Food intake in the real world: implications for nutrition and aging

Effects of RVD-hemopressin (α) on feeding and body weight after standard or cafeteria diet in rats

Palatability and variety of foods are major reasons for hedonic eating, and hence for obesity. Hemopressin, a hemoglobin α chain-derived peptide, plays antagonist/inverse agonist role on cannabinoid (CB)1 receptors, while RVD-hemopressin(α)[RVD-hp(α)], a N-terminally extended form of hemopressin, has been reported as an allosteric modulator of CB1 and CB2 receptors. We investigated the effects of 14 daily intraperitoneal injections of RVD-hp(α), in Sprague-Dawley rats fed a highly palatable cafeteria-style (CAF) diet (30% fat, 56% carbohydrate, 14% protein; 4.20 kcal/g) compared to standard laboratory chow (STD) food (3.5% fat, 63% carbohydrate, 14% protein, 19.5% other components without caloric value; 3.20 kcal). Food intake, body weight and locomotor activity were recorded throughout the study. Finally, rats were sacrificed and agouti-related peptide (AgRP), neuropeptide Y (NPY), pro-opiomelanocortin (POMC) and cocaine- and amphetamine-regulated transcript (CART) and fatty acid amide hydrolase (FAAH) gene expression in the hypothalamus was measured by real-time reverse transcription polymerase chain reaction. We found that CAF diet increased food intake as compared to STD diet. In both STD and CAF diet fed rats, RVD-hp(α) treatment inhibited food intake, increased locomotor activity but did not modify body weight. In vehicle injected animals, CAF as compared to STD diet increased AgRP gene expression. RVD-hp(α) treatment decreased POMC mRNA levels in both diet groups and lowered the elevated AgRP levels induced by CAF diet. RVD-hp(α) treatment plays an anorexigenic role paralleled by increased locomotor activity both in STD and CAF diet fed rats. The inhibition of feeding could be partially mediated by lowering of hypothalamic POMC and AgRP gene expression levels.

Optimizing nutrition in older people

Older adults are at increased risk of malnutrition, for a variety of physiological and psychological reasons. This has implications for health, quality of life, independence and economic circumstances. Improvements in nutrition are known to bring tangible benefits to older people and many age-related diseases and conditions can be prevented, modulated or ameliorated by good nutrition. However, practical and realistic approaches are required to optimize diet and food intake in older adults. One area where improvements can be made relates to appetite. Encouraging older adults to prepare meals can increase appetite and food intake, and providing opportunities for older adults to eat a wide variety of foods, in company, is a simple strategy to increase food intake. The protein requirement of older adults is subject to controversy and although considered the most satiating macronutrient, it appears that protein does not elicit as great a satiating effect in older adults as it does in younger individuals. This indicates that there is potential to increase protein intake without impacting on overall energy intake. Other areas where simple practical improvements can be made include both packaging of foods that are easy to prepare and the education of older adults on the safe storage and preparation of food. Research into improving the diets and nutritional status of older adults has indicated that many of the strategies can be easily and cost-effectively undertaken.

Occurrence of Malnutrition and Associated Factors in Community-Dwelling Older Adults: Those with a Recent Diagnosis of Cancer Are at Higher Risk

OBJECTIVES

In older adults, nutritional health is essential for good quality of life and living independently at home. Especially in cancer patients, malnutrition is common and known to complicate treatment. This study aims to evaluate the nutritional status and its associated factors in community-dwelling older adults with and without cancer.

DESIGN

This is an observational study.

SETTING

This study focuses on older community-dwelling people.

PARTICIPANTS

This study included older people with and without cancer (≥70 years). Cancer patients included patients with a new diagnosis of breast, lung, prostate, or colorectal cancer.

MEASUREMENTS

Data collection included measures of nutritional status, quality of life, depression, fatigue, distress and functional status. We used multivariate logistic regression analysis to assess the association between personal characteristics and malnutrition.

