Showing papers in "Food & Nutrition Research in 2006"

Can we predict who adopts health-promoting foods? Users of functional foods in Finland

Abstract: Background: Healthy eating has a social pattern, with women and those in high socioeconomic positions most likely to follow dietary guidelines. However, little is known about the association of sociodemographic and health factors with the use of health-promoting functional foods. Objective: The study examined the use of functional foods in Finland. Four widely used product types were examined in detail with respect to sociodemographic factors and personal efforts to promote health. Design: Data were obtained by computer-assisted telephone interviews of 1210 respondents representing the Finnish population above 15 years of age. Logistic regression analysis was applied to analyse the predictors of use of functional foods. Results: Sociodemographic variables were associated with the use of functional foods. The role of gender and age varied. In most cases, high education or high occupational position predicted use. Use was also associated with viewing healthy eating as important and consuming other functional foods. Efforts to lower cholesterol levels predicted the use of cholesterol-lowering spreads. Conclusions: Both sociodemographic factors and personal health efforts play a role in the adoption of functional foods. High socioeconomic position predicts use, whereas age and gender remain product specific. An important aspect is the connection of functional foods with efforts to lead a healthy life. For healthorientated consumers, functional foods may represent a complementary health practice. Keywords: consumers; eating; functional foods; health; sociodemographics

The New Nutrition Science project

Abstract: The New Nutrition Science project is the result of confluent thinking, especially within the past 10 years. It is a joint Initiative of the International Union of Nutritional Sciences and the World Health Policy Forum. It gives nutrition science, with its expression in food and nutrition policy, a new conceptual framework, a new definition, three dimensions and extended principles. The objective of the New Nutrition Science project is to enable nutrition science to gain all possible relevance in the circumstances of the twenty-first century. It remains work in progress. As expressed in the Giessen Declaration, the result of a workshop meeting held at the University of Giessen, the three dimensions of the new nutrition science are biological, social and environmental. Its concerns are personal, population, and planetary health and welfare. The broad conceptual framework of the New Nutrition Science project looks forward, and also marks a return to the days when nut rition science, and its predecessor discipline dietetics, had most salutary impact on public health. It takes into account the most pressing concerns that face us now, including a continued rising human population, the persistence of malnutrition, the rise of obesity and diabetes in early life, increased inequality within and between nations and populations, rapid changes in global and local food supplies, and the diminution and draining of natural resources. It is only by combining biological, social and environmental approaches that nutrition science can fulfil its potential to preserve, maintain, develop and sustain life on earth. Keywords: conceptual framework of nutrition; definition of nutrition; dimensions of nutrition; Giessen Declaration; principles of nutrition; three-dimensional nutrition science

Long-chain polyunsaturated fatty acids and inflammation

Abstract: Although part of the normal host response to infection or injury, inflammation is involved in many pathological conditions and disease states. Most interest in the influence of fatty acids on inflammatory processes has centred on the opposing actions of n-6 and n-3 polyunsaturated fatty acids (PUFAs). The n-6 PUFA arachidonic acid gives rise to the eicosanoid family of inflammatory mediators (prostaglandins, leukotrienes and related metabolites) and through these regulates the activities of inflammatory cells, the production of inflammatory cytokines, etc. Consumption of long-chain n-3 PUFAs [eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA)] decreases the amount of arachidonic acid in inflammatory cell membranes and so available for eicosanoid production. Thus, consumption of long-chain n-3 PUFAs results in decreased production of eicosanoids from arachidonic acid. EPA acts as an alternative substrate for eicosanoid synthesis giving rise to mediators tha t are less potent than the analogues produced from arachidonic acid. EPA and DHA give rise to newly discovered families of mediators termed E- and Dresolvins, respectively, which have anti-inflammatory and inflammation-resolving actions. In addition to this range of effects, long-chain n-3 PUFAs affect cell-signalling processes and gene expression in inflammatory cells, resulting in decreased expression of inflammatory cytokines and adhesion molecules. Such long-chain n-3 PUFA-induced effects may be of importance in protecting against the development of and lowering the severity of acute and chronic inflammatory conditions. There is good evidence for the efficacy of long-chain n-3 PUFAs in rheumatoid arthritis, with less strong evidence in other inflammatory conditions. The precursor n-3 PUFA, ?-linolenic acid, exerts some anti-inflammatory effects at very high intakes, perhaps reflecting the need for its conversion to EPA to be effective. Keywords: arachidonic acid; cytoki n e; eicosanoid; fish oil; inflammation; macrophage

The role of polyunsaturated lipids in membrane raft function

Abstract: Docosahexaenoic acid (DHA), with 22 carbons and six double bonds, is the longest, most unsaturated fatty acid commonly found in humans. It represents the extreme example of an omega-3 (n-3) polyunsaturated fatty acid. Since early epidemiology studies, DHA has been linked to alleviation of an enormous number of human afflictions, including heart disease, cancer and neurological disorders. How one simple molecule can affect so many seemingly unrelated abnormalities has been a contentious question for many years. One research direction has investigated events that follow the uptake of DHA into animal cell plasma membrane phospholipids. Summarized here is a variety of membrane properties impacted by the incorporation of DHA. DHA’s dynamic shape, consisting of multiple configurations, is very different from what its static, stick structure would indicate. DHA-containing phospholipids have a wide hydrophobic base compared with their hydrophilic head and so induce nega tive curvature strain that severely impacts the activity of a variety of important membrane proteins. The unusual structure means that DHA-rich membranes are also surprisingly thin and support high permeability, compression, fusion and flip-flop rates. DHA does not exist in an environment that is independent from other membrane lipids. Of particular interest is the interaction of DHA-containing phospholipids with the major lipid raft components cholesterol and sphingomyelin. From a wide variety of biophysical studies, primarily done on model lipid monolayers and bilayers, a new hypothesis is proposed suggesting that DHA may alter plasma membrane lipid raft structure and hence essential cell signaling events. A fundamental role for DHA affecting a feature common to all cells, membrane structure and function, may explain its wide variety of reputed health benefits. Keywords: docosahexaenoic acid; lipid rafts; membrane structure; polyunsaturated fatty acids; n-3

