Preface

In the European Union, the proportion of older people has increased in recent decades and it is predicted to increase from 25 to 40% by 2030. Together with climate changes and the increase of energy demand the aging of the population is becoming a major challenge than humanity is going to cope with. One of the major contributors to population aging is the reduced mortality among older people, which is largely due to a combination of improved lifestyles, prevention, and treatment that mainly prevent cardiovascular damages. Moreover, improved delivery of health care may have been of primary importance in decreasing old-age mortality in this century. Therefore, population aging can reasonably be described as both an outcome of, and a challenge for, European health systems. This demographic explosion emphasizes the critical importance of identifying strategies able to counteract or delay aging and the onset of age-related diseases and disabilities, and thus contribute to increasing the number of elderly European citizens in good health, and reducing age-related medical and social costs. A large part of Horizon 2020, the new work-programme of European Commission, is devoted to interventions to promote health in elderly. In 2011, the EU launched the European Innovation Partnership on Active and Healthy Aging, aimed at applying innovation to better respond to Europe's aging societies and add 2 years of good health to the average European by 2020. Evidence is increasing that the promotion of so-called healthy or active aging not only increases healthy life expectancy and postpones much health care expenditure, but also has wider economic benefits because people who live a long and healthy life are more inclined to stay in the labor force and have a strong incentive to invest in skill development. Actions will include efforts to improve living conditions and care together with primary prevention, including interventions against alcohol consumption, smoking, obesity, sedentary lifestyles and poor diets. Within this scenario epidemiological studies and intervention trials have shown that in the elderly nutrition play a major role in healthy aging, and in reducing risk of disease and improving quality of life. In particular, experimental evidence indicates that specific, key dietary constituents affect inflammation and immune function as well as single organs such as heart, bone, brain, muscle, and gastrointestinal tract. Despite its enormous complexity, one of the key mechanisms of aging is inflammation as exemplified by the fact that a typical feature of the aging process is the development of a chronic, low grade, inflammatory status named inflammaging that plays a pivotal role in the most important geriatric conditions, such as sarcopenia, frailty, and disability, as it is shared by the major age-related diseases, thus contributing to elderly morbidity and mortality. However, available data in the literature suggest that inflammaging is malleable and reversible, and can be at least in part counteracted and slowed down through changes in life-style and diet. The FP7-KBBE-NU-AGE project (G.A. n°266486) coordinated by Prof. Claudio Franceschi from University of Bologna, Italy, targets nutrition as a major modulator of inflammaging and other age-related functional outcomes. The underlying hypothesis of NU-AGE is that a whole diet approach will have greater beneficial effect on overall health than single nutrient interventions. Simultaneous changes in a select range of dietary constituents, with a focus on reducing chronic low grade inflammation, will ensure that the subtle effects observed from single nutrients will act in concert to optimize healthy aging. Thus, the NU-AGE consortium will comprehensively study the effect of a Mediterranean diet newly designed according to the nutritional needs of people over 65 years of age, the so-called “NU-AGE diet”. A total of 1250 non-frail and pre-frail volunteers of 65–79 years old, equally subdivided into males and females, will be characterized before and after the dietary intervention by measuring a limited number of robust parameters capable of providing reliable data about different domains/subsystems (health and nutritional status, physical and cognitive functions, immunological, biochemical and metabolic parameters). A sub-group of subjects will be further characterized by advanced techniques (genetics, epigenetics) and high-throughput “omics” (transcriptomics, metagenomics, metabolomics) in order to identify cellular and molecular targets and mechanisms responsible for the effects of the whole diet intervention. This approach will allow an evaluation of the whole-organism response by a systems biology approach, considering several tissues and organs/systems as a functional network instead of assessing the single tissue and organ responses separately. Here, we present a special edition of MAD dedicated to this project consisting of fifteen papers, encompassing the main topics. First of all, this special issue will focus on the conceptual framework and design of NU-AGE, with an update on inflammaging (Santoro et al.), and a critical reappraisal of the rationale of the “NU-AGE diet” (Berendsen et al.). Then, the special issue addresses some of the most critical aspects of nutrition in the elderly, which should illustrate the overall complexity of the dietary requirement in old age. The various contributions are devoted not only to classical topics such as protein-energy homeostasis (Boirie et al.) and micronutrients such as copper, zinc and selenium (Mocchegiani