With this brief background of fats, fatty acids and cholesterol, consideration may be given to what happens to the fats we eat in our ordinary diet. Fats are utilized by the body for quick energy; if excess fats are eaten, the liver stores them temporarily so that the fats may be gradually released over a period of time. The blood stream is the mechanism utilized by the body for distributing this energy throughout the system. Research chemists were puzzled about how the blood conveyed fat, since it was known that fat does not dissolve in watery substances such as blood. Research revealed the secret. The body creates what scientists call lipoproteins—that is, combinations of fats, protein and cholesterol—because lipoproteins can and do dissolve in the blood.
The body creates these lipoproteins—the combinations of fat, protein and cholesterol—primarily to transport the energy foods in solution in the blood stream. After the lipoproteins are formed, they flow out into the blood and are carried through the body. The fats, now in solution in the blood, burn readily and are soon disposed of. The proteins are soluble in the blood and are also easily used up. The remaining constituent of the lipoprotein is the cholesterol. Until very recently, it was assumed that the body could not use up cholesterol, for it was not a type of food, such as fat, protein or carbohydrate. But the last few years of study indicate that the consumption of cholesterol in foods does have an effect on the serum cholesterol level, tending to raise it in most persons. That is true in even comparatively modest amounts of dietary cholesterol; for example, three-quarters of a pound of steak with fatty marbling, containing 1 gram, eaten daily will increase the cholesterol level in the vast majority of individuals. Therefore, it suggested that the daily consumption of cholesterol should be lowered to not more than 300 milligrams per day. Later on, when the cholesterol level is reduced to 210 or less, it should be possible to relax the restriction, if the intake of polyunsaturated to saturates remains proportionately high. Obviously, this discussion is an oversimplification of the problem, with the more technical details being limited or omitted for the sake of clarity.
Is diet the sole cause of coronary heart disease? It would appear that diet is vitally related to atherosclerosis, but many other factors remain to be resolved. Conclusions regarding certain unsolved factors may require many, many years. Some factors may be given increased importance as investigations and research continue, whereas others may eventually be eliminated from consideration. These factors include other diseases, the sex differential, overweight, heredity and family history, emotions and stress, age, occupation, exercise, salt in the diet, tobacco and alcohol, and starches.