Allison went on to demonstrate that people who were heterozygous for sickle-cell hemoglobin were in fact resistant to malaria order malegra fxt plus 160 mg line, and that the selective advantage of malaria resistance could account for the frequency and geographic distribution of the sickle-cell trait (Allison 1964) cheap malegra fxt plus 160mg without prescription. Although Haldane’s insight and Allison’s research stimulated a search for other genetic variants that were main- tained because they conferred resistance to malaria, such as glucose-6-phosphate dehydrogenase deficiency (Luzzatto, Usanga, and Reddy 1969), they too did not lead to a broader incorporation of evolutionary thinking into medicine. The emergence of antibiotic-resistant bacteria shortly after the introduction of antibiotics into clinical medicine is the most striking example of the medical relevance of evolution (Dubos 1942). Concerns about antibiotic resistance led to important studies on the mechanisms of resistance and to the development of new antibiotics that overcame this resistance. Recognition that the spread of antibiotic-resistant bacteria was due to selection for antibiotic resistance led to calls for the more responsible use of these drugs. Moreover, little attention was given to understanding the dynamics of selection or the ways in which regimens of antibiotic usage might modulate the strength of selection for antibiotic resistance. Perlman Until recently, the hierarchical organization of the nervous system, the preva- lence of disease-associated alleles, and the spread of antibiotic resistance were simply isolated instances of the application of evolutionary concepts to medi- cine. Stimulated by the pioneering publications of Randolph Nesse and George Williams in the 1990s, however, physicians and other scientists have now begun to integrate evolutionary biology and medicine into a coherent discipline (Nesse and Williams 1994;Williams and Nesse 1991). This is the new field of Darwin- ian, or evolutionary, medicine (Gluckman, Beedle, and Hanson 2009; Stearns and Koella 2008;Trevathan, Smith, and McKenna 2008). Given that the theory of evolution by natural selection is the central, unify- ing theory in biology and that our understanding of disease is heavily based on our knowledge of human biology, it may seem surprising that evolutionary med- icine is such a new field. Yet there are many reasons why evolutionary biology and medicine developed as separate disciplines and have until recently remained isolated from one another. When Darwin proposed his theory of evolution by natural selection, medicine was already a well-established profession, with a his- tory in the West going back at least 2,500 years to Hippocrates. In the 19th cen- tury, medical practice stressed careful physical examination of patients, descrip- tion of the natural histories of diseases, and correlation of the signs and symptoms of disease with autopsy findings. Later, with the rise of the germ the- ory of disease, medicine became increasingly focused on laboratory diagnoses and on identifying the etiologies or causes of disease (Porter 1998). Medicine was taught in its own institutions, which were typically based in hospitals, and the medical curriculum was already crowded. There was no room and no appar- ent need to bring the theory of evolution into medical education, research, or practice. Evolutionary biology did not develop into an academic discipline until long after Darwin. At the time of the Flexner Report (Flexner 1910), which laid the foundations for today’s science-based medical education, there were still no uni- versity departments, professional societies, or scholarly journals devoted to evo- lution. Only after the integration of evolutionary biology with genetics in the 1930s and 1940s did evolutionary biology become a mature science (Ruse 2009). Even then, evolutionary biology and medicine continued to develop as separate disciplines, with little interaction. Evolutionary biologists were con- cerned with classification of species, with enriching and analyzing the fossil record, and with finding evidence of natural selection in the wild. Except for paleontological studies of human origins, most evolutionists shied away from human biology. Many of these biologists worked in museums and field stations, isolated from medical centers, and they may not have wanted to be associated with the eugenics programs of the early 20th century that had been embraced by some evolutionists (Kevles 1995). Perhaps most importantly, as the following brief review of the theory of evolution by natural selection will make clear, evo- lutionary biology and medicine have different and seemingly incompatible ways 170 Perspectives in Biology and Medicine Evolution and Medicine of understanding biological phenomena. Evolutionary biologists and physicians have been concerned with different problems, they speak different specialized languages, and they see the natural world in different ways. These differences