Immune system changes in winter increase risk of heart disease and diabetes

During the winter months, our immune system changes to fight off infections and illness. But according to new research from the University of Cambridge, these changes increase the risk of inflammation, and, in turn, the risk of diabetes, heart disease, arthritis, and even some mental health disorders.
It has long been established that heart disease, multiple sclerosis, schizophrenia, and type 1 diabetes diagnoses are more likely in winter, but this is the first study to explain why.
We need stronger immune defences during winter, because we are more likely to develop illness and infection. But when the immune system reacts, there is a large increase in the number of inflammatory molecules in our bodies, and these molecules can sometimes attack the body’s own tissues, increasing the likelihood of heart disease and type 2 diabetes.
Recent studies have suggest there may also be a link between inflammation and severe mental health disorders, including depression and Alzheimer’s disease, both of which are more likely to affect people with diabetes.
The researchers examined data from several countries, including a diverse range of climates. In total, the data of over 16,000 people were used. Countries examined included the UK, USA, Australia, Iceland, and The Gambia.
The researchers analysed a total of 22,000 genes, and a quarter of them varied according to the seaso, particularly those associated with immunity and inflammation.
“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 not one had appreciated the extent to which this actually occurred,” said Professor John Todd, the lab’s director.
“The implications for how treat disease like type 1 diabetes, and even how we plan our research studies, could be profound.
“In the UK we see a rise in new cases of type 1 diabetes in January, February and March, for example. Our results suggest that part of the reason for this is heightened inflammation and that gene activity is involved.
“Given that our immune systems appear to put us at great 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 son’ to improve their health and well-being.”