The role of diet in the etiology and treatment of atherosclerosis

Diet among oil-workers on off-shore oil installations in the Norwegian sector of the North Sea

Dietary studies based on 24 h recalls were carried out on four oil installations in the Norwegian sector of the North Sea. Two hundred and three persons were interviewed about what they had eaten the previous 24 h. Food purchased for the installations in the previous 5 months was recorded. Results based on 24 h recalls showed that average daily intake of energy was 12.2 MJ of which 17% came from protein, 44% from fat and 39% from carbohydrate, including 8% from sugar. Meat, vegetables, fresh fruits, seafood (shellfish), french fries, eggs, cream and ice-cream were important components of the diet, while bread, fish and cereals played a minor role. Average daily intake (mg) of nutrients were: calcium 1244, iron 15, vitamin A 1049 micrograms, vitamin D 4.1 micrograms, thiamin 1.6, riboflavin 2.2, nicotinic acid 22, ascorbic acid 143. Dietary fibre intake, estimated as unavailable carbohydrate, was on average 19 g, and the average daily intake of cholesterol was 755 mg. Intakes were compared with the Norwegian recommended dietary allowance. Most of the employees chose a diet which when eaten over a longer period of time may contribute to the development of coronary heart diseases (CHD) and thereby increase the morbidity and mortality from CHD in the oil industry.

Polyunsaturates, endogenous eicosanoids, and cardiovascular disease

The role of dietary polyunsaturated fats in the prevention of human vascular disease has not been defined, but population and intervention studies have suggested that omega-3 fatty acids (FAs) from marine lipids may have a number of potentially beneficial effects. Eicosanoids are extremely potent autacoids made from polyunsaturated fatty acids and have effects on many vascular parameters, so that the physiological effects of dietary supplementation with polyunsaturated fats are often attributed to alterations in endogenous eicosanoid production. Few studies have attempted to correlate in vivo eicosanoid synthesis and functional effects during such dietary maneuvers, however. This article reviews the relationship between dietary polyunsaturates and endogenous eicosanoid synthesis in man, with particular emphasis on recent studies of the effects of omega-3 FAs. Data on omega-3 FAs and platelet-vascular interactions, blood pressure, and vascular reactivity in human subjects are also summarized, with interpretation of recent work addressing a number of controversial points. A discussion of the significance and future direction of such investigations concludes that further clinical trials in selected patient groups are warranted.

Effects of exercise on cardiovascular disease risk in women with NIDDM

The effect of a 4-month exercise program on measures of cardiovascular disease (CHD) risk was observed in women (mean age = 59.2 +/- 3.9 years) of postmenopausal years with NIDDM, who demonstrated fair to normal control of blood glucose control. The women were randomly assigned to either an exercise (n = 5) or control (n = 5) group. Initially, both groups had a similar body mass index, resting heart rate and blood pressures, blood glucose and hemoglobin A1. After 4 months, the exercise group demonstrated a 32% increase (P less than 0.03) in both absolute and relative maximum oxygen uptake (VO2) while the control group remained unchanged. Significant differences were found between the exercisers and non-exercisers for absolute (F(1,8) 4.94, P = 0.057) and relative (F(1,8) 7.67, P = 0.024) maximum VO2 from pretest to posttest. Body weight (kg) and body fat (%) remained unchanged for both groups. Although total cholesterol was found to be reduced by 13% for the exercise group (P less than 0.03) and 11% for the controls (P less than 0.01), a 15% decrease (P less than 0.03) in high-density lipoprotein (HDL) was observed for the control group, only. Hence, a marked difference (P less than 0.03) in the risk ratio was observed between the exercise and control groups. These data suggest that physical exercise may play an important role in the maintenance of HDL mass and in the reduction of CHD risk factors in women of postmenopausal years with NIDDM.

Histoautoradiographic detection of 3H-thymidine and 3H-proline in the vascular wall of domestic swine in experimental atherosclerosis. Is there an effect of saturated/unsaturated fatty acids in high cholesterol diet?

In vitro labeling of arterial wall samples from domestic swine with tritiated thymidine or proline was used to establish the effect of unsaturated (sunflower oil) or saturated (beef tallow) fatty acids in the presence of enteral cholesterol on DNA and collagen synthesis. Histoautoradiography of samples incubated in vitro gives labeling patterns and indices comparable to in vivo labeling. Preliminary results show that these nutrient fats do not differ in their effect on the DNA and collagen synthesis of vascular wall cells both in the presence and absence of intimal changes.

