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
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
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.