823 resultados para Nutrition--In adolescence
Resumo:
Previous research has shown that the stress hormone corticosterone can increase depressive and anxiety-like behavior in rats as well as dampen the HPA response to a novel stressor (Kalynchuk et aI., 2004; Johnson et aI., 2006). Several studies have also shown that adolescence is a period of increased sensitivity to the negative effects of stressors (reviewed in McCormick et aI., 2010), which are often the result of exposure to corticosterone, and yet there is no research to date examining the effects of corticosterone administration during adolescence. The purpose of these experiments is to determine both the immediate and enduring effects of prolonged exposure to corticosterone in adolescence and adulthood on anxiety-like behavior, depressive behavior, and the HPA response. In Experiment 1 adolescent and adult rats were administered an injection of 40 mg/kg of corticosterone or vehicle daily for 16 days. Ha l f of the rats were then tested on the elevated plus maze (EPM) one day after their last injection, and the following day were tested on the forced swim test (FST). After the FST, which is a stressor, blood samples were collected at three time points, and the plasma concentrations of corticosterone were determined using a radioimmunoassay. The remaining rats were left undisturbed for three weeks, and then underwent the same testing as the first group. Corticosterone treatment had little effect on anxiety-like and depressive behavior, but it did alter the HPA response to the FST. In those rats tested soon after the period of injections, corticosterone dampened the HPA response as compared to vehicle treated rats in both adolescent and adult treated rats. For the adolescent treated rats that were tested several weeks later, corticosterone treatment increased HPA response as compared to the vehicle treated rats, but the same was not true for the adult treated rats. I t was hypothesized that the lack of behavioral effects of the corticosterone treatment may be the result of the vehicle injections inducing a stress response and thereby both groups would have similarly altered behavior. In Experiment 2 rats were administered corticosterone dissolved in their drinking water with 2.5% ethanol, or jus t the 2.5% ethanol or plain water, to determine the effects of corticosterone treatment without a stressor present. The regular drinking water was replaced with treated water for 16 days either during adulthood or adolescence, and as before, rats were either tested in the FST one day after the water was removed or three weeks later. Again there was no effect of treatment on depressive behavior. Similar to what was observed in Experiment 1, corticosterone treatment dampened the HPA response to a stressor for the rats tested soon after the treatment period. However, in Experiment 2 there was no effect of treatment on HPA response in those rats tested several weeks after they were treated. These results indicate that corticosterone can have a lasting effect on the HPA when administered in adolescence by injections but not in drinking water, which is likely because of the different schedules of exposure and rates of absorption between the two administration methods.
Resumo:
The development of high throughput techniques ('chip' technology) for measurement of gene expression and gene polymorphisms (genomics), and techniques for measuring global protein expression (proteomics) and metabolite profile (metabolomics) are revolutionising life science research, including research in human nutrition. In particular, the ability to undertake large-scale genotyping and to identify gene polymorphisms that determine risk of chronic disease (candidate genes) could enable definition of an individual's risk at an early age. However, the search for candidate genes has proven to be more complex, and their identification more elusive, than previously thought. This is largely due to the fact that much of the variability in risk results from interactions between the genome and environmental exposures. Whilst the former is now very well defined via the Human Genome Project, the latter (e.g. diet, toxins, physical activity) are poorly characterised, resulting in inability to account for their confounding effects in most large-scale candidate gene studies. The polygenic nature of most chronic diseases offers further complexity, requiring very large studies to disentangle relatively weak impacts of large numbers of potential 'risk' genes. The efficacy of diet as a preventative strategy could also be considerably increased by better information concerning gene polymorphisms that determine variability in responsiveness to specific diet and nutrient changes. Much of the limited available data are based on retrospective genotyping using stored samples from previously conducted intervention trials. Prospective studies are now needed to provide data that can be used as the basis for provision of individualised dietary advice and development of food products that optimise disease prevention. Application of the new technologies in nutrition research offers considerable potential for development of new knowledge and could greatly advance the role of diet as a preventative disease strategy in the 21st century. Given the potential economic and social benefits offered, funding for research in this area needs greater recognition, and a stronger strategic focus, than is presently the case. Application of genomics in human health offers considerable ethical and societal as well as scientific challenges. Economic determinants of health care provision are more likely to resolve such issues than scientific developments or altruistic concerns for human health.