RESULTS

Data were available for 657 people; 383 people without cancer and 274 with a cancer diagnosis. Overall, malnutrition was detected in 245 (37.5%) people; in cancer patients this was 66.1%. Multivariate analysis showed that having cancer (OR 14.4, 95% CI: 8.01 - 23.3), being male (OR 2.38, 95% CI: 1.49 - 3.70), having depression (OR 13.5, 95% CI: 6.02-30.0), distress (OR 2.60, 95% CI: 1.55 - 4.37) and impaired instrumental activities of daily living (IADL) (OR 2.63, 95% CI: 1.63 - 4.24) were associated with a higher risk of malnutrition.

CONCLUSION

The prevalence of malnutrition in community-dwelling older people is high, particularly in patients with cancer. Benchmarking and routine screening of older patients may be helpful strategies to increase awareness of (risk of) malnutrition among professionals.

RelAte: pilot study of the effects of a mealtime intervention on social cognitive factors and energy intake among older adults living alone

Mealtime interventions typically focus on institutionalised older adults, but we wanted to investigate whether they may also be effective among those living independently. Using a randomised controlled trial design, we assessed the effects of a novel mealtime intervention on self-efficacy, food enjoyment and energy intake. A total of 100 adults living alone aged over 60 years were randomised to the treatment or control conditions: all received a guidebook on nutrition and culinary skills. Treatment group participants received a weekly visit from a trained volunteer who prepared and shared a meal with them. Participants in the treatment group showed improvements relative to those in the control group at borderline significance (P=0·054) for self-efficacy and at significance for food enjoyment. Significant improvements were observed in female participants in the treatment but not in the control group in energy intake (although following corrections for multiple comparisons, only the effect on food enjoyment remained significant). These findings will inform the design of future complex interventions. For this type of intervention to be successful, more focus has to be placed on making interventions more personalised, potentially according to sex. Findings are important for nutritional sciences as they indicate that, in order to improve energy intake and food enjoyment among older adults, multimodal nutritional interventions including social components may be successful.

Environmental Strategies to Promote Food Intake in Older Adults: A Narrative Review

Aging is often accompanied by lower intakes of food energy and consequent negative effects on health. To some extent this is due to declines in physiological ability, including the sensory responsiveness to regulate food intake. Fortunately, environmental factors may still influence food intake in older adults. Factors such as social facilitation, modeling, and nutrition knowledge and skills have been shown to stimulate their food intake. While environmental factors such as the eating location, portion size, food presentation, and labeling are known to influence eating behavior, their effectiveness in stimulating food intake in older persons is not well delineated. It is suggested that improving the environmental stimuli that promote food intake is a viable strategy to overcome age-related declines in nutrient intakes. This strategy is so promising that further research is warranted.

Increased Intake of Foods with High Nutrient Density Can Help to Break the Intergenerational Cycle of Malnutrition and Obesity

A workshop held at the University Medical Center in Groningen, The Netherlands, aimed at discussing the nutritional situation of the population in general and the role diet plays during critical windows in the life course, during which the body is programmed for the development of non-communicable diseases (NCDs). NCDs are increasingly prevalent as our society ages, and nutrition is well known to play an important role in determining the risk and the time of onset of many common NCDs. Even in affluent countries, people have difficulties to achieve adequate intakes for a range of nutrients: Economic constraints as well as modern lifestyles lead people to consume diets with a positive energy balance, but low in micronutrients, resulting in increasing prevalence of obesity and suboptimal nutritional status. Information about nutrient density, which refers to the content of micronutrients relative to energy in food or diets, can help identify foods that have a low calorie to nutrient ratio. It thus allows the consumption of diets that cover nutritional needs without increasing the risk of becoming obese. Given the impact a nutrient dense, low energy diet can have on health, researchers, food industry and governments jointly should develop options for affordable, appealing nutrient-rich food products, which, in combination with physical activity, allow for optimal health throughout the life-course.

