Global Changes in Diet and Activity Patterns as Drivers of the Nutrition Transition
Barry M. Popkin, USA
The nutrition transition relates to broad patterns of diet, activity and body composition that have defined our nutritional status in various stages of history. The world is rapidly shifting from a dietary period in which the higher-income countries were dominated by patterns of nutrition-related noncommunicable diseases (NR-NCD’s) (while the lower and middle world were dominated by receding famine) to one in which the world is increasingly being dominated by NR-NCD’s. Dietary changes appear to be shifting universally toward a diet dominated by higher intakes of caloric sweeteners, animal source foods, and edible oils. Activity patterns at work, leisure, travel, and in the home are equally shifting rapidly toward reduced energy expenditure. Large-scale declines in food prices (e.g., beef prices) increased access to supermarkets, and urbanization of urban and rural areas are key underlying factors
Regional Case Studies – China
Shi-an Yin, China
The status of Childhood Malnutrition and Obesity in China was reviewed, according to 2002 National Nutritional and Health Survey in China and the data from survey on National student Health and Physical Fitness of China in 2005. The quick economic development change has been achieved from 1979 to 2008 in China, and faced a transition period characteristic of the significant increase of prevalence of chronic noncommunicable diseases. Compared with the results in 1992, the status of body weight and height of preschool children in urban and rural areas were significantly improved; the prevalence of malnutrition (underweight and stunting) in the urban and rural areas was significantly reduced; the National averaged prevalence of overweight and obesity for the children under 6 y were 3.4% 2.0% estimated by the Chinese and WHO standards respectively; the deficiency of micronutrients, including calcium, zinc, vitamin A, vitamin B1 and B2, is rather common in the preschool and school children. The current data showed that the situation of growth and development of Chinese children is far from ideal. Now we are facing double challenges, which mean malnutrition and the increase of overweight and obesity in children.
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This paper explores whether there is any evidence that the rapid development of the obesity epidemic in emerging nations, and its unusual coexistence with malnutrition, may have evolutionary origins that make such populations especially vulnerable to the obesogenic conditions accompanying the nutrition transition. It is concluded that any selection of so-called ‘thrifty genes’ is likely to have affected most races due to the frequency and ubiquity of famines and seasonal food shortages in ancient populations. Although it remains a useful stimulus for research, the thrifty gene hypothesis remains a theoretical construct that so far lacks any concrete examples. There is currently little evidence that the ancestral genomes of native Asian or African populations carry particular risk alleles for obesity. Interestingly, however, there is evidence that a variant allele of the FTO gene that favours leanness is not active in Asians or Africans. There is also some evidence that Caucasians may be less prone to developing Type 2 diabetes mellitus than other races suggesting that there has been recent selection of protective alleles. In the near future, recently-developed statistical methods for comparing genome-wide data across populations are likely to reveal or refute the presence of any thrifty genes and might indicate mechanisms of vulnerability.
Prenatal origins of undernutrition
Parul Christian, USA
Undernutrition continues to be high in many regions of the developing world. Birth weight, a common proxy measure of intrauterine growth, is influenced by nutritional, environmental and life style factors during pregnancy and, in turn, affects immediate survival and function, and is a determinant of later life risk of chronic diseases. Maternal pre-pregnancy weight and height are independently associated with birth weight and also modify the effects of pregnancy weight gain and interventions during pregnancy on birth weight and perinatal mortality. Other prenatal factors commonly known to impact birth weight include maternal age, parity, sex, and birth interval, whereas lifestyle factors such as physical activity and maternal stress, as well as environmental toxicants have variable influences. Tobacco and other substance use and infections, specifically ascending reproductive tract infections, malaria, and HIV can cause intrauterine growth restriction (IUGR). Few studies have examined the contribution of prenatal factors including low birth weight to childhood wasting and stunting. Studies that have, with adequate adjustment for confounders, have generally found odds ratios associated with low birth weight ranging between 2 and 5. Even fewer studies have examined birth length or maternal nutritional status as risk factors. More research is needed to determine the proportion of childhood undernutrition attributable to IUGR so that interventions can be targeted to the appropriate life stages.
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Postnatal origins of malnutrition
Marc-André Prost, UK
Obesity and nutrition-related chronic disorders are fast rising in developing countries. But undernutrition – stunting, underweight, wasting and micronutrient deficiencies - still affect millions of preschool children in both rural and urban settings increasing the risks of morbidity and mortality, impairing cognitive development, reducing productivity and increasing the risk of chronic diseases in later life. In addition undernutrition has a transgenerational effect. In this chapter I review the evidence for a synergistic effect of inadequate nutrition (breastfeeding, complementary feeding), infection, and inappropriate mother-child interactions on growth and nutritional deficiencies. Underlying socioeconomic, environmental and genetic factors are also explored. Finally some perspectives on how urbanisation and globalisation may affect the prevalence and distribution of undernutrition are discussed. Fighting child undernutrition is still an urgent necessity and a moral imperative.