Reorganization of a hospital catering system increases food intake in patients with inadequate intake

Abstract: Background: Low food intake is a frequent problem in undernourished hospital patients. Objective: To study whether a reorganization of a hospital catering system enabling patients to choose their evening meal individually, in combination with an increase in the energy density of the food, increases the energy and protein intake of the patients. Design: Observational study comparing the food intake before and twice after the implementation of the new system, the first time by specially trained staff and the second time by ordinary staff members, following training. The amount of food served, eaten and wasted was measured, and energy and protein intake calculated. Results: The quartile of patients with the lowest energy intake consumed on average 128 kJ per patient [(95% confidence interval (CI) 79-178 kJ] with the old system; with the new system they consumed 560 kJ per patient (95% CI 489-631 kJ) on the first occasion, and 1021 kJ per patient (95% CI 939-1104 kJ) on the second occasion. With the old system, the wastage was on average 276 g per patient (48% of the total amount produced) compared with 118 g per patient (30%) and 78 g (21%) on the two test occasions with the new system. Conclusions: Reorganization of a hospital catering system can increase energy and protein intake and reduce waste substantially. Keywords: hospital food; nutritional risk; undernutrition

Fruit and vegetable intake: vitamin C and beta-carotene intake and serum concentrations in six-year-old children and their parents

Abstract: Background: Intake of fruit and vegetables, which are important sources of antioxidant nutrients, has frequently been inversely related to the risk of chronic diseases. Objective: To investigate the serum concentration of vitamin C and β-carotene in relation to fruit and vegetable intake in 6-year-old children and their parents. Design: An observational study on families of healthy 6-year-old children in the Greater Reykjavik area. Serum vitamin C and β-carotene were analysed. Fruit and vegetable intake of children and their parents was assessed by 3 day weighed food records and by a food frequency questionnaire. Results: A positive correlation was seen in serum vitamin C concentration (r=0.454-0.570, p<0.005) and serum β-carotene concentration (r=0.385-0.497, p<0.02) between family members. The total intake of fruit, vegetables and fruit juice was 164±124 g (mean±SD), 302±181g and 238±175 g for children, mothers and fathers, respectively. Family members ’ intake of fresh fruit, fruit juice and green leafy vegetables was positively related (r=0.227, p<0.02 and r=0.313, p<0.01 between children and their mother and father, respectively, and r=0.247, p<0.05 between parents). Conclusions: The relationship between children’s and their parents’ fruit and vegetable intake is supported in the present study by an even stronger correlation of serum vitamin C and β-carotene between family members. Interventions aimed at increasing fruit and vegetable consumption by children should focus on the whole family. Keywords: antioxidants; child; fruit; nutrition; parent-child relationship; vegetables

Developmental establishment of epigenotype: a role for dietary fatty acids?

Abstract: Human epidemiologic data indicate that nutrition during prenatal and early postnatal development can affect susceptibility to various chronic diseases in adulthood (the developmental origins hypothesis). Controlled studies in animal models corroborate that nutritional exposures during critical periods of development wield lasting influences on gene expression and metabolism, but our understanding of the fundamental biological mechanisms underlying such phenomena remains rudimentary. Nutritional influences on the developmental establishment of epigenetic gene regulatory mechanisms could link early nutrition to adult chronic disease susceptibility. Just as genetic variation contributes to individual susceptibility to chronic disease, it is increasingly evident that so too does epigenetic variation. Very little is known about the factors that contribute to interindividual variation in epigenotype. It is critically important to determine whether nutrition and other en vironmental influences during development affect the establishment of human epigenotype. Most previous studies of nutritional influences on epigenetic regulation have focused on nutrients known to affect one-carbon metabolism. For example, supplementation during development with methyl donors including folic acid and vitamin B12 appears to induce DNA hypermethylation at specific loci by increasing the flux through the DNA methylation pathway. This article will consider the mechanisms by which fatty acid nutrition during prenatal and early postnatal nutrition might affect the establishment of epigenetic gene regulatory mechanisms. Choline, a component of the phospholipid phosphatidylcholine, stands at the intersection of lipid and one-carbon metabolism; upon conversion to betaine, its three methyl groups are available to one-carbon metabolism. Potentially much more important than providing methyl groups for DNA methylation, dietary fatty acids could affect the establishment o f epigenetic mechanisms by stimulating transcription of specific genes during critical developmental windows. For example, the peroxisome proliferator activated receptor-a (PPAR-a) transcription factor is activated by a variety of fatty acids to transactivate specific genes. PPAR-amediated transcriptional activation during critical ontogenic periods could impede epigenetic silencing of genes involved in fatty acid metabolism. Lastly, recent data indicate that lipids and lipoprotein components interact directly with chromatin structure to influence gene expression. Hence, intake of specific dietary fatty acids during development could induce persistent changes in gene expression by altering the establishment of epigenetic mechanisms. Keywords: DNA methylation, Developmental origins, Epigenetics, Metabolic imprinting, Nutrition