Dietary patterns and incidence of depression in a cohort of community-dwelling older Canadians

OBJECTIVES

To investigate the association of dietary patterns with a 3-year incidence of depression among healthy older adults.

DESIGN

Multiple logistic regression models adjusted for age, sex, marital status, smoking, education, total energy intake, physical activity, body mass index, hypertension, functional autonomy, cognitive functioning, social activities, and stressful life events. Energy and macronutrient intakes were also analyzed as potential predictors of depression.

SETTING

Cities of Montréal, Laval, and Sherbrooke in Quebec, CA.

PARTICIPANTS

Community-dwelling older adults, free of depression at baseline (N=1,358, 67-84 y), followed for 3y in the Québec Longitudinal Study on Nutrition and Aging (NuAge).

MEASUREMENTS

Dietary patterns derived from principal components analysis of three 24 h-recalls at baseline, and depression incidence as measured by the 30-item Geriatric Depression Scale (≥11) and/or use of antidepressants at follow-up years.

RESULTS

170 people (63% women) became depressed over the 3 years. People in the highest tertile of adherence to the "varied diet" had lower risk of depression before adjustment (OR 0.58, 98% C.I. 0.38-0.86) but not significant once age and sex were controlled. No other dietary pattern was associated with the incidence of depression. The highest tertile of energy intake was associated with lower depression incidence after controlling for all confounders (OR 0.55, 95%CI 0.34-0.87).

CONCLUSION

Among healthy older adults, dietary patterns do not appear to be related to depression. Those who eat less, however, possibly reflecting declining health, are at higher risk of becoming depressed.

Country of origin predicts nutrition risk among community living older people

OBJECTIVES

To assess the nutrition risk status of community living older people and to identify associated risk factors.

DESIGN

A cross-sectional study using convenience sampling.

SETTING

North Shore City, Auckland, New Zealand. Data collection was carried out by a research nutritionist using computer assisted personal interviewing in the participant's own home.

PARTICIPANTS

Fifty-one independently living people aged between 80 and 85 years.

MEASUREMENT

A survey using three validated questionnaires: Practitioner Assessment of Network Type (PANT) to evaluate social networks; Elderly Assessment System (EASY-Care) to evaluate physical and mental wellbeing and Seniors in the Community: Risk Evaluation for Eating and Nutrition Version II (SCREEN II) to assess nutrition risk.

RESULTS

A third of the participants (31%) were at high risk of malnutrition (SCREEN II score <50; range 29-58 out of maximum score of 64). The majority of participants (82%) lived alone and nearly half (47%) had supportive social networks including close relationships with local family, friends and neighbours. Low self-rated health, disability and social factors (being born outside of New Zealand, losing a spouse and loneliness) were key underlying factors associated with being at nutrition risk.

CONCLUSION

Nutrition risk is common among aged individuals living in the community. Health and social factors that shape eating behaviours place older people at increased nutrition risk. Strategies are needed for the early identification of risk factors to prevent nutrition problems. Engaging older people at risk to share meal preparation and dining experiences may foster better outcomes.

Resident interactions at mealtime: an exploratory study

Social interaction is thought to be important for psychological wellbeing and is necessary for developing relationships between older adults living in facilities. This study seeks to describe the social interaction that occurs amongst tablemates at mealtime in retirement homes, as well those things that influence resident-to-resident interaction. Fourteen lunch time periods were the basis for qualitative participant observation. Two or three researchers collected data in each period, with each observing two tables, resulting in 63 individual table observations at a retirement living facility dining room in a medium-sized city in Southern Ontario. Residents attending mealtime in the dining room were (~ 100). The type, extent and influences on social interactions amongst tablemates were recorded in detailed field notes. Qualitative thematic analysis, using a constant comparison procedure, was used to summarize and make sense of the data. A variety of social interactions occurred amongst tablemates including: making conversation, providing assistance, sharing, humouring, showing appreciation and affection, and rebuffing/ignoring/excluding. Interactions were influenced by tablemate roles, resident characteristics, and the social and physical environment, including staff. Social interactions or lack thereof are important for relationship development and mealtime environment. Describing the types of interaction and what influences them is a first step towards promoting social engagement which can enhance quality of life for residents. Further investigation through interviews with residents on the meaning of mealtime and companionship at meals will build a deeper understanding of the importance and influences on social interaction in this setting.

