Early Gut Reactions

Fruit fly intestines (cell nuclei in blue) develop twice as many hormone-producing cells (pink dots) when fed a diet high in cholesterol early in life.

Rebecca Obinski, Matthew Sieber, and Allan Spradling

Starting life with a healthy diet may be even more important to long-term health than previously thought. New research on the guts of fruit flies, Drosophila, reveals how a particular nutrient (or lack of it) can have far-reaching consequences for how the gut develops—and even its risk for developing tumors.

The intestines of fruit flies, like those of mammals, have three primary types of cells: stem cells, and the two kinds of cells that stem cells produce, either nutrient-absorbing enterocytes or hormone-producing enteroendocrine cells. Allan Spradling and two colleagues at the Carnegie Institution for Science in Baltimore, Maryland, undertook a series of experiments exploring whether the early diet of fruit flies affected the composition of cells in their guts as young adults.

First, the researchers fed newly hatched fruit flies a diet of either “normal” yeast paste, yeast low in lipids (a key component in fat), or yeast high in cholesterol (a type of lipid molecule). After ten days, they examined the cellular makeup of the flies’ guts. Flies on the low-lipid diet had significantly fewer enteroendocrine cells, the hormone producers, in the lower gut, compared to flies fed a normal diet. In contrast, flies fed the high-cholesterol diet showed a boost in the number of enteroendocrine cells produced in the lower gut.

This effect of diet was shown to affect a key process early in life. Flies who fed on normal yeast for a week before shifting to a low-lipid diet avoided the drop in enteroendocrine cells. For flies fed the opposite pattern—first a low-lipid diet and then a switch to regular food—the reduction in enteroendocrine cells in the gut lining persisted long after shifting to a normal diet. Furthermore, these flies held onto 14–18 percent more cholesterol in their bodies. This suggests early diet can affect an animal’s metabolism even after changing diet later.

The researchers also found that a low-lipid diet, which decreases enteroendocrine cell production, suppressed the development of enteroendocrine tumors in the intestine. “This study can lead the way to a better understanding of how diet and other environmental variables influence our bodies and lives,” says Spradling. (Developmental Cell)