Resumo:
Two controlled microcosm experiments aimed at a critical re-assessment of the contributions of divergent arbuscular mycorrhizal (AM) fungi to plant mineral nutrition were established that specifically targeted Plantago lanceolata–Glomus intraradices (B.B/E) and –Gigaspora margarita (BEG 34) symbioses developed in a native, nutrient limited, coastal dune soil. Plant tissue nitrogen (N), phosphorus (P) and potassium (K) status as well as plant growth parameters and levels of mycorrhizal colonization were assessed at harvest. In addition to the general well-established mycorrhizal facilitation of P uptake, the study was able to demonstrate a G. intraradices-specific contribution to improved plant nitrogen and potassium nutrition. In the two respective experiments, G. intraradices-inoculated plants had 27.8% and 40.8% more total N and 55.8% and 23.3% more total K when compared to Gi. margarita inoculated counterparts. Dissimilar overall contribution of the two isolates to plant nutrition was identified in AM-genus specific differences in plant tissue N:P:K ratios. G. intraradices inoculated and non-mycorrhizal plants generally exhibited N:P:K ratios indicative of P limitation whereas for Gi.margarita mycorrhizal plants, corresponding ratios strongly implied either N or K limitation. The study provides further evidence highlighting AM functional biodiversity in respect to plant nutrient limitation experienced by mycorrhizal P. lanceolata in an ecologically relevant soil system.
Resumo:
Fat is a major contributor to energy intake in most Western diets, supplying 35–40% of food energy. It is described as being ‘energy-dense’, because a gram of fat (9 kcal/g) yields more than twice as much metabolisable energy as a gram of either carbohydrate or protein (4 kcal/g). Most of the fat we consume in our diet is in the form of triacylglycerol (90-95%), with cholesterol and phospholipids making up the bulk of the remainder. Dietary advice invariably stresses the importance of fat reduction, yet fats have diverse roles in human nutrition. They are important as a source of energy, both for immediate utilisation by the body and in laying down a storage depot (adipose tissue) for later utilisation when food intake is reduced, they act as a vehicle for the ingestion and absorption of fat-soluble vitamins, and they have diverse structural and functional roles in the body. Cholesterol is also an essential component of cell membranes and is the precursor for synthesis of hormones. This chapter describes the structure, digestion, transport and functional properties of dietary fat in the body and explains the basis of associations between fat consumption and chronic disease.
Resumo:
Patients with neurological disorders have an increased risk of oral and systemic diseases due to compromised oral hygiene. If patients lose the ability to swallow and chew food as a result of their disorder, enteral nutrition is often utilized. However, this type of feeding may modify salivary antioxidant defenses, resulting in increased oxidative damage and the emergence of various diseases. The aim of this study was to evaluate the effects of enteral nutrition on biochemical parameters in the unstimulated whole saliva composition of patients with neurological disorders. For this, enzymatic (superoxide dismutase - SOD; glutathione peroxidase - GPx) and non-enzymatic (uric acid; ferric ion reducing antioxidant power - FRAP) antioxidant activity, as well as a marker for oxidative damage (thiobarbituric acid reactive substances - TBARS) were analyzed. Unstimulated whole saliva was collected from 12 patients with neurological disorders and tube-feeding (tube-fed group - TFG), 15 patients with neurological disorders and normal feeding via the mouth (non-tube-fed group - NTFG), and 12 volunteers without neurological disorders (control group - CG). The daily oral hygiene procedures of TFG and NTFG patients were similar and dental care was provided monthly by the same institution's dentist. All patients exhibited adequate oral health conditions. The salivary levels of FRAP, uric acid, SOD, GPx, TBARS, and total protein were compared between studied groups. FRAP was increased (p < 0.05) in the NTFG (4651 +/- 192.5 mmol/mL) and the TFG (4743 +/- 116.7 mmol/mL) when compared with the CG (1844 +/- 343.8 mmol/mL). GPx values were lower (p < 0.05) in the NTGF (8.24 +/- 1.09 mmol/min/mg) and the TFG (8.37 +/- 1.60 mmol/min/mg) than in the CG (15.30 +/- 2.61 mmol/min/mg). Uric acid in the TFG (1.57 +/- 0.23 mg/dL) was significantly lower than in the NTFG (2.34 +/- 0.20 mg/dL) and the CG (3.49 +/- 0.21 mg/dL). Protein was significantly lower in the TFG (5.35 +/- 0.27 g/dL) than in the NTFG (7.22 +/- 0.57 g/dL) and the CG (7.86 +/- 0.54 g/dL). There was no difference in the salivary flow rate and SOD between groups. Enteral nutrition in patients with neurological disorders was associated with lower oxidative damage, resulting in increased salivary. antioxidant capacity. These results emphasize the importance of oral care for this population to prevent oral and systemic diseases. (C) 2014 Elsevier Ltd. All rights reserved.