have helped to keep these fields apart and continue to hinder their integration. The Theory of Evolution by Natural Selection Although our understanding of evolution has increased greatly since Darwin’s time, biologists still use essentially the same arguments to support the theory of evolution by natural selection as Darwin did when he proposed it. Darwin began by pointing out the abundant variation that exists among indi- vidual organisms in a population. The first two chapters of On the Origin of Species (1859) are devoted to a discussion of variation, first in domesticated species and then in nature. Darwin focused on small, often barely discernible, variations; he regarded the greatly deviant organisms that occasionally arise in nature as “monstrosities” that had no role in evolution. Of course, people had long been aware of variations among organisms within populations or species. As Ernst Mayr (1964) has emphasized, however, before Darwin species were understood in typological or essentialist terms. In this view, each species was thought to be characterized by a unique, unchanging essence. Variation was seen as an irrelevant distraction, due to imperfections in the material realization of the ideal form of the species. Biologists no longer think of species as having ideal or essential forms: instead, they commonly think about species (at least extant, sex- ually reproducing species) in terms of Mayr’s biological species concept. Ac- cording to this concept, species comprise populations of organisms that can interbreed and produce viable offspring in nature but that otherwise exhibit a wealth of variation and change over time—in other words, species evolve (Mayr 1988a). Variation remains a critical aspect of evolutionary thinking because it provides the raw material for evolution by natural selection. Next, Darwin pointed out that, while the number of organisms in a popula- tion might potentially increase without limit, the resources needed to support these populations are finite. In other words, the reproductive capacity of the organisms in a population must greatly exceed what we now call the carrying capacity of the environment, the population that the local habitat can sustain. This inequality between reproductive potential and environmental resources means that individual organisms in a population must compete for survival and reproduction. Darwin called this competition the “struggle for existence,” a con- cept based on Thomas Malthus’s Essay on the Principle of Population (1798); in The Origin, he refers to the struggle for existence as “the doctrine of Malthus applied with manifold force to the whole animal and vegetable kingdoms” (Darwin 1859, p. Malthus was concerned with the disparity between human popu- lation growth and the availability of food. Darwin expanded Malthus’s ideas from spring 2013 • volume 56, number 2 171 Robert L. Perlman humans to all species and from food to all of the environmental resources that organisms need to survive and reproduce. Evolutionists understand the struggle for existence in what Darwin called “a large and metaphorical sense” (p. Organisms struggle to secure food and other resources they need to grow and develop, to avoid being eaten by predators, to attract mating partners and repro- duce, and to promote the survival of their offspring. Although the term may conjure visions of hand-to-hand combat, the struggle for existence is primarily a struggle between organisms and their environments. Only occasionally does the struggle for existence involve a direct physical confrontation between two individuals of the same species, as in two dogs fighting over a scarce piece of meat or two males fighting to mate with a female. The environment in which the struggle for existence takes place includes both the physical or nonliving environment (air, water, sunlight, climate, etc. The biotic environment comprises all of the other species with which organisms interact or on which they depend (di- rectly or indirectly), as well as other members of their own species. Organisms of other species constitute especially important components of an organism’s environment. For this reason, evolution is closely connected to ecology and to the ecological relationships among species. Many of us in developed countries live in environments in which our interactions with organisms of other species are largely hidden. Our direct experience is limited to our pets, to the plants and animals in our gardens and parks, to the insects and other pests that annoy or plague us, to infectious microorganisms, and to the food we eat, much of which we purchase prepackaged in grocery stores. We should remember, however, that our lives and our health are intimately related to and affected by the innumer- able species that form part of our environment—those that contribute to our health, as well as those that cause disease. Those individuals that are successful in the struggle for existence will survive, reproduce, and leave offspring; in evolutionary