When It Comes to Immunity, You Are What You Eat

Mouse study shows how diet altered by gut microbes spurs development of immune cells

Illustration of intestinal bacteria in the gut microbiome
Image: iLexx/iStock/Getty Images Plus

At a glance:

  • Research in mice shows gut bacteria feed on common fatty acids, and the byproduct of this process stimulates the rise of immune cells in the gut.
  • Immune cascade spurred by fatty acid consumption shielded the mice against disease-causing gut bacteria.
  • Study offers striking demonstration of how diet and gut microbes work together to build the human immune system.

The notion that diet and health are inextricably linked is hardly novel. For millennia, people have known that poor nutrition is responsible for many health problems. But the precise mechanisms that explain just how diet alters the function of our cells, tissues, and organs have remained poorly understood.

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Now, a study led by Harvard Medical School researchers sheds light on this process, pinpointing a critical intermediary between food and health — the gut bacteria that make up our microbiome, or the collection of microorganisms that live in symbiosis with humans.

The work, which was conducted in mice and published June 28 in Nature, shows that gut microbes feast on common fatty acids such as linoleic acid and convert them to conjugated linoleic acid (CLA). This byproduct then serves as a signal for a biological cascade that ultimately spurs a specific type of immune system to develop and reside in the small intestine.