Nutritional interventions for optimizing healthy body composition in older adults in the community: a protocol for an umbrella review of studies of effectiveness and qualitative perceptions and experiences

Abstract

<jats:sec> <jats:title>Review question/Objective</jats:title> <jats:p>What is the effectiveness of nutritional interventions for optimizing healthy body composition in older adults living in the community, and what are these people's qualitative perceptions and experiences?</jats:p> <jats:p>The objectives of this umbrella review are to measure and compare the overall effectiveness of nutritional interventions for optimizing healthy body composition in older adults living in the community and to better understand how they perceive and experience the nutritional interventions.</jats:p> </jats:sec> <jats:sec> <jats:title>Background</jats:title> <jats:p>The World Health Organization (WHO) defines healthy ageing (active ageing) as "the process of optimizing opportunities for health, participation and security in order to enhance quality of life as people age<jats:italic toggle="yes">"</jats:italic>.1 <jats:sup>(p.12)</jats:sup> Further: "Active ageing applies to both individuals and population groups. It allows people to realize their potential for physical, social, and mental wellbeing throughout the life course and to participate in society according to their needs, desires and capacities, while providing them with adequate protection, security and care when they require assistance."1 <jats:sup>(p.12)</jats:sup> </jats:p> <jats:p>Nutrition (healthy eating) is a key behavioral determinant of healthy ageing.1-3 Importantly, both cross-sectional and longitudinal studies have shown that improved dietary patterns and nutritional intake is possible, and can reduce the effect of chronic disease in older adults.3 </jats:p> <jats:p>Nutrition-related risks to healthy ageing tend to focus on the increasing prevalence of overweight and obesity and the link with chronic conditions of cardiovascular disease, metabolic syndrome and cognitive decline.3 Other health outcomes that are known to be food and/or nutrition related are bone health and cancer.3 Interventions to prevent or treat overweight or obesity commonly involve diet and exercise, and may also include surgical interventions, psychological interventions (cognitive behavior therapy and behaviour therapy), acupuncture, pharmaceutical, and commercial weight loss products.</jats:p> <jats:p>Conversely, being underweight can be a significant health risk in older people. Oral health problems, reduced appetite and anorexia can affect dietary intake and lead to malnutrition in older people, significantly increasing risks of poorer outcomes including frailty, which has been defined as: a medical syndrome with multiple causes and contributors that is characterized by diminished strength, endurance, and reduced physiologic function that increases an individual's vulnerability for developing increased dependency and/or death".4 <jats:sup>(p.392)</jats:sup> </jats:p> <jats:p>Physical frailty can be potentially prevented or treated with specific interventions, including protein/calorie supplementation, vitamin D, exercise and reduction of polypharmacy.4 Sarcopenia (reduced muscle mass) is a common component of frailty.</jats:p> <jats:p>Body Mass Index (BMI) is a simple index calculated from height and weight information, using the equation:</jats:p> <jats:p>

