The role of nutrition in viral disease

Malnutrition has been associated with a decrease in immune function. Impairment of immune function may lead to increased susceptibility to infection with viruses. Although there are many studies documenting the effect of host nutritional status on immune functions, fewer studies have examined the effect of host nutritional status on viral pathogenesis. This review examines the relationship between viral infection and the nutritional status of the host, and documents that not only can the nutritional status of the host affect immune function, but can have profound effects on the virus itself. One mechanism by which nutritional status affects the virulence of the viral pathogen involves selection for virulent viral genotypes. Other mechanisms remain to be elucidated.     

Gender‐Specific Effects of Early Nutritional Restriction on Adult Obesity Risk: Evidence From Quasi‐Experimental Studies

In countries undergoing nutrition transition and historically poor minority groups in wealthy countries, obesity tends to be more common in women than men. A potential contributor to this female excess of obesity is a mismatch between perinatal nutritional restriction and a later calorie‐rich environment. Several epidemiologic and quasi‐experimental studies support a gender‐differential effect of early nutritional deprivation on adult obesity. The quasi‐experimental studies are of particular interest because results of quasi‐experimental studies are typically less vulnerable to confounding bias than observational studies. Four quasi‐experimental studies—exploiting 20th century famines that occurred in Europe, Africa, and Asia—provide evidence that perinatal nutritional restriction followed by relative caloric abundance may increase adult obesity risk to a greater extent in women than men. If the findings are accurate and generalizable to contemporary food environments, they suggest that the female offspring of poor, or otherwise nutritionally restricted, women in rapidly developing and wealthy countries may be at particularly high risk of adult obesity. Research into gender‐specific effects of early life nutritional deprivation and its interactions with later environmental exposures may provide insight into global gender differences in obesity prevalence.     

Nutritional factors in relation to heavy metal toxicants.

An increased environmental exposure to various toxic heavy metals such as lead, cadmium, or mercury seems to be a fact of 20th-century life. But relatively little attention has been paid to the possible implications of sucy exposure for the nutritional status of humans and animals. This review summarizes the information available concerning the effect of various nutritional factors in resistance to metal toxicants and the effect of heavy metal toxicity on nutritional status. In particular, the following questions are considered: 1) Are there any examples of heavy metal toxicity that are potentiated by a nutritional deficiency? 2) Is there any evidence that nutritional deficiency can be caused by heavy metal toxicity? 3) Is there any proof that heavy metal toxicity can be decreased by an excess intake of nutrients: 4) Is there any proof that heavy metal toxicity can be increased by an excess intake of nutrients? The discussion is focused primarily on studies with animal models but, wherever possible, implications for human health are pointed out.     

Nutritional stress affects corticosterone deposition in feathers of Caspian tern chicks

Stressful environmental conditions affect the adrenocortical function of developing animals, which can have consequences for their fitness. Discovery of the avian stress hormone corticosterone (CORT) in feathers has the potential to broaden the application of endocrine research in ecological and evolutionary studies of wild birds by providing a long‐term measure of CORT secretion. Mechanisms of CORT deposition in feathers are not well known and few studies have related feather CORT to circulating plasma CORT during feather growth. Our objective was to experimentally test the validity of using feather CORT as a measure of CORT secretion in developing birds experiencing nutritional stress. Caspian tern Hydroprogne caspia chicks were fed ad libitum or restricted (35% less than ad libitum) diets for four weeks. We measured CORT in feathers from these chicks to examine the relationship between feather CORT concentrations and nutritional limitation, circulating plasma CORT, and feather development. We found that feather CORT was higher in controls fed ad libitum than in restricted individuals, despite higher levels of plasma CORT in restricted chicks compared to controls. Feather mass and growth rates were strongly and positively related to feather CORT concentrations in both treatments. This is the first experimental study to show that feather CORT concentrations can be lower in response to nutritional stress, even when plasma CORT concentrations are elevated. Our results indicate that CORT deposition in feathers may be confounded when feather mass and growth rates are compromised by nutritional stress. We conclude that feather CORT can be used for assessing nutritional stress in growing birds, but the direction of response depends on how strongly stress affects feather development.     