terms, producing offspring who themselves survive and reproduce is the definition of success. Biologists com- monly use the term fitness, sometimes modified as reproductive or evolutionary fit- ness to avoid confusion, to denote this reproductive success. The term “survival of the fittest,” introduced by the English philosopher Herbert Spencer (1864), has become a widely used metaphor to describe the evolutionary process. This metaphor may be misleading, however, because it is easy for people who are concerned with “fitness” today to think that evolutionary fitness refers to some- thing akin to physical fitness. In evolutionary terms, fitness does not simply refer to strength or endurance, but to all of the traits that enable organisms to func- tion—to survive and produce offspring—in their environments.
Electronic thermometers may also be usable over wider ranges than conventional thermometers order 160 mg malegra fxt plus overnight delivery. Electronic tympanic membrane thermometers (which let you read temperature from the ear) make it easy to avoid cross-infection malegra fxt plus 160mg visa, but again, they need a power supply. Basal thermometers are thermometers designed to be read to at least 1/20th of a degree (1/10th of a Fahrenheit degree), rather than the 1/10th degree (2/10th of a Fahrenheit degree) of most standard mercury thermometers. Hypothermia thermometers are thermometers that allow the reading of temperatures lower than standard thermometers, usually having ranges that extend down to 30 degrees (86 degrees F) or lower. Hyperthermia thermometers are thermometers that allow the reading of higher than normal temperatures to more accuracy than standard thermometers. Purchase recommendations: For each ten people have at least two standard thermometers, one basal thermometer, and one hypothermia thermometer. Hyperthermia thermometers should be purchased at the rate of one to every twenty people if you expect to see heat injuries commonly, otherwise, a normal clinical thermometer will usually suffice. Rectal versus oral versus universal tips - get universal tips (midway between oral and rectal, and they can be used for either in a pinch) for the clinical and basal thermometers, rectal for the hypothermia and hyperthermia thermometers. Then there are the simple but easily overlooked tools that make ongoing care not only practical but less strenuous and safer for both patient and caregiver. Bandage Scissors: Designed to cut away bandages next to the body without poking holes in your patient. Permanent Marker: To write on dates or times on dressings to know when they were last changed if there is more than one caregiver. Also used to mark skin (it wears off with repeated washing and normal skin replacement). Transfer Belt: Known by various names such as walking belt, safety belt, gait belt, etc. The commercial version is a 3” wide sturdy fabric strap that is easily buckled around the patient so the caregiver can assist them with standing up, transferring, or walking. It can also be fashioned from a pair of sturdy pants suspenders or an ordinary (wide) clothing belt. It provides a handle for the caregiver to grab on to by placing it around the middle (lower stomach area) of the patient and holding onto the rear of the belt. It isn’t always practical to reach into your pocket for everything and setting tools, dressings, etc. Clothing Protectors: Another simple yet important item that can be fashioned readily from any soft or fluid resistant material. Intended to catch spills while eating/feeding and protect the patient while washing hair or performing treatments. They may tie behind the neck or have a wrap-around collar that fastens with Velcro. By protecting from spills they also save a lot of time by guarding against the necessity of clothing and bed linen changes. Flashlight: This serves a dual role as both as assessment tool for the eyes, ears, nose and mouth, and the means to check a patient at night without awakening them with overhead lighting. Gowns: Caring for people may routinely require exposing differing areas of their body for washing, administering medications, changing dressings and bandages or measuring vital signs. Having to undress a person each time is time-consuming and impractical as well as potentially painful. Modesty dictates that we be able to cover the patient when exposure is not otherwise needed. Open back gowns while the bane of hospitalized patients world-wide represent the most practical means of combining protection with accessibility when shirt and pant style clothing is not practical or possible, as when casts or external appliances interfere. Vanity issues aside it may be necessary to trim nails to address issues of hygiene (germs love to hide under nails) and prevent inadvertent self-injury by a patient who may flail about with pain or fever delirium. Having properly designed and sized clippers for the fingers and toes makes this task much easier for all concerned. Providing On-Going Care Having identified