Researchers found that cholesterol levels tend to fluctuate with the change in seasons. While it has been known that heart attacks increase in winter months, it was not known if high cholesterol levels may be more likely to occur in winter months. High cholesterol is, of course, a known heart-disease risk factor.

The study of some 227,000 people who had regular checkups with primary care doctors between the years of 2008 and 2010 found that LDL (bad) cholesterol increased 7mg/dL, on average, in the winter months compared to summer months. The rise in LDL was more pronounced in women and middle-aged people.

Summer months were found to yield higher levels of HDL (good) cholesterol, which was 9 percent more prevalent.

Researchers suggested that the changes may be due to changes in physical activity and diet based on the temperature changes. People were found to exercise less in winter and also to eat more calories and fatty foods in the colder temps. Shorter days in winter, also mean less exposure to vitamin D from the sun, and vitamin D has been found to improve the bad-to-good cholesterol ratio.

Those at upper cholesterol limits may be at higher heart-disease risk in winter months and should be aware of this, though researchers say more study is needed to fully understand this phenomenon.

Have You noticed your cholesterol levels to be different according to the season?