Gut reaction: environmental effects on the human microbiota - PubMed (original) (raw)
Gut reaction: environmental effects on the human microbiota
Melissa Lee Phillips. Environ Health Perspect. 2009 May.
No abstract available
Figures
(opposite) The gut contains thousands of microbial species, including: 1) Ruminococcus 2) Bifidobacterium 3) Peptostreptococcus 4) Staphylococcus 5) Lactobacillus 6) Acidaminococcus 7) Fusobacterium 8) Eubacterium 9) Clostridium 10) Coprococcus 11) Escherichia 12) Butyrivibrio 13) Bacteroides 14) Brachyspira
The microbiota is similar to an organ in that it performs functions essential for our survival. And just as with the heart or the lungs, when an environmental agent alters the function of the microbiota, the result can be disease. Bacteroides species are some of the most common bacteria in the human gut. They are involved in many important metabolic activities, including fermentation of carbohydrates, utilization of nitrogenous substances, and biotransformation of bile acids and other steroids. But Bacteroides can also cause many types of infections and abscesses in the GI tract and elsewhere in the body.
Temporal Profiles of the Most Abundant Gut Microbes as Measured in 14 Infants
Both human and animal studies have shown that even a one-time antibiotic treatment can lead to long-term shifts in microbial populations. The health consequences of these long-term shifts are still largely unknown. Clostridium difficile is often acquired in a hospital setting by patients on antibiotics. Antibiotics alter the normal flora of the intestines, which allows for colonization by C. difficile. Once colonized, the bacteria release endotoxins that can cause colitis and severe diarrhea.
Work over the past decade or two links intestinal microbiota very closely with many parameters of host biology in both health and disease. In most cases, however, the microbiota–disease connection remains simply a correlation; it’s not yet clear if microbial shifts actually cause disease or if they simply reflect a diseased state. Helicobacter pylori is the main cause of chronic superficial gastritis and is associated with both gastric and duodenal ulcers, yet it is also associated with a reduced risk of adenocarcinoma in the lower esophagus. It lives in the interface between the surface of gastric epithelial cells.
The differences between each person’s microbiota will influence not only their health risks but also how they respond to medical and lifestyle interventions. Being able to sequence thousands of microbes quickly and easily will likely open the door to considering the individual’s microbiota in the development of personalized medicine. Lactobacillus acidophilus occurs naturally in the gut, mouth, and vagina. It is also the most commonly used probiotic. This bacterium produces lactase, and L. acidophilus supplements are often given to lactose-intolerant individuals.
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