Time-restricted eating has been linked to a number of health benefits, including an extension of life span in laboratory tests. As a result, techniques like intermittent fasting are a popular issue in the wellness sector.
However, it is unclear exactly how it alters the body’s molecular structure and how those changes interact with other organ systems.
Salk researchers have now demonstrated in mice how time-restricted eating affects gene expression in more than 22 different body and brain locations. Genes respond to their environment by producing proteins through a process known as gene expression.
The findings, published in Cell Metabolism on January 3, 2023, have implications for a wide range of health conditions where time-restricted eating has shown potential benefits, including diabetes, heart disease, hypertension, and cancer.
“We found that there is a system-wide, molecular impact of time-restricted eating in mice,” says Professor Satchidananda Panda, senior author and holder of the Rita and Richard Atkinson Chair at Salk. “Our results open the door for looking more closely at how this nutritional intervention activates genes involved in specific diseases, such as cancer.”
For the study, two groups of mice were fed the same high-calorie diet. One group was given free access to the food. The other group was limited to eating just during a nine-hour feeding window each day.
By changing the timing of food, we were able to change the gene expression not just in the gut or in the liver, but also in thousands of genes in the brain.
Professor Satchidananda Panda
After seven weeks, tissue samples from 22 organ groups and the brain were taken at various periods during the day or night, and their genetic makeup was examined. The tissues used in the samples came from the liver, stomach, lungs, heart, adrenal gland, hypothalamus, various kidney and intestine components, and various brain regions.
The authors found that 70 percent of mouse genes respond to time-restricted eating.
“By changing the timing of food, we were able to change the gene expression not just in the gut or in the liver, but also in thousands of genes in the brain,” says Panda.
Time-restricted eating altered about 40% of the genes in the brain, pancreas, and adrenal gland. These organs are important for hormonal regulation. Hormonal imbalance is linked to a variety of ailments, including diabetes and stress problems. Hormones coordinate functions in various sections of the body and brain. The findings provide recommendations on how time-restricted eating may assist in managing certain disorders.
Interestingly, not all sections of the digestive tract were affected equally. Time-restricted eating activated the genes in the duodenum and jejunum, the upper two sections of the small intestine, but not in the ileum, which is at the bottom of the small intestine.
This discovery may pave the way for new lines of investigation into the effects of professions involving shift work, which mess with our circadian rhythm, our 24-hour biological clock. Previous research by Panda’s team showed that time-restricted eating improved the health of firefighters, who are typically shift workers.
The researchers also found that time-restricted eating aligned the circadian rhythms of multiple organs of the body.
“Circadian rhythms are everywhere in every cell,” says Panda. “We found that time-restricted eating synchronized the circadian rhythms to have two major waves: one during fasting, and another just after eating. We suspect this allows the body to coordinate different processes.”
Panda’s group will then focus on the impact of time-restricted eating on particular ailments or systems that were mentioned in the study, such as chronic kidney disease and atherosclerosis, an arterial hardening that frequently occurs as a precursor to heart disease and stroke.
Other authors include Shaunak Deota, Terry Lin, April Williams, Hiep Le, Hugo Calligaro, Ramesh Ramasamy, and Ling Huang of Salk; and Amandine Chaix of the University of Utah.
