This research on C. elegans roundworms showed that a small amount of one type of food could trigger changes in growth, development and lifespan. The authors extend the findings to people eating small amounts of junk food triggering unwanted effects, for someone who eats healthy otherwise.
"What we discovered was a large network of metabolic and regulator genes that can integrate internal cellular nutritional needs and imbalances with external availability," said Watson. "This information is then communicated to information processing genes in the worm to illicit the appropriate response in the animal."
These findings suggest the existence of a genetic regulatory network that facilitates rapid responses to internal physiological and external environmental cues in order to maintain a metabolic balance in the worm. Interestingly, a similar phenomenon is involved in mutations that lead to inborn metabolic diseases in humans; classes of genetic diseases resulting from defects in genes that code for enzymes which help convert nutrients into usable materials in the cell. These diseases are usually treated by dietary interventions designed to avoid build-up of toxins and to supplement patients with metabolites that may be depleted. [emphasis mine]
While the insight that genetic regulatory networks can have rapid responses to diets, to make our metabolism balance with the food that's available to us sounds reasonable, I'm not sure the author's conclusion is warranted from this study.
Sometimes you just can't resist a tiny piece of chocolate cake. Even the most health-conscious eaters find themselves indulging in junk foods from time to time. New research by scientists at the University of Massachusetts Medical School (UMMS) raises the striking possibility that even small amounts of these occasional indulgences may produce significant changes in gene expression that could negatively impact physiology and health.