Effect of dietary fructose on lipid metabolism, body weight and glucose tolerance in humans

Abstract: The prevalence of obesity is increasing worldwide. Increasing body weight together with decreasing physical activity is expected to increase the incidence of several diseases related to lifestyle, such as adult type diabetes and vascular atherosclerotic diseases. It has been postulated that increasing consumption of fructose may be a contributory factor in the development of obesity and the accompanying metabolic abnormalities. Most studies supporting these hypotheses, however, are animal studies, which suggest that consumption of high amounts of fructose may stimulate lipogenesis and thus alter lipid metabolism and increase body weight. This review explores the effects of dietary fructose on lipid metabolism in humans, with the conclusion that the data so far do not support any significant specific adverse effect of fructose apart from its energy content. A small amount of fructose may even improve glucose tolerance, and studies to date on diabetic subjects indic ate that isocaloric replacement of some glucose-based carbohydrates with fructose may improve metabolic control. Keywords: cholesterol; diabetes; fructose; oral glucose tolerance; triglycerides

Resolvins and protectins: novel lipid mediators in anti-inflammation and resolution

Abstract: A well-integrated inflammatory response and its natural resolution are essential to homeostasis. Hence, it is important to achieve a complete understanding of the molecular events that govern termination of acute inflammation. Recent studies uncovered endogenous pathways in inflammatory exudates taken from the resolution phase that actively generate new families of locally acting mediators from the essential fatty acids eicosapentaenoic acid and docosahexaenoic acid. These new chemical families were coined resolvins and protectins because in animals specific members of these families control the duration and magnitude of inflammation. Hence, mapping of these resolution circuits, mediators and their target signaling pathways of these potent agonists of resolution has provided new avenues for appreciating the molecular basis of many inflammatory diseases. This overview covers recent advances on the biosynthesis and actions of these novel anti-inflammatory lipid medi ators, with a focus on the stereochemical basis of the potent actions of resolvin E1 and protectin D1. These previously unappreciated families of lipid-derived mediators were originally isolated from experimental murine models of acute inflammation captured during natural self-limited resolution. Since they have proven anti-inflammatory, proresolving, and protective properties in experimental models of disease, it follows that potential defective resolution mechanism(s) may underlie the current appreciation of inflammatory disease phenotype(s). Keywords: anti-inflammatory; aspirin; human leukocytes; lipid mediators

Dietary fatty acids and colon cancer

Abstract: Although epidemiological evidence to support a preventive role for n-3 fatty acids in relation to colorectal cancer development is currently not convincing, there is a substantial and consistent literature based on a diverse range of animal models and in vitro studies to suggest that an increase in the ratio of n-3 to n-6 fatty acids in the diet is likely to be beneficial in this respect. Studies using intermediate markers of disease risk are strongly indicative of a protective effect of n-3 fatty acid consumption. The epidemiological evidence suffers from a lack of intervention studies with tumour as an endpoint, and in many of the observational studies, a low level of consumption or small ranges of intake combined with the fact that most studies were not designed specifically to identify dietary fat quality. A wide range of potential mechanisms has been investigated in relation to how different polyunsaturated fatty acids might modify risk, including alterations in luminal, paracrine and endocrine factors, as well as direct effects on cell division, differentiation and apoptosis. Keywords: n-3 fatty acids; colorectal cancer; nuclear receptors; prostaglandins inflammation

Serum cholesterol-lowering efficacy of stanol ester incorporated in gelatin capsules

Abstract: Background: The cholesterol-lowering properties of plant sterols have been known since the 1950s. In most clinical studies the efficacy of plant stanol ester has been studied when incorporated into mayonnaise, regular or low-fat spreads or yoghurt. Objective: The purpose of this study was to confirm the cholesterol-lowering efficacy of plant stanol ester when incorporated in capsules as part of a normal everyday diet. Design: The study had a randomized double-blind parallel design with an intervention period of 3 weeks. Forty-two subjects were randomized to receive either the active capsule (2 g of stanol) or the placebo capsule. Results: Stanol ester capsules effectively decreased the low-density lipoprotein (LDL)-cholesterol level by 8.5% [95% confidence interval (CI) 4.1 to 13.0%, p<0.001 vs baseline, p<0.05 vs placebo]. Total cholesterol concentration was reduced by 4.6% (95% CI 1.3 to 8.0%, p<0.01) and the apolipoprotein B level by 6.5% (95% CI 2.0 t o 11.0%, p<0.01) versus baseline. The LDL/HDL ratio was reduced by 10.6% (95% CI 5.2 to 16.0%, p<0.001) versus baseline. Conclusions: Plant stanol ester reduces LDL-cholesterol effectively, even when provided in a fat-free matrix such as capsules. Keywords: adult; cholesterol lowering; gelatin capsule; intervention; serum cholesterol; stanol ester

AMP-activated protein kinase and its regulation by adiponectin and interleukin-6

Abstract: they develop more severe atherosclerosis than control mice. Whether AMPK activation by other means prevents the development of the metabolic syndrome in the IL-6 or adiponectin KO mice remains to be determined. Keywords: AMPK, adipon e ctin, Interleukin-6, metabolic syndrome, T2DS