Community covariates of malnutrition based mortality among older adults

PURPOSE

The purpose of this study was to identify community level covariates of malnutrition-based mortality among older adults. A community level framework was delineated which explains rates of malnutrition-related mortality among older adults as a function of community levels of socioeconomic disadvantage, disability, and social isolation among members of this group.

METHODS

County level data on malnutrition mortality of people 65 years of age and older for the period 2000-2003 were drawn from the CDC WONDER system databases. County level measures of older adult socioeconomic disadvantage, disability, and social isolation were derived from the 2000 US Census of Population and Housing. Negative binomial regression models adjusting for the size of the population at risk, racial composition, urbanism, and region were estimated to assess the relationships among these indicators.

RESULTS

Results from negative binomial regression analysis yielded the following: a standard deviation increase in socioeconomic/physical disadvantage was associated with a 12% increase in the rate of malnutrition mortality among older adults (p < 0.001), whereas a standard deviation increase in social isolation was associated with a 5% increase in malnutrition mortality among older adults (p < 0.05).

CONCLUSIONS

Community patterns of malnutrition based mortality among older adults are partly a function of levels of socioeconomic and physical disadvantage and social isolation among older adults.

A multidimensional approach to understanding under-eating in homebound older adults: the importance of social factors

PURPOSE

The purpose of this study was to identify relationships between medical, functional, economic, oral health, social, religious, and psychological factors and under-eating in homebound older adults. The focus of the study was on identifying potentially modifiable factors amenable to social and behavioral interventions.

DESIGN AND METHODS

A total of 230 homebound older adults who were currently receiving home health services participated in interviews in their homes using a questionnaire to assess eating behaviors and factors that could possibly affect those eating behaviors. Interviewers measured height and weight, and participants completed three 24-hr dietary recalls.

RESULTS

The mean age of participants was 79.1 years. The sample comprised 78% women and 38% African Americans. We found that 70% of participants were under-eating, defined as not consuming enough calories to maintain their current body weight. Participants who were at higher risk of under-eating included men, those receiving either infrequent care or very frequent care by a caregiver, those who had been hospitalized prior to receipt of home health services, and those with a higher body mass index.

IMPLICATIONS

Findings from the study have implications for both practice and policy. Experts must develop evidence-based interventions targeted at under-eating in this particularly vulnerable and growing population of homebound older adults. This study provides an initial foundation for the development of targeted evidence-based behavioral nutritional interventions that are noninvasive and cost effective.

Immunosupportive therapies in aging

The primary role of the immune system is to protect the organism against pathogens, but age-associated alterations to immunity increase the susceptibility of the elderly to infectious disease. The exact nature of these changes is still controversial, but the use of screening procedures, such as the SENIEUR protocol to exclude underlying illness, helped to better characterize the changes actually related to physiological aging rather than pathology. It is generally agreed that the most marked changes occur in the cellular immune response reflecting profound alterations in T cells. Much of this is due to thymic involution as well as changes in the proportions of T cell subpopulations resulting from antigen exposure, and altered T cell activation pathways. However, a body of data indicates that innate immune responses, including the critical bridge between innate and adaptive immunity, and antigen presenting capacity are not completely resistant to senescence processes. The consequences of all these alterations are an increased incidence of infections, as well as possibly cancers, autoimmune disorders, and chronic inflammatory diseases. The leading question is what, if anything, can we do to prevent these deleterious changes without dangerously dysregulating the precarious balance of productive immunity versus immunopathology? There are many potential new therapeutic means now available to modulate immunosenescence and many others are expected to be available shortly. One main problem in applying these experimental therapies is ethical: there is a common feeling that as ageing is not a disease; the elderly are not sick and therefore do not require adventurous therapies with unpredictable side-effects in mostly frail individuals. Animal models are not helpful in this context. In this chapter we will first briefly review what we think we know about human immunosenescence and its consequences for the health status of elderly individuals. We will then discuss possible interventions that might one day become applicable in an appropriate ethical environment.

