Research Front Maps
Research front maps are diagrammatic representations of the core papers comprising each front. They are selected from the current Research Front set that are relevant to the featured special topic, in this case, Obesity. The title for this Research Front Map is “GUT MICROBIAL ECOLOGY AND OBESITY,” containing 29 core papers. Source dates: 1999-December 31, 2009 (sixth bimonthly period 2009).
Each circle represents a highly cited paper whose bibliographic information is displayed when the user clicks on the circle. The solid lines between circles represent the strongest co-citation links for each paper (that is, indicating that the papers are frequently cited together); weaker links are indicated by dashed lines. Papers close to each other on the map are generally more highly co-cited. The most recent paper(s) are indicated in pink. Annotations may have been added to this map which represent the main research themes. These appear as labels attached to specific regions on the maps.

Two groups of beneficial bacteria are dominant in the human gut, the Bacteroidetes and the Firmicutes. Here we show that the relative proportion of Bacteroidetes is decreased in obese people by comparison with lean people, and that this proportion increases with weight loss on two types of low-calorie diet. Our findings indicate that obesity has a microbial component, which might have potential therapeutic implications.

Washington University School of Medicine, St Louis, Missouri 63108, USA

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Justin Sonnenburg, a microbiologist at Stanford, suggests that we would do well to begin regarding the human body as “an elaborate vessel optimized for the growth and spread of our microbial inhabitants.” This humbling new way of thinking about the self has large implications for human and microbial health, which turn out to be inextricably linked. Disorders in our internal ecosystem — a loss of diversity, say, or a proliferation of the “wrong” kind of microbes — may predispose us to obesity and a whole range of chronic diseases, as well as some infections. “Fecal transplants,” which involve installing a healthy person’s microbiota into a sick person’s gut, have been shown to effectively treat an antibiotic-resistant intestinal pathogen named C. difficile, which kills 14,000 Americans each year. (Researchers use the word “microbiota” to refer to all the microbes in a community and “microbiome” to refer to their collective genes.) We’ve known for a few years that obese mice transplanted with the intestinal community of lean mice lose weight and vice versa. (We don’t know why.) A similar experiment was performed recently on humans by researchers in the Netherlands: when the contents of a lean donor’s microbiota were transferred to the guts of male patients with metabolic syndrome, the researchers found striking improvements in the recipients’ sensitivity to insulin, an important marker for metabolic health. Somehow, the gut microbes were influencing the patients’ metabolisms.
Our resident microbes also appear to play a critical role in training and modulating our immune system, helping it to accurately distinguish between friend and foe and not go nuts on, well, nuts and all sorts of other potential allergens. Some researchers believe that the alarming increase in autoimmune diseases in the West may owe to a disruption in the ancient relationship between our bodies and their “old friends” — the microbial symbionts with whom we coevolved.
These claims sound extravagant, and in fact many microbiome researchers are careful not to make the mistake that scientists working on the human genome did a decade or so ago, when they promised they were on the trail of cures to many diseases. We’re still waiting. Yet whether any cures emerge from the exploration of the second genome, the implications of what has already been learned — for our sense of self, for our definition of health and for our attitude toward bacteria in general — are difficult to overstate. Human health should now “be thought of as a collective property of the human-associated microbiota,” as one group of researchers recently concluded in a landmark review article on microbial ecology — that is, as a function of the community, not the individual.
Such a paradigm shift comes not a moment too soon, because as a civilization, we’ve just spent the better part of a century doing our unwitting best to wreck the human-associated microbiota with a multifronted war on bacteria and a diet notably detrimental to its well-being. Researchers now speak of an impoverished “Westernized microbiome” and ask whether the time has come to embark on a project of “restoration ecology” — not in the rain forest or on the prairie but right here at home, in the human gut.

Connie’s comments: The goal is to have an alkaline body. Start your day with water with freshly squeezed lemon. Flush the toxins in our body with foods rich in fiber and are alkaline such as whole foods of vegetables, nuts, grains and fruits. 70% of our immune system reside in our intestine. A clean intestine free of bugs will do well with our health. In care homes, most of our elderly are suffering from constipation with daily diet rich in meat for many of their years. Drugs also exacerbate their condition. Live a healthy lifestyle, free from damaging effects of toxins, drugs, meat rich diet and other chemicals unknown to us.