Resumo:
Guidelines for nutrition support in pancreatitis have been inconsistently adapted to clinical practice. The International Consensus Guideline Committee (ICGC) established a pancreatitis task force to review published guidelines for pancreatitis in nutrition support. A PubMed search using the terms pancreatitis, acute pancreatitis, chronic pancreatitis, nutrition support, parenteral nutrition, enteral nutrition, and guidelines was conducted for the period from January 1999 to May 2011. Eleven guidelines were identified for review. The ICGC used the following process to develop unified guideline statements: summarize the strength of evidence (grading) of the guidelines; establish level of evidence for ICGC statements as high, intermediate, and low; assign published guideline levels of evidence; and define an ICGC grading system. International Pancreatitis Guideline Grades were established as follows: platinum-high level of evidence and consistent agreement among the guidelines; gold-acceptable level of evidence and no conflicting statements in guidelines; and silver-single existing guideline statement with no conflict in other guidelines. Eighteen ICGC statements were derived from the 11 published pancreatitis guidelines. Uniform agreement from widely disparate groups (United States, Europe, Japan, and China) resulted in 4 platinum-level guideline statements for nutrition in pancreatitis: nutrition support therapy (NST) is generally not needed for mild to moderate disease, NST is needed for severe disease, enteral nutrition (EN) is preferred over parenteral nutrition (PN), and use PN when EN is contraindicated or not feasible. This methodology provides a template for future ICGC nutrition guideline development. (JPEN J Parenter Enteral Nutr. 2012;36:284-291)
Resumo:
Food and Nutrition Security (FNS) must be ensured to everybody. The school environment is favorable to the formation of healthy habits and citizenship. The National Curriculum Parameters (PCNs) guide the promotion of health concepts in a transversal way in the school curriculum. This study aimed to identify and analyze the approach used for food and nutrition themes in Fundamental Education's teaching material and its interface with the concept of FNS and the PCNs. Documental research was conducted on the teaching material from 5th to 8th grades of Fundamental Education in Public School of the state of Sao Paulo. The diffuse presence of food and nutrition themes was found in most disciplines in all bimesters in the four series, which shows the interdisciplinarity in health. It was found that the PCNs are related to the concept of SAN in its various aspects and that most subjects include topics that approach this relationship. In the correlation between themes, there is emphasis to health promotion and food production. The methodology used in the teaching material presents the theme, but not the correspondent content, what made the analysis of its suitability impossible. We conclude that there is the approach of the issues related to food and nutrition in the teaching material, some of them in an inconsistent way; it is the educators' task to select the contents and the appropriate strategy, doing an effort of constant update. This isbeing proposed by the State, however it is not accessible to all professionals and therefore still depends on the initiative of each teacher.
