This is different than what other studies have found, Moura said. A possible explanation is Campinas's climate. The city's elevation is roughly 1,800 to 2,500 feet above sea level, and the winters are mild and dry.
Moura said these changes may be even more extreme in the United States, Europe or other areas that have bigger climate changes between winter and summer.
He next plans to look at patients with heart disease to see whether the seasonal change in cholesterol results in more heart attacks.
What these findings mean for patients isn't clear, said Dr. Gregg Fonarow, a spokesman for the American Heart Association and a professor of cardiology at the University of California, Los Angeles.
"This study suggests there may be modest seasonal variation ... with higher LDL levels in winter months compared to summer, but further studies are needed to confirm these findings and whether there is any meaningful impact on cardiovascular risk," Fonarow said.
Because this study was presented at a medical meeting, the data and conclusions should be viewed as preliminary until published in a peer-reviewed journal.
To learn more about cholesterol, visit the American Heart Association.
SOURCES: Filipe Moura, M.D., State University of Campinas, Brazil; Gregg Fonarow, M.D., spokesman, American Heart Association, and professor, cardiology, University of California, Los Angeles; March 9, 2013, presentation, American College of Cardiology annual meeting, San Francisco
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