Figure 42.2 The Microbial Community of the Human Gut Depends on the Host’s Diet
The microbial community of the human gut is large and diverse, with both beneficial and detrimental species. Previous in vitro studies suggested that two naturally occurring indigestible carbohydrates, oligofructose and inulin, can increase the growth rates of beneficial bifidobacteria, which in turn inhibit growth of several potentially detrimental bacteria. To test whether these results would hold-up in a more natural situation, eight human subjects were fed a controlled diet for 45 days, which included a 15-day period in the middle of the experiment during which 15 grams of oligofructose was substituted for 15 grams of sucrose. Throughout the experiment the bacterial flora in each subject’s stools was measured. Results showed that with an oligofructose diet there was a significant increase in the abundance of bifidobacteria and a significant decrease in the abundance of several potentially pathogenic bacteria. An additional study demonstrated a similar effect of an inulin diet. Thus, there is both in vitro and in vivo evidence that diet can influence the microbial community of the human gut. Consumption of oligofructose or inulin can lead to a possibly healthier bacterial flora. Oligofructose and inulin occur naturally in plants such as artichokes, chicory, onions, and asparagus, which can be readily added to a healthy human diet. More recent studies have demonstrated links between gut flora and disease, with manipulation of gut flora becoming an active area of research for the treatment and prevention of various diseases.
Original paper
Gibson, G. R., E. R. Beatty, X. Wang, and J. H. Cummings. 1995. Selective stimulation of bifidobacteria in the human colon by oligofructose and inulin. Gastroenterology 108: 975–982.
http://dx.doi.org/10.1016/0016-5085(95)90192-2
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