'Tis the season.

'Tis the season

While you're out there buying holiday gifts, feasting and resolution-making, consider this: A new study indicates that your cholesterol level may be about to go up by about 7.4 milligrams per deciliter of blood. (The median level in middle-aged Americans is 200 mg/dl.) Surprisingly, increased eating and decreased activity reported by the subjects accounted for only about a third of the cholesterol change, suggesting some other cyclical pattern is at work.

David J. Gordon and his colleagues at the National Heart, Lung, and Blood Institute found the change while looking for long-term trends in data collected for up to 10 years in 1,446 men with high cholesterol levels. To their surprise they found a yearly, cyclic pattern peaking Dec. 15 to Jan. 12 and hitting a nadir in June. Gordon suspects the winter increase holds for other men as well; for women he's less certain. The researchers were also surprised to find that among the 12 cities where data were collected, the two with the least seasonal changes, Houston and San Diego, showed greater cholesterol changes than cities as far north as Minneapolis.

The holiday cholesterol elevation is not enough to be health-threatening, but it could make a doctor think that a patient on a strict cholesterol-lowering diet is cheating. "I don't know what's really causing the seasonal effect," says Gordon.