The Cholesterol Lowdown

It should be a slam-dunk health message for consumers: High blood-cholesterol levels are bad. This can lead to cardiovascular disease (CVD), the No. 1 killer in America. According to an April 26, 2006, American Heart Association (AHA) survey, 50% of adult respondents with elevated blood cholesterol of 200 or greater did not perceive themselves to be at high risk for CVD. But for the nearly 100 million Americans plagued with above-normal cholesterol levels, this problem is, quite literally, as serious as a heart attack.

Cholesterol basics

Cholesterol is a waxy substance made by the liver and also provided in the diet by animal products like meat, poultry, fish and dairy. While the body requires cholesterol to insulate nerves, make cell membranes and produce hormones, it makes plenty on its own, so dietary sources are superfluous. Too much cholesterol in the blood promotes plaque buildup on artery walls, which leads to hardening and narrowing. Insufficient blood and oxygen flow to the heart can cause chest pain and blood-supply blockage to a portion of the heart, which can result in a heart attack. Plaques can also rupture, forming blood clots that can cut off blood supply.

Cholesterol circulates in the bloodstream in units called lipoproteins. High-density lipoprotein (HDL), the good cholesterol, carries cholesterol away from the arteries. Studies suggest high blood levels of HDL reduce heart-attack risk. Low-density lipoprotein (LDL), the bad cholesterol, carries cholesterol to body tissues. Too much LDL can clog the arteries and increase the risk of heart attack and stroke. Desirable blood cholesterol levels include total cholesterol below 200 mg/dl; LDL below 100 mg/dl; and HDL above 60 mg/dl.

To lower cholesterol

The National Heart, Lung, and Blood Institute of the National Institutes of Health developed the National Cholesterol Education Program (NCEP) in 1985, with the goal of reducing heart disease by decreasing the number of Americans with high blood cholesterol. The Third Report of the Expert Panel on Detection, Evaluation, and Treatment of High Blood Cholesterol in Adults (ATP III) provides NCEPs latest recommendations on cholesterol management, which emphasize aggressive treatment for those at high risk, as well as Therapeutic Lifestyle Changes (TLC) that incorporate dietary strategies to reduce cholesterol levels.

These include:

Saturated FatLess than 7% of daily calories should come from saturated fat, fatty acids that have a chemical makeup in which the carbon atoms are saturated with hydrogen atoms. Studies indicate high intakes of saturated fat in the diet are linked with higher levels of LDL. Saturated fatty acids are found in fairly high levels in animal products such as fatty meats, poultry with skin, whole-milk dairy products and lard. They are also found in tropical oils, and in especially high levels in coconut oil and palm kernel oil. Palm oil is often called a tropical oil, but its total saturate level is lower and its fatty-acid ratio is different. The typical fatty-acid profile in palm oil is 45% palmitic, 40% oleic, 10% linoleic and 5% stearic. According to the American Palm Oil Council, Torrance, CA, the literature suggests that both stearic acid and palmitic acid, which comprise virtually all the saturated fats in palm oil, have neutral to favorable impact on serum lipid profiles compared to lauric and myristic acid.

Dietary CholesterolLess than 200 mg per day of dietary cholesterol is recommended within TLC, as dietary cholesterol can raise blood cholesterol levels, although not quite to the degree as saturated fat. Typical dietary sources include animal products, including liver and organ meats, egg yolks, shrimp and whole-milk dairy products.

However, current research does not put such a large emphasis on dietary cholesterol. According to Elisa Maloberti, director of egg product marketing, American Egg Board, Park Ridge, IL, dietary cholesterol, once thought to play a primary role in determining plasma cholesterol levels, is now understood to have a negligible effect on blood lipids in most healthy people. Many cholesterol-containing foods are also naturally high in saturated fat. Eggs are one of the rare exceptions. While eggs contain cholesterol, they have very little saturated fat (one large egg contains only 1.5 grams) and are low in calories (only 75 calories per large egg). Rather than cholesterol, research has made the link between saturated fat intake and heart disease much clearer. In fact, the American Heart Association has stopped recommending any specific limitation on daily egg intake.

Total FatTotal fat (including saturated fat) should make up 25% to 35% of daily calories. While fats high in monounsaturated and polyunsaturated fatty acids dont necessarily raise cholesterol levels, TLC suggests keeping total fat levels down, since fat is calorie-dense and can promote weight gain.

Trans FatsTLC recommends trans fat intake be low, since it raises blood cholesterol levels in a similar fashion as saturated fats. The majority of trans fat in our diets comes from hydrogenated vegetable oils. While some trans fat naturally occurs in animal products, it isnt clear whether these naturally occurring trans fats have the same bad effects on cholesterol levels as those that have been industrially manufactured, according to AHA. However, there is some epidemiologic evidence that naturally occurring trans fats may not possess the same health risks. More research needs to occur to understand this issue.

Plant Stanols/SterolsPlant stanols and/or sterols can further reduce cholesterol levels. While they are found in small amounts in plant foodsfrom 7 grams per 100 mg tomatoes up to as much as 714 grams per 100 mg sesame seedsplant stanols and sterol ingredients from sources like soybean and (from a pine) oils are used in functional foods, like spreads and juices. They block cholesterol absorption by the digestive tract, which, with a suggested intake of 2 grams per day, helps lower LDL by about 5% to 15%.

Soluble FiberSoluble fiber intake of 10 to 25 grams per day can help lower cholesterol levels by blocking intestinal cholesterol absorption. Studies reveal that increasing soluble fiber intake 5 to 10 grams per day can reduce LDL by about 5%.

CaloriesTLC includes recommendations for consuming only enough calories to reach or maintain a healthy weight, since losing excess weight can improve LDL cholesterol levels.

While zero-trans fat products have realized a positive spin for their beneficent cholesterol buzz, products that are low in saturated fat, total fat, and contain cholesterol-lowering functional ingredients like soluble fiber and plant sterols/stanols are also sitting pretty, especially if the millions of consumers with elevated cholesterol become motivated enough to eat their way to a healthy heart.

Sharon Palmer is a registered dietitian with 16 years of experience in health-care and foodservice management. She writes on food and nutrition for newspapers, magazines, websites and books. Palmer makes her home in Southern California and can be reached at [email protected].