Nutritional requirements of the aged

The age of the population continues to increase. At the turn of the century, 4% (about 3.1 million people) were 65 years of age or older. Today the percentage has increased to 12%, or 27.4 million people, and the prediction for the 21st century may increase to 17 to 20%. It should be noted that the number of individuals 85 years of age and older, as well as those over the age of 100, is increasing rapidly. The nutritional problems of the elderly are related to physiological decline, to low economic status and limited food consumption, and to a multitude of disease processes and the therapeutic regimens prescribed to cure or treat those illnesses. Examined as a group, the elderly at first appear to be less uniform in their health status than younger members of the population. However, only 10% of the elderly population contributes to the disproportionate (30%) expenditure of health care services. A majority of the elderly are normal, healthy individuals. Yet, with each decade of life the percentage of the elderly population needing additional care increases. The national nutritional surveys (National Food Consumption Survey and the National Health and Nutrition Examination Surveys, I and II) used entirely different methodologies, but reported very similar findings. The mean intake of this population was actually quite good, revealing low intakes of calcium and iron in the elderly female population. However, the standard deviation of the intake data strongly suggests a major portion of the population is at nutritional risk. For more than 30% of the population, nutrient intakes below two thirds of the recommended dietary allowances (RDA) occurred for calories, calcium, and vitamin A, while for more than 20% of the population, iron and vitamin C were at risk. Although the data evaluating the effects of age on the nutritional requirements of the elderly are limited, careful interpretation of the existing assessment and intervention efforts can provide some basic guidelines. Generalities about calorie intake must be avoided, and emphasis must be placed on calorie needs. Enhanced activity should be encouraged. Protein intake for the majority of elderly exceeds the RDA, but with increased age a greater amount of high quality protein is needed to maintain nitrogen balance. The group at greatest risk is the poor elderly who may not be able to afford enough high quality protein. Increased consumption of complex carbohydrates serves several functions including decreased caloric density and enhanced nutrient intake. Decreasing total dietary fat decreases caloric intake and indirectly decreases dietary cholesterol.(ABSTRACT TRUNCATED AT 400 WORDS)

Heterogeneity of cholesterol homeostasis in man. Response to changes in dietary fat quality and cholesterol quantity

Studies were carried out to examine the effects of dietary fat and cholesterol on cholesterol homeostasis in man. 75 12-wk studies were carried out during intake of 35% of calories as either saturated or polyunsaturated fat, first low and then high in dietary cholesterol. Dietary fat and cholesterol intakes, plasma lipid and lipoprotein levels, cholesterol absorption and sterol synthesis in isolated blood mononuclear leukocytes were measured during each diet period. In 69% of the studies the subjects compensated for the increased cholesterol intake by decreasing cholesterol fractional absorption and/or endogenous cholesterol synthesis. When an increase in plasma cholesterol levels was observed there was a failure to suppress endogenous cholesterol synthesis. Plasma cholesterol levels were more sensitive to dietary fat quality than to cholesterol quantity. The results demonstrate that the responses to dietary cholesterol and fat are highly individualized and that most individuals have effective feedback control mechanisms.

Exercise training attenuates stress-induced hypertension in the rat

The ability of exercise training to block the generation of hypertension produced by chronic stress in the borderline hypertensive rat was tested. Twenty-three male borderline hypertensive rats, F1 offspring of spontaneously hypertensive and Wistar-Kyoto rats, were divided into three groups. Two groups (8 rats per group) were subjected to 2 hours of daily, predictable, uncontrollable tail shock for 12 weeks. One of these groups was also given 2 hours of daily swim stress (exercise trained). A third group served as a maturation control and received neither intervention (n = 7). After 12 weeks of stress, direct recording of blood pressure verified the pattern observed with tail cuff: shock only group, 180/118 +/- 3/3 mm Hg; exercise-trained and shocked group, 166/108 +/- 4/2 mm Hg; and control group, 160/98 +/- 6/4 mm Hg (mean +/- SEM). Systolic and diastolic blood pressures in the shock only group were significantly higher than in both the other groups (p less than 0.05). The control group differed from the exercise-trained and shocked group only in diastolic BP (p less than 0.05). During a short-term stress session plasma norepinephrine levels in the exercise-trained and shocked group were significantly lower than those in the shock only group (555 +/- 56 vs 776 +/- 84 pg/ml; p less than 0.05). These results indicate that an alteration of autonomic function resulted from the exercise training, but its contribution to the resistance of the exercise-trained and shocked rats to stress-induced hypertension is unclear.

Serum lipid peroxides in rats treated chronically with adriamycin

Rats treated chronically with the anticancer agent adriamycin exhibited lipid peroxides in the serum and hyperlipidemia. Independent assay methods based on thiobarbituric acid reactivity and iodometric titration confirmed the presence of both lipid endoperoxides and hydroperoxides. Fractionation studies indicated that lipid peroxides were mainly associated with neutral lipids, including triglycerides, cholesterol esters and cholesterol, rather than with phospholipids. The lipid peroxides were distributed throughout the major serum lipoprotein classes. Although the origin of the lipid peroxides has not been established, the dose dependence for elevation of serum lipid peroxides approximately corresponds to that required for the development of cardiomyopathy. These findings support the conclusion that lipid peroxides are formed in vivo in rats treated chronically with adriamycin.