Did you know that cholesterol levels can vary by season? That's the finding of a new Brazilian study that looked at the cholesterol levels of patients from winter months compared to summer months.

When patients in Campinas, Brazil had their cholesterol checked in the winter, their levels of LDL, or "bad" cholesterol rose an average of 7 milligrams per deciliter which was about 8 percent higher, on average, than those of patients whose blood was tested during the summer. In the summer, levels of HDL, or "good" cholesterol, were about 5 milligrams per deciliter higher.

"In the winter, people should be careful with their cholesterol levels," said lead researcher Dr. Filipe Moura, a doctoral student at the State University of Campinas.

Moura's team collected data on about a quarter of a million people who had their cholesterol checked in primary-care centers in the Brazilian city of Campinas between 2008 and 2010.

Why would cholesterol levels be higher in winter than in other seasons? Researchers speculate that the lack of sun could be an issue as vitamin D has been shown to improve the ratio of good cholesterol to bad. And it doesn't take a scientist to know that people tend to exercise less and eat more heavy, meat-based comfort foods in the winter than they do in the summer.

Can this seasonal change in cholesterol found in Brazil translate to higher cholesterol in the winter worldwide? Winters in Campinas are mild and dry, so Moura thinks the changes may be even more dramatic in the United States and other areas that have bigger climate changes between winter and summer.

The study findings were scheduled to be presented March 9 at the annual meeting of the American College of Cardiology in San Francisco.

Cholesterol levels rise in winter, study finds
New study finds patients' levels of 'bad' cholesterol were 8 percent higher in the winter than in summer.