Conservation of biotrophy in Hygrophoraceae inferred from combined stable isotope and phylogenetic analyses

The nutritional modes of genera in Hygrophoraceae (Basidiomycota: Agaricales), apart from the ectomycorrhizal Hygrophorus and lichen-forming taxa, are uncertain. New δ(15)N and δ(13)C values were obtained from 15 taxa under Hygrophoraceae collected in central Massachusetts and combined with isotopic datasets from five prior studies including a further 12 species using a data standardization method to allow cross-site comparison. Based on these data, we inferred the probable nutritional modes for species of Hygrophorus, Hygrocybe, Humidicutis, Cuphophyllus and Gliophorus. A phylogeny of Hygrophoraceae was constructed by maximum likelihood analysis of nuclear ribosomal 28S and 5.8S sequences and standardized δ(15)N and δ(13)C values were used for parsimony optimization on this phylogeny. Our results supported a mode of biotrophy in Hygrocybe, Humidicutis, Cuphophyllus and Gliophorus quantitatively unlike that in more than 450 other fungal taxa sampled in the present and prior studies. Parsimony optimization of stable isotope data suggests moderate conservation of nutritional strategies in Hygrophoraceae and a single switch to a predominantly ectomycorrhizal life strategy in the lineage leading to Hygrophorus. We conclude that Hygrophoraceae of previously unknown nutritional status are unlikely to be saprotrophs and are probably in symbiosis with bryophytes or other understory plants.     

Current perspectives in avian nutrition: domestic animal models and their role in conservation management

As biodiversity declines, wildlife conservation focuses on in situ and ex situ management strategies. Zoo-based breeding programmes are often designed to contribute to the conservation of species that are threatened in the wild. Diet contributes to the reproductive success, disease status and longevity of all animals. It is near-impossible to replicate a species' diet in captivity using only the species they consume in the wild, but the nutritional composition of a wild diet, if known, can be closely matched using commercially available foods for which the nutritional composition has been calculated. Ecological research has identified food items of importance in the diet of many species. However, the nutritional composition of these food items is rarely evaluated, even though the composition of wild food items is important in understanding the dietary adaptations and requirements of wildlife. In contrast, the nutritional requirements of domestic species are well researched and can be used to predict a range of plausible nutrient requirements of some wild species, especially those with similar life histories. Access to wild populations provides further opportunities for nutritional science to determine the requirements of individual species. Small-scale dietary experimentation undertaken at conservation institutions may show positive effects on health and welfare but is rarely published in the scientific literature. This review describes current standards in nutritional management of birds and recommends pathways for filling knowledge gaps. Research on mammals has dominated the nutrition literature, so there is a relative lack of nutritional management information for birds. We combine concepts of domestic animal nutrition with recent findings on the nutritional requirements of birds to provide a foundation for further studies of avian nutrition. We call for the broader zoological community to share data and collaborate on nutritional research to support conservation institutions in nutritional management of wild birds.     

Analysis of the effects of early nutritional environment on inbreeding depression in Drosophila melanogaster

The impact of nutritional deficiencies early in life in determining life-history variation in organisms is well recognized. The negative effects of inbreeding on fitness are also well known. Contrary to studies on vertebrates, studies on invertebrates are not consistent with the observation that inbreeding compromises resistance to parasites and pathogens. In this study, we investigated the effect of early nutrition on the magnitude of inbreeding depression in development time, adult body size and adult resistance to the bacterium Serratia marcescens in Drosophila melanogaster. We found that early nutritional environment had no effect on the magnitude of inbreeding depression in development time or adult body size but may have played a small role in adult resistance to the bacterial infection. Estimates of heritabilities for development time under the poor nutritional environment were larger than those measured under the standard nutritional conditions.     

Soporte nutricional basado en la evidencia en la enfermedad inflamatoria intestinal

Patients with inflammatory bowel disease are at risk for malnutrition. Consequently all patients with inflammatory bowel disease should undergo nutritional screening to identify those who require thorough nutritional evaluation. When nutritional support is indicated, enteral nutrition (oral or through a tube) should be used. There are no significant differences between elemental and non-elemental enteral diets in inducing remission of Crohn's disease (CD). Nevertheless, given that non-elemental diets are better tolerated, most authors prefer polymeric diets. Enteral nutrition should not be used as the primary treatment of choice in patients with CD, since they are less effective in inducing remission than steroid therapy. Although dietary fat (quantity and type of fat) might influence the course of the disease, recommendations cannot be made on the basis of the available studies. Equally, there is insufficient evidence that glutamine is effective in inducing remission in CD. The use of probiotics presents a high level of evidence in maintenance treatment and in the prevention of postoperative pouchitis, although the level of evidence is lower in ulcerative colitis and CD. Further studies are required to investigate several issues such as dose, treatment duration, the separate or combined use of several strains, as well as the concomitant use of prebiotics, symbiotics or antibiotics.     

