Lactobacillus acidophilus is a bacterium that occurs naturally in the human intestine. It is also used in foods such as yogurt, kefir, milk, soy beverages, and fermented food products like miso and tempeh, or sold as dietary supplements as capsules, tablets or powders. There has been increased interest in acidophilus for its health benefits including its protective effects on the human colon.
Probiotics and Prebiotics
The World Health Organization and the Food and Agriculture Organization of the United Nations define probiotics as "live microorganisms which, when administered in adequate amounts, confer a health benefit to the host." Microorganisms are microscopic living organisms such as such as bacteria, yeasts and viruses. Some of the beneficial probiotics include Lactobacillus acidophilus, Bifidobacterium bifidum, and Saccharomyces boulardii (yeast).
By comparison, "prebiotics" are non-digestible food components such as insoluble fiber which are structural plant components that cannot be digested by human enzymes but serve as food for friendly bacteria in the gut such as Lactobacillus iners sp.nov., Lactobacillus coleohominis and Thermobacterium intestinale.
Anaerobic Bacteria, Dietary Fiber, and Protective Short-Chain Saturated Fatty Acids
When insoluble fiber reaches the colon, it is fermented by Lactobacillus acidophilus and other colonic microflora to produce acetic, butyric and propionic acids, which are short-chain saturated fatty acids. These acids change the colon's pH, from slightly alkaline to acidic -- an inhospitable medium that blocks the growth of harmful bacteria such as Escheria coli. E. coli has been shown to initiate the cellular dysfunction of intestinal epithelial cells which in turn can promote colon cancer.
Bowel Regularity
Without friendly bacteria in the gut, insoluble fiber would remain undigested, which could likely block the large intestines. These bacteria, acidophilus included, breakdown insoluble fibers. The digested material yields 2 calories per gram. In lieu of the calories, the bacteria assists in the speedy removal of waste material in the colon. The increased fecal weight from digested fiber and water, as there is less time for the colon to absorb water, facilitates laxation.
Reduces Colon Exposure to Toxins
Shorter fecal transit time facilitated by "friendly" bacteria reduces the colon's exposure to harmful compounds such as deoxycholate. Recall that these bacteria "digest" insoluble fiber and in the process changes the pH of the colon from alkaline to acid. This acidity prevents the bacterial enzyme 7-alpha-deoxylase to convert cholate into deoxycholate -- a toxic compound.
Prevents Diarrhea
In general, the colon "cleanses" itself. However, when the system is compromised by antibiotics or illness, "unfriendly" microorganisms including bacteria, yeasts, fungi and parasites infiltrate the colon and cause further misery and discomfort. Siitonen and colleagues, as published in the 1990 issue of the Annals of Medicine, discovered that probiotic-enriched yogurt prevented antibiotic-associated diarrhea in healthy volunteers.
Side Effects and Risks
There have been few reports concerning the ill effects of supplemental acidophilus either as tablets, capsules or powder or as probiotics in food. However, people with active infections should consult their health care providers before using these products. If you are concerned about the safety of these products, consult your doctor, or a national government agency specializing in alternative medicine.
References
- Pubmed: Effect of Lactobacillus GG yogurt in prevention of antibiotic associated diarrhea
- Pubmed: Phenotypic and phylogenetic characterization of a novel Lactobacillus species from human sources: description of Lactobacillus iners sp. nov.
- Pubmed: Protective effects of Lactobacillus plantarum against epithelial barrier dysfunction of human colon cell line NCM460
- NCCAM National Centers for Complimentary and Alternative Medicine: An Introduction to Probiotics
- UniProt: Taxonomy: Species Lactobacillus acidophilus
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