Opportunities in the Nutrition and Food Sciences Research Challenges and the Next Generation of Investigators (1994) / Chapter Skim
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5 UNDERSTANDING DIET, HEALTH, AND DISEASE RELATIONSHIPS
5 UNDERSTANDING DIET, HEALTH, AND DISEASE RELATIONSHIPS
Pages 143-179
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From page 143... ...
We define clinical nutrition, the focus of this chapter, broadly to include concepts of health promotion as well as those pertaining to the dietary treatment of diseases and metabolic disorders that is, disease prevention as well as therapeutics. A person's age, sex, and stage of growth have a direct impact on his or her nutritional requirements; in turn, nutritional state may influence the rate of growth, development, and aging.
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From page 144... ...
Food intakes can be related directly to neurotransmitter function in the brain. This arises from studies of the function of neuropeptides and amino acids as neurotransmitters and their role in neurodegenerative disease and from an increasing understanding of neurotransmitter receptors and the manner in which they are modulated by ions, free radicals, and the simultaneous action of other transmitters.
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From page 145... ...
The past successes of the nutrition and food sciences have enabled us to eradicate or significantly reduce the incidence of straightforward nutrient deficiencies, uncover links between diet and chronic diseases, and begin to identify how dietary choices affect development throughout life. Today's science pro
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From page 146... ...
It is now recognized that a woman's nutritional status at the time she conceives influences several aspects of her physiological response to pregnancy, relationships between her weight gain and the infant's birthweight, and the infant's anatomical development. Research now shows that, during lactation, mothers are generally able to produce milk of sufficient quantity and quality to support normal infant growth rates for at least the first three months of life, even when the mother's dietary supply of nutrients is limited, and for four to six months under the desirable conditions common in industrially developed countries.
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From page 147... ...
Calcium supplements lower mean blood pressure in some people. In addition, preliminary clinical trials in which pregnant women were given calcium supplements suggest a lowered frequency of preeclampsia.
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From page 148... ...
What is the role of overall diet quality, physical activity, occupation, stress, and quality of life? Are vitamin-mineral supplements beneficial during pregnancy and lactation and preferable to fostering improved nutrient intake through diet'?
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From page 149... ...
. The dietary treatment of Von Gierke's disease is an equally impressive example of nutritional therapy based upon knowledge of metabolic pathways.
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From page 150... ...
Meeting this research challenge should reveal the earliest mechanisms that determine food intake en cl its affective consequences, including food selection, feeding disorders, and the development of obesity. Develop a better understanding of the tong-term consequences of nutritional insults on early development The hypothesis that growth failure in early childhood predicts functional impairment at later ages has been substantiated recently in the follow-up to a supplementary feeding study conducted in Guatemala between 1969 and 1977.
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From page 151... ...
Similarly, studies of spontaneously hypertensive and salt-sensitive strains of rats also suggest that maternal diets during gestation and preweaning diets modulate blood pressure responses. Also, diets in early infancy can affect whether insulin-dependent diabetes develops in rat strains genetically predisposed to the abnormality.
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From page 152... ...
"Wet," or exudative, AMD is characterized by subretinal neovascularization, an aggressive growth of blood vessels from the choriocapillaris up through the retina that causes hemorrhage and scarring in the retina. Almost 90 percent of severe visual loss in AMD occurs in the 10 percent of cases with wet AMD.
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From page 153... ...
Opportunities in the area of body composition assessment encompass a wide range of challenges in human physiology coupled with biophysics and bioengineering. Research Opportunities Explore relationships between lean body mass and selected functional indicators In [ate adult life Cross-sectional data show that loss of lean body mass (LBM)
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From page 154... ...
The investigation of mechanisms responsible for these associations presents scientists with research questions relevant to clinical nutrition and patient management. Explore relationships among body composition, cytokines, and immune responses The immune system is a large component of the body's nonmuscle lean mass.
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From page 155... ...
Explore the relationship of the accumulation and distribution of body fat during childhood to [ong-term health Adipose tissue is of interest because of well-established associations between the total amount and distribution of body fat (particularly deep visceral fat) and the risk of chronic diseases in adults, such as hypertension, diabetes mellitus, cardiovascular disease, and certain cancers.
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From page 156... ...
Therefore, most of the research has been in women. Among the many risk factors identified are age, sex, race, genetics, reproductive factors, cigarette smoking, alcohol, physical activity, medical history (e.g., rheumatoid arthritis, insulin-dependent diabetes mellitus, or osteoarthritis)
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From page 157... ...
Conversely, both acute and chronic inflammatory conditions, as well as infectious and neoplastic diseases, result in several metabolic changes in the body that can adversely affect nutritional status. The roles of various nutrients in specific gene expression that regulate immunoactive cell functions, such as the production of cytokines and cell-cell interactions, are poorly understood.
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From page 158... ...
Cytokines are also modulated by the consumption of selected fatty acids, fat, water-soluble vitamins, and trace elements. Eicosanoids are 20carbon polyunsaturated fatty acids (PUFA)
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From page 159... ...
. LTB4 NK Cytotoxicity Adhesion Chemotaxis Deg ran ulation Cytokine Production Lymphocyte Proliferation NK ()
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From page 160... ...
Interactions between the CNS and nutrition, therefore, offer a challenging array of opportunities for research. Research Opportunities Enhance our understanding of the rote of nutrients and other food components in the development of the CNS and in treating develop~nental disorders of the CNS We understand the role of adequate maternal nutrition in preventing low-birthweight babies, but we are only beginning to elucidate the role of specific micronutrients in fetal development.
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From page 161... ...