et al.), but also to neglected topics such water, hydratation and drinking dietary patterns (Hooper et al.), as well as to specific micronutrients such as iron (Fairweather-Tait et al.), owing to its clinical importance (anemia in the elderly). This special issue addresses hot topics which recent literature suggests of utmost importance to understand the systemic effects of nutrition and nutritional interventions such as that adopted by NU-AGE. Thus, there are three papers that, within an inflammaging perspective, are devoted to: (i) the interaction between diet and the gut microbiota (Candela et al.); (ii) the effect of an elderly tailored diet on cognitive decline and on the gut–brain axes (Caracciolo et al.); (iii) nutritional interventions (caloric restriction, supplementation with nutrients involved in one-carbon metabolism and bioactive food components) that impact on the epigenetic profile (DNA methylation and microRNA) of cells and organs of the body (Bacalini et al.). A paper including new experimental data on the effect of resistance-type exercise training with or without protein supplementation on cognitive functioning in frail and pre-frail elderly people (van de Rest et al.) can be considered as a complement of some of the above mentioned papers within the generally recognized scenario that physical activity has been proposed as one of the most effective strategies to prevent the age-related cognitive decline. Taking into account that the major aim of the NU-AGE project is to test the hypothesis that an appropriate Mediterranean diet ad hoc modified to meet the elderly requirements will decrease the level and intensity of inflammaging, two papers are dedicated to the effect of diet on immunosenescence (Maijó et al.) and the changes occurring with age in adipose tissue(s) (Zamboni et al.), both assumed as major sources of inflammatory stimuli in old bodies. Finally, a paper by Collino and colleagues discusses the emerging perspective of a personalized and subject-tailored nutrition in the elderly, a perspective which is becoming realistic owing to the use of new “omics” (metabolomics). This approach has several advantages, as it can help in identifying key molecular mechanisms/targets affected by diet and related to inflammaging, and in revealing basic profiles of health and functions (biomarkers) in the elderly. Two final papers try to put the problem of the best diet for attaining an active and healthy aging in a broader perspective. The first illustrates another major final aim of NU-AGE, i.e. the idea to put all the clinical, biological and omics data in an ad hoc re-designed database in order to allow an integrated analysis of all the collected data within a system biology perspective of inflammaging and nutrition (Calcada et al.). The second paper enlarges our European horizon and opens the eyes on another famous diet to attain healthy longevity in another part of the world, the so-called “Okinawan diet” (Willcox et al.), addressing this topic in a comprehensive and critical way. European Union and the EU-funded large projects are interested not only in the health and wellbeing of EU citizens but also in the wellbeing of EU economy, which in turn can affect the money available for welfare. Thus, the NU-AGE project was asked not only to perform basic investigations on diet and healthy aging but also to investigate the determinants of food choices in elderly, and finally to exploit the knowledge gained by NU-AGE in order to help food industries to set up new food product prototypes and to design advanced traditional foods for the old citizens in Europe. Thus, the NU-AGE consortium is constituted not only by scientists, but also by food industries and by the EU Federations of Food & Drink Industries. This part is not covered by the NU-AGE special issue in MAD, however, it is interesting to stress the link between basic food science and its economic outcomes and the social/behavioral aspects of nutrition in the elderly. To this aim the interested MAD reader is referred to the first results recently published by members of NU-AGE consortium (Irz et al., Public Health Nutrition journal, 2013). These results indicate that diet quality among the EU elderly is low on average and highly heterogeneous. Education, not living alone, and being a female are all characteristics that are positively associated with diet quality after controlling for other socio-demographic factors. The results also established that the causal relationship between diet quality and health is bi-directional: diet quality influences health and health influences diet quality. Although intuitive, this result implies that feedback mechanisms in the relationship between diet quality and health should be considered carefully when analyzing the benefits from promoting healthy eating to the elderly. To conclude, even if the NU-AGE project is represented by a core of basic and omics food science, its integrated perspective also includes research on how aging affects eating behavior as well as on the acceptability and understanding of food with nutrition/health claims. Within this scenario, NU-AGE is committed to develop guidelines for best practice in communicating to the elderly about food to improve health and wellbeing. This interdisciplinary, trans-sectoral project will integrate complementary approaches and perspectives into a unique knowledge base that will be transferred to industries to deliver products, tools and services that will support the elderly in respect of recommended diets, lifestyles and advice for healthy longevity.