Postprandial lipid metabolism

Abstract: Atherogenic effects of postprandial lipoproteins are supported by many studies comparing patients with advanced clinical signs or early markers of cardiovascular disease with subjects without vascular disease. Postprandial lipoprotein abnormalities are more frequent in individuals with type 2 diabetes and other states of insulin resistance, which could be a major factor accounting for the higher rate of cardiovascular diseases observed in these conditions. In patients with type 2 diabetes multiple abnormalities of lipoproteins of both endogenous and exogenous origin are observed also in the presence of good blood glucose control and normal fasting triglyceridaemia, and a direct role of insulin resistance in the development of postprandial dyslipidaemia has been demonstrated. Clinical and experimental studies have demonstrated that a high fat consumption is associated with impaired insulin sensitivity and may worsen postprandial hypertriglyceridemia in individuals with type 2 diabetes and/or hyperlipidaemia. In addition to the amount of fat also the physical structure of the food in which fat is present is able to influence postprandial lipaemia. Data on the effects of dietary fatty acid (FA) modifications in humans are scarce. These studies have provided some evidence that dietary polyunsaturated FA, particularly those of the n-3 class, induce an attenuated postprandial lipaemic response as compared to saturated FA (SFA) and monounsaturated FA (MUFA); however, the data are often conflicting and their interpretation is, generally, controversial. Very little is known in patients with type 2 diabetes, in whom both insulin sensitivity and postprandial lipaemia are particularly relevant. In a medium term (3 weeks) study in type 2 diabetic patients, a MUFA rich diet did not modify insulin sensitivity as compared to the SFA rich diet. The MUFA diet induced a higher early peak of chylomicrons and a significantly lower postprandial response o f small VLDL after a standard test meal, rich in saturated fat. In conclusion, postprandial lipoprotein abnormalities are a frequent feature of type 2 diabetes and of other conditions clustering with insulin resistance. The total amount of fat, more than the specific type of fatty acid, seems to influence postprandial lipoproteins. Data are needed on long term interventions as well as on the interactions between dietary fat and other food components or physical structure. Keywords: postprandial lipoproteins; metabolism of dietary fat

Lipid-induced cell stress and insulin resistance

Abstract: In our Westernized society, although some excess body fat is stored inside its proper place, adipose tissue, the surplus of circulating fatty acids is also excessively stored in the liver, heart, pancreas and skeletal muscle. In these tissues, intracellular fat accumulation, in combination with a low oxidative capacity, is associated with decreased insulin sensitivity. Although the exact mechanism behind the negative effect of intracellular lipid accumulation on insulin sensitivity has not been completely unravelled, ample evidence suggests that fatty acid intermediates, such as diacylglycerol, fatty acyl-coenzyme-A and ceramides, can hamper insulin signalling. However, recent evidence also points towards a role for reactive oxygen species in the development of insulin resistance. The present review will focus on how fatty acids in combination with oxidative stress can lead to lipid-induced oxidative damage, thereby impairing mitochondrial function and facilitatin g the accumulation of muscular lipids. Keywords: type 2 diabetes; muscle; mitocondria; UCP3; reactive oxygen species; fatty acid

Behavioural determinants of daily energy intake during a 28 day outdoor expedition in Arctic Norway

Abstract: Background: Energy requirements during expeditions are often inadequately matched by concurrent energy intake, to the potential detriment of human health. Objective: This study investigated the behavioural determinants of daily energy intake (DEI) on expedition. The study was conducted primarily with a view to enhancing DEI in the expedition situation. Design: Twelve adolescents recorded energy intake, energy expenditure and various behavioural factors associated with energy intake concurrently for 28 days using adapted food diaries, while on expedition in Arctic Norway. Results: Data tested for reliability and validity (n=217) were analysed using correlation and regression analyses. Greater DEI was significantly independently associated with a greater number of eating occasions, greater time spent consuming, greater happiness before consuming and greater pleasantness of the food consumed. Conclusions: These findings suggest that energy intake on expedition can be enhanced by allowing plenty of opportunity and time for consuming, ensuring that morale remains high, and providing foods that are perceived as pleasant by those consuming. These practical suggestions could benefit human health and wellbeing in the expedition situation. Keywords: adolescents; eating situation; energy expenditure; energy intake; expedition; food consumed; food diaries

n-6 Fatty acids and adipogenesis

Abstract: There is evidence from animal and human studies that changes in the balance of essential polyunsaturated fatty acids may alter the early stages of adipose tissue development Consistent with these observations, cellularity of human adipose tissue from obese patients depends on the age of obesity onset Under isoenergetic conditions, pups from wild-type mice mothers fed a linoleic acid (LA) diet were 40% heavier 1 week after weaning than those from mothers fed a LA/?-linolenic acid (LNA) diet, and the weight difference was maintained at the adult age The LA-induced enhancement of fat mass was abolished in mice invalidated for the cell-surface prostacyclin receptor (ip-1- mice), demonstrating the critical role of arachidonic acid and the prostacyclin receptor in excessive adipose tissue development Changes observed over recent decades in the fatty acid composition of dietary fats observed in breast milk and formula milk, ie an increase in LAwith slight or no ch ange in LNA content, in concert with a positive energy balance, may be responsible at least in part for the dramatic rise in the prevalence of childhood overweight and obesity Since prevention of obesity appears critical to avoid difficult if not insurmountable health problems in the future, the composition of dietary lipids should be reconsidered from the very beginning of the food chain Keywords: adipose tissue; arachidonic acid; development; food; linoleic acid; milk

