Date of Award:

1964

Document Type:

Thesis

Degree Name:

Master of Science (MS)

Department:

Nutrition, Dietetics, and Food Sciences

Department name when degree awarded

Nutrition and Biochemistry

Abstract

A number of research studies have shown that aging is a continuous and cumulative process of biological changes which frequently result in cardiovascular diseases in the older age group. Degenerative diseases of old age such as atherosclerosis and coronary artery diseases appear to be related to abnormal lipid metabolism. The findings which indicate serum cholesterol values rise with age are by no means unanimous. The combined evidence in the literature points out that serum cholesterol of newborn infants is low, then rises steadily with age in both sexes from adolescence through middle age with a higher value in males than in females. The serum cholesterol level reaches the maximum in the sixth decade of life and then drops for men while for women it rises. Also, the changes in serum phospholipid and total lipid levels with age were similar to the changes in serum cholesterol levels in both sexes.

Several factors such as age, sex, metabolism, heredity, environment, and endocrine functions have been found to alter serum lipid levels. These factors appear to be associated to a complex pattern; the precise proportions of which have not as yet been clearly defined. The environmental factor plays an important role in altering the serum lipid valued and various aspects of this factor can easily be studied and modified by workers. One of the components of the environmental factor, dietary fat has been studied extensively, yet, the exact relation which it has to the development of atherosclerosis has not been settled. The amount and kind of fat and the nature of constituent fatty acids in the diet are considered to be the influential factors directly affecting serum lipid levels. Most of the workers have indicated that the unsaturation of the fatty acids or the ratio between polyunsaturated and saturated fatty acids might best explain the serum cholesterol-regulating activity of the various fats. Many investigators have demonstrated that the substitution of certain vegetable oils for certain animal fats in human diets leads to a decrease of serum cholesterol and phospholipid values. Of the vegetable oils which were studied, corn oil, due to its high content of plant sterols and unsaturated fatty acids, has the most effective hypocholesterolemic activity. However, this is no proof that the lowering of serum cholesterol levels decreases coronary heart diseases, but there is circumstantial evidence that lowering is desirable.

Serum lipid is present as many fractions, namely, free cholesterol, cholesterol esters, triglycerides or neutral fat, free fatty acids and phospholipids. More than one-third of the total lipids usually are cholesterol esters, about one-third phopholipids, one-fifth triglycerides, and about one-tenth is free cholesterol. Although the absolute concentration of lipid values varies, the ratio between the free and esterified cholesterol is constant and is approximately 1:3. Considerable variation in the concentration of serum lipids is found among different individuals, but the lipid in serum appears to be maintained within a range which is characteristic for each individual and from which large deviations do not ordinarily occur in the absence of disease or therapeutic treatment.

There are relatively few studies of the blood lipid levels of older people. Hence, there is limited information on the kind and amount of different lipids in the serum of normal, senior citizens who are 65 to 90 years of age and less information on studies of the effect of diet on their blood levels. Further work with the older age people is desirable.

The objectives of this study were to determine the normal levels of serum cholesterol, total lipids, and phospholipids of older people on the usual diet and to determine the effect of the substitution of corn oil for all other fats used in cooking on these serum lipids. The research was based on a group of forty older, institutionalized subjects, men and women, ranging from 62 to 95 years of age, in the Sunshine Terrace home. Studies were made on serum lipids while the subjects were on the usual house diet and after corn oil was used as the only source of cooking fat in the same kind of diet. Venous blood samples were taken in each period for serum cholesterol, total lipid and phospholipid determinations. Dietary records were also collected for dietary calculation.

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