Resumo:
Background: Digestive complications in enteral nutrition (EN) can negatively affect the nutrition clinical outcome of hospitalized patients. Diarrhea and constipation are intestinal motility disorders associated with pharmacotherapy, hydration, nutrition status, and age. The aim of this study was to analyze the frequency of these intestinal motility disorders in patients receiving EN and assess risk factors associated with diarrhea and constipation in hospitalized patients receiving exclusive EN therapy in a general hospital. Materials and Methods: The authors performed a sequential and observational study of 110 hospitalized adult patients fed exclusively by EN through a feeding tube. Patients were categorized according to the type of intestinal transit disorder as follows: group D (diarrhea, 3 or more watery evacuations in 24 hours), group C (constipation, less than 1 evacuation during 3 days), and group N (absence of diarrhea or constipation). All prescription drugs were recorded, and patients were analyzed according to the type and amount of medication received. The authors also investigated the presence of fiber in the enteral formula. Results: Patients classified in group C represented 70% of the study population; group D comprised 13%, and group N represented 17%. There was an association between group C and orotracheal intubation as the indication for EN (P<.001). Enteral formula without fiber was associated with constipation (logistic regression analysis: P<.001). Conclusion: Constipation is more frequent than diarrhea in patients fed exclusively by EN. Enteral diet with fiber may protect against medication-associated intestinal motility disorders. The addition of prokinetic drugs seems to be useful in preventing constipation. (Nutr Clin Pract. XXXX;xx:xx-xx)
Resumo:
STUDY OBJECTIVE: The objective of this study was to investigate the impact of two different socioeconomic status (SES) measures on child and adolescent self reported health related quality of life (HRQoL). The European KIDSCREEN project aims at simultaneous developing, testing, and implementing a generic HRQoL instrument. DESIGN AND SETTING: The pilot version of the questionnaire was applied in school surveys to students from 8 to 18 years of age, as well as to their parents, together with such determinants of health status as two SES indicators, the parental educational status and the number of material goods in the family (FAS, family affluence scale). PARTICIPANTS: Students from seven European countries: 754 children (39.8%; mean: 9.8 years), and 1142 adolescents (60.2 %; mean: 14.1 years), as well as their respective parents. MAIN RESULTS: In children, a higher parental educational status was found to have a significant positive impact on the KIDSCREEN dimensions: physical wellbeing, psychological wellbeing, moods and emotions, bullying and perceived financial resources. Increased risk of low HRQoL was detected for adolescents in connection with their physical wellbeing. Family wealth plays a part for children's physical wellbeing, parent relations and home life, and perceived financial resources. For adolescents, family wealth furthermore predicts HRQoL on all KIDSCREEN dimensions. CONCLUSIONS: There is evidence to suggest that exposure to low parental educational status may result in a decreased HRQoL in childhood, whereas reduced access to material (and thereby social) resources may lead to a lower HRQoL especially in adolescence.
Resumo:
Within the context of the health reforms introduced in Spain in the early 20th century and the influence of international health organisations on their development, this article analyses the growing interest that surrounded nourishment and food-related problems at that time in relation to healthcare, the diagnosis provided by hygienists of such problems, and the public health measures applied to resolve them. The issue of hygienic diet and the collective aspect of nutritional problems became priorities in the field of healthcare. Two of the most prominent initiatives involved setting up a Department of Nutrition and Food Hygiene and Bromatological Technique during the early years of the Second Republic, as part of the National School of Health, as well as a Food Hygiene Service. Spanish hygienists underlined the importance of education and the dissemination of information about food hygiene, health and nutrition, in order to overcome the qualitative and quantitative deficiencies observed in the average diet of the Spanish population.
