Nutritional modulation is one approach to successful aging. In animals, dietary restriction increases life span. Alterations in the macronutrient and micronutrient constituent of the diet can modulate gene expression. Anorexia is common in elderly persons. The results of studies in animals suggest that aging is associated with a decrease in the opioid feeding drive and an increase in the satiating effect of cholecystokinin. Unrecognized depression is a common, treatable cause of anorexia and weight loss in elderly persons. Protein synthesis decreases in elderly persons; nevertheless, nitrogen balance can be maintained in patients with fairly low intakes of protein. Carbohydrate intolerance is common and may be modulated by nutritional intervention and physical activity. The role of cholesterol in the development of heart disease in very old persons is controversial. Homebound and institutionalized elderly persons often do not expose their skin to sunlight; because the skin of older persons has a decreased ability to form vitamin D, the vitamin D status in these persons is precarious and they are at risk for osteopenia. Vitamins are often abused by elderly persons. Drug administration alters the vitamin requirements of persons. Borderline zinc state has been associated with deteriorating immune function, especially in persons who have diabetes mellitus or who abuse alcohol. Zinc administration appears to protect against the deteriorating vision associated with age-related macular degeneration. Selenium deficiency seems to be associated with an increased prevalence of cancer.
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An investigation was undertaken to study the rate of incorporation and disappearance of trans isomers of octadecenoic and octadecadienoic acids from different tissues of rats fed 15% fat diets containing trans fatty acids for 3 months. At the end of 3 months some of the animals were killed and the remaining animals were changed over to a diet containing only trace amounts of trans fatty acids. Thereafter, representative animals were killed at 2, 4, 8, and 12 weeks. The fatty acid composition of tissue lipids was measured by gas liquid chromatography. Trans octadecenoate was primarily incorporated into phospholipids and triglycerides of plasma, liver, kidney, heart, adipose tissue, and red blood cells. Trans isomers of octadecadienoate accumulated in triglycerides of plasma, liver, kidney, heart, and adipose tissue while only small amounts accumulated in tissue phospholipids and cholesteryl esters. After removal of trans fatty acids from the diet, the time of disappearance of trans isomers of octadecenoate and octadecadienoate from tissues varied. With the exception of adipose tissue, 8 weeks after the trans fatty acid diet was discontinued, only negligible amounts of trans fatty acids were present in rat tissues, demonstrating that tissues studied can metabolize trans fatty acids.
A representative sample of the 1968-1969 California avocado crop was analyzed, using standard techniques, at approximately 8, 12, 16, and 20% fat for the Fuerte variety and at 16 and 20% fat for the Hass variety. In addition to the fat measurement, the content of water, fiber, protein, 7 fatty acids, 11 vitamins, and 17 minerals was determined at each fat level. A serving of Fuerte avocado (80.8 g) was found to have 132 calories. Correlation among the fat, water, protein, and ash in the Fuerte resulted in the following: 7'0 water = 89.49 -'70 fat; % fiber = 3.45 -0.0735% fat; 70 protein = 1.483 + 0.052% fat; and 70 protein = 5.807 -0.048% water, in the rang? from 8 to 22% fat. The percent of the Recommended Dietary Allowance (RDA) (1974) for children, provided by one-half of a Fuerte avocado (80.8 g), was found to vary from 170 for calcium to 19% for vitamin E; however, most nutrients were supplied at 6-1170 of the RDA for all major age and sex groups.In 1967 the Nutritional Research Committee of the California Avocado Advisory Board recommended that a representative sample of the whole California avocado crop be analyzed to provide nutritionists with accurate data upon which to base evaluations on the use of avocados. Since about 90% of all California avocados found in the market are the Fuerte and Hass varieties, analysis of these two would be representative of the whole crop. It was decided that samples should be taken from all growing areas within California in order to average variances in the soil, climate, fertilizers, and tree selection, and this was done. Furthermore, not only were the Fuerte and Hass specimens analyzed separately, but the Fuerte avocados were measured at four times during their harvesting period and the Hass twice, so that the nutrient content would be known for the different stages of maturity of the product.Although new analyses have continued to be made on avocados. recent literature still quotes values reported more than 15 years ago. Thus, the recent Life Science Book "Food and Nutrition" (Sebrell and Haggerty, 1967) used the data in Wooster (1958) which was taken from USDA Circular No. 549 in 1940 by Chatfield and Adams. Improvements in techniques, standards, and food technology indicate the need for this new analysis which attempts to quantitate all the important nutrients found in avocados, from a sample representing the average California avocado. (1958), from whom the avocados were obtained, have records from each packing house on the ratio of size to fat content, since by law avocados with less than 8% fat cannot be sold; thus, it was possible to select avocados of an approximate oil content by size. The maximum oil content of avocados as commercially marketed is about 20%; therefore, the most typical avocado, the Fuerte, was sampled at 8, 12, 16, and 20% oil while the less common variety, the Hass, was collected at 16 and 20% fat. The packing house records were used to select avocados from each of the five commercial California districts to make a sample representative of ...
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