Frigid temps may cause bad cholesterol to rise

A woman covers her face while walking through the snow on February 13, 2014 in New York City. John Moore, Getty Images

A new study, published in the midst of yet another springtime cold spell, finds one's cholesterol levels often vary by season and worsen when temperatures dip.

Researchers at Johns Hopkins Ciccarone Center for the Prevention of Heart Disease say this phenomenon is largely driven by related behavioral changes, such as the tendency to consume more foods rich in carbohydrates and fat, and to exercise less. These lifestyle changes may cause lipid levels to rise.

"In the summer, we tend to get outside, we are more active and have healthier behaviors overall," said lead author Dr. Parag Joshi, cardiology fellow at Johns Hopkins Hospital, in a press release. "In the colder months, we tend to crawl into our caves... So you have a lipid signature of higher risk, but it's probably driven by a lot of behaviors that occur with the changing seasons."

The study, which was presented this week at the American College of Cardiology's 63rd Annual Scientific Session, is the largest to-date on the links between cholesterol and seasonal behavior. The research is considered preliminary until it is published in a peer-reviewed medical journal.

Researchers analyzed data on 2.8 million U.S. adults who were referred for regular cholesterol testing by their doctors from 2006 to 2013.

Overall the researchers found LDL cholesterol and non-HDL cholesterol levels -- both known as the "bad" cholesterol -- were higher in winter than they were during summer. Both types of cholesterol were 3.5 percent higher in men and 1.7 percent higher in women during the cold season.

Triglycerides, which are tied to obesity and physical inactivity, were 2.5 percent higher in men during the winter. Overall women seemed to fare better than men year-round.

Prior research has found prolonged frigid temperatures can increase one's risk for heart attacks. During the winter, blood vessels in the body tend to constrict, which increases blood flow, and ultimately makes the heart work harder.

A study presented last February at the American Stroke Association's International Stroke Conference 2014 linked temperature changes to stroke risk. In that study, each 5-degree Fahrenheit temperature drop increased risk for stroke hospitalization by 6 percent, while each 5-degree increase in dew point was associated with a 2 percent increase in risk for stroke-related hospitalization. Additionally, researchers found a 1-degree Fahrenheit increase in average temperature lowered risk for stroke hospitalization by 0.86 percent and decrease stroke death risk by 1.1 percent.

CBS News medical contributor Dr. Tara Narula, a cardiologist at Lenox Hill Hospital in New York City, noted in February that mood changes linked to winter's cold and short days may also be a contributing factor to health woes.

"In general there is seasonal affective disorder that we talk about too. Where you want to eat carbs, stay in bed, you're a little depressed. And all of this plays into your risk for heart disease," Narula said on "CBS This Morning."

The researchers behind this new study stressed their findings don't mean wintertime should call for obsessive monitoring of cholesterol levels. Rather they suggest this information may be useful by encouraging one maintain the healthy habits of warmer months year-round.


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