In research presented at a recent conference in China, Zhao and collaborators analyzed people’s microbial communities before putting them on a specialized diet. Some gained weight and some lost it. Zhao was able to predict who would benefit by looking at the makeup of that person’s microbiome prior to the diet.
Knight points out that China is an ideal location for this type of research for two reasons: BGI, a sequencing center in Beijing, has massive sequencing power (the institute is expected to surpass the entire sequencing capability of the United States later this year). “And you have access to a large population of people willing to engage in research like being restrained in what they eat for a long time,” he says.
Knight is collaborating with Jeff Gordon at Washington University, in St. Louis, to analyze how gut microbes affect children’s ability to put on weight. Food supplements of peanut butter, milk powder, and vitamins have helped many children suffering from malnutrition in poor countries. But a substantial number don’t respond; in some cases, identical twins living in the same house and eating the same food will respond differently. “Have they picked up some pathogen causing malnutrition or lost some kind of microbe?” says Knight, who ultimately hopes to develop a cheap diagnostic test that would enable tailored supplements.
The two scientists are also studying Crohn’s disease and ulcerative colitis, two forms of inflammatory bowel disease, which flair up periodically in sufferers. “We want to understand how the microbial community changes between relapse and then potentially use that for treatment,” says Knight.
Preliminary research in David Relman’s lab at Stanford highlights what antibiotics do to our gut microbes. His team analyzed the microbiomes of healthy people given two five-day courses of the antibiotic Cipro six months apart. Individuals responded very differently to the drugs. “We see a drop in abundance related to Cipro and a drop in diversity,” said Relman at a talk at MIT last week. “Some people go back to predrug diversity and some don’t.” After the second exposure, the microbial community never returns to the initial state. “Maybe someday we will be able to predict who will be susceptible to antibiotic-linked problems, like diarrhea or colitis,” he says.
Relman’s study highlights the potential complexity of studying antibiotics and weight loss. Despite his own experience, Knight certainly doesn’t recommend taking a course of antibiotics to lose weight: “That’s like weeding a garden with a bulldozer and hoping what grows back is what you want,” he says. “We want a much more specific way to control these communities.”
Knight offers another potential explanation for his weight loss–that he is recording both his food intake and exercise routine as part of the experiment. “When you know people in the lab will be going over your records, you might be more conscious of what you’re doing,” he says.