As the weather warms, it’s not just the weather that changes. Your immune system undergoes powerful alterations that affect your chances of illness.
A study at the University of Cambridge in England shows that as winter gradually shifts to summer, the summer sun causes 25 percent of your genes to change the way they behave and alter your vulnerability to getting sick.
Previously, research has demonstrated that conditions like heart disease, type 1 diabetes, multiple sclerosis and the way your body handles vitamin D shifts depending on the season. But the latest study shows that many of these changes are rooted in shifts in the way the immune system functions.
“This is a really surprising – and serendipitous – discovery as it relates to how we identify and characterize the effects of the susceptibility genes for type 1 diabetes,” says researcher John Todd, the director of the JDRF/Wellcome Trust Diabetes and Inflammation Laboratory. “In some ways, it’s obvious – it helps explain why so many diseases, from heart disease to mental illness, are much worse in the winter months. But no one had appreciated the extent to which this actually occurred. The implications for how we treat disease like type 1 diabetes, and even how we plan our research studies, could be profound.”
The scientists found that an important gene called ARNTL, which lowers inflammation, is much more active during the warmer part of the year. The lack of action of this gene during winter is probably the reason that inflammatory diseases like cardiovascular disease and arthritis are worse in the colder months.
The researchers also discovered that genes linked to how people respond to vaccination are more active during the winter. That suggests that vaccines, in general, are less effective during the summer.
According to Todd: “Given that our immune systems appear to put us at greater risk of disease related to excessive inflammation in colder, darker months, and given the benefits we already understand from vitamin D, it is perhaps understandable that people want to head off for some ‘winter sun’ to improve their health and well-being.”
One important takeaway message from this study is the need to be sure you take enough supplemental vitamin D in the wintertime to stay healthy. Vitamin D is both a hormone and a vitamin. Also, it’s an immune activator. Immune cells called macrophages check for sufficient vitamin D before swinging into action to fight invaders and illness. And you usually don’t get enough sun in winter to let the body make enough vitamin D.
As summer arrives, you need to help your body adjust to the new season. To do that, get outside more and get more sun, not less. As the researchers note: “The environmental perturbation of our molecular clocks is thought to be deleterious to health which may help explaining the increasing complex disease burden in industrialized countries.” That’s researcher-speak for warning that all the time we spend indoors under artificial light is confusing the body’s paleo-rhythms that depend on sunlight to stay in sync.
