A small clinical trial supported by the National Institutes of Health has discovered that eating at nighttime–like many shift workers do–can increase the amount of glucose in the blood, while eating only during the daytime could prevent the higher glucose levels that are associated with nighttime work schedule.
According to the study authors the findings could result in new behavioral interventions that improve the health of shift workers (e.g., hotel workers, truck drivers and first responders) who are at a higher risk for developing diabetes, heart disease and obesity.
The new study, which the researchers noted is the first study to show the benefits of this kind of food timing interventions in humans, is published online in the journal Science Advances. It was funded primarily through the National Heart, Lung, and Blood Institute, part of NIH.
This lab study has revealed a potential intervention to reduce the adverse metabolic effects of shift work, which is a well-known health risk for the general population. We are looking forward to future studies to confirm these findings and uncover the underlying biological causes.
Marishka Brown, Ph.D. Director, NHLBI’s National Center on Sleep Disorders Research
The researchers recruited 19 healthy young participants (seven women and 12 males). After a preconditioning exercise, participants were randomly assigned to a 14-day controlled laboratory protocol that involved the simulation of working conditions during the night and two meals per day. One group ate during the nighttime to mimic a normal meal plan for night-time workers, while the other group was fed during the daytime.
The researchers then assessed the effects of these meal schedules on their circadian rhythms. This is the internal process that regulates not only the cycle of sleep-wake, but also the 24-hour cycle that governs virtually every aspect of your body’s functions, including metabolism.
The study found that eating at night increased glucose levels – a risk factor for developing diabetes – however, limiting meals to the daytime prevented this effect. Particularly, the average glucose levels for those who ate during the night increased by 6.4 percent during the simulation night work, while those who ate during the daytime had no significant rises.
“This is the first study in humans that demonstrates the benefits of meal timing as a countermeasure against the combined negative effects of impaired glucose tolerance and disrupted rhythms of the circadian cycle that result from simulated night work,” said study leader Frank A.J.L. Scheer, Ph.D., professor of medicine at Harvard Medical School and director of the Medical Chronobiology Program at Brigham & Women’s Hospital in Boston.
The researchers said that the mechanisms behind the observed effects are complex. Researchers believe that circadian misalignment is the reason for the effects of nighttime eating on glucose levels in simulated work-nights. That corresponds to the mistiming between the central circadian “clock” (located in the hypothalamus in the brain) and the sleep/wake behavioral and light/dark cycles, which may affect peripheral “clocks” throughout the body. This study shows that the mistiming of the central circadian clock and the fasting/eating cycle plays an essential role in increasing glucose levels. The research also suggests that positive effects of eating during the daytime on glucose levels during simulated night work may be driven by a better alignment of these central and peripheral “clocks.”
“This study confirms that the food you eat can affect your health outcomes, including blood sugar levels,” said Sarah L. Chellappa (M.D., Ph.D.), co-leader of the study and researcher at the University of Cologne’s department for nuclear medicine. Chellappa was previously a part of Scheer in the Brigham & Women’s Medical Chronobiology Program.
To translate these findings into practical and effective time-based meal planning, the researchers said further research is required and includes real-life shift workers in their normal work environment.
Chellappa S.L., and Chellappa S.L., and. (2021). The consumption of food during the day prevents internal circadian disalignment, as well as glucose intolerance during work at night. Science Advances. doi.org/10.1126/sciadv.abg9910.
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