Breast-feeding and protection against infection

Abstract: Microbial exposure and the immune system of the newborn The newborn starts to be colonized in the upper respiratory tract and gastrointestinal tract, as well on the skin, directly from birth onwards. Delivery next to the anus exposes the newborn to the mother’s intestinal microflora, in which harmless anaerobes are predominant, but where aerobic and facultative anaerobes are also prevalent. Some of the latter may contain species that are potentially pathogenic. Before the strict anaerobes have totally taken over, reaching levels over 99%, there is an early period where they have not yet reached numbers high enough to compete successfully with the aerobes and facultative anaerobes for space and nutrients and bring their numbers down. The potential pathogens may then reach levels at which they can initiate infections. Thereafter, the infant is also at a special risk of infections because of its somewhat limited host defences. This is strikingly illustrated by the high early infant mortality caused by infections, as seen in poor regions across the world (1, 2). The infant has a complete immune system at delivery, but it is very small. It will start to expand as soon as it meets all the microbes on the mucosal membranes, especially in the gut. The neonate remains deficient in several defensive functions during the first weeks and months of life (3). This includes, in particular, various aspects of phagocytes and their functions, but also reduced antigen presentation, a slow start to the production of secretory immunoglobulin A (SIgA), which normally protects mucosal membranes where most infections start, and a somewhat reduced capacity of cell-mediated immunity.

Regulation of fatty acid transport and storage: influence of acylation-stimulating protein

Abstract: Postprandial lipemia and fatty acid fluxes occur several times daily, resulting in very efficient absorption of dietary fat and redistribution to various tissues. Absorbed dietary lipids are incorporated into chylomicrons to distribute triglycerides either for storage in adipose tissue or for immediate use in muscle. Commonly, the dietary sources of fat exceed the actual needs and the tissues are faced with dealing with the excess. Under these circumstances, the removal process of dietary triglycerides and fatty acids becomes overloaded, resulting in excessive postprandial lipemia and accumulation of chylomicrons, remnant particles and non-esterified fatty acids. These particles are associated with disruptions in lipoprotein metabolism and changes in inflammatory factors, thus their association with cardiovascular disease, metabolic syndrome and diabetes is not surprising. Dietary factors, not just fat, influence postprandial fluxes. This leads to the question: do we need a standardized fat tolerance test? The recognition of the factors influencing postprandial lipemia and fatty acid uptake and clearance is constantly increasing. Numerous proteins, transporters, enzymes and hormones have been shown to affect fatty acid flux at the level of absorption, peripheral uptake and hepatic remnant clearance. This summary targets fatty acid fluxes, with a focus on acylation-stimulating protein. Keywords: C3adesArg; lipoprotein lipase; postprandial; triglyceride

Molecular mechanisms for biological endpoints of n-3 fatty acids

Abstract: Accumulating evidence in both humans and animal models clearly indicates that a group of very long-chain polyunsaturated fatty acids, the n-3 (or omega-3) fatty acids, have distinct and important bioactive properties compared with other groups of fatty acids. The n-3 fatty acids are known to reduce many risk factors associated with several diseases, such as cardiovascular diseases, diabetes and cancer. The mechanisms whereby n-3 fatty acids affect gene expression are complex. As examples, n-3 fatty acids regulate two groups of transcription factors, sterol regulatory element binding proteins and peroxisome proliferator activated receptors, which are critical for modulating the expression of genes controlling both systemic and tissuespecific lipid homeostasis. Modulation of specific genes by n-3 fatty acids and cross-talk between these genes are responsible for many effects of n-3 fatty acids. Keywords: atherosclerosis; gene expression; n-3 fatty acids; SREBP

Promoting breast-feeding with weak arguments

Abstract: There is no doubt that breast-feeding represents the optimal nutrition during early infancy. It is also well known that poor breast-feeding is a reason, or even the major reason for infant mortality due to malnutrition and infection in developing countries. These, and other benefits of breast-feeding are good reasons to encourage breast-feeding in many countries. The arguments are not equally important, however, in affluent countries, with good hygiene and wellinformed parents. For many years, some paediatricians, notably allergologists, have claimed that breast-feeding also protects against the development of allergic diseases, while an equal number of studies has failed to support this, or even reported an increased incidence of allergies in breast-fed babies. The fact is that there is little or no support for any major impact of breast-feeding on allergy development. The interpretation of findings seems often to be biased by the desire to prove that breast-feeding is always beneficial and a reluctance to accept that it could be associated with any problems at all. A recent Swedish study is an example of this (1). A birth cohort was followed up to 4 years of age and it was reported that ‘‘exclusive breast-feeding for 4 months or more reduced the risk for eczema at the age of 4 years (OR 0.88; 95% CI 0.72–1.08) although this result was not statistically significant’’. Therefore, the analyses were done in a different way, by excluding children with eczema and asthma during the period of breast-feeding. By doing this, the authors slightly strengthened their finding, now observing an odds ratio of 0.78 with 95% confidence interval of 0.63–0.96. The authors state that ‘‘in no other previous studies has the possibility of diseaserelated modification of breast-feeding behavior been addressed’’. By excluding infants who developed symptoms while they were breast-fed and by creating an arbitrary and undefined group of children with ‘‘severe allergic disease’’, they could obtain further support for a protective role of breast-feeding. The paper is an example of how analyses can be geared to promote a desired outcome. From a public health point of view it is artificial and unreasonable to exclude those infants who manifest eczema or wheezing while breast-fed, and certainly unacceptable to conclude that ‘‘breast-feeding for 4 months or more reduces the risk for eczema and onset of the allergy march’’. One could perhaps argue that the authors are stretching their data to promote a good thing; but advice given to the general public should be based on adequately analysed good studies of a similar quality, as requested before therapies are recommended. It is simply not true that ‘‘breast is best’’ under all circumstances. The often very strong and sometimes even dogmatic force upon the mother to breast-feed for at least 6 months may prevent her from returning to work if she wished to do so, and cause feelings of guilt if she wished to terminate breast-feeding for various reasons. Today, in countries such as in Scandinavia, it is not easy to confirm major nutritional or immunological advances of breast-feeding over feeding with modern infant formulae. Without discussing causes or consequences, it can be stated that the prevalence of childhood allergies has tripled in Sweden since the early 1970s, despite the fact that breast-feeding has also tripled during the same period, to 73% breast-feeding up to at least 6 months among Swedish infants born in 2003.

