Diet Tied to Changes in Gene Expression and Health: You are What You Eat

A small slice of that chocolate cake couldn't hurt, could it? Apparently, it can. Two new studies reveal that even occasional indulgences in junk food could produce significant changes in gene expression that could negatively impact physiology and health.

The papers, published in Cell, examined a transparent roundworm called C. elegans. Researchers wanted to see exactly how diet affected gene expression in this organism--especially when it came to crucial physiological changes. They fed one set of worms a natural diet of Comamonas bacteria. The other set they fed the standard laboratory diet of E. Coli bacteria.

In the end, the researchers found that worms fed the Comamonas bacteria had fewer offspring, lived shorter lives and developed more quickly than the ones that were fed E. Coli. In particular, they identified at least 87 changes in the worm's gene expression depending on which diet it was fed. The changes themselves were independent of the TOR and insulin signaling pathways, gene expression programs that are typically active in nutritional control. Instead, the researchers found that the changes occurred in a regulator that controls molting, which determines the development and growth of the worm.

"Importantly, these same regulators that are influenced by diet in the worms control circadian rhythm in humans," said Lesley MacNeil, first author on the paper, in a news release. "We already know that circadian rhythms are affected by diet. This points to the real possibility that we can now us. C. elegans to study the complex connections between diet, gene expression and physiology and their relation to human disease."

What is perhaps more interesting is the fact that even a small amount of Comamonas bacteria introduced into a diet otherwise composed of E. Coli could induce dramatic changes in gene expression and physiology. The finding seems to hint that different diets are not "healthy" or "unhealthy." Instead, certain quantities of foods may be optimal under different conditions and could promote different physiological outcomes.

The researchers weren't done yet, though. In another study, they looked for genes that led to an abnormal response to diet in the worm. They found a large network of metabolic and regulator genes that can actually integrate internal cellular nutritional needs and imbalances with external availability. The findings could allow researchers to use the genetic regulatory network in the worm in order to compare how dietary regimens can be used to mitigate human metabolic diseases.

With these two studies, the researchers found that diet is all important--even the smallest bit can help or hurt. In addition, the worm could potentially be used in future studies to examine the complex interaction between diet, gene expression and physiology in humans.