Does your risk of metabolic disease depend on the time of year?
If you want to avoid metabolic disease, you should live extra healthily at certain times of year. That may be the advice to come out of the research that Lewin Small is about to embark on at the Novo Nordisk Foundation Center for Basic Metabolic Research, supported by DKK 1.2 million from the Danish Diabetes Academy.
The background to his research is that a strong link has been found in mammals between circadian and diurnal cycles and the animals’ metabolism, and disrupting these cycles can have a profound effect on metabolic parameters. But is this also true of humans? If it is, Dr Small hopes to find a method of identifying the times of year when people are most susceptible to metabolic disease, and perhaps to use that knowledge to change medication regimens or make it possible to advise patients in the risk zone to pay more attention than normal to exercise and diet at times when the risk is greatest.
Lewin Small explains that studies of the interplay between energy metabolism and circadian rhythms in mice normally use a 12:12-hour light/dark cycle, which mimics a day close to the equinox.
‘But in many countries not close to the equator, such as Denmark, the number of hours of daylight varies widely between winter and summer. In fact, half the world’s population lives at latitudes where there is at least 4 hours’ variation in daylight between winter and summer’, he says.
While seasonal variations in people’s metabolic health can have a significant impact on the timing and effectiveness of treatment, the interplay between the seasonal cycle and energy metabolism is still not fully understood. Lewin Small’s hypothesis is that changes in the light/dark cycle will affect both the circadian rhythm of particular organs’ internal clock and the processes involved in storing and using energy.
‘We want to investigate this hypothesis by studying the energy metabolism and expression of genes involved in circadian rhythm regulation in mice kept under one of three light/dark cycles: summer, winter or equinox’, says Lewin Small.
The plan is to conduct metabolic tests on the mice over a 12-week period and then to examine the expression of genes involved in circadian rhythm regulation in different metabolic tissues over several time intervals. The metabolic and circadian data will then be analysed to determine whether seasonal daylight affects circadian rhythm, diurnal cycle and metabolic health.
Lewin Small BSc (Hons), PhD
Novo Nordisk Foundation Center for Basic Metabolic Research,
University of Copenhagen
+45 9110 8278