our goals we can move on the issue of how we are to address them. There are several areas that need to be addressed as part of the entire care “package” or plan. Databases: Vital Signs Having a database of vital signs is the key to recognizing abnormal vital signs later on. In an ideal situation you would have a record that details normal laying, sitting and standing blood pressures for your patient, as well as a resting pulse, and respirations, along with a temperature. Make sure to note whether the normal pulse is - 152 - Survival and Austere Medicine: An Introduction regular and strong in quality and rhythm, or irregular, weak, or bounding (very strong). Having a database of temperatures over time will allow you to gauge the effectiveness of antibiotics, for instance, or the onset of an infection. Similarly a person who is acutely dehydrated will see an increase in their temperature. Pulse Pulses may indicate a general state of health in the absence of illness or injury. A very rapid, thin pulse may indicate the presence of shock, whereas a slow pulse might signal that the patient is relaxed and relatively pain free. Since pulse rates vary widely amongst people the change in pulse rate and quality is more important than the rate itself. For example, for a person whose normal pulse rate at rest is 68 an increase of 20 per minute may indicate the presence of unaddressed pain. Blood Pressure Blood pressures are always obtained using a blood pressure cuff, either manually operated or electronic. Cuffs come in different sizes with a standard blood pressure cuff suitable for adolescents and adults. An upper arm larger than approximately 15 cm will require a larger cuff for an accurate reading or a false high will result. Conversely an arm smaller than approximately 8 cm will require a smaller diameter cuff or a false low reading will result. Breathing Normal breathing rates for an adult range between 14 and 20 per minute, or one breathe every 3 – 4 seconds. During times of illness this may increase, with more than 30 breaths a minute considered very significant. In addition to rate the apparent effort used to breath can also be indicative of distress or absence of same. Respiratory infections can cause labored breathing, evidenced by increased effort and rate. By tracking breathing rates and quality along with other vital signs it is possible to determine whether treatments are having a positive effect. Other Data to Collect and Record Bowel Movements As we age our bowel movements tend to become less frequent. Older - 153 - Survival and Austere Medicine: An Introduction adults may not have a proper bowel movement for several days without regular use of fiber in their diet and/or laxatives. As a rule a person should have one medium to large bowel movement at least every 3 days. Urination It is not necessary to record urine outputs for everyone but for some cases – especially burns - measuring output against fluids taken in (Intake and Output) is necessary to determine whether fluid balance is being maintained. The effects of disease, loss of fluids through other sources such as perspiration, vomiting, bowel movements, etc may affect this somewhat but as a general rule plan on a measured output of one and a half litres. Anything less than half this amount may be indicative of kidney malfunction and is cause for serious concern. For certain types of patients, such as burn cases or those with heart failure, matching Intake and Output (I & O) against daily weights can be critical to determine if an output deficit is the result of retained fluids. Weight Weight by itself may mean little other than as a general indication of nutritional status but changes in weight can be significant in terms of indicating changes in the patient’s condition. For instance fluid retention or loss can vary a person’s weight by several pounds (2 – 3 kilograms) per day. Sudden fluid gain can precipitate heart failure, and also may indicate failing kidney function if present along with decreasing urine output.
For solid cancer risk after an exposure of 100 mSv purchase malegra fxt plus 160 mg free shipping, upper and lower boundaries of the 95% confidence interval differ by a factor of 5 buy malegra fxt plus 160mg low price. It is important to distinguish between a manifest ‘health effect’ and ‘health risk’, when describing such health implications for an individual or a population. A manifest health effect in an individual (such as skin burns) can be unequivocally attributed to radiation exposure only if other possible causes for an observable tissue reaction are excluded. Cancer cannot be unequivocally attributed to radiation exposure because radiation is not the only possible cause and there are, at present, no known biomarkers that are specific to radiation exposure. However, it is recognized that there is a need for such estimations by health authorities to allocate resources or to compare health risks. This is valid if applied consistently and the uncertainties in the estimations