Frameworks of population obesity and the use of cultural consensus modeling in the study of environments contributing to obesity

Obesity in Eastern Europe has been linked to privilege and status prior to the collapse of communism, and to exposure to free-market economics after it. Neither formulation is a complete explanation, and it is useful to examine the potential value of other models of population obesity for the understanding of this phenomenon. These include those of: thrifty genotypes; obesogenic behaviour; obesogenic environments; nutrition transition; obesogenic culture; and biocultural interactions of genetics, environment, behaviour and culture. At the broadest level, obesity emerges from the interaction of thrifty genotype with obesogenic environment. However, defining obesogenic environments remains problematic, especially in relation to sociocultural factors. Furthermore, since different identity groups may share different values concerning the obesogenicity of the environment, a priori assumptions about group homogeneity may lead to flawed interpretations of the importance of sociocultural factors in obesogenic environments. A new way to identify cultural coherence of groups and populations in relation to environments contributing to obesity is put forward here, that of cultural consensus modeling.

Much communication with family and appetite among elderly persons in Japan

The purpose of this study is to examine cross-sectionally the factors associated with appetite among the elderly persons living in the community in Japan. The subjects of this study were 754 non-institutionalized elderly men and women aged 65 years and older living in community in Japan. The data were collected by face-to-face interviews. The factors related to subjective health was examined using multiple logistic regression analyses. Four hundred and forty-nine (56.4%) participants evaluated appetite as very good; 239 (30.0%) as somewhat good; 92 (11.6%) as little/not at all. Subjects with good appetite were more physically active, had less depressive symptoms, subjective stress, much more communication with family and much more social support, as compared to those without appetite. Appetite was significantly associated with better subjective good health after controlling for other variables in the model. Only communication with family was significantly associated with good appetite after controlling for other variables (odds ratio, OR=2.43; 95% confidence interval, CI=1.30-4.74). The indirect effect of communication with family on appetite was much greater than the direct effect. These findings suggest that communication with family may be beneficial promoter of the appetite in the elderly.

Dietary variety and its effect on food intake of elderly adults

BACKGROUND

Older people frequently have poor food intake. This present study investigated the effect of dietary variety on food intake in younger and older people.

METHODS

Eighteen young adults (mean age = 26 years) and 18 older adults (mean age = 70 years) consumed four consecutive courses of sandwiches on two occasions. In the plain treatment, each course of sandwiches was of the same type, while in the variety treatment four courses, each of a different type of sandwich, were served. Each time the participants were presented with a serving of sandwiches and asked to eat as much as they liked.

RESULTS

In the plain condition, the older adult group consumed more than their young counterparts. This situation was reversed for the variety condition when the young group ate more than the older adults. Interestingly, the older adult group ate more when a variety of sandwiches was presented. This may be contrary to what is predicted by the sensory-specific satiety model of eating behaviour.

CONCLUSIONS

This study suggests that presenting the older people with a varied meal may be a valid strategy to improve food intake in this group.

