Elevated blood levels of some forms of cholesterol, a waxy, fat-like substance, can raise the risk of heart disease. While it may seem that just cutting fats out of your diet would help lower cholesterol levels, most cholesterol in your body doesn't come from foods your eat. In addition, some dietary fats actually lower rather than raise your cholesterol levels.
Cholesterol Sources
Around 75 percent of cholesterol in your body comes not from what you eat but rather is manufactured in your liver and other cells, the American Heart Association says. Only 25 percent of the cholesterol in your body comes from foods.
Types of Cholesterol
More than one type of lipids, or fats, makes up your total cholesterol level. High-density lipoproteins, often abbreviated to simply HDL, appear to decrease your risk of developing heart disease, the main danger of elevated cholesterol levels, by removing excess cholesterol from your blood and taking it back to the liver. High-density lipoprotein may also remove cholesterol from plaque. Low-density lipoproteins, or LDL, take cholesterol from your liver and distribute it to cells that need it to function. Low-density lipoproteins become a problem only when they become too abundant.
Types of Dietary Fats
Dietary fats also come in several varieties. Some fats, like saturated fats or trans fats, increase LDL levels in your blood. Saturated fats, found mainly in animal fats, are the main dietary cause of high serum cholesterol, according to the AHA. Others, like omega-3 and omega-6 fatty acids, found mostly in fatty fish, nuts, certain oils such as canola oil and some plants, can reduce LDL levels and increase HDL levels if you use them to replace saturated fats in your diet. Increasing "good" fats can increase "good" cholesterol levels.
Dangers
Excess LDL clings to the inside walls of blood vessels, damaging and irritating the vessels and allowing LDL to build up on the walls, potentially blocking blood flow through the blood vessels. The buildup, called plaque, can cause a heart attack if blood can't reach the heart muscle. Blood clots can form at the site, break off and lodge in blood vessels in the brain, causing stroke.
Recommendations
Keep your total fat intake to 25 to 35 percent of your daily calorie intake, the AHA recommends. Saturated fats should make up only 7 percent of your daily calorie intake and trans fats 1 percent. The main source of trans fats in the diet include foods created in the process of hydrogenation, such as margarine, shortening, cooking oils and processed foods made from them. Limit dietary cholesterol to 300 milligrams a day; 200 mg a day if you have heart disease.