are fully taken into account, and the projected health effects are notional. It has also regularly evaluated the evidence for radiation induced health effects from studies of Japanese atomic bombing survivors and other exposed groups, and has reviewed advances in the mechanisms of radiation induced health effects. An important source of evidence is population based surveys of radiation use and exposure in medicine, as such surveys identify the levels and trends of exposure, and highlight the procedures requiring intervention by virtue of doses or frequency of procedures. Gaps in treatment capabilities and possible unwarranted dose variations for the same procedure are also identified. This imbalance in health care provision is also reflected in the availability of radiological equipment and of practitioners. In epidemiological surveys of populations exposed to radiation, there are statistical fluctuations and uncertainties due to selection and information bias, exposure and dose assessment, and model assumptions used when evaluating data. In addition, transferring the risk estimate based on data from an epidemiological study to a population of interest needs to take into account differences in location, setting, data collection period, age and gender profile, genetic disposition, doses, type of radiation and acute versus protracted exposures . The uncertainty of cancer risk after exposure to ionizing radiation is, therefore, often underestimated. For solid cancer risk after an exposure of 100 mSv, upper and lower boundaries of the 95% confidence interval differ by a factor of 5. The uncertainty of excess risk for a specific cancer type is considerably higher than for all solid cancers . It is important to distinguish between a manifest ‘health effect’ and ‘health risk’ (likelihood of a future health effect to occur), when describing such health implications for an individual or a population. A manifest health effect in an individual could be unequivocally attributed to radiation exposure only if other possible causes for an observable tissue reaction (such as skin burns; deterministic effect) were excluded. Cancer (stochastic effects) in individuals cannot be unequivocally attributed to radiation exposure because radiation is not the only possible cause and there are, at present, no known biomarkers that are specific to radiation exposure. An increased incidence of stochastic effects in a population could be attributed to radiation exposure through epidemiological analysis, provided the increased incidence is sufficient to overcome the inherent statistical uncertainties . In general, a manifest increased incidence of health effects in a population cannot reliably be attributed to radiation exposures at levels that are typical of the global average background levels of radiation or the levels applied at medical radiological diagnostics. The reasons are: (i) the uncertainties associated with risk assessment at low doses; (ii) the absence of radiation specific biomarkers; and (iii) the insufficient statistical power of epidemiological studies . When estimating radiation induced health effects in a population exposed to incremental doses at levels equivalent to or below natural background, it is not recommended to do this simply by multiplying the very low doses by a large number of individuals. However, it is recognized that there is a need for such estimations by health authorities to allocate resources or to compare health risks. This is valid if applied consistently and the uncertainties in the estimations are fully taken into account, and the projected health effects are notional . While the magnitude of medical exposures can be assessed, it is very difficult to estimate the health risks from such uses as there are still many uncertainties in estimating cancer risk due to ionizing radiation and in attributing other health effects to and inferring risk from medical radiation exposure. Thus, the uncertainty increases when extrapolating risk estimates from moderate dose to low dose. Therefore, it is not surprising to note that a statistically significant increase in radiation induced cancer is seen only when the exposure is 100 mSv or above . Varna, 2010), National Centre of Radiobiology and Radiation Protection, Varna (2010). It highlights some of the more important presentations at the conference as well as issues that arose during discussion and that require further investigation and action. At the conference, the necessity of a commitment to a safety culture within institutions and organizations providing health care to patients was emphasized. The safety culture must support and reinforce efforts to provide adequate protective measures for patients and staff exposed to ionizing radiation used for diagnosis of disease and injury, and for the treatment of cancer. Elements of a safety culture are: (i) leadership; (ii) evidence based practice; (iii) teamwork; (iv) accountability; (v) communication; (vi) continuous learning; and (vii) justice. These