Resumo:
Adolescents - defined as young people between 10 and 19 years of age1 - are, in general, a relatively healthy segment of the population.2 However, the developmental changes that take place during adolescence may affect their subsequent risk for diseases and for a variety of health-related behaviors. In fact, early onset of preventable health problems (e.g. obesity, malnutrition, STDs) and the engagement in health risk behaviors (e.g., sedentary life style, excessive alcohol consumption, unprotected sex) during adolescence, are likely to put them at greater risk for physical and mental health problems at a later stage in life. Moreover, health related problems and health risk behaviors may disrupt adolescents' physical and cognitive development and therefore may affect their ability to think and act in relation to decisions about their health in the future.1 In summary, health-related behaviors in adolescence, apart from their influence on the continuum of "health-disease", they also have the potential to influence future behaviors. In fact, several studies have shown that past behaviors are good predictors of future behaviors .3,4 Thus, promoting healthy practices during adolescence and taking measures to better protect young people from health risks are essential for the prevention of health problems in adulthood.5 According to the World Health Organization, the main problems affecting young people include mental health problems (such as behavioral disorders, eating disorders, suicide, anxiety or depression), the use of substances (illegal substances, alcohol and tobacco), interpersonal violence, nutrition (a proper nutrition consists of healthy eating habits and physical exercise), unintentional injuries (which are a leading cause of death and disability among young people, with road traffic injuries accounting for about 700 deaths per day), sexual and reproductive health (for example, risky sexual behaviors, early pregnancy and childbirth) and HIV (resulting from sexual transmission and drug injection).5,6 On the other hand, the number of children and youth with chronic health conditions has increased dramatically in the past four decades7 as larger numbers of chronically ill children survive beyond the age of 10.8 Despite the lack of data on adolescents' health making it difficult to determine the prevalence of chronic illnesses in this age group9, it is known that one in ten adolescents suffers from a chronic condition worldwide.10 In fact, national population based studies from Western countries show that 20-30% of teenagers have a chronic illness, defined as one that lasts longer than six months.8 The most prevalent chronic illness among adolescents is asthma and the one with the highest incidence is diabetes mellitus, particularly type II.9 Traditionally, healthcare professionals have been mainly investing in health education activities, through the transmission of knowledge with a view to creating habits, customs and behaviors, and promoting healthy lifestyles. However, empowering people does not only consist of giving them the right information11 , i.e. good information is not enough to cause people to make changes.12 The motivation or desire to change unhealthy behaviors and habits depends on many factors, namely intrinsic motivation, control over personal decisions, self-confidence and perception of effectiveness, personal ambivalence, and individualized assistance.12 Many professionals assume that supplying knowledge is sufficient for behavioral changes; however, even very good advice often fails to generate behavioral change. After all, people continue to engage in unhealthy behaviors despite clearly knowing what they should do and how to change. "What is lacking is the motivation to apply that knowledge".13, p.1233 In fact, behavioral change is a complex phenomenon with multiple determinants that also includes motivational variables. It is associated with ambivalent processes expressed in the dilemma between keeping the current status and moving on to new ways of acting. For example, telling adolescents that if they keep on engaging in a certain behavior, they are increasing the risk of developing a long-term condition such as cardiovascular disease, stroke or diabetes is rarely enough to trigger the desired behavioral change; people are more likely to change when they believe that the change is really effective and that they are able to implement it.12 Therefore, it is essential to provide specific training for "healthcare professionals to master motivational techniques, avoid confrontation with the users, and facilitate behavioral changes".14 In this context, motivating patients to make behavioral changes is also an important nursing task where change in lifestyle is a major element of patients' treatment and preventive interventions.15 One of the nurse's goals is to help improve a patient's health or help them to manage existing health conditions. Once nurses are in a position where they have to focus on accomplishing tasks and telling patients what needs to be accomplished16, the role of the nurse is expanding even more into the use of motivational strategies.17 MI is bringing nurses back to therapeutic communication and moving them closer to successful health promotion and disease management, by promoting behavior change and empowering their patients. As the nursing profession evolves, MI is seen as a challenge and the basis of nurse's interactions with individuals, families and communities.16, 17 In the same way, MI may be taken as an essential tool in the provision of nursing care to adolescents, being itself a workspace with possible therapeutic effects regarding problems, clarification of