When you eat may be just as important as what you eat when it comes to heart health, Indian-origin researchers have found.
Researchers at San Diego State University and the Salk Institute for Biological Studies found that limiting the time span during which fruit flies could eat prevented ageing- and diet-related heart problems.
The researchers also discovered that genes responsible for the body’s circadian rhythm are integral to this process.
Previous research has found that people who tend to eat later in the day and into the night have a higher chance of developing heart disease than people who cut off their food consumption earlier.
Girish Melkani, a biologist at SDSU teamed up with Satchidananda Panda, a circadian rhythms expert at the Salk Institute, to address whether changing the daily eating patterns of fruit flies could affect their heart health.
Shubhroz Gill, a postdoctoral researcher in Panda’s lab and now at the Broad Institute in Boston, was the lead author on the study.
In their experiments, one group of 2-week-old fruit flies was given a standard diet of cornmeal and allowed to feed all day long. Another group was allowed access to the food for only 12 hours a day.
Over the course of several weeks, Melkani and Gill recorded how much food the flies were eating and tested a battery of health measures related to their sleep, body weight and heart physiology.
After three weeks, they found that flies on the 12-hour time-restricted feeding schedule slept better, didn’t gain as much weight and had healthier hearts than their “eat anytime” counterparts, though they ate similar amounts of food.
The researchers observed the same results after five weeks.
“In very early experiments, when we compared 5-week-old flies that were fed for either 24 hours or 12 hours, the hearts of the latter were in such good shape that we thought perhaps we had mistaken some young 3-week-old fruit flies for the older group,” Gill said.
Another set of experiments revealed that the benefits of a time-restricted diet were not exclusive to young flies.
When the researchers introduced these dietary time restrictions to older flies, their hearts became healthier.
Next, the researchers sequenced the RNA of the flies at various points in the experiment to find which of their genes had changed as a result of time-restricted feeding.
They identified three genetic pathways that appear to be involved: the TCP-1 ring complex chaperonin, which helps proteins fold; mitochondrial electron transport chain complexes (mETC); and a suite of genes responsible for the body’s circadian rhythm.
Researchers repeated their experiments using mutant strains of flies with nonfunctional versions of the TCP-1 and circadian rhythm genes. In these flies, time-restricted feeding granted no health benefits, strengthening the case that these genetic pathways play key roles.