The year in microbiomes

Scientists have long known that people are cozy homes for bacteria — but figuring out the myriad roles of bacteria in the body is still a work in progress. This year, scientists pegged microbes as important players in several aspects of human health, including obesity and cancer. Highlights from 2014 include:

1. Obesity

Blasting away babies’ gut bacteria could boost weight gain later in life. Infant mice dosed with antibiotics chunked out as adults; researchers blame the bulge on the mice’s microbial makeup, which differed from that of drug-free mice (SN: 9/20/14, p. 12).

2. Jet lag

Messing with gut microbes’ schedules may make people fat. After crossing a few time zones, travelers housed more bacteria linked to obesity than they did before the trip. In mice, jet-lagged gut microbes prompted weight gain (SN: 11/29/14, p. 12).

3. Colon cancer

Gut microbes might explain the link between eating a Western diet and developing colon cancer. Bacteria that feast on sugar may churn out a chemical that turns on tumor growth, a study in mice suggested (SN: 8/23/14, p. 12).

4. Placenta

Babies get their first brush with bacteria in the womb, an analysis of microbes in the placentas of 48 women found. Scientists once believed placentas to be sterile, but they are home to some of the same bacteria found in people’s mouths (SN: 6/28/14, p. 6).

5. Drugs

Microbes in people may be tiny drug mills, making thousands of chem­icals including antibiotics, scientists found after peeking into the genetic blueprints of 2,430 bacteria collected from the human body (SN: 10/18/14, p. 8).