ARE you spending enough time in the sun? As well as keeping our bones strong, vitamin D – the hormone our skin makes when exposed to ultraviolet rays – may also help regulate our body clocks.
We all have a small group of “clock genes” which switch on and off during the day. As a result, the levels of the proteins they code for rise and fall over a 24-hour period. Enforced routines such as night shift work can play havoc with our health – increasing our risk of a stroke, for example.
To find out whether a lack of vitamin D might be responsible, Sean-Patrick Scott and his colleagues at the Monterrey Institute of Technology and Higher Education in Mexico looked at the behaviour of two clock genes in human fat cells. When the cells were immersed in blood serum, they acted as they would in the body: the clock genes’ activity oscillated over a 24-hour period.
Dosing the cells with vitamin D instead produced the same effect. No such effect was seen in cells placed inside a nutrient broth.
“Vitamin D synchronises the cells,” says Scott. “Our results explain some of the benefits of sunlight,” he says. “Vitamin D is one of the ways we might be able to maintain circadian rhythms in the body.”
Julia Pakpoor of the University of Oxford says clinical trials are needed to confirm the effect in people, but she adds, “We should all make sure we are vitamin D replete regardless.” The work was presented at the World Stem Cell Summit in San Antonio, Texas, last month.
This article appeared in print under the headline “Sunshine hormone keeps our internal clocks on track”