Your body actually needs fat, and it may blow your (nutritional) mind, but a healthy body also needs cholesterol. Look carefully and you find cholesterol in and around your cells, in your fatty tissue, in your organs, and in your glands. What’s it doing there? Plenty of useful things. For example, cholesterol
Protects the integrity of cell membranes.
Helps enable nerve cells to send messages back and forth.
Is a building block for vitamin D (a sterol), made when sunlight hits the fat just under your skin.
Enables your gallbladder to make bile acids, digestive chemicals that, in turn, enable you to absorb fats and fat-soluble nutrients such as vitamin A, vitamin D, vitamin E, and vitamin K.
Is a base on which you build steroid hormones such as estrogen and testosterone.
Doctors measure your cholesterol level by taking a sample of blood and counting the milligrams of cholesterol in 1 deciliter (1/10 liter) of blood. When you get your annual report from the doctor, your total cholesterol level looks something like this: 225 mg/dl.
Translation: You have 225 milligrams of cholesterol in every tenth of a liter of blood. Why does this matter? Because cholesterol makes its way into blood vessels, sticks to the walls, and forms deposits that eventually block the flow of blood. The more cholesterol you have floating in your blood, the more cholesterol is likely to cross into your arteries, where it may increase your risk of heart attack or stroke.
As a general rule, the National Cholesterol Education Program (NCEP) says that for adults, a cholesterol level higher than 250 mg/dl is a high risk factor for heart disease; between 200 mg/dl and 250 mg/dl is considered a moderate risk factor; below 200 mg/dl is considered a low risk factor.
Cholesterol levels alone are not the entire story. Many people with high cholesterol levels live to a ripe old age, but others with low total cholesterol levels develop heart disease. Worse yet, recent research indicates that low cholesterol levels may increase the risk of stroke. In other words, cholesterol is only one of several risk factors for heart disease. Here are some more:
An unfavorable ratio of lipoproteins
Smoking
Obesity
Age (being older is riskier)
Gender (being male is riskier)
A family history of heart disease
To estimate your own risk of heart disease/heart attack, check out the NCEP 10-year heart attack risk calculator.
Even if you allow yourself to indulge in (a few) high-cholesterol ice cream cones and burgers every day of the year, your cholesterol level may still be naturally lower in the summer than in winter.
The basis for this intriguing culinary conclusion is the 2004 University of Massachusetts SEASONS (Seasonal Variation in Blood Lipids) Study of 517 healthy men and women ages 20 to 70. The volunteers started out with an average cholesterol level of 213 mg/dl (women) to 222 mg/dl (men). A series of five blood tests during the one-year study showed an average drop of 4 points in the summer for men and 5.4 points for women. People with high cholesterol (above 240 mg/dl) did better, dropping as much as 18 points in the summer.
University of Massachusetts cardiologists say one explanation for the summer downswing is that people tend to eat less and be more active in summer. They lose weight, and weight loss equals lower cholesterol.
One bit of wisdom from this study is obvious: Being physically active reduces your cholesterol level.