Why is there still confusion about the impact of breast-feeding on the risk of allergy development?

Abstract: The incidence of allergies has tripled in Sweden and other highly developed countries in the past 20 years. Allergies are now the most common chronic disease in childhood, affecting approximately one-third of Swedish schoolchildren. In response to this development, Swedish authorities formulated advice to parents on how to reduce the risk of their children becoming allergic. One such recommendation was to breast-feed exclusively for 4 (or 6) months and postpone the introduction of solid foods. Since the early 1970s, breastfeeding has tripled in Sweden, but simultaneously, allergies have also tripled in Sweden and other wealthy Western countries. There is reason to examine the foundations for the advice to breast-feed to hinder allergy development. What is allergy? Allergy is defined as immune-mediated hypersensitivity. The allergic individual mounts an immune response to harmless substances, termed allergens, present in the environment. Renewed exposure produces symptoms that are caused by an activation of immunological and inflammatory reactions. Development of an immune response to an allergen is termed sensitization and is a prerequisite for the development of allergy. However, sensitization is not equivalent to allergy, because an individual can be sensitized without developing typical symptoms when exposed to the allergen. The reasons for this are not known, but probably relate to complex networks of factors that down-regulate various inflammatory reactions. Different immunological mechanisms may produce allergies. Hence, allergies may be divided into three groups based on the pathological mechanisms: immunoglobulin E (IgE)-mediated allergy, also termed atopic allergy; T-cell-mediated allergy, or contact allergy; and other types of allergy.

Infant feeding and later obesity risk: what is the relationship?

Abstract: Obesity is considered a global epidemic because the prevalence is increasing worldwide at an alarming rate (1, 2). Obese children often experience considerable psychosocial distress. Persistence of childhood obesity into adult life is common and associated with markedly increased morbidity and mortality. Available therapeutic interventions are costly and have less than satisfactory long-term success. Thus, strategies for effective prevention are particularly important. Genetic predisposition is a major determinant of obesity risk, but there are strong modulating effects of exogenous factors. In addition to current lifestyle, events during early life modulate later obesity risk, which is an example of metabolic programming or metabolic imprinting. To investigate whether breast-feeding has longterm programming effects on the prevalence of overweight and obesity, BMI values were recorded in Bavarian children at school entry (n /134 577) (3). Questionnaires were given to 13 345 children examined in two rural regions. The analysis was confined to 5-year-old (n /1975) and 6-year-old (n /7382) German children (total 9357). The main exposure was exclusive breast-feeding and its duration. To identify covariables potentially associated with breast-feeding, several additional items were considered. The duration of breast-feeding was associated with a progressive reduction in the prevalence of overweight, and even more so of obesity, in children at school entry. Previously breast-fed and non-breast-fed children differed significantly in several indicators of social class and lifestyle. Parental education was the only factor accounting for a /10% shift in the odds ratio for breastfeeding and overweight and obesity from unity. After inclusion of other factors which remained associated in the final logistic regression model, the adjusted odds ratios indicate that being ever breastfed reduced the risk of overweight by more than 20%, and breast-feeding for 6 months or more reduced the risk by over 35%. Even more pronounced effects were observed with respect to obesity (25% and 43%, respectively). Although lifestyle factors may contribute to the observed protective effect, Kramer found a similar dose-related, protective effect in Canadian individuals born in the 1960s (4). Lifestyle in Canada in the 1960s was very different, and breast-feeding rates were very low, compared with Bavaria in the 1990s. The findings of the present study were also confirmed in several other cohort studies, including the German multicentre allergy study (MAS) (5), the German ISAAC study (6), two cohorts in the USA (7, 8) and a study on Scottish children (9). Data from a cross-sectional survey of school children in the Czech Republic in 1991, i.e. children who grew up in an Eastern socialist country with a relatively homogeneous lifestyle, have also been evaluated (10). Data on 33 768 schoolchildren aged 6 /14 years were analysed using multiple logistic regression analysis. Children who had ever been breast-fed had a lower overall prevalence of overweight [9.3%, 95% confidence interval (CI) 8.9 to 9.6%] than children who were never breastfed (12.4%, 95% CI 11.3 to 13.6%). Similarly, the prevalence of obesity was clearly lower in previously breast-fed children (3.2%, 95% CI 3.0 to 3.4%) than in previously formula-fed children (4.4%, 95% CI 3.7 to 5.2%). The effect of breast-feeding on overweight/obesity did not diminish with age in children aged 6 /14 years, and could not be explained by parental education, parental obesity, maternal smoking, high birthweight, watching television, number of siblings or physical activity. Adjusted odds ratios for breast-feeding were 0.80 (95% CI 0.71 to 0.90) for overweight and 0.80 (95% CI 0.66 to 0.96) for obesity. This reduced prevalence of overweight/obesity in an Eastern European country with living conditions of a socialist society suggests Early nutrition and future health