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Malnutrition, Long-term Health and the Effect of Nutritional Recovery
Anne-Lydia Sawaya, Brazil
It is estimated that over 51 million people in Brazil live in slums, areas where a high prevalence of malnutrition is also found. In general, the population of “slum dwellers” is growing at a faster rate than urban populations. This condition is associated with poor sanitation, unhealthful food habits, low birth weight, and stunting. Stunting is of particular concern as longitudinal and cross-sectional studies of stunted adolescents have shown a high susceptibility to gain central fat, lower fat oxidation, and lower resting and postprandial energy expenditure. In addition, higher blood pressure, higher plasma uric acid and impaired flow-mediated vascular dilation were all associated with a higher level of hypertension in low birth weight and stunted children. In particular, stunted boys and girls showed also lower insulin production by pancreatic beta cells. All these factors are linked with higher risk of chronic diseases later in life. Among stunted adults, alterations in plasma lipids, glucose and insulin have also been reported. However, adequate nutritional recovery with linear catch-up growth, after treatment in nutritional rehabilitation centers, can moderate the alterations in body composition, bone density and insulin production.
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The role of epigenetics in mediating environmental effects on phenotype
Emma Whitelaw, Australia
Epigenetics is being suggested as a possible interface between the genetic and environmental factors that together give rise to phenotype. In mice there exists a group of genes, known as metastable epialleles, which are sensitive to environmental influences, such as diet, and undergo molecular changes that remain for the life of the individual. These modifications are epigenetic and in some cases they survive across generations, that is, through meiosis. This is termed transgenerational epigenetic inheritance. These findings have led to the idea that similar processes might occur in humans. Although it is clear that the lifestyle of one generation can significantly influence the health of the next generation in humans, in the absence of supporting molecular data, it is hard to justify the notion that this is the result of transgenerational epigenetic inheritance. What is required first is to ascertain whether genes of this type, that is genes that are sensitive to epigenetic state, even exist in humans.
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Protein restriction, fatty liver and methionine metabolism
Satish Kalhan, USA
The coexistence of intrauterine and neonatal malnutrition and the development of obesity, type II diabetes and related comorbidities have been confirmed in a number of studies in humans and in animal models. Data from studies in animals suggest that epigenetic changes as a result of altered methylation of the genomic DNA may be responsible for such metabolic patterning. Methionine, an essential amino acid, plays a critical role in the methyltranferases involved in the methylation by providing the one-carbon units via the methionine transmethylation cycle. Because of its interaction with a number of vitamins (B12, folate, pyridoxin), its regulation by hormones, i.e. insulin and glucagon, and by the changes in redox state, methionine metabolism is effected by nutrient and environmental influences and by altered physiological states. In the present review the impact of human pregnancy, dietary protein restriction and fatty liver disease on methionine metabolism is discussed. The role of methionine in metabolic programming in a commonly used model of intrauterine growth retardation and in propagation of fatty liver disease is briefly described.
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Adiposity and Comorbidities: Favorable Impact of Caloric Restriction
Eric Ravussin, USA
The focus of this chapter is on research involving long-term calorie restriction (CR) to prevent or delay the incidence of the metabolic syndrome with age. The current societal environment is marked by overabundant accessibility of food coupled with a strong trend of reduced physical activity, both leading to the development of a constellation of disorders including central obesity, insulin resistance, dyslipidemia and hypertension (metabolic syndrome).
Prolonged CR has been shown to extend median and maximal lifespan in a variety of lower species (yeast, worms, fish, rats, and mice). Mechanisms of this lifespan extension by CR are not fully elucidated, but possibly involve alterations in energy metabolism, oxidative damage, insulin sensitivity, and functional changes in neuroendocrine systems. Ongoing studies of CR in humans now makes it possible to identify changes in “biomarkers of aging” to unravel some of the mechanisms of its anti-aging phenomenon.
Analyses from controlled human trials involving long-term CR will allow investigators to link observed alterations from body composition down to changes in molecular pathways and gene expression, with their possible effects on the metabolic syndrome and aging.