doubts, and development of skills.18 In fact, MI may be particularly applicable in work with adolescents because of their specific developmental stage. Adolescents attempt to establish their own autonomy and identity while struggling with social interactions and moral issues, which leads to ambivalence.19 Consistent with the developmental challenges during adolescence, "MI explicitly honors autonomy, people's right and irrevocable ability to decide about their own behavior"20 while allowing the person to explore possibilities for change of risky or maladaptive behaviours.19 MI can be defined as a directive, client-centred counselling style for eliciting behavior change by helping clients to explore and resolve ambivalence. It is most centrally defined not by technique but by its spirit as a facilitative style of interpersonal relationship.21 It is a set of strategies and techniques widely used in clinical practice based on the transtheoretical model of change. The Stages of Change model describes five stages of readiness—precontemplation, contemplation, preparation, action, and maintenance—and provides a framework for understanding behavior change.22 The MI has been widely tested and applied in different areas, such as modification of addictive behaviors, interventions with offenders in the context of justice, eating disorders, promotion of therapeutic adherence among chronic patients, promotion of learning in school settings or intervention with adolescents at risk.18,23 In general, clinical practice has been adopting the perspective of motivation as something relatively immutable, i.e., the adolescent is either motivated for change/treatment and, in these conditions, the professional's role is to help him/her, or the adolescent is not motivated and then change/treatment is not feasible. Alternatively the theoretical model underlying the MI technique postulates that the individual's adherence to change/treatment depends on his/her motivation, which can change throughout the therapeutic intervention. As several studies found positive results for effects of MI24-26 and its use by health professionals is encouraged23,27 nurses may play an important role in patients' process of change. As nurses have a crucial role in clinical contexts, they can facilitate the process of ending risk behaviors and/or adopting positive health behaviors through some motivational techniques, namely with adolescents. A considerable number of systematic reviews about MI already exist pointing to some benefits of its use in the treatment of a broad range of behavioral problems and diseases.13,28,29 Some of the current reviews focus on examining the effectiveness of MI for adolescents with diverse health risks/problems 30-32. However, to date there are no reviews that present and assess the evidence for the use of nurse-led MI in adolescents. Therefore, we have little knowledge of what works for whom (which adolescent subpopulation) under what circumstances (in which setting, for what problem) in relation to motivational interviewing by nurses. There is a clear need for scoping or mapping the use of MI by nurses with adolescents to identify evidence gaps and to inform opportunities for future development in nursing practice. On the other hand, information regarding nurse-led implemented and evaluated interventions, techniques and/or strategies used, contexts of application and adolescents subpopulation groups is dispersed in the literature33-36 which impedes the formulation of precise questions about the effectiveness of those interventions conducted by nurses and therefore the realization of a systematic review. In other words, it is known that different kind of motivational interventions have been implemented in different contexts by nurses, however does not exist a map about all the motivational techniques and/or strategies used. Furthermore the literature does not clarify which is the role of nurses at cross professional motivational intervention implemented programs and finally the outcomes and evaluation of interventions are unclear. Thus, the practical implication of this mapping will be clarifying all these aspects. Without this clarification is not possible to proceed to the realization of a systematic review about the effectiveness of the use of motivational interviews by nurses to promote health behaviors in adolescents, in a particular context and/or health risk behavior; or regarding the effectiveness of certain technique and/or strategy of MI. Consequently, there are important questions about the nature of the evidence in this area that need to be answered before formulating a precise question of effectiveness. This scoping review aims to respond to these questions. An initial search of the JBI Database of Systematic Reviews & Implementation Reports, Cochrane Database of Systematic Reviews, , Database of promoting health effectiveness reviews (DoPHER), The Campbell Library, Medline and CINAHL, has revealed that currently there is no Scoping Review (published or in progress) on the subject. In this context, this scoping review will examine and map the published and unpublished research around the use of MI by nurses implemented and evaluated to promote health behaviors in adolescents; to establish its current extent, range and nature and identify its feasibility, outcomes and gaps in the evidence defining research priorities in this field. This scoping review will be informed by the JBI methodology37 that suggests a five stage methodological framework for conducting scoping reviews which includes: identifying the research question, searching for relevant studies, selecting studies, charting data, collating, summarizing and reporting the results.
