A person's diet has a strong influence on four risk factors associated with heart disease: high blood cholesterol, high blood pressure, obesity, and diabetes mellitus. So people watching their cholesterol, blood pressure, weight, or blood sugar should also be watching their diets.

Public health officials have issued a number of dietary guidelines and recommendations to help people eat a "heart-healthy" diet, a diet that can help prevent coronary artery disease, the leading cause of death in North America. There's no one food that can prevent heart disease, or even a short term eating plan that will reverse atherosclerosis. A heart-healthy diet consists of making the right daily food choices that add up to a lifetime of good dietary habits.

We need only a very small amount of fat in the diet to maintain good health; extra fat is extra calories, which contribute to obesity. Recent research shows that a given number of calories consumed as fat results in more fat storage than the same number of calories consumed as carbohydrate or protein. In other words, it is metabolically efficient to store fat in adipose tissue, but not as efficient to turn carbohydrate or protein into fat.

A diet high in fat, particularly saturated fat, also raises blood cholesterol level. Foods high in saturated fat include butter, cream, whole milk, cheese, some shortenings and margarines, and palm and coconut oils. Some food labels list how much and what types of fat have been added to food products. Lean cuts of meat, poultry, and fish have less saturated fat than fatty cuts such as prime rib. Chicken fat is found under the skin, so by trimming the skin you remove most of the fat. Cooking methods such as broiling and baking are preferable to frying.

Cholesterol intake should be limited by restricting consumption of egg yolks, meats, and organ meats. Cholesterol is found in muscle tissue itself, so simply trimming the visible fat from meats does little to decrease its cholesterol content.

Research has suggested that people who include fish in their diet have a lower risk of heart disease. Cold-water fish such as salmon, mackerel, trout, bluefish, and herring contain omega-3 fatty acids. These fatty acids may prevent heart disease by decreasing the tendency of platelets to clump and perhaps by lowering total serum cholesterol as well.

People who consume diets high in fish oils produce less thromboxane, which promotes platelet clumping and is a powerful vasoconstrictor. Fewer clots and more open arteries mean a lower risk of blockage. Although fish oil contains substantial amounts of cholesterol, some studies have shown that people who consumed fish oil reduced their serum cholesterol levels.

Scientists are reluctant to recommend fish oil supplements at this point, because their safety for long-term consumption is not known. But eating more fish is a good idea. A study from the Netherlands found that people who eat only one or two fish meals a week, regardless of the type of fish consumed, had a lower incidence of heart disease than people who ate less fish.

Carbohydrate foods do not increase total serum cholesterol and are less likely to cause obesity than fatty foods, although too much of any food means extra calories. Complex carbohydrates are especially good because they have a lot of nutrition per calorie and are rich in vitamins and minerals. They are also high in the type of fiber (watersoluble) that helps decrease serum cholesterol. Complex carbohydrates include grains such as wheat, rice, corn, oats, and their products such as cereals, breads, and pasta; peas and beans, such as split peas, lentils, kidney beans, and chickpeas; and starchy vegetables such as potatoes, yams, and winter squashes.

Some research has suggested that people consuming a diet high in complex carbohydrates can maintain or even lose weight while eating as much as they want to of these foods. They don't count calories or portions, and eat until they are full. Researchers theorise that people consuming a diet high in these foods feel full and quit eating before they have consumed too many calories. Just the opposite can happen with foods high in fat. Since a lot of calories are contained in a small volume, you can eat hundreds of calories in a very short period of time.

It is unfortunate that dieters have shunned complex carbohydrates for years. Many people would still omit the potato rather than the steak when trying to lose weight. Yet even a small (3.5 oz) steak is high in fat and may have over 400 calories, while a baked potato has almost no fat and only about 90 calories. It's important to prepare these complex carbohydrate foods without high-fat sauces or other added fats, however. The 90-calorie baked potato becomes a high-fat, high calorie dish as soon as you add butter or sour cream.

Simple sugars are found naturally in fruits, vegetables, and dairy products. Refined sugars (sucrose, dextrose, syrups, and other sugar products) provide empty calories; that is, they have no other beneficial nutrients. Moreover, they are often consumed with fats in pies, pastries, cakes, cookies, and candies, all high-caloric foods.

Hypertension (high blood pressure) is more prevalent in population groups that consume high levels of sodium. A taste for salt (sodium chloride) developed early in life can lead to hypertension in later years. Some research suggests that it may take years for a high salt intake to cause hypertension, so most people do not realise that their salt intake is harming their health.

Sodium in the form of salt or monosodium glutamate (a "flavour enhancer") is found in most prepared foods, such as soups, sauces, and canned fish and meat; condiments such as soy sauce and steak sauce; pickled and cured foods; and salty foods such as potato chips and pretzels. High sodium levels are also present in some vegetables, such as celery and mushrooms.

Too much alcohol is associated with increased risk of hypertension. No one can say exactly how much is too much, but most authorities agree one or two drinks a day are probably safe. Alcoholic drinks are empty calories and can also contribute to obesity.