It seems that while what we eat is very important to our health, when we have our meals has an impact on our bodies as well. Researchers have learned more about how the timing of food intake influences our body’s internal clock or circadian rhythm. The findings, which have been reported in Cell show that insulin is a critical signal that can match meal times to the circadian rhythm. This work may help those that disrupt the body clock (such as by traveling or working nights) to relieve the negative health effects caused by such disruptions. The short video below outlines the work.
"We already know that modern society poses many challenges to our health and wellbeing - things that are viewed as commonplace, such as shift-work, sleep deprivation, and jet lag, disrupt our body clock. It is now becoming clear that circadian disruption is increasing the incidence and severity of many diseases, including cardiovascular disease and type 2 diabetes," noted Dr. David Bechtold, a senior lecturer at the University of Manchester.
The cells in our bodies can respond to the 24-hour cycle that helps govern aspects of our physiology; the circadian rhythm helps control hormone levels, sleep and wakefulness, and other parts of our daily life. Cues from the environment, like daylight and mealtimes, help set the rhythm. Synchronizing our body’s clock to the environmental cycle is important to health. Disruptions to the rhythm are harmful to health, and eating at weird times is thought to be one major disruptor. As such, researchers want to learn more about how our body clocks sense and respond to the timing of meals.
In this work, scientists from the Medical Research Council (MRC) Laboratory of Molecular Biology (LMB) in Cambridge and the University of Manchester found that a molecule that controls the level of glucose in the blood, insulin, is a vital signal, communicating meal times to the circadian clocks of the body. The researchers used cell culture and a mouse model to show that after eating, as the body releases insulin, cells adjust their circadian rhythms. They do so through a protein that works as part of the body clock, called PERIOD.
"At the heart of these cellular clocks is a complex set of molecules whose interaction provides precise 24-hour timing. What we have shown here is that the insulin, released when we eat, can act as a timing signal to cells throughout our body," explained the leader of the Cambridge team Dr. John O'Neill, of the MRC LMB.
If mice were exposed to insulin at odd times, such as when they would otherwise be sleeping, it altered their circadian rhythm.
"Our data suggests that eating at the wrong times could have a major impact on our circadian rhythms. There is still work to do here, but paying particular attention to meal timing and light exposure is likely the best way to mitigate the adverse effects of shift-work. Even for those who work more traditional hours, being careful about when we eat is an important way to help maintain healthy body clocks, especially as we age," explained lead author Dr. Priya Crosby, a researcher at the MRC LMB.