doses in the hopes they will survive.
For purposes of maintaining a healthy level of friendly intestinal bacteria, a higher dose of probiotics is not necessarily better. Higher doses may be indicated for shorter periods, however, if a specific medical need is being addressed.
Similarly, it can actually be more beneficial if a single strain of probiotic is used rather than multiple strains because this will limit the effects of possible interactions of multiple strains. So one targeted strain may be more beneficial.
Depending on the clinical benefits one is looking to achieve, it is possible that certain strains may counteract the benefits of others in a multi-species mixture, resulting in an ineffective product. It’s wise, therefore, to always choose strains that have been studied for a particular effect and, if a combination is considered, to be aware that potential interactions may occur between different bacterial species.
References:
1. FAO/WHO. Health and Nutritional Properties of Probiotics in Food including Powder Milk with Live Lactic Acid Bacteria. Report of a Joint FAO/WHO Expert Consultation on Evaluation of Health and Nutritional Properties of Probiotics in Food Including Powder Milk with Live Lactic Acid Bacteria; 2001.
2. Gibson GR, et al. Nutr Res Rev. 2004;17:259-75.
3. Kolida S, et al. J Nutr. 2007;137:2503S-2506S.
4. Tsilingiri K, et al. Gut. 2012 Jul;61(7):1007-15.
5. Dunlap BS, et al. Clinical Pediatrics. 2009;48(5):522-7.
6. Gluck U, et. Am J Clin Nutr. 2003;77:517-20.
7. Sanders ME, et al. Antonie Leeuwenhoek. 1999;76:293-315.
8. ConsumerLabs.com. Product Review: Probiotic Supplements (Including Lactobacillus acidophilus, Bifidobacterium, and Others); 2006.
9. Savini M, et al. Nutrients. 2010 Mar;2(3):330-9.
10. Bohbot JM, et al. Infect Dis Obstet Gynecol. 2012:Article ID 503648.
11. Strompfová V, et al. Folia Microbiol (Praha). 2012 Jul;57(4):347-50.
12. Jayalalitha V, et al. IJARR. 2012;2(1):1-6.
13. Subramanian S, et al. Curr Opin Infect Dis. 2006;19(5):475-84.
14. Lykova EA, et al. Eksp Klin Gastroenterol. 2005;(6):51-7, 113.
15. Bondarenko VM, et al. Zh Mikrobiol Epidemiol Immunobiol. 2006;(6):57-63.
16. Mohammad MA, et al. Int J Food Sci Nutr. 2006;57(7-8):470-80.
17. Casas IA, et al. Microb Ecol Health Dis. 2000;12:247-85.
18. Fujisawa T, et al. Int J Syst Bacteriol. 1992;42:487-91.
19. McGroarty JA. FEMS Immunol Med Microbiol. 1993;6:251-64.
20. Bruce AW, et al. Can J Microbiol. 1988;34:339-43.
21. Gupta K, et al. J Infect Dis. 1998;178:446-50.
22. Madsen KL, et al. Gastroenterology 1999;116:1107-14.
23. Lievin V, et al. Gut 2000;47:646-52.
24. Macfarlane GT, et al. BMJ 1999;318:999-1003.
25. Rastall RA. J Nutr 2004;134:2022S-2026S.
26. Boyle RJ, et al. Am J Clin Nutr. 2006;83(6):1256-64.
27. Floch M, Kim AS. Probiotics: A Clinical Guide. Thorofare, NJ: Slack Incorporated;2010:352.
28. Farnsworth ER. Probiotics and Prebiotics. In: Wildman REC (Ed). Handbook of Nutraceuticals and Functional Foods, 2nd Ed. Boca Raton: CRC Press; 2007:335-52.
29. Kneifel W, Salminen S (Eds). Probiotics and Health Claims. New York: Wiley-Blackwell; 1011:360.
30. Lee YK, Salminen S. Handbook of Probiotics and Prebiotics, 2nd Ed. New York: Wiley-Interscience; 2008:596.
Source: A Probiotic Primer
