By Brian Palmer
NEW YORK —
NEW YORK — Corey Goodman sees financial opportunity in strange places, specifically the human bowel. In 2010 the former president of Pfizer’s innovation center founded Second Genome, a company dedicated to identifying the varieties of bacteria in stool samples and manipulating them to improve human health. Goodman’s start-up has raised millions of dollars from venture capitalists. Earlier this year, Johnson and Johnson partnered with Second Genome, becoming the first big pharma company to invest heavily in the microbiome.
There are good reasons the smart money may be on researching human waste. Describing the microbiome could lead to treatments for conditions like celiac disease and the nebulous but widespread irritable bowel syndrome. Even more lucrative would be a new weight loss medication. The market for weight loss products is worth more than $60 billion, although recent sales data suggest that Americans have lost interest in traditional diet pills.
Turning to gut flora has intuitive appeal: Microbes vastly outnumber human cells in our intestines, and early research has shown significant person-to-person variation in the makeup of our gut flora. These microbes might influence how people digest their food and therefore how much they weigh. The American Gut Project has created genetic profiles for the microbiomes of hundreds of Americans, with plans for thousands more. Early results show that the guts of people consuming a so-called paleo diet are rich in the bacterial phylum Firmicutes, while people suffering from celiac disease are Firmicutes-poor.
Some intriguing news has come from a heartbreaking source: starving children.
Those results, however, say very little about how human gut flora interact with our own genetic makeup, how gut flora composition changes over time, whether it’s possible to manipulate gut flora without changing diet, or even whether we can effect a long-term change in a person’s intestinal microbiome at all. Moreover, our basic understanding of how gut flora impact digestion is absurdly limited. Probiotics sales approached $28 billion in 2011, and are forecast to surpass $44 billion by 2018, but no one really knows what conditions Americans are using them for, or whether they’re helping.
Some intriguing news, however, has recently come from an unexpected and heartbreaking source: starving children in Africa. In January a group of scientists working in Malawi, the United States, and London published a paper that may represent a breakthrough in understanding the malleability of the intestinal microbiome. They followed pairs of twins under the age of 3. In some pairs, one twin suffered from kwashiorkor, a particularly dire form of malnutrition characterized by swelling, liver dysfunction, rashes and skin ulcerations, while the other twin, for unknown reasons, remained healthy.
Assuming parents wouldn’t deliberately deny food to only one of their twins, there’s no obvious reason why one sibling could suffer from severe malnutrition while the other didn’t. The explanation seems to reside in the intestine. The researchers found that the makeup of the healthy twins’ gut flora evolved in a predictable way as they aged from infancy to 3, while the gut flora of the afflicted children failed to develop the right mix of bacterial helpers. The stalling of microbial development in the intestines persisted even after the sick children were given peanut-based nutritional supplements.
It’s worth pausing here to make an obvious but important point. The real value in the study is how it may help doctors treat kwashiorkor, which has devastated African children over the past century. Its impact on affluent Americans hoping to slim down is less obvious, somewhat ironic, and far less important. All that said, these findings are potentially financially significant as a business opportunity for the developed world. The kwashiorkor study shows that genetically similar individuals can host vastly different communities of bacteria, and that those differences influence how food is processed, how nutrients are absorbed, and yes, how much you weigh. It will provide a launching point for researchers to determine whether doctors can deliberately impose similar changes on patients in both the developed world and in wealthy nations.
While microbial flora can likely be manipulated and can affect weight, a simple fecal transplant won’t be a magic bullet. Like gastric bypass or other weight loss interventions, the future recipients of novel gut flora will have to work to maintain their weight through appropriate diet and probably exercise. A change in the microbiome will at best represent a kick-start to weight loss, not a stand-alone solution. A single-celled organism can’t solve all of your problems.