Food and nutrition security embraces meeting energy, protein and nutrient needs for healthy life. Food systems overlap with agricultural systems in the area of food production, but also comprise the diverse set of institutions, technologies and practices that govern the way food is marketed, processed, transported, accessed and consumed.
The food system activities are grouped into four categories: producing food, processing and packaging food, distributing and retailing food, and consuming food. The review paper aims at highlighting the connections and linkages between food sustainability and food security.
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There are very strong linkages between food and nutrition security, responsible environmental stewardship and greater fairness in food management. The pattern of epigenetic information is transmitted via mitosis and is specific to each cell and tissue type and is essential to maintenance of the organism's gene expression profile. Since epigenetic effects can suffer interference from the environment during development, they are extremely relevant to the field of DOHaD studies.
The hypothalamus-pituitary-adrenal axis in early life and programming mechanisms. Exposure to glucocorticoids during the fetal period has been proposed as being one of the principal programming factors for increased risk of chronic diseases among individuals born with low birth weight, 39 being associated with an increased probability of later development of hypertension, diabetes and psychiatric disorders, such as depression and anxiety.
Abnormal HPA axis activity during vulnerable periods of development is thought to be related to the programming of an individual's pattern of health. This abnormality is attributed to chronic exposure to maternal glucocorticoids or to stress during gestation. Glucocorticoids are the largest subclass of steroidal hormones that regulate metabolic, cardiovascular, immune system and behavioral responses.
The GR is widely distributed throughout the brain and peripheral tissues. In its inactive state, GR is part of a multi-protein compound made up of several heat shock proteins. In the majority of vertebrates, secretion of glucocorticoids follows a pronounced circadian rhythm, with peaks corresponding to the start of the active phase of the daytime cycle. Regulation of HPA axis activity is to a great extent performed by means of negative feedback via glucocorticoids to components of the central nervous system CNS , increasing or reducing its activity in accordance with physiological requirements.
Glucocorticoids are of fundamental importance to gestation in mammals, since they are involved in maternal metabolic adaptation. During gestation, lipophilic steroids easily pass through the placenta, but levels of fetal glucocorticoids are much lower than maternal levels. In humans, maternal plasma levels of corticotropin-releasing hormone CRH, produced by the placenta increase exponentially as the pregnancy progresses, reaching their peak at birth.
With premature deliveries this increase is much more rapid. Stimulation of the fetal pituitary by CRH increases ACTH production and, consequently, adrenal cortisol production, resulting in maturation of the fetal HPA axis and inducing formation of surfactant in the lungs.
In mammals, the responsiveness of the HPA axis fluctuates during the perinatal period, being moderately responsive at the time of birth, but reducing in intensity during the neonatal period. According to the concept of programming, exposure to a stimulus or stress during these first days determines neurochemical and behavioral alterations that can be observed throughout life.
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Although "hyporesponsive", these individuals responded acutely to the stress of being separated from their mothers even when not exposed to any other additional stressor, 69 and this response increased progressively over the subsequent 24 hours. Furthermore, during this phase, transcortin levels are very low and the majority of glucocorticoids circulate in plasma in their unbound and, therefore, biologically active form. One interesting example of the interaction between genes and environment, with relation to the HPA axis, is the model which evaluates natural differences in maternal care among rats, demonstrating that the environment in which offspring grow up is correlated with their reactivity to stress; where the young of mothers who exhibited more caring behavior licking and grooming are less responsive than the young of mothers who exhibited less of these behaviors.
The importance of childhood growth patterns. The initial studies relating low birth weight with increased cardiovascular risk were primarily based on intrauterine growth restriction IUGR as the causative factor of these associations. Recent evidence suggests that a child's growth pattern during the first years of life is also strongly influenced by the pattern of fetal growth, which may determine an increase in the probability that unfavorable metabolic outcomes will occur.
Abnormal postnatal growth patterns have a significant relationship with the development of chronic diseases in later life, particularly in preterm NB with IUGR. Current practice recommends stimulation and promotion of the growth of low birth weight infants, aiming to reduce morbidity and mortality rates and to preserve neurocognitive aspects. However, some clinical studies have proposed that rapid weight gain catch up during this early period may be associated with increased incidence of cardiovascular disease in maturity. The risk factors for cardiovascular diseases 82 and for obesity 83 are consistently found in groups of individuals who have gained a great deal of body weight between birth and school age or preadolescence, particularly those who were born small or had low birth weight.
In other words, the consequences of a given body weight are conditioned as much by intrauterine as by later childhood growth. Therefore, the growth patterns that predispose to the development of chronic diseases are complex and it is important to make a distinction between early and late catch up.
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While the first appears to be beneficial, as discussed above, childhood obesity is known to have harmful effects over the long term, especially in the population of low birth weight babies, and must be prevented. For these reasons, despite having been approved by the Food and Drug Administration FDA in and in Europe in , and despite being currently recommended in the specialist literature, 84 the use of growth hormone GH for children who are small for gestational age and those with small stature remains controversial.
It is true that the psychosocial impact of the increase in final height has been recognized, however the knowledge that late catch up may have damaging consequences for this population over the long term makes indicating this treatment an arduous decision. Even the consensus document on the management of individuals born small for gestational age, which recommends the use of GH throughout childhood and adolescence in order to increase of final height, states that it is not currently known whether treatment of people born small for gestational age with GH during childhood and adolescence is associated with benefits or with amplified risks as metabolic consequences in adulthood.