Weight concerns and beliefs about obesity in the Norwegian population

Abstract: Background: The obesity epidemic is a challenge for health systems globally. There has been a focus on obesity in health systems, but it is also important to understand how people describe their weight and their motivation to lose weight. Objective: To describe the desire to lose weight and beliefs about the causes and treatment of obesity in a representative sample of the Norwegian population. Design: In a cross-sectional survey, 1019 men and women aged 30-60 years took part in a computer-assisted telephone interview conducted in April 2005. The interview was part of an omnibus questionnaire. Results: Of all respondents, 76% describing themselves as overweight and 27% of normal-weight respondents wished to lose weight. The main reason for weight loss was better health among men (40%) and better wellbeing among women (37%). Almost 82% of men and 87% of women believed that heredity is important for obesity. Less than 10% believed that obesity is a disease, while 24 % believed that obesity is a disease and has other causes. In answer to the question of what would be the best treatment for overweight and obesity (with more than one response being possible), the majority (91%) believed that a change of diet and exercise is best, while less than 5% believed that treatment by medical specialists, family physicians, dietitians, commercial groups, prescription medication or surgery is best. Only 7% believed that weight loss after a successful weightloss programme would be completely maintained 2 years later. These percentages did not vary much with age, geographical location, gender or income. Conclusions: The desire to lose weight was motivated primarily by the desire for better health and well-being. A dichotomy exists in the perceptions of obesity: while the role of heredity was widely recognized, very few believed in the effectiveness of medical treatments. Keywords: heredity; obesity treatment; survey; weight loss

Novel aspects of eicosanoid signaling through the use of gene-targeted mice

Abstract: Eicosanoids are lipid mediators consisting of prostaglandins, leukotrienes, lipoxins and related compounds derived primarily from arachidonic acid and to a lesser extent from eicosapentaenoic and di-homo-gammalinolenic acids. This large class of bioactive lipids is derived from the initial release of polyunsaturated fatty acid from the sn2 position of glycerophospholipids predominantly from cytosolic phospholipase A2 and subsequent conversion by either prostaglandin H synthases-1 and -2 (PGHS-1, PGHS-2; also known as COX- 1, COX-2), lipoxygenases or various members of the cytochrome P450 family. Eicosanoids control a vast array of physiological functions, including female reproductive function and parturition, platelet aggregation and vascular homeostasis, as well as renal function and roles in inflammation initiation and resolution. The authors have been studying the functions and signaling of eicosanoids, in particular the prostaglandin class of molecules, using a series of induced mutant mouse strains created in the laboratory by manipulation of the PGHS-1 and PGHS-2 genes by gene targeting in embryonic stem cells. The two strains of mice most fully characterized to date are referred to as ‘‘low-dose aspirin genetic mimic’’ or PGHS-1 knockdown and ‘‘selective COX-2 inhibitor genetic mimic’’ or PGHS-2 Y385F. This brief review describes the utility of these mouse models for unraveling new insights into eicosanoid signaling. Keywords: aspirin; cardiovascular; coxib; inflammation; prostaglandin

Dietary lipids and the brain during development and ageing

Abstract: The brain and retina are rich in long-chain polyunsaturated fatty acids (LCPs). Docosahexaenoic acid (C22:6 n-3; DHA) particularly has been shown to affect retinal and brain development in humans. Provision of n-3 LCPs in preterm and term babies is associated with enhanced retinal electrical responses to light stimuli and to a pattern of brain cortex-related visual acuity maturation that is similar to that observed in infants fed on human milk. Evidence supporting the potential importance of n-3 LCP consumption for good cognitive health in older age is also beginning to emerge. Cross-sectional and prospective data indicate that higher fatty fish and n-3 LCP consumption is associated with reduced risk of impaired cognitive function or dementia. The evidence suggests that n-3 LCPs act by inhibiting hepatic triglyceride synthesis as well as modulating eicosanoid function, inducing vascular relaxation, and diminishing inflammatory processes and platelet aggregation. T his article reviews the role of LCPs in the brain during development and ageing, and the mechanisms that may explain the observed effects. Keywords: n-3 fatty acids; docosahexaenoic acid; brain; retina; development; ageing

Reply: Breast-feeding and childhood eczema

Abstract: Bjorksten and Lundback (1) raise the question of whether breast-feeding reduces the risk of allergic diseases and in particular eczema. In two recent meta-analyses, breast-feeding during the first months of life was associated with an approximately 30% reduced risk of asthma (odds ratio (OR) 0.70, 95% confidence interval (CI) 0.60/0.81) and eczema (OR 0.68, 95% CI 0.52/0.88), respectively (2, 3). For both outcomes, the risk reduction seemed to be more pronounced in children with heredity for allergy. When studying the association between exposures and health outcome it is essential to avoid disease- related modification of exposure. This is a particu- lar problem in studies of breast-feeding and allergy. Children may have their debut of allergic disease during the first year of life and in such cases the mother is likely to continue to breast-feed for a longer period than otherwise. There are two ways to avoid such bias; either with a Cox regression analysis where duration of breast-feeding is set to onset of disease, or by excluding those children where onset of disease has occurred during breast- feeding. However, if such bias is not controlled in the analysis the associations may be biased. In the study by the present group (4), based on 4000 children followed from birth, children with early symptoms of eczema were excluded. This approach was chosen since, owing to the way in which data were collected, the exact age of the child when the eczema started was not known, and thus the person-time at risk, which is critical in Cox regres- sion, could not be estimated. However, the author agrees that excluding children is a weakness and as a consequence these results cannot be generalized to the group of children with very early symptoms. The association between exclusive breast-feeding and various phenotypes of eczema with all children and after exclusion of children with early symptoms is presented in Fig. 1. In the upper panel the analysis is performed with all children included and in the lower panel with children with early eczema during exclusive breast-feeding excluded (n /265). From a statistical point of view, there is no significant difference between the association of breast-feeding and the three phenotypes of eczema whether children with an overlap of disease and exposure are excluded or not (Fig. 1). Bjorksten and Lundback point out that the increase in allergic diseases during the past few decades in Sweden is associated with an increase in breast-feeding duration, implying that breast-feed- ing cannot be a protective factor. We would never draw conclusions on causality based on ecological data and it is obvious that time trends in occurrence of allergy are explained by a complex pattern of