Interactions between the "cognitive" and "metabolic" brain in the control of food intake

If the new environment and modern lifestyle cause obesity in individuals with thrifty genes by increasing energy intake, it is important to know by what mechanisms hyperphagia occurs and why energy balance is not kept in check by the homeostatic regulator. The argument is developed that procuring and ingesting food is an evolutionarily conserved survival mechanism that occupies large parts of the brain's computing capacity including not only the hypothalamus but also a number of cortico-limbic structures. These forebrain systems evolved to engage powerful emotions for guaranteed supply and ingestion of beneficial foods from a sparse and often hostile environment. They are now simply overwhelmed with an abundance of food and food cues that is no longer interrupted by frequent famines. After briefly reviewing structure and functions of the relevant cortico-limbic structures and the better-known hypothalamic homeostatic regulator, the review focuses mainly on interactions between the two systems. Although several cortico-limbic processes are sensitive to metabolic depletion and repletion signals, it appears that they are underlying the same reversible leptin resistance that renders hypothalamic circuits insensible to continuously high leptin levels during periods of feast. It is hypothesized that this naturally occurring leptin resistance allowed temporary neutralization of satiety mechanisms and evolved as a response to survive subsequent periods of famine. With today's continuous and abundant food availability for a segment of the population, the powerful cognitive processes to eat and the resulting overweight can partially escape negative feedback control in prone individuals most strongly expressing such thrifty genes.

Preference for palatable food is reduced by the gamma-hydroxybutyrate analogue GET73, in rats

Palatability and variety of foods are major reasons for "hedonic" eating, and hence for overeating and obesity. Palatable food and drugs of abuse share a common reward mechanism, and compounds that block the reinforcing effect of drugs of abuse preferentially suppress the intake of palatable foods. This research was aimed at studying the influence of the gamma-hydroxybutyrate analogue N-(4-trifluoromethylbenzyl)-4-methoxybutanamide (GET73) - that inhibits alcohol consumption - on consumption and reinforcing effect of palatable food. Adult male rats were used. For place preference conditioning, sweetened corn flakes were used as the reinforcer, and GET73 (50, 100 and 200mgkg(-1)) or vehicle were orally (p.o.) administered either 30min before each training session and the test session, or only before the test session. To study the influence on consumption, GET73 was given p.o. at the same doses once daily for 12 days to rats given free access to both palatable and varied food (cafeteria diet) or to standard chow. Both acquisition and expression of palatable food-induced conditioned place preference were inhibited by GET73, either administered throughout the conditioning period or only before the test session. GET73 reduced also the consumption of cafeteria food, while that of standard chow was increased. At these doses, GET73 had no detrimental effect on open-field behaviour. GET73 seems to specifically attenuate the gratification produced by varied and palatable food, without affecting the consumption of not particularly palatable chow. Since, overweight and obesity are mostly due to the overeating of palatable and varied foods, drugs like GET73 could represent a somewhat ideal and rational approach to obesity treatment.

Factors influencing food intake in patients with heart failure: a comparison with healthy elders

BACKGROUND AND RESEARCH OBJECTIVE

Promoting adequate nutritional intake of patients with heart failure (HF) is an essential component of comprehensive management. This goal can be hampered by decreased appetite, as well as psychological, social, and HF-related factors that can affect food intake. Factors related to aging may also affect food intake in older patients. The purpose of this study was to compare patients with HF to healthy elders regarding the extent to which they perceived how appetite and hunger, emotional and social, and illness factors affected the amount of food they ate in the previous week.

SUBJECTS AND METHODS

Sixty-seven patients with HF were recruited from 3 Midwestern HF clinics. As part of a larger study examining nutrition in HF, patients filled out the Food Eating Experiences and Diet (FEED) questionnaire, an instrument designed to assess factors affecting appetite and hunger. Patients were asked to rate their hunger and appetite on a visual analog scale. On Likert-type scales, they rated the extent to which appetite/hunger, emotional/social, and illness factors affected the amount of food intake. Sixty-eight healthy elders were recruited from 2 Midwestern senior citizen centers. As part of a study collecting a large data set for comparison with HF patients, healthy elders provided demographic and health information and filled out the FEED questionnaire.

RESULTS AND CONCLUSIONS

Factors rated as affecting food intake most often by patients with HF were decreased hunger sensations, diet restrictions, fatigue, shortness of breath, nausea, anxiety, and sadness. Factors rated most often by healthy elders as affecting food intake were diminished hunger sensations, early satiety, eating alone, and decreased senses of taste and smell. Among patients with HF, many factors unique from those present due to age were reported to affect food intake.