elements are essential to a safety culture and must, therefore, be present in any organization that reinforces radiation protection. Over 25 years (1982–2006) in the United States of America alone, the average individual dose from medical radiation increased by a factor of 5. These increases occurred even though the actual dose delivered to individual patients decreased for many imaging procedures. The increases in average and collective dose reflect the growing usefulness of medical imaging as a consequence of improved technologies, new procedures and applications, and increased access to imaging. This is encouraging news, because it demonstrates that increasing numbers of patients are receiving the medical benefits of imaging and therapeutic procedures employing ionizing radiation. The tracking of imaging procedures and radiation doses is recommended as a way for institutions and agencies to monitor trends in procedures and radiation doses delivered collectively to patients. This process lends a sense of personal empowerment to individuals, but may also mislead patients into thinking that their collective exposure can be estimated by adding doses to different body regions from separate modalities. In any event, the decision to administer an imaging procedure to a patient should always be based on the benefits/risks of the procedure without regard to previous exposures the patient may have received. There was considerable discussion about justification and optimization of imaging procedures at the conference, while less attention was paid to proper implementation and evaluation of the procedures. The four elements collectively comprise the continuous quality improvement cycle for imaging procedures shown in Fig. It was recognized that both overutilization and underutilization of medical imaging compromise the concept of justification of imaging procedures. However, these shortcomings can be addressed relatively successfully through the use of decision support systems to guide the referring physician in selecting the proper imaging examination for the patient. Digital radiography presents a number of challenges with regard to patient protection and procedure optimization. Interventional procedures have increased remarkably over the past couple of decades, and have improved patient outcomes and reduced patient mortality and morbidity as a consequence. The Image Wisely campaign has been launched to improve quality and reduce dose in adult imaging in the manner so successfully achieved by the Image Gently campaign for paediatric imaging. Collaboration in this effort with organizations concerned with similar issues in other countries was encouraged. Anatomically correct phantoms for validation of Monte Carlo methods for organ dose calculations are being developed. Also of concern is the use of adjectives such as ‘low’, ‘very low’ and ‘ultra low’ as adjectives preceding dose in articles published in the literature. These terms are relative and vary with time, geographic location and patient size. The journal Radiology has stated that it will not accept these modifiers of dose in submitted papers, and the journal Medical Physics will take a similar position in the near future. Radiation oncology has changed radically over the past 2–3 decades, and today is a highly complex field dominated by software as well as sophisticated hardware. Non-standard photon and particle beams are widely used under conditions that can cause major errors if commissioning and ongoing quality control are inadequate. Several examples of such inadequacies were described in which patients were severely injured or killed by improper physics procedures. Other challenges of the modern era of radiation oncology include improved methods for in vivo dosimetry, better compensation for patient motion, increased biological understanding of individual differences in radiation sensitivity, and the propensity for developing second cancers, especially in children. New unsealed sources that target tumours through the use of antibodies, nanoparticles and tumour specific agents constitute an exciting arena for future developments. One observation made at the conference was that as the complexity of diagnostic and therapeutic devices increases, quality assurance measures must be simplified 1 www. The challenge of improving the care of patients in countries with greatly limited resources was raised several times during the conference, and was recognized as a great and unfulfilled need across the globe. It was widely recognized that health care is a collaborative partnership between those who provide care and those who receive it, and that true collaboration requires: (i) truthfulness and directness; (ii) partnership and collaboration; (iii) openness and transparency; (iv) understanding of benefits, risks and options; and (v) engagement and involvement of all parties. It was recognized that all medical procedures employing ionizing radiation should be provided within a culture of safety. Such a culture requires active leadership from the top, but is everyone’s responsibility if it is to be fulfilled.
