LA JOLLA, CAWhen you eat may be just as vital to your health as what you eat, found researchers at the Salk Institute for Biological Studies. Their experiments in mice revealed that the daily waxing and waning of thousands of genes in the liverthe body's metabolic clearinghouseis mostly controlled by food intake and not by the body's circadian clock as conventional wisdom had it.
"If feeding time determines the activity of a large number of genes completely independent of the circadian clock, when you eat and fast each day will have a huge impact on your metabolism," says the study's leader Satchidananda (Satchin) Panda, Ph.D., an assistant professor in the Regulatory Biology Laboratory.
The Salk researchers' findings, which will be published in a forthcoming issue of the Proceedings of the National Academy of Sciences, could explain why shift workers are unusually prone to metabolic syndrome, diabetes, high cholesterol levels and obesity.
"We believe that it is not shift work per se that wreaks havoc with the body's metabolism but changing shifts and weekends, when workers switch back to a regular day-night cycle," says Panda.
In mammals, the circadian timing system is composed of a central circadian clock in the brain and subsidiary oscillators in most peripheral tissues. The master clock in the brain is set by light and determines the overall diurnal or nocturnal preference of an animal, including sleep-wake cycles and feeding behavior. The clocks in peripheral organs are largely insensitive to changes in the light regime. Instead, their phase and amplitude are affected by many factors including feeding time.
The clocks themselves keep time through the fall and rise of gene activity on a roughly 24-hour schedule that anticipates environmental changes and adapts many of the body's physiological function to the appropriate time of day.
"The liver oscillator in particular helps the organism to ada
|Contact: Gina Kirchweger|