Cholesterol Levels May Vary By Season
Brazilian study doesn't necessarily mean that heart attack or stroke risk rises in winter
By Steven Reinberg
THURSDAY, March 7 (HealthDay News) -- Cholesterol levels increase with winter's arrival and drop again as warmer weather returns, a new study by Brazilian researchers suggests.
"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.
Whether these changes in cholesterol are putting patients at risk for heart attacks or stroke isn't clear, Moura said. It's a complex picture and these changes might have a role, but there are many other factors, he added.
There are several possible reasons cholesterol varies by season, Moura said, including changes in diet, exercise and exposure to the sun.
"In the winter, people consume more calories and eat fattier foods, which could have an effect on their bad cholesterol," he said. "Also, it's common for people to exercise less during the winter and stay in more."
People also get less sun in the winter, so they get less vitamin D, which can have an effect on cholesterol, Moura said. He also noted that during the winter people are prone to colds and the flu, which can effect cholesterol levels.
The study findings were scheduled to be presented Saturday at the annual meeting of the American College of Cardiology in San Francisco.
Moura's team collected data on more than 227,000 people who had their cholesterol checked in primary-care centers in the Brazilian city of Campinas between 2008 and 2010.
The researchers found that during the winter, low-density lipoprotein (LDL), or "bad" cholesterol, rose an average of 7 milligrams per deciliter compared to the summer, which is about an 8 percent increase during the cold months. During the summer, levels of high-density lipoprotein (HDL), the "good" cholesterol, rose about 9 percent, but so did levels of fats in the blood called triglycerides, which rose about 5 percent, the researchers found.
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.