The intake of cholesterol by American adults ranges from less than 100 mg/d to just under 770 mg/d (Appendix Table E-15) proven 160mg malegra fxt plus. It is important to recognize that lower intakes of saturated fatty acids and cholesterol are observed for vegetarians cheap malegra fxt plus 160 mg fast delivery, especially vegans (Janelle and Barr, 1995; Shultz and Leklem, 1983). Because certain micronutrients, saturated fats, and cholesterol are consumed mainly through animal foods, it is possible that diets low in saturated fat and cholesterol are associated with low intakes of these micronutrients. When the micronutrient intakes of Seventh-day Adventist vegetarians and nonvegetarians were measured, there were no significant reductions in micronutrient intakes with the lower saturated fat (7. Similarly, the intakes of most micronutrients were not significantly lower for vegans, except for vitamin B12 (0. Analysis of nutritionally adequate menus indicates that there is a mini- mum amount of saturated fat that can be consumed so that sufficient levels of linoleic and α-linolenic acid are consumed (as an example see Appendix Tables G-1 and G-2). Other than soy products that are high in n-6 and n-3 fatty acids, many vegetable-based fat sources are also high in saturated fatty acids, and these differences should be considered in plan- ning menus. To minimize saturated fatty acid intake requires decreased intake of animal fats (e. Saturated fatty acids can be reduced by choosing lean cuts of meat, trimming away visible fat on meats, and eating smaller por- tions. The amount of butter that is added to foods can be minimized or replaced with vegetable oils or nonhydrogenated vegetable oil spreads. Vegetable oils, such as canola and safflower oil, can be used to replace more saturated oils such as coconut and palm oil. Such changes can reduce saturated fat intake without altering the intake of essential nutrients. A reduction in the frequency of intake or serving size of certain foods such as liver (375 mg/3 oz slice) and eggs (250 mg/egg) can help reduce the intake of cholesterol, as well as foods that contain eggs, such as cheese- cake (170 mg/slice) and custard pie (170 mg/slice). There are a number of meats and dairy products that contain low amounts of cholesterol (e. Therefore, there are a variety of foods that are low in saturated fat and cholesterol and also abundant in essential nutrients such as iron, zinc, and calcium. Trans fatty acids are high in stick margarine and those foods containing vegetable shortenings that have been subjected to hydrogenation. Examples of foods that contain relatively high levels of trans fatty acids include cakes, pastries, doughnuts, and french fries (Litin and Sacks, 1993). Therefore, the intake of trans fatty acids can be reduced without limiting the intake of most essential nutrients by decreasing the serving size and frequency of intake of these foods, or by using unhardened oil. Several studies suggest that these changes are primarily due to a reduction in lipid uptake by adipocytes (Pariza et al. Blankson and coworkers (2000) conducted a study in overweight and obese men and women given either placebo or 1. After 12 weeks, none of the groups exhibited significant reductions in body weight or body mass index. Ip and Scimeca (1997) conducted a study in female rats chemically induced for mammary tumors and fed a diet containing either 2 percent or 12 percent linoleic acid. A number of adverse clinical effects, including impaired laxation and increased risk of cancer, obesity, heart disease, and type 2 diabetes, have been associated with the chronic consumption of low amounts of Dietary Fiber or Functional Fiber. The studies to support a beneficial role of these fibers are reviewed in Chapter 7. Certain animal studies have shown that some fibers can actually enhance mineral absorption (Demigné et al. There are several potential mechanisms by which ingestion of Dietary Fiber may actually enhance mineral status. For example, a more acidic pH in the colon is produced with fiber fermentation, and this results in more ionized calcium, which is better absorbed (Rémésy et al. Dietary Fiber in the colon can also stimulate bacterial fermentation, which has been associated with increases in calcium, magnesium, and potassium absorption (Demigné et al. Many fiber sources, such as karaya gum, sugar beet fiber, and coarse bran, are also excellent sources of minerals (Behall et al. Several investigators have shown that inulin and fructooligosaccharides actually enhance calcium and magnesium absorption (Coudray et al. There is also indirect evidence of this same enhancement with calcium in humans (Trinidad et al. A direct effect of fiber on mineral absorption has also been reported in humans where inulin increased the apparent absorption and balance of calcium (Coudray et al. Gastrointestinal distress can occur with the consumption