Notwithstanding, it is important to point out that fetal growth should be considered a relevant risk factor for chronic diseases, although it cannot be treated as a causative factor. In other words, chronic diseases are not programmed in themselves, but the tendency towards the development of diseases appears to be programmed. There are countless interactions between fetal growth and variables involving the childhood and adolescent environments, however, the best way to approach the problem is to focus on the stages of life and their interactions with fetal and neonatal history.
Long-term consequences of nutrition during the first years of life. The association between neonatal events and increased risk of diseases in adulthood is not necessarily linked to low birth weight alone. Here, other programming mechanisms and signals appear to be important. Of these, one of the most often studied is nutrition at the start of life, about which little is yet known.
During the beginning of the 20th century the medical literature had already demonstrated an interest with relation to the impact of postnatal nutrition on somatic growth and on specific organs by means of dietary manipulation during critical periods. It is known that breastfed children exhibit growth kinetics that are different from those of children fed on formula. Since experimental studies have demonstrated that excessive nutrition during the neonatal period is associated with increased risk of obesity and metabolic syndrome in adulthood, 89 it is possible that this may be one of the mechanisms by which breastfeeding is able to protect against diseases throughout life.
It is also known that the compositional differences between breastmilk and artificial formula, such as the quantities of calories and proteins, are an important variable in this context. Another factor possibly involved is the different feeding behavior of breastfed babies, which exhibit a different frequency of suckling, 90 and also a greater degree of control over the quantity of milk consumed. Specifically in relation to lifelong protection, it has been shown that, for example, breastfeeding preterm infants is associated with an improved plasma lipid profile during adolescence, 92 and also with lower blood pressure levels.
Although several different studies, including meta-analyses and employing body mass index BMI as categorical variable, have demonstrated that breastfeeding is associated with a lower incidence of obesity, 94,95 those studies that have concentrated on body composition have not been able to establish the same association, or have identified very discrete effects. Additionally, this author also mentions the possibility of reverse causality, i.
Developmental origins of health and disease (DOHaD)
Although some studies indicate there are acute benefits to dietary supplementation with long chain polyunsaturated fatty acids n-3 and n-6 LCPUFA in artificial formula, 99 and also to prebiotics and probiotics given to the mother during pregnancy and breastfeeding, their long-term effects on the neurological and immunological development of individuals are not yet clear, and, in this context, further studies are needed. Scientific approaches. The study of DOHaD is an area of research that combines information from a variety of branches of knowledge, and is an interesting interface between the biological sciences and the area of health.
The questions and hypotheses are investigated with a variety of scientific approaches, including:. Large cohort studies based on perinatal databases compiled at the start of the 20th century were the basis for the construction of the first DOHaD models, primarily through the studies of Barker et al. Although this is the most appropriate approach for highlighting associations between early events and later outcomes, epidemiological studies do not prove causality.
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Furthermore, human cohorts are expensive and demand a great deal of involvement on the part of the research team and also the individuals being studied, and, in the case of DOHaD research, they only produce results over the long term. Losses to follow-up during the study period, questions about the validity of associations observed in adults for the current pediatric population and about superimposition of findings in different world populations limit the application of their results.
Clinical studies are relatively quicker to carry out than cohort studies and have elucidated important questions in the area, although they are still limited by ethical considerations. Relatively easy to carry out, less costly, faster and highly informative. Studies undertaken with animals have contributed a great proportion of the information known on the subject. However, extrapolation of the results to humans is extremely delicate and fragile. For example, many of the species used bear multiple young, making comparison with humans difficult. Species with single pregnancies have been proposed as alternatives sheep for example , but the differences in the degree of maturity at birth also interfere with comparisons.
This concept of scientific research, where researchers divide their time between "the bench and the bed", has an impressive number of followers among DOHaD researchers. With the ease of execution of basic studies, researchers apply acquired knowledge to generate hypotheses and questions relevant to human physiology, adapting protocols to tests that can be carried out with patients. DOHaD in developing countries. The majority of DOHaD studies have been carried out in developed countries, and the relevance of applying this evidence to healthcare in developing countries is only now beginning to be established.
The match or mismatch model, where the greatest risk of chronic diseases is the result of the highest degree of contrast between the fetal environment and the environment in which the individual grows up, reflects the experience of many people who live in developing countries.
The incidence of IUGR is high in these areas, partly because of the high prevalence rates of malnutrition among women. On the other hand, economic ascent and agricultural improvements have transformed the nutrition of children and adults, and the emergence of obesity in developing countries has been reported in many parts of the world.
Brazil also follows this pattern of contrast, even when different social classes are taken into consideration.
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It is important to observe that, in the large cohorts from Europe which started off DOHaD studies Hertfordshire, England and Helsinki, Finland , the association between low birth weight and cardiovascular diseases remains significant even when the current BMI of the people being analyzed is not taken into consideration.
However, similar studies carried out in Africa, China and India were only able to detect the same significant association when they adjusted their analysis for adult BMI. This suggests that there is a different pattern in developing countries, where being born with low birth weight only becomes a problem when followed by obesity.
One interesting study carried out in India demonstrates that insulin resistant adults born with low birth weight could be characterized by an increase in BMI between the ages of 2 and 12 years, even though they did not reach levels considered as overweight or obese by international standards.