Do Cholesterol Levels Change With the Seasons?

If you're watching your cholesterol, take note of the season the next time you have it checked. Research has shown that cholesterol levels peak during winter, but decline in the summer.

In a study of 517 men and women, the University of Massachusetts Medical Center in Worcester found that men's cholesterol levels peak in December and women's cholesterol levels peak in January. Seasonal changes appear to be greater in women.

In their report, published in the Archives of Internal Medicine, researchers speculate that lower cholesterol readings in the summer might be attributed to higher activity levels and warmer weather.

Although the increases in the study group were greater in those who had elevated cholesterol levels to start with, the fluctuations overall weren't that dramatic.

However, if you happen to be a borderline patient, the difference may be important.

Importance of cholesterol checks

High blood cholesterol is one of the major risk factors for heart disease, which is why it's so important to have your cholesterol checked. Too much cholesterol (a fat-like substance) builds up in the walls of your arteries and, in time, causes your arteries to become narrowed, which restricts blood flow to the heart.

Getting tested

A blood test called a "lipoprotein profile" can determine your cholesterol numbers. This blood test is done after a nine- to 12-hour fast and gives information about your:

• Total cholesterol - the higher the number, the greater your risk for heart disease.
• LDL (bad) cholesterol - the main source of cholesterol buildup and blockage in the arteries.
• HDL (good) cholesterol - what helps keep the cholesterol from building up in the arteries.
• Triglycerides - another form of fat in your blood.

A total cholesterol level below 200 mg/dL (milligrams of cholesterol per deciliter of blood) is desirable. A level of 200 to 239 mg/dL is borderline high, and 240 mg/dL and above is high.

The National Cholesterol Education Program (NCEP) recommends that men and women 20 and older have a cholesterol test every five years. However, if you have a high total cholesterol level, borderline high cholesterol levels and other heart disease risk factors (such as smoking or obesity) or normal total cholesterol and low HDL cholesterol, you should be tested more frequently.

Lowering cholesterol

You can't control some of the factors that may affect cholesterol levels, such as heredity, your age or your gender. Cholesterol levels rise as men and women age. Also, women's LDL cholesterol tends to rise after the age of menopause.

However, there are a variety of other factors that affect cholesterol levels that you can control. For instance:

• Diet. Saturated fat in the food you eat is largely to blame for making your blood cholesterol level rise, but cholesterol in food also matters. Eating foods that are low in saturated fat (such as lean meats, fish, skinless poultry, fruits, vegetables and whole grain foods) and limiting foods that are high in cholesterol (liver and other organ meats, egg yolks and full-fat dairy products) can help lower your cholesterol level.

• Weight. Being overweight increases your cholesterol and your risk of heart disease. Lose weight and you can help lower your LDL and total cholesterol levels, as well as your triglyceride levels, and help raise your HDL cholesterol.

• Exercise. Regular physical activity can help lower LDL cholesterol levels and raise your HDL cholesterol. It also helps you lose weight. Exercising for 30 minutes a day can make a difference.

Sometimes lifestyle changes aren't enough to lower cholesterol levels, and your doctor may prescribe a cholesterol-lowering medication. Even if you begin drug treatment, though, you will need to continue to follow through with exercising and watching your diet and your weight.

Remember, if your cholesterol readings are borderline high or borderline normal, consider having them checked again - at a different time of year.

Related Articles What's Your Cholesterol IQ? What Do My Cholesterol Results Mean? Would a Cholesterol Drug Help? Step Up To Good Cholesterol

External Sources Third Report of the Expert Panel on Detection, Evaluation, and Treatment of High Blood Cholesterol in Adults (Adult Treatment Panel III). National Cholesterol Education Program. National Heart, Lung and Blood Institute. Ockene IS et al. Seasonal variation in serum cholesterol levels: treatment implications and possible mechanisms. Archives of Internal Medicine 2004 Apr 26;164(8):863-870.

This article was reviewed and updated June 2007.

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