Resumo:
Background: Despite improvements in child health, malnutrition still remains one of the main public health challenges in Iran. Objectives: The aim of this study was to compare under nutrition among under-five children with regard to ethnicity in rural area in north Iran. Patients and Methods: In three cross-sectional studies 7575 subjects in three time-periods including 2339 children in 1998, 2749 in 2004, and 2487 in 2013, were evaluated. All under-five-children in 20 out of 118 villages were chosen by random sampling and assessed. Under nutrition was defined as underweight, stunting and wasting lower than -2 SD (Z < -2 SD). Results: Generally, stunting was declined 17.1% and underweight and wasting were increased 0.9% and 1%, respectively during 15 years (1998 - 2013). Underweight increased 0.5% in Fars-natives and 3.2% in Turkmans and it was decreased 0.9% in Sistanis. Statistical difference in Turkman children among the three stages of the study was significant (P = 0.001). Stunting has decreased 28.7% in Fars-natives and 35.1% in Sistanis, it was increased 9.3% in Turkman group. Statistical differences among three stages in inter-ethnic groups were significant (P = 0.001 for all). Compared the group with good economic status, the odds ratio was 1.831 in poor economic group (P = 0.001). The risk of under nutrition in Sistanis was 1.754 times more than in Fars-natives (P = 0.001). Conclusions: Under nutrition remains one of the main health problems in under-five-year children in north Iran being more common in Sistani children. Stunting in Sistani children deeply decreased while in Turkman children slightly increased during the 15-year period study. Poor economic status is a risk factor for under nutrition in this area.
Mineral Nutrition Of Campos Rupestres Plant Species On Contrasting Nutrient-impoverished Soil Types.
Resumo:
In Brazil, the campos rupestres occur over the Brazilian shield, and are characterized by acidic nutrient-impoverished soils, which are particularly low in phosphorus (P). Despite recognition of the campos rupestres as a global biodiversity hotspot, little is known about the diversity of P-acquisition strategies and other aspects of plant mineral nutrition in this region. To explore nutrient-acquisition strategies and assess aspects of plant P nutrition, we measured leaf P and nitrogen (N) concentrations, characterized root morphology and determined the percentage arbuscular mycorrhizal (AM) colonization of 50 dominant species in six communities, representing a gradient of soil P availability. Leaf manganese (Mn) concentration was measured as a proxy for carboxylate-releasing strategies. Communities on the most P-impoverished soils had the highest proportion of nonmycorrhizal (NM) species, the lowest percentage of mycorrhizal colonization, and the greatest diversity of root specializations. The large spectrum of leaf P concentration and variation in root morphologies show high functional diversity for nutritional strategies. Higher leaf Mn concentrations were observed in NM compared with AM species, indicating that carboxylate-releasing P-mobilizing strategies are likely to be present in NM species. The soils of the campos rupestres are similar to the most P-impoverished soils in the world. The prevalence of NM strategies indicates a strong global functional convergence in plant mineral nutrition strategies among severely P-impoverished ecosystems.
Resumo:
OBJETIVO: Investigar os níveis séricos e a prevalência de inadequação da ingestão dietética de folato e das vitaminas B6 e B12, identificando os alimentos contribuintes para a ingestão desses nutrientes. MÉTODOS: Estudo observacional, transversal, em adolescentes de 16 a 19 anos, de ambos os sexos, conduzido em Indaiatuba (SP). Coletou-se o registro alimentar de 3 dias não consecutivos. A dieta habitual foi estimada pela remoção da variabilidade intrapessoal, e a prevalência de inadequação da ingestão, pelo método da estimated average requirement como ponto de corte. As análises bioquímicas de folato, B6 e B12 foram conduzidas de acordo com os métodos aceitos na literatura. RESULTADOS: O estudo foi conduzido com 99 adolescentes, a maioria do sexo feminino (58,6%), com média de idade de 17,6 (desvio padrão, DP 0,9) anos. As médias da concentração sérica de folato, B6 e B12 foram de 9,2 (DP 3,4) ng/mL, 18,7 (DP 5,1) nmol/L e 397,5 (DP 188,4) pg/mL, respectivamente; e a prevalência de inadequação da ingestão das vitaminas foi de 15,2, 10,2 e < 1%, respectivamente. Os alimentos que mais contribuíram para a ingestão dos nutrientes foram, para folato: pão francês, macarrão e feijões; para B6: arroz branco, carne de frango e carne bovina; e para B12: carne bovina magra, leite integral e carne bovina gorda. CONCLUSÕES: As prevalências de inadequação de folato, B6 e B12 mostraram-se baixas, possivelmente em decorrência da melhoria do acesso e da disponibilidade de alimentos, fontes dietéticas das vitaminas. Os feijões, presentes na dieta tradicional brasileira, ainda estão entre os principais alimentos que contribuíram para a ingestão de folato, mesmo após a fortificação mandatória com ácido fólico no Brasil.