One of the health care subjects we are most asked about is cholesterol. Cholesterol-controlling pharmaceuticals are widely publicized and the medical market profits significantly from their sales. But what exactly is cholesterol? What role does it play in your overall health? And how can olive oil offer a natural solution to help balance cholesterol levels and offset potentially harmful diseases like atherosclerosis (heart disease) and hypertension (high blood pressure)?
WHAT IS IT?
First, it is important to understand that cholesterol, in and of itself, is not bad for you. On the contrary, the body needs cholesterol to function properly. It is the balance of three types of cholesterol (HDL (“good”), LDL (“bad”), and triglycerides) in your body that determine whether it is providing an optimum benefit.
The American Heart Association provides a simple explanation: “Cholesterol is a soft, fat-like, waxy substance found in the bloodstream and in all your body's cells. It is normal to have cholesterol. Cholesterol is an important part of a healthy body because it is used for producing cell membranes and some hormones, and serves other needed bodily functions. But too much cholesterol in the blood is a major risk for coronary heart disease (which leads to heart attack) and for stroke. Hypercholesterolemia is the medical term for high levels of blood cholesterol.”
Cholesterol comes from two sources: your body and food. Your liver and other cells in your body make about 75 percent of blood cholesterol. The other 25 percent comes from the foods you eat. Cholesterol cannot dissolve in the blood. It has to be transported to and from the cells by carriers called lipoproteins.
LDL (Bad) Cholesterol
When too much low-density lipoprotein or LDL cholesterol circulates in the blood, it can slowly build up in the inner walls of the arteries that feed the heart and brain. Together with other substances, it can form plaque, a thick, hard deposit that can narrow the arteries and make them less flexible. This condition is known as atherosclerosis. If a clot forms and blocks a narrowed artery, it can result in a heart attack or stroke.
LDL cholesterol is produced naturally by the body, but many people inherit genes from their mother, father, or even grandparents that cause them to make too much. Eating saturated fat, trans fats, and dietary cholesterol also increases how much you have.
HDL (good) Cholesterol
About one-fourth to one-third of blood cholesterol is carried by high-density lipoprotein (HDL). HDL cholesterol is known as “good” cholesterol, because high levels of HDL seem to protect against heart attack. Low levels of HDL (less than 40 mg/dL) also increase the risk of heart disease. Medical experts think that HDL tends to carry cholesterol away from the arteries and back to the liver, where it is passed from the body. Some experts believe that HDL removes excess cholesterol from arterial plaque, slowing its buildup.
Triglyceride is also a form of fat made in the body. Elevated triglycerides can be due to overweight/obesity, physical inactivity, cigarette smoking, excess alcohol consumption, and a diet very high in carbohydrates (60 percent of total calories or more). People with high triglycerides often have a high total cholesterol level, including a high LDL (“bad”) level and a low HDL (“good”) level. Many people with heart disease and/or diabetes also have high triglyceride levels.
Lp(a) is a genetic variation of LDL (bad) cholesterol. A high level of Lp(a) is a significant risk factor for the premature development of fatty deposits in arteries. Lp(a) is not fully understood, but it may interact with substances found in artery walls and contribute to the buildup of fatty deposits.
HOW DOES DIET AFFECT IT?
The daily recommended cholesterol limit is less than 300 milligrams for people with normal LDL (“bad”) cholesterol levels. People with high LDL blood cholesterol levels or who are taking a blood cholesterol-lowering medication should eat less than 200 mg of cholesterol per day.
Yet, the typical American diet is rich in saturated fatty acids provided by animal fats and processed (e.g. partially hydrogenated oils like margarine) fats. Almost every meal offers an assortment of these “bad for you” fats found in butter, margarine, fried foods, processed cheese, red meats – all accompanied by excessive amounts of carbohydrates. For example, eating one egg for breakfast, drinking two cups of coffee with one tablespoon of half-and-half each, lunching on four ounces of lean turkey breast without skin and one tablespoon of mayonnaise, and having a 6-ounce serving of broiled, short loin porterhouse steak for dinner would account for about 510 mg of dietary cholesterol that day — nearly twice the recommended limit.
This dietary pattern encourages cholesterol imbalance and has created a population at high risk of coronary disease, diabetes, and obesity. On the other hand, it is widely acknowledged that the Mediterranean diet delivers the opposite effect. Rich in monounsaturated and omega-3 and 6 (polyunsaturated) fats, green vegetables and fish, and olive oil, this type of diet has been credited with balanced cholesterol levels, lower incidences of heart disease and diabetes, and longer life spans.
WHAT ROLE CAN OLIVE OIL PLAY?
Olive oil has always served a central role in the Mediterranean diet, providing a strong source of mono-unsaturated and poly-unsaturated fats. These contributions to an overall healthy diet can have positive effects on cholesterol levels by helping to maintain a better balance between HDL (“good”) cholesterol and LDL (“bad”) cholesterol.
Research studies have confirmed that diets high in saturated fats are known to raise LDL, while diets high in mono-unsaturated and poly-unsaturated fats tend to decrease LDL levels. A meta-analysis of 27 human trials designed to examine the effect of poly-unsaturated and mono-unsaturated fatty acid rich diets on blood lipid levels found that both types of dietary fats may potentially lower total and LDL cholesterol levels.
Further studies have revealed that other than its high mono-unsaturated content, unprocessed (such as extra-virgin) olive oil contains non-fat components such as certain phenolic compounds that have a wide range of health benefits including positive effects on cholesterol (both “good” and “bad”) levels and LDL oxidation.
American Heart Association 07/02/09
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Visioli F, Galli C. Biological properties of olive oil phytochemicals. Crit Rev Food Sci Nutr. 2002;42(3):209-21.