Cholesterol and Fat
Cardiovascular disease involves the blockage of arteries that provide oxygen within the muscular walls of the heart. The death of even a small portion of this muscle from lack of oxygen can result in the disorganization of the heartbeat and thus a failure of the heart to meet the body’s oxygen needs.
The plaques that build up in blood vessels and that narrow the flow of blood contain a high proportion of cholesterol. The typical diet of affluent Westerners with their high intake of animal foods (i.e., meat, eggs, and dairy products) is rich in cholesterol. One recommendation, therefore, has been to lower cholesterol intake, in particular the intake of egg yolks (even though in the past eggs were regarded as the perfect food because they contained everything the rapidly growing embryonic chicks needed).Cholesterol, however, is a vital constituent of cell walls, and we, like other animals, synthesize it continuously, regulating that synthesis (at least to some extent) according to dietary intake. Some studies indicated that people with high blood levels of cholesterol were at greater risk from cardiovascular heart disease. But evidence mounted that cholesterol levels in the blood were affected more by the dietary intake of saturated fat than by simple cholesterol intake. “Saturated,” in this context, means saturated with hydrogen. In practice, saturated fats are those, like beef or mutton fat, butter, and some types of margarine, that are solid at room temperature.
In contrast, most vegetable fats, which are called “oils” because they are normally in the liquid state - for example, corn oil and olive oil - are more unsaturated. Margarines are made from vegetable oils that are saturated by hydrogen to various extents. Soft, or “tub,” margarines are the least saturated. Of current interest is whether the fat content of the “affluent diet,” in which fats typically provide 40 percent of the calories, should be reduced or whether there is something about unsaturated fat that counteracts the adverse effects of animal fats. In particular, the “omega-threes” found in fish oils are under intensive study. Also, strong evidence exists that people with high blood pressure (hypertension) are at increased risk from cardiovascular heart disease, and that a high salt intake promotes this condition.