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Obesity, Inflammation, and Macrophages
Vidya Subramanian, USA
The World Health Organization estimates that since 1980 the prevalence of obesity has increased more than three-fold throughout much of the world, and this increase is not limited to developed nations [1]. Indeed, the incidence of obesity is increasing most rapidly among rapidly industrializing countries raising the specter of a burgeoning epidemic in obesity associated diseases, including diabetes, dyslipidemia, non-alcoholic fatty liver disease and atherosclerosis [1, 2]. Reducing the rates of obesity and its attendant complications will require both coordinated public health policy and a better understanding of the pathophysiology of obesity. Obesity is associated with low grade chronic inflammation, a common feature of many complications of obesity that appears to emanate, in part from adipose tissue. In obese individuals and rodents adipose tissue macrophage accumulation is a critical component in the development of obesity induced inflammation. The macrophages in adipose tissue are bone marrow derived and their number is strongly correlated with body weight, body mass index and total body fat. The recruited macrophages in adipose tissue express high levels of inflammatory factors that contribute to systemic inflammation and insulin resistance. Interventions aimed at either reducing macrophage numbers or decreasing their inflammatory characteristics improves insulin sensitivity and decreases inflammation. Macrophage accumulation and adipose tissue inflammation are dynamic process under the control of multiple mechanisms. Investigating the role of macrophages in adipose tissue biology and the mechanisms involved in their recruitment and activation in obesity will provide useful insights for developing therapeutic approaches for treating obesity induced complications.
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Obesity, hepatic metabolism and disease
Arthur McCullough, USA
Nonalcoholic steatohepatitis (NASH), which is the most severe histological form of nonalcoholic fatty liver disease (NAFLD), is emerging as the most common clinically important form of liver disease in developed countries. Although its prevalence is 3% in the general population, this increases to 20-40% in obese patients. Since NASH is associated with obesity, its prevalence has been predicted to increase along with the growing epidemic of obesity and type II diabetes mellitus. The importance of this observation comes from the fact that NASH is a progressive fibrotic disease, in which cirrhosis and liver-related death occur in 25% and 10% in these patients, respectively, over a 10-year period. This is of particular concern given the increasing recognition of NASH in the developing world.
Treatment consists of treating obesity and its co-morbidities: diabetes and hyperlipidemia. Nascent studies suggest that a number of pharmacological therapies may be effective, but all remain unproven at present. Histological and laboratory improvement occurs with a 10% decrease in body weight. Bariatric surgery is indicated in selected patients.
A greater understanding of the pathophysiological progression of NASH in obese patients must be obtained in order to develop more focused and improved therapy.
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New approaches to optimising early diets
Staffan Polberger, Sweden
Most extremely low birth weight (ELBW; < 1000 g) infants will survive if cared at a tertiary neonatal intensive care unit, and should be given optimal nutrition for brain development. Human milk confers nutritional and non-nutritional advantages over infant formula, and is started during the first hours of life. In Sweden, most ELBW infants are fed individually with mother´s own milk (preferred) and banked milk, with supplementary parenteral nutrition.. There is an enormous variation in particularly fat and protein content in milk between mothers, during the day and the course of lactation. Infra-red macronutrient analyses on 24-hour collections of mother’s milk are performed once a week allowing for optimal protein and energy intakes. All banked milk is analyzed, and the most protein-rich milk is given to a newborn ELBW infant. After two weeks, the milk may be fortified if the protein or energy intakes needs to be further increased, and fortification is continued throughout the tube-feeding period. Parenteral nutrition is continued until the enteral intake constitutes 75-80% of the total volume intake. Protein markers, e.g. serum urea and transthyretin are assessed, and growth is monitored by measurements of weight, crown-heel length and head circumference.
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Community based approaches to address childhood undernutrition and obesity in developing countries
Prakash Shetty, UK
Community based approaches have been the mainstay of interventions to address the problem of child malnutrition in developing societies. Many programmes have been in operation in several countries for decades and originated largely as social welfare, food security and poverty eradication programmes. Increasingly conceptual frameworks to guide this activity have been developed as our understanding of the complex nature of the determinants of undernutrition improves. Alongside this evolution, is the accumulation of the evidence of the types of interventions in the community that are effective, practical and sustainable. The changing environment is probably determining the changing scenario of child nutrition in developing societies with rapid developmental transition and urbanisation being responsible for the emerging problems of obesity and other metabolic disorders largely the result of the linkages that are now well recognised between child undernutrition and early onset adult chronic diseases. This dramatic change is contributing to the double burden of malnutrition in developing countries. Community interventions hence need to be integrated and joined up to reduce both aspects of the malnutrition in societies. The evidence that community based nutrition interventions can have a positive impact on pregnancy outcomes and child under nutrition needs to be evaluated to enable programmes to prioritise and incorporate those interventions that work in the community. Programmes that are operational and successful also need to be evaluated and disseminated in order to enable countries to generate their own programmes tailored to tackle the changing nutritional problems of the children in their society.
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