of high fiber diets, but this often subsides with time. Epidemiological analysis from 53 devel- oping countries indicated that 56 percent of deaths in young children were due to the potentiating effects of malnutrition in infectious diseases (Pelletier et al. The increased duration or susceptibility to infec- tious diseases such as respiratory infections and diarrhea are due, in part, to the involvement of protein in immune function. Impaired Growth Low protein intake during pregnancy is correlated with a higher inci- dence of low birth weight (King, 2000). These deficits can be corrected by the provision of a high protein diet (Badaloo et al. Low Birth Weight Rush and coworkers (1980) found decreases in both gestational length and birth weight and increases in very early premature births and mortal- ity with high density protein supplementation (additional 40 g/d) in poor, black pregnant women at risk of having low birth weight infants. In contrast, Adams and coworkers (1978) reported no differences from the controls in mean birth weights of infants of mothers at risk of having a low birth weight infant when these women were supplemented with 40 g/d of protein. No reports were found of protein toxicity in healthy pregnant or lactating women that were not at risk of having a low birth weight infant. Risk of Nutritional Inadequacy High quality protein is typically consumed via animal products, and therefore vegetarians may consume less high quality protein than omni- vores. Because animal foods are the primary sources of certain nutrients, such as calcium, vitamin B12, and bioavailable iron and zinc, low protein intakes may result in inadequate intakes of these micronutrients. As an example, Janelle and Barr (1995) reported significantly lower intakes of riboflavin, vitamin B12, and calcium by vegans who also consumed lower amounts of protein (10 versus 15 percent of energy) compared with nonvegetarians. Vegetable protein has been shown to decrease plasma cholesterol con- centrations in experimental animals and humans (Nagata et al. When the ratio of casein:soybean protein in the diet was decreased, there was a reduction in total and non-high density lipoprotein cholesterol concentrations (Fernandez et al. In laboratory animals, it was shown that the onset of atherosclerosis was significantly reduced when animals were fed a textured vegetable protein diet compared to a beef protein diet (Kritchevsky et al. The magnitude of this effect for a doubling of the protein intake, in the absence of change in any other nutrient, is a 50 percent increase in urinary calcium (Heaney, 1993). This has two potential detrimental consequences: loss of bone calcium and increased risk of renal calcium stone formation. Loss of calcium from bone is thought to occur because of bone mineral resorption that provides the buffer for the acid produced by the oxidation of the sulfur amino acids of protein (Barzel and Massey, 1998). However, although increased resorption of bone with increased protein intake has been shown (Kerstetter et al. It has recently been concluded that there may be no need to restrain dietary protein intake. Poor protein status itself leads to bone loss, whereas increased protein intake may lead to increased calcium intake, and bone loss does not occur if calcium intake is adequate (Heaney, 1998). In a recent prospective study of men and women aged 55 to 92 years, consumption of animal protein was positively associated with bone mineral density in women, but not in men (Promislow et al. In contrast, Dawson-Hughes and Harris (2002) reported no association between protein intake and bone mineral density in 342 healthy men and women aged 65 years and older. However, when the individuals were given cal- cium citrate malate and vitamin D in addition to the high protein intake, there was a favorable change in bone mineral density. Kidney Stones It has been estimated that 12 percent of the population in the United States will suffer from a kidney stone at some time (Sierakowski et al. The most common form of kidney stone is composed of calcium oxalate, and its formation is promoted by high concentrations of calcium and oxalate in the urine. A high animal protein intake in healthy humans increases urinary calcium and oxalate and the overall probability of form- ing kidney stones by 250 percent (Robertson et al. Conversely, restricting protein intake improved the lithogenic profile in hypercalciuric patients (Giannini et al. Also, the incidence of calcium oxalate stones has been shown to be associated with consumption of animal pro- tein (Curhan et al. In this study, 50 patients were given low animal protein (56 to 64 g/d) and high fiber, plus adequate fluid and calcium, whereas 49 control patients were only instructed to take adequate water and calcium. However, as protein intake was not the only variable, and in view of the data described above suggesting benefits from lower protein intake, further investigation is necessary.
U. Trano. Adams State College. 2019.