Urinary C-peptide measurement as a marker of nutritional status in macaques

Studies of the nutritional status of wild animals are important in a wide range of research areas such as ecology, behavioural ecology and reproductive biology. However, they have so far been strongly limited by the indirect nature of the available non-invasive tools for the measurement of individual energetic status. The measurement of urinary C-peptide (UCP), which in humans and great apes shows a close link to individual nutritional status, may be a more direct, non-invasive tool for such studies in other primates as well and possibly even in non-primate mammals. Here, we test the suitability of UCPs as markers of nutritional status in non-hominid primates, investigating relationships between UCPs and body-mass-index (BMI), skinfold fatness, and plasma C-peptide levels in captive and free-ranging macaques. We also conducted a food reduction experiment, with daily monitoring of body weight and UCP levels. UCP levels showed significant positive correlations with BMI and skinfold fatness in both captive and free-ranging animals and with plasma C-peptide levels in captive ones. In the feeding experiment, UCP levels were positively correlated with changes in body mass and were significantly lower during food reduction than during re-feeding and the pre-experimental control condition. We conclude that UCPs may be used as reliable biomarkers of body condition and nutritional status in studies of free-ranging catarrhines. Our results open exciting opportunities for energetic studies on free-ranging primates and possibly also other mammals.     

Nutritional status of the Indian population

High prevalence of low birth weight, high morbidity and mortality in children and poor maternal nutrition of the mother continue to be major nutritional concerns in India. Although nationwide intervention programmes are in operation over two decades, the situation has not changed greatly. In addition, the Indian population is passing through a nutritional transition and is expected to witness higher prevalences of adult non-communicable diseases such as diabetes, hypertension and coronary heart disease according to the theory of ‘fetal origin of adult disease’. Clearly, there is a need for examining several issues of nutritional significance for effective planning of interventions. In particular, maternal nutrition and fetal growth relationship, long term effects of early life undernutrition, interactions of prenatal nutritional experiences and postnatal undernutrition are some of the major issues that have been discussed in the present paper with the help of prospective data from various community nutrition studies carried out in the department.     

Methodology in the study of seabass (Lates calcarifer Bloch): nutritional requirements in Singapore

This paper describes the effort of the Marine Aquaculture Section of the Primary Production Department in Singapore and the Institut Francais de Recherche pour l'Exploitation de la Mer in developing adequate facilities for fish nutritional requirement studies in Singapore, and in introducing appropriate nutritional methodology so that results are reliable and accurate. One of the first achievements was the demonstration of homogeneous fish (tropical seabass, Lates calcarifer Bloch) growth response in a newly established tank system before any nutritional experiments were initiated. The application of statistical procedures that take into consideration the power of a test and number of replications required has allowed for more accurate interpretation of results. This can be seen in the results of the first nutritional requirement experiment on the optimal dietary protein level of the seabass at constant energy.     

Contributions of nutrition science to anthropological research.

Certain investigations of nutrition scientists have demonstrated the effects of cultural practices on nutrient intake. Anthropologists, too, have studied diets and food-related behavior, although until recently their interests infrequently included nutritional status. In the last decade, nutrition scientists' research helped stimulate the creation of an interdisciplinary specialty, nutritional anthropology, that combines techniques from both nutritional and anthropological science in the study of food use in relation to health. Practitioners of this expanding field make useful contributions to research in human nutrition through study of social aspects of the diet of individuals and groups. Their assistance can be particularly helpful in studies of populations in developing countries and of ethnic minorities in this country. Certain unanswered nutritional questions, which might more readily be solved by the combined efforts of nutritionists and nutritional anthropologists than by either professional alone, are presented.     

Do stable isotopes reflect nutritional stress? Results from a laboratory experiment on song sparrows

Stable isotope analysis is an increasingly valuable tool in ecological studies and shows promise as a measure of nutritional stress in wild animals. Thus far, however, the only studies on endotherms that have conclusively shown changes in δ¹⁵N and δ¹³C values in response to nutritional stress were conducted on fasting animals and animals growing under extreme levels of food restriction. We conducted a laboratory experiment to test whether δ¹⁵N and δ¹³C values provide a general index of nutritional stress. We compared the isotopic composition of whole blood, liver, muscle and feathers between two groups of juvenile song sparrows (Melospiza melodia) hand-reared in captivity under identical conditions except for feeding regime. To verify that our experimental treatment induced a biologically meaningful level of nutritional stress, we simultaneously measured the effects on physiology, growth and development at multiple scales. While food-restricted birds were physiologically stressed, physically smaller, and showed poorer growth and brain development compared to ad libitum-fed birds, there was no effect of feeding regime on either δ¹⁵N or δ¹³C values in any tissue. Instead of a continuum where the level of change in ¹⁵N or ¹³C contents corresponds to the level of nutritional stress, we suggest there may be a threshold level of nutritional stress below which such isotopic changes are likely to be negligible.     