The diet of the child - the health of the grown-up? Summary of discussions

Abstract: The reports by Berthold Koletzko, Lars Åke Hanson, Agnes Wold and Olle Hernell in this issue are based on presentations at a conference entitled ‘‘The diet of the child / the health of the grownup?’’, arranged by the Swedish National Committee of Nutrition Research of the Royal Swedish Academy of Sciences, the Swedish Society of Clinical Nutrition of the Swedish Society of Medicine and Swedish Nutrition Foundation SNF, on 16 November 2005. The importance of early feeding for obesity, infections and allergy was in focus. The final discussions, chaired by Olle Hernell, between a panel of speakers and with participation from the audience had a focus on recommendations regarding early feeding, especially the importance of breast-feeding. The scientific evidence base, ethical aspects and practical implications were debated. Feeding of the young child and its implications for future health have been in focus since the World Health Organization (WHO) launched its ‘‘Global strategy on infant and young child feeding’’ in 2001. The WHO recommendation on infant feeding can be summarized as exclusive breast-feeding for 6 months and thereafter breast-feeding and adequate complementary feeding up to 2 years or beyond. In 2003 the Swedish authorities adapted the WHO recommendation in 2003 as follows: ‘‘During the first period of life breast milk is the best nutrition. For most infants exclusive breastfeeding during the first six months is sufficient. For nutritional reasons breastfeeding should be complemented by other food items from six months, but it is an advantage if breast milk could continue to be the base of the diet during the first year or longer.’’ This is recommended providing it is possible for the mother and her infant. The earlier recommendation proposed introduction of other food at 4 /6 months. So, the slight change in relation to the earlier recommendations is 6 months’ exclusive breastfeeding, in line with the WHO recommendations. Wulf Becker (National Food Administration, Uppsala, Sweden) summarized why we have our nutrition recommendations and the criteria of the recommendations. Criteria are based on different types of studies: intervention studies, including randomized controlled trials, epidemiological studies and population studies. Most studies have been carried out on adults and then extrapolated to infants and children, as it is often not possible to conduct studies on children. For the young infant, breast milk is regarded as having the ideal nutrient content. Bengt Björkstén [National Institute of Environmental Medicine (IMM), Karolinska Institutet, Stockholm, Sweden] summarized the reasons why we give advice at all, and the principles behind this. Prevention of illness and promotion of health are the main reasons. The aims of prevention should be to reduce the prevalence of illness, reduce injuries, reduce suffering, increase quality of life, and increase possibilities to make individual informed choices and to reduce costs for the community. Advice should have the intended effect, be reasonable, be possible to accomplish, be cost-effective and have well-defined groups to be informed. Ethical considerations should include that the advice must not cause any damage, the right to make your own decisions, efficiency of measures and justice, not to discriminate and to distribute the resources in a fair way. WHO has defined principles of prevention as follows: (i) the problem should be common and have serious consequences; (ii) the causes must be known; (ii) measures taken must be effective, safe and acceptable; (ii) there must exist economic resources to accomplish the recommendations; and (ii) health-economic consequences must be evaluated. Mainly from the perspective of earlier advice and recommendations aiming at preventing allergy, it was questioned whether advice should be given Early nutrition and future health

Fatty acid composition in relation to the metabolic syndrome and associated cardiovascular risk factors

Abstract: Fatty acid metabolism is important in relation to the development of insulin resistance and the metabolic syndrome. Elevated total non-esterified fatty acid concentrations predispose to an atherogenic lipoprotein profile, but the individual properties of specific fatty acids are also of importance for the development of the metabolic syndrome. The objectives of this study were to investigate the relationships between fatty acid composition and selected cardiovascular risk factors associated with the metabolic syndrome [small, dense low-density lipoprotein (LDL) particles and oxidative stress], and to investigate estimates of adipose tissue D9-desaturase activity. A cohort of approximately 300 healthy Swedish men (aged 62-64 years), extensively characterized in relation to components of the metabolic syndrome, was investigated cross-sectionally. Increases in fatty acids typical of milk products were associated with reduced numbers of potentially atherogenic small, dense LDL particles, and n-3 fatty acids were independent (negative) predictors of oxidative stress. D9-Desaturase activity in human adipose tissue needs more detailed investigation in relation to the metabolic syndrome. In conclusion, the quality of dietary fat is of importance in relation to the development of cardiovascular risk factors associated with the metabolic syndrome. Keywords: insulin resistance; LDL particle size; oxidative stress; stearoyl CoA desaturase