Study: Cholesterol Levels Change With the Seasons
April 26, 2004 -- The amount of artery-clogging cholesterol running through your veins may peak during the winter months, but don't go blaming the fruitcake just yet.
A new study shows that total cholesterol level may change with the seasons and reach their highest point in December for men and in January for women. In addition, the study shows that women and people with high cholesterol may be particularly susceptible to seasonal variations in their cholesterol levels.
But researchers say changes in diet alone don't explain these changes. Instead, they say a combination of factors, including changes in physical activity, light exposure, temperature, blood volume, and food availability, may play a role in creating seasonal variation in cholesterol levels.
Cholesterol Levels Vary by Season
In the study, published in the April 26 issue of the Archives of Internal Medicine, researchers followed a group of 517 healthy volunteers for one year and collected information on diet, physical activity, light exposure, and cholesterol levels.
Researchers found that the average total cholesterol level was 222 mg/dL (milligrams per deciliter) in men and 213 mg/dL in women. According to national guidelines, a cholesterol level over 240 mg/dL is considered high, while a total cholesterol less than 200 is considered desirable.
The study showed that during the 12-month period, cholesterol levels increased by an average of four points in men and by more than five points in women. Individual increases in cholesterol levels were greater among people with high cholesterol levels at the start of the study.
Researchers also found that there were increases in the number of men and women whose cholesterol levels reached the threshold of 240 or more during the winter months. For example, 7% more men and 47% more women had cholesterol levels of 240 mg/dL or greater in winter.
Overall, 22% more people had total cholesterol levels of 240 mg/dL or greater in the winter than in the summer months.
Researchers say more studies are needed to understand the effects of seasonal variation in cholesterol levels. But at this point, season-specific cholesterol guidelines aren't justified.