The effect of the presence of others on caloric intake in homebound older adults

BACKGROUND

Undernutrition in homebound older adults is a significant problem. The purpose of this study was to investigate the effect of the presence of others, both within the household and during meals, on caloric intake in homebound older adults.

METHODS

In-depth interviews and three 24-hour dietary recalls were obtained from 50 older adults who were receiving home health services. Descriptive statistics were used to characterize participants, and hierarchical linear modeling was performed to evaluate predictors of caloric intake per meal.

RESULTS

Participants' mean age was 77. Females composed 65% and African Americans composed 42% of the sample. Analyses are based on 553 meal observations. The majority (84%) of participants consumed all meals for each of the 3 days of data collection; however, they consumed an average of only 1305 calories per day. Hierarchical linear modeling analysis indicated that persons who had others present during meals consumed an average of 114.0 calories more per meal than those who ate alone (p =.009) and that women consumed 76.7 fewer calories per meal than did men (p =.045). The presence of others within the household had no effect on caloric intake.

CONCLUSION

This research suggests that a simple and inexpensive way to increase caloric intake in homebound older adults is to make arrangements for family members or caregivers to eat with them.

Dietary Fat Intake and Proinflammatory Cytokine Levels in Patients With Heart Failure

BACKGROUND

Dietary fat intake affects proinflammatory cytokine levels of healthy adults. Whether dietary fats have similar effects in patients with heart failure (HF) is unknown. The purposes of this study were to determine (1) effect of dietary fat on interleukin (IL)-6, tumor necrosis factor (TNF)-alpha, and soluble receptors sTNF-R1 and sTNF-R2 levels in patients with HF and (2) subsequent impact of these levels on event-free survival.

METHODS AND RESULTS

Forty-two patients provided 4-day food diaries and blood for cytokines. Event-free survival curves were calculated by Kaplan-Meier method and groups compared using log-rank test. IL-6 was not related to fat intake. TNF-alpha levels were elevated in patients with diets higher versus lower in saturated (6.9 +/- 5 versus 4.2 +/- 2 pg/mL) and trans fats (6.8 +/- 4.5 versus 4.5 +/- 2.8 pg/mL). Patients consuming diets higher in polyunsaturated fats had lower sTNF-R1 (2391 +/- 1010 versus 3373 +/- 2098 pg/mL) and sTNF-R2 (3803 +/- 1187 versus 5974 +/- 3275 pg/mL) levels. Higher omega-3 intake produced similar results: sTNF-R1 (2323 +/- 1304 versus 3307 +/- 1973) and sTNF-R2 (4117 +/- 2646 versus 5409 +/- 2801). Event-free survival was decreased in patients with higher TNF-alpha and sTNF-R1 levels.

CONCLUSION

Dietary fat intake may affect proinflammatory cytokine levels in patients with HF. Research to determine whether changing composition of dietary fat can alter proinflammatory cytokine activity of HF patients is warranted.

Neural control of appetite: cross-talk between homeostatic and non-homeostatic systems

The new lifestyle in the modern world is causing a rapid increase in the prevalence of obesity and associated health problems. Increased availability of palatable and energy dense foods, combined with a lack of physical activity overpower a homeostatic regulatory system that evolved to survive periods of famine rather than preventing obesity. Environmental and lifestyle factors influence energy balance mainly through their impact on cortico-limbic brain structures dealing with reward, cognitive, and social aspects of food intake and voluntary physical activity. To find new behavioral and pharmacological treatments of obesity, it will be important to identify the specific pathways that link these externally driven processes with the homeostatic regulatory system.