Phenotypic flexibility as a measure of health: the optimal nutritional stress response test

Nutrition research is struggling to demonstrate beneficial health effects, since nutritional effects are often subtle and long term. Health has been redefined as the ability of our body to cope with daily-life challenges. Physiology acts as a well-orchestrated machinery to adapt to the continuously changing environment. We term this adaptive capacity “phenotypic flexibility.” The phenotypic flexibility concept implies that health can be measured by the ability to adapt to conditions of temporary stress, such as physical exercise, infections or mental stress, in a healthy manner. This may offer a more sensitive way to assess changes in health status of healthy subjects. Here, we performed a systematic review of 61 studies applying different nutritional stress tests to quantify health and nutritional health effects, with the objective to define an optimal nutritional stress test that has the potential to be adopted as the golden standard in nutrition research. To acknowledge the multi-target role of nutrition, a relevant subset of 50 processes that govern optimal health, with high relevance to diet, was used to define phenotypic flexibility. Subsequently, we assessed the response of biomarkers related to this subset of processes to the different challenge tests. Based on the obtained insights, we propose a nutritional stress test composed of a high-fat, high-caloric drink, containing 60 g palm olein, 75 g glucose and 20 g dairy protein in a total volume of 400 ml. The use of such a standardized nutritional challenge test in intervention studies is expected to demonstrate subtle improvements of phenotypic flexibility, thereby enabling substantiation of nutritional health effects.

Electronic supplementary material

The online version of this article (doi:10.1007/s12263-015-0459-1) contains supplementary material, which is available to authorized users.     

Kinetic studies of lipoprotein metabolism in the metabolic syndrome including effects of nutritional interventions

Nutritional interventions may favourably regulate dyslipoproteinemia and, hence, decrease cardiovascular disease risk. Lipoprotein kinetic studies afford a powerful approach to understanding and defining the mechanisms by which such interventions modulate lipoprotein metabolism. Stable isotope tracers and compartment models are now commonly employed for such studies. We review the recent application of tracer methodologies to the study of dyslipoproteinemia in the metabolic syndrome. We also focus on the effects of nutritional intervention studies that have addressed the effects of weight loss, n-3 fatty acids, plant sterols and alcohol on very low density lipoprotein, LDL and HDL metabolism. The potential for statin treatment as an adjunct to dietary modification is also discussed. New tracer methodologies are discussed, specifically those referring to reverse cholesterol transport. The nutritional interventions discussed in this review are readily transferable into clinical preventive practice. The potential benefits to be gained by weight loss and fish oil supplementation in the metabolic syndrome extend beyond their specific and positive effects on lipoprotein metabolism. Furthermore, recent developments in tracer methodologies afford new tools for probing the in-vivo pathways of lipoprotein metabolism in future studies.     

Geometry of nutrition in field studies: an illustration using wild primates

Nutritional geometry has shown the benefits of viewing nutrition in a multidimensional context, in which foraging is viewed as a process of balancing the intake and use of multiple nutrients. New insights into nutrient regulation have been generated in studies performed in a laboratory context, where accurate measures of amounts (e.g. eaten, converted to body mass, excreted) can be made and analysed using amounts-based nutritional geometry. In most field situations, however, proportional compositions (e.g. of foods, diets, faeces) are the only measures readily available, and in some cases are more relevant to the problem at hand. For this reason, a complementary geometric method was recently introduced for analysing multi-dimensional data on proportional compositions in nutritional studies, called the right-angled mixture triangle (RMT). We use literature data from field studies of primates to demonstrate how the RMT can provide insight into a variety of important concepts in nutritional ecology. We first compare the compositions of foods, using as an example primate milks collected in both the wild and the laboratory. We next compare the diets of different species of primates from the same habitat and of the same species (mountain gorillas) from two distinct forests. Subsequently, we model the relationships between the composition of gorilla diets in these two habitats and the foods that comprise these diets, showing how such analyses can provide evidence for active nutrient-specific regulation in a field context. We provide a framework to relate concepts developed in laboratory studies with field-based studies of nutrition.