HEALTH Study: Cholesterol levels change with seasons

The participants' levels peaked in January, when temperatures were lowest.
TORONTO GLOBE AND MAIL
The arrival of spring not only cheers people up, it can bring about a significant drop in cholesterol levels, according to a new study.
The research, published in Tuesday's edition of the Archives of Internal Medicine, suggests that there are important seasonal variations in cholesterol, particularly among women and people already suffering from high cholesterol.
Ira Ockene of the University of Massachusetts Medical Center in Worcester, Mass., said the finding raises the possibility that some people, in particular those tested in the winter, may be misdiagnosed as having high cholesterol.
But the researchers themselves said the findings are too preliminary to warrant changing treatment guidelines based on seasonal variations, and a leading Canadian expert cautioned that, because treatment decisions are never based on a single blood test, the practical effects of the finding will be negligible.
"We've known for a long time that cholesterol levels do vary -- they vary from season to season and from day to day," Ruth McPherson, spokeswoman for the Heart and Stroke Foundation of Canada, said in an interview.
"We don't have a problem of overtreatment of cholesterol, we have a problem of undertreatment," she said.
Seasonal differences
The new study, conducted on 517 healthy volunteers in central Massachusetts, revealed that cholesterol levels peak in January, when the temperature is lowest, and bottom out in the heat of summer. The variations were in the range of 2 percent to 3 percent, but still significant.
Among the study participants, the average cholesterol level was 222 milligrams per deciliter of blood in men and 213 mg/dl in women. Cholesterol levels increased, on average, by 5.4 mg/dl in women, and by 3.9 mg/dl in men.
In the United States people are considered to have high cholesterol if their cholesterol exceeds 240 mg/dl. In Canada, they are considered to have high cholesterol if the level exceeds 200 mg/dl.
In the study group, 22 percent more people were categorized as having high cholesterol in the winter than in the summer.
The most effective means of lowering cholesterol are weight loss and exercise, though the condition is frequently treated with prescription drugs.