Why some people tend to get heart attacks
in winter
Cholesterol levels seem to fluctuate significantly with the change
of seasons, which may leave some people with borderline high cholesterol at
greater cardiovascular risk during the winter months, a study has revealed.
While prior studies have
shown that heart attacks and heart-related deaths increase during the winter
months, researchers in Brazil were interested in finding out whether the
prevalence of high cholesterol—a well-known cardiovascular risk factor—might
follow a similar pattern.
"People should be
aware that their cholesterol and triglyceride levels vary significantly
year-round, which in some cases, may lead to a misinterpretation of a person's
actual cardiovascular risk," Filipe Moura, MD, a PhD student at the State
University of Campinas, Brazil and the study's lead investigator said.
"This should
especially concern those who are near the upper cholesterol limit as they may
be at higher risk than expected. This is not to say these patients should have
check-ups all the time, but we do have to keep a close eye on them and know
seasonal variation may play a role," he said. Researchers prospectively
evaluated the lipid profiles of 227,359 individuals who had health check-ups in
primary care centers in the city of Campinas, Brazil, between 2008 and 2010.
In this analysis—the
largest study to date to evaluate cholesterol levels by season—data reveal that
low density lipoprotein (LDL) or "bad" cholesterol increased an
average of 7mg/dL during the winter compared to summer.
Researchers said that this moderate, but significant, increase in
LDL cholesterol was enough to result in an 8 percent overall increase in the prevalence of high
cholesterol during the winter. While the rise in LDL was more pronounced in
women and middle-aged people, Dr. Moura said that this is most likely due to
the larger sample size in these categories after stratification by sex and age.
Cholesterol levels
during the summer months painted a very different picture, with higher levels
of high density lipoprotein (HDL), the "good" cholesterol, and
triglycerides, which were respectively 9 percent and 5 percent more prevalent.
Along with the
environmental changes of each season also come alterations in exercise and
dietary habits that can influence cholesterol levels. For example, people tend
to exercise less and consume a greater number of calories and fatty foods in
the winter.
The shorter days of
winter also mean less sun exposure and subsequently lower concentrations of
vitamin D. Vitamin D has been shown to improve the ratio of bad to good
cholesterol.
11.03.2013
Where there is movement, there is improvement
Rick
Helders
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