Frailty is the loss of resources in several domains leading to the inability to respond to physical or psychological stress. The evaluation of frailty is generally carried out using the Comprehensive Geriatric Assessment. For this evolving and potentially reversible syndrome, screening and early intervention are a priority in primary health care, and general practitioners require a simple screening tool. The aim of the present work was to review the literature for validated screening instruments for frailty in primary health care setting. A search was carried out on PubMed and Cochrane Central in June 2011. A total of 10 instruments screening for frailty in primary health care were listed, analysed and compared. It is difficult to show which tool today is the best for screening for frailty in the elderly in primary care settings. Two instruments are potentially suitable - the Tilburg Frailty Indicator and the SHARE Frailty Index. In addition, these instruments require validation in larger studies in primary health care settings and with more quality criteria.

Normal functioning of the immune system is crucial to the health of man, and diet is one of the major exogenous factors modulating individual immunocompetence. Recently, nutrition research has focused on the role of foods or specific food components in enhancing immune system responsiveness to challenges and thereby improving health and reducing disease risks. Assessing diet-induced changes of immune function, however, requires a thorough methodological approach targeting a large spectrum of immune system parameters. Currently, no single marker is available to predict the outcome of a dietary intervention on the resistance to infection or to other immune system-related diseases. The present review summarises the immune function assays commonly used as markers in human intervention studies and evaluates their biological relevance (e.g. known correlation with clinically relevant endpoints), sensitivity (e.g. within-and between-subject variation), and practical feasibility. Based on these criteria markers were classified into three categories with high, medium or low suitability. Vaccine-specific serum antibody production, delayed-type hypersensitivity response, vaccine-specific or total secretory IgA in saliva and the response to attenuated pathogens, were classified as markers with high suitability. Markers with medium suitability include natural killer cell cytotoxicity, oxidative burst of phagocytes, lymphocyte proliferation and the cytokine pattern produced by activated immune cells. Since no single marker allows conclusions to be drawn about the modulation of the whole immune system, except for the clinical outcome of infection itself, combining markers with high and medium suitability is currently the best approach to measure immunomodulation in human nutrition intervention studies. It would be valuable to include several immune markers in addition to clinical outcome in future clinical trials in this area, as there is too little evidence that correlates markers with global health improvement.Immune function: Marker: Diet: Human studies: Infections Task and objectivesThe major function of the immune system is to protect the body against infectious diseases. The immune system can be divided into innate and adaptive immunity. The immune system operates at the systemic as well as at the local level, which includes the mucosal tissue such as in the upper airways and the gut. A fundamental characteristic of the immune system is that it involves multiple, functionally differing cell types, which permit a large variety of defence mechanisms. Assessing the status of the immune system and its functionality therefore requires a thorough methodological approach targeting a large spectrum of immune †A draft version of this review was extensively discussed with experts from the fields of nutrition, (clinical) immunology, mucosal immunology, gastroenterology and immunotoxicology during a Workshop, organised by the European branch of the International Life Sciences Institute (ILSI Europe), on 'Markers

Immune function declines with age, leading to increased infection and cancer rates in aged individuals. In fact, recent progress in the study of immune ageing has introduced the idea that rather than a general decline in the functions of the immune system with age, immune ageing is mainly characterized by a progressive appearance of immune dysregulation throughout life. Changes appear earlier in life for cell-mediated immunity than for humoral immunity. Thus, agerelated modifications in cell-mediated immunity, i.e. changes in naive : memory T-cells, mature : immature T-cells, T-helper 1 : T-helper 2 cells are more important in the elderly than changes in humoral immunity, i.e. CD5 : CD5+ cells or length of antibody responses. Such evolution of the immune system has been linked to declining thymus function and to accumulative antigenic influence over the lifespan. In contrast, innate immunity (macrophage functions) is preserved or even increased during the ageing process. This finding shows that the 'primitive' immune system is less affected by the ageing process than the sophisticated specific immune system. The present review focuses on innate and cell-mediated immune changes with ageing. It provides evidence that primary changes (intrinsic modifications in the immune system) and secondary changes (resulting from environmental influences during the lifespan) exert different influences on the immune system. Primary changes, occurring in healthy individuals, seem less important nowadays than they were considered to be previously. For example, interleukin 2 secretion in some very healthy aged individuals is comparable with that in younger adults. Primary immune changes may not explain the increased incidence and severity of infections observed in the elderly population. Secondary immunological changes are far more frequent and are certainly responsible for most of the immune modifications observed in the elderly population. Environmental factors leading to secondary immune dysfunctions include not only antigenic influence, which is a reflection of diseases experienced over the lifespan, but also many other factors such as drug intake, physical activity and diet; factors for which important changes occur in the elderly population. Nutritional factors play a major role in the immune responses of aged individuals and the present review shows that nutritional influences on immune responses are of great consequence in aged individuals, even in the very healthy elderly.

Nutrition has a strong influence on the immune system of the elderly. Aging induces dysregulation of the immune system, mainly as a result of changes in cell-mediated immunity. Aging is associated with changes to the equilibrium of peripheral T and B lymphocyte subsets, such as decreases in the ratios of mature to immature, naive to memory, T helper 1 subset (TH1) to TH2, and CD5- to CD5+ cells. As a consequence, cell-mediated immune responses are weaker and neither cell-mediated nor humoral responses are as well adapted to the antigen stimulus. Undernutrition, common in aged populations, also induces lower immune responses, particularly in cell-mediated immunity. Protein-energy malnutrition is associated with decreased lymphocyte proliferation, reduced cytokine release, and lower antibody response to vaccines. Micronutrient deficits, namely of zinc, selenium, and vitamin B-6, all of which are prevalent in aged populations, have the same influence on immune responses. Because aging and malnutrition exert cumulative influences on immune responses, many elderly people have poor cell-mediated immune responses and are therefore at a high risk of infection. Nutritional therapy may improve immune responses of elderly patients with protein-energy malnutrition. Supplementation with high pharmacologic doses of a single nutrient (zinc or vitamin E) may be useful for improving immune responses of self-sufficient elderly people living at home. Therefore, nutritional deficiency must be treated in the elderly to reduce infectious risk and possibly slow the aging process.

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