Studies of the survival and cognitive development of these infants will increase the effectiveness of such support and provide insights into nutritional issues that are difficult to approach in normal children. Explore potential links between nutritional status, aging, and brain function Recent observations correlate a narrowing of the carotid arteries with elevated concentrations of homocysteine in the blood, concentrations that, in turn, are correlated with mild deficiencies of folate and vitamins BG and BT,.
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From page 162... ...
Recent research on the control of food intake goes far beyond earlier studies on the regulation of body weight to delineate neural networks that respond to specific nutrients and neurotransmitters that affect communications within the targeted network. For example, the neurotransmitter galanin is involved specifically in the ingestion of fats, whereas neuropepticle Y subserves carbohydrate intake.
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From page 163... ...
Other studies revealed that obese weight cyclers, or "yo-yo" dieters, showed increased preferences for sweet, high-fat foods relative to obese individuals of stable body weight. Sensory preferences appear to differ among clinical populations of women at extremes of body weight and may prove to be a valuable tool in distinguishing between potential subtypes of human obesity.
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From page 164... ...
Capturing these opportunities will increase our understanding of how taste preferences link metabolic variables to food preferences and individual experiences in the reaulation of patina behaviors. c, a, NEW OPPORTUNITIES: UNDERSTANDING DIET AND DISEASE RELATIONSHIPS Cancer There is intense interest in the relationship of diet to cancer.
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From page 165... ...
Each of these possibilities provides key opportunities for research on the relationship between fat and cancer. Identify the role of constituents offruits and vegetables in determining cancer risk Evidence that certain foods can protect against cancer is mounting rapidly.
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From page 166... ...
Dyslipidemia, hypertension, and hyperuricemia often afflict obese persons with Type II diabetes. These conditions are often familial and are associated with premature atherosclerosis, myocardial infarction, stroke, and peripheral vascular disease.
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From page 167... ...
Improve dietary management of Type II diabetes Restricted intake of energy-yielding nutrients and weight reduction will substantially improve insulin resistance and result in lower insulin concentrations. However, there is still debate regarding the relative amounts of dietary protein, carbohydrate, and fats that are optimum in the diet, as well as the ideal quantity and proportion of polyunsaturated versus saturated fatty acids.
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From page 168... ...
This suggests that one highly effective dietary treatment is already available to control hypertension. While studies are needled to clarify the roles of the various nutrients and their potential interactions, among the most pressing research needs is exploration of the molecular mechanisms by which nutrition can be used to control blood pressure and the mechanisms underlying the remarkable benefits of weight reduction in controlling this disorder.
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From page 169... ...
While there is little doubt that omega-3 fatty acids improve regulation of blood pressure, monounsaturated fatty acids, as well as saturated fatty acids, neec! to be investigated.
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From page 170... ...
Further, populations migrating from areas with a low incidence of CHD to high-incidence regions also experience substantial increases in CHD, emphasizing the importance of lifestyle over genetic factors in explaining many geographical differences. Research Opportunities Improve our understc~nding of the biological mechanisms linking CHD to the consumption of dietary fats The intake of saturated fatty acids (saturated fat)
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From page 171... ...
In more recent studies, substituting monounsaturated for saturated fat decreased LDL cholesterol without decreasing HDL cholesterol, whereas substituting carbohyclrates for saturated fats decreased both LDL and ElDL. Furthermore, LDL particles rich in monounsaturated fatty acids appear to be snore resistant to oxidation, which may make them less atherogenic, at least compared to LDL enriched in polyunsaturated fatty acids.
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From page 172... ...
At least as important as the severity of obesity is the distribution of body fat. Even a modest increase in visceral fat increases all risk factors for CHD.
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From page 173... ...
We cannot yet conclude that lowering chronically elevated plasma homocysteine or increasing vitamin intake will cause regression of vascular disease. However, a strong case can be made for preventing the marginal or manifest vitamin deficiency states that may contribute substantially to this potentially important risk factor for cardiovascular disease, the largest cause of mortality among the elderly.
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From page 174... ...
In addition to being a direct risk to health, it increases the risk of chronic diseases such as coronary heart disease, Type II diabetes, hypertension, and several cancers. A major advance in our understanding of human obesity has been the recent demonstration of the importance of genetic factors in its etiology.
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From page 175... ...
Determining the genetic and physiological basis of this vulnerability will improve our understanding of obesity and increase our understanding of the short- and long-term homeostatic controls of food intake. Identify the metabolic role of energy reserves in the regulation of body composition and weight A critical area for future research in obesity is regulation of body weight.
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From page 176... ...
Longitudinal studies of infants, children, and adults are needed to determine the relative contribution of different risk factors to the clevelopment of adiposity and obesity. Studies of persons at genetically determined high risk of obesity are particularly necessary; we need to learn the relative contribution of total energy expenditure, resting metabolic rate, and food intake on body composition during growth and development.
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From page 177... ...
The process by which a pre-adipocyte becomes an adipocyte and the stimulatory factors that promote this process at various sites in the body and at various ages needs to be explored in much more depth. Develop improved treatments for obesity At the present time, over $30 billion is spent each year on programs and products designed to control body weight, and the market is growing.
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From page 178... ...
j73 OffOBTC\~TlES IN T~E \~\ 4~ Fang SC1E\~S the immune response. The role of Lt-soluble vitamins rise merits increused scrutiny.
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From page 179... ...
We chose examples in two categories: research targeting ways to maximize functions important to well-being and optimal development (in the areas of reproduction, growth and development, body composition, immune function, central nervous system function, and food-related behavior) and research that focuses on disorders and diseases influenced by diet (cancer, diabetes, hypertension, cardiovascular disease and arteriosclerosis, vision-related disorders of aging, obesity, and diarrhea in infancy and early childhood)
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