Clinical endocrinology and metabolism. Regulation of energy homeostasis by peripheral signals

The increased incidence of obesity makes it imperative to understand the regulation of food intake and body weight. We review the signals that interact with the brain to control energy homeostasis, i.e. energy intake and expenditure. Three broad categories can be distinguished. Signals generated in the gastrointestinal tract during meals ('satiety' signals, e.g. cholecystokinin) elicit satiation and contribute to stopping the meal. The potency of these acutely acting signals must be increased if they are to be used therapeutically. Hormonal signals whose secretion is proportional to body fat (adiposity signals, leptin and insulin) robustly reduce food intake and body weight by directly stimulating receptors locally in the brain. Therapeutic applications will have to find ways to circumvent the systemic actions of these hormones, targeting only the brain. Satiety and adiposity signals interact with neuronal circuits in the brain that utilize myriad neurotransmitters to cause net catabolic or anabolic responses. Considerable effort is being directed towards finding ways to intervene in specific circuits to help accomplish weight loss.

The utility of animal models of human energy homeostasis

The prevalence of obesity among adults and children has increased steadily over the last few years worldwide, reaching epidemic proportions. Particularly alarming is the link between obesity and the development of chronic disorders such as heart disease, type 2 diabetes, hypertension and some cancers (Bjorntorp, 1997). Environmental causes of obesity are thought to include a sedentary lifestyle and an abundance of highly palatable energy-dense foods (Hill et al. 2003). Genetic factors also contribute to susceptibility to obesity, although the genetic basis of most human obesities is thought to be polygenic (Comuzzie & Allison, 1998; Barsh et al. 2000). The present paper considers some of the animal models used to infer aspects of human obesity, with an emphasis upon their usefulness.

Effect of ambience on food intake and food choice

Eating takes place in a context of environmental stimuli known as ambience. Various external factors such as social and physical surroundings, including the presence of other people and sound, temperature, smell, color, time, and distraction affect food intake and food choice. Food variables such as the temperature, smell, and color of the food also influence food intake and choice differently. However, the influence of ambience on nutritional health is not fully understood. This review summarizes the research on ambient influences on food intake and food choice. The literature suggests that there are major influences of ambience on eating behavior and that the magnitude of the effect of ambience may be underestimated. Changes in intake can be detected with different levels of the number of people present, food accessibility, eating locations, food color, ambient temperatures and lighting, and temperature of foods, smell of food, time of consumption, and ambient sounds. It is suggested that the manipulation of these ambient factors as a whole or individually may be used therapeutically to alter food intake and that more attention needs to be paid to ambience in nutrition-related research.

Neural systems controlling food intake and energy balance in the modern world

PURPOSE OF REVIEW

Obesity continues to increase around the globe, and creates a major health problem because of its comorbidities such as diabetes and cardiovascular disease. Considering that the major cause of most human obesities is the modern lifestyle in a rapidly changing environment, this suggests that the battle is between brain areas controlling internal metabolic homeostasis and those dealing with cognitive and emotional processing of external information. Thus, this review is intended to bridge this apparent neural dichotomy and highlight possible ways of interactions between these homeostatic and nonhomeostatic systems.

RECENT FINDINGS

Rapid progress has been made in identifying the molecular mechanisms underlying the neural circuits regulating food intake and energy balance. Specific populations of peptidergic neurons in the medial hypothalamus can be considered metabolic integrators sensing both short and long-term availability of fuels. These cell groups in turn connect with various other brain regions to orchestrate adaptive responses through changes in food intake, as well as endocrine and autonomic responses. Alternatively, the impact of the environmental changes on ingestive behavior have been documented, and many of the underlying cortico-limbic pathways are starting to be identified. It has been proposed that a switch from instinctual control of energy balance to a more cognitive control will be necessary to stop the obesity epidemic.

SUMMARY

The realization that there is nothing wrong with the homeostatic regulatory system in common obesity suggests that a systematic investigation of pathways that link the 'cognitive' with the 'metabolic' brain might be a more promising area of research. Such an investigation would reveal new molecular and cellular mechanisms providing new drug targets, leading to behavioral therapies that are directed more towards the causes of common obesity.