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</jats:p> <jats:p>Although there are some limitations to their use and interpretation (discussed in more detail below), BMI ranges are commonly used to classify underweight, normal weight, overweight and obesity (Table 1 ). In 2011-12, 63.4% of Australians aged 18 years and over were overweight or obese, comprised of 35.0% overweight and 28.3% obese (Table 1 ).5 A further 35.2% were of normal weight. Proportionally, in older Australians (aged 65 or greater) there were slightly more overweight and obese older Australians (71.9%), and slightly less underweight (1.1%) than the whole population (Table 1 ). Although sample size is low for underweight Australians, potentially limiting the validity of the data, in those 75 years and over the prevalence of underweight was 1.9%. Further, using the definition of frailty (above), it is estimated that in those 65 years and older, the prevalence of frailty ranges from 4-17% (mean 9%), with a higher prevalence when psychosocial frailty is also present.6 The prevalence of frailty was almost twice as great in women (9.6%) than men (5.2%), and increases markedly in persons older than 80 years of age.4 </jats:p> <jats:p>Although BMI has been a useful measure to raise awareness about health risks in the general population, limitations in the usefulness of BMI as a marker for risk of health harms due to overweight and underweight have been widely raised7-10 For example, it is more appropriate to define obesity as an excess accumulation of body fat, as it is the excess adipose tissue, not the excess weight, which causes chronic co-morbid conditions such as cardiovascular disease.7 Similarly, as discussed by Lukaski,11 there are some protections from metabolic and cardiovascular diseases conferred to 'metabolically healthy obese' people, who have a high level of insulin sensitivity, normal lipids, low inflammation and no hypertension, but a BMI classified as obese. Instead, measures of body composition are proposed as being more informative for assessment of nutrition status and health risks.</jats:p> <jats:p>Body composition measurement involves precise and accurate measurement of both the soft tissue composition (i.e. fat, and fat-free or lean mass) and the bone mineral (mass and quality). These variables provide <jats:italic toggle="yes">in vivo</jats:italic> measurements of body energy stores (fat or adipose tissue), structure (bone) and functional capacity (muscle mass or body cell mass).7, 9 The common measures of body composition include fat-free soft mass (FFSM), per cent body fat, skeletal muscle, fat mass (FM), bone mineral content (BMC) and bone mineral density (BMD).8, 10, 12 </jats:p> <jats:p>Broadly, there are two models of measurement of body composition proposed: a more widely used two-compartment model partitioning the body into fat mass and fat-free mass, and a less frequently used four-compartment model of body mass, total body volume, total body water (TBW) and bone mineral.9, 10 There are a range of non-invasive methods of body composition measurement methods including traditional techniques such as skinfolds, bioelectrical impedance, dilution techniques, air displacement plethysmography, dual energy X-ray absorptiometry and magnetic resonance spectroscopy.10 More recently developed techniques include three dimensional photonic scanning and quantitative magnetic resonance.10 </jats:p> <jats:p> <jats:bold>Optimal body composition</jats:bold> </jats:p> <jats:p>There are a number of factors to consider when attempting to define what constitutes "optimal" body composition. In addition to well-known gender differences in body composition, body composition changes with age - older people have less muscle mass, less bone mass, expanded extracellular fluid volumes and reduced body cell mass compared to younger adults.13, 14 A small proportion of older people are simultaneously obese and sarcopenic ("sarcopenic obesity") and therefore at high risk of disability.15 Conversely, up to 70% of older adults are obese or overweight,5 and potential candidates for intentional weight loss to reduce risk factors for cardiovascular disease and diabetes and improve physical function. However, intentional weight loss has not been widely advocated for older, community dwelling adults because of uncertainty as to whether the benefits outweigh the risks.16, 17 This uncertainty has been partly ascribed to the association of unintentional weight loss, which accompanies many diseases affecting older people, with increased mortality in observational studies.18, 19 Although there are documented adverse effects of intentional weight loss on some body composition measures (muscle and bone), there is a lack of evidence documenting benefits in mortality or disability and only limited evidence from small clinical trials about reductions in risk factors for cardiovascular disease and diabetes.18 In practice, healthcare providers are reluctant to recommend weight loss in overweight and obese adults, with rates of weight loss advice provision to people with obesity, even those with obesity-related health problems, being less than 50%.18 This may also be related to the perceived intransigence of the problem of obesity in older people.20 </jats:p> <jats:p>Current practice relating to optimizing body composition in older adults through health promotion, nutrition and health care policy is therefore more strongly weighted to alleviating malnutrition and frailty in vulnerable people than to addressing the high prevalence of overweight and obesity.18, 20 Despite some confusion about the latter group, there are a number of position statements from US-based organisations advocating intentional weight loss for overweight and/or obese older adults. The National Heart, Lung and Blood Institute recommended that treatment for obesity should be offered to older people: "Age alone should not preclude treatment for obesity in adult men and women".21 <jats:sup>(p41)</jats:sup>Similarly, the American Society for Nutrition and the Obesity Society recommend weight loss therapy for older adults who are obese and who have functional impairments or medical complication that could be improved by weight loss. The therapy should minimise muscle and bone loss.22 Australian guidelines, while acknowledging that weight loss improves functional mobility and physical performance in older people, do not give explicit advice on weight loss for older people apart from advice that approaches to increasing physical activity be individualized.23 </jats:p> <jats:p>In summary, while the benefits of weight gain on key health outcomes such as morbidity and mortality for those who are underweight are generally clearly defined, the benefits of weight loss in overweight or obese people are somewhat less clear, particularly for older people. While our understanding of relationships between nutritional status and health outcomes including mortality and morbidity (such as the development of cardiovascular disease, metabolic syndrome and cognitive decline) improves, and there are a number of systematic reviews that examine the effectiveness of: (i) single intervention (such as nutritional supplementation or caloric restriction) or (ii) combined interventions (such as diet and exercise) in improving the nutritional status of people, there are no current umbrella reviews that collate and summarize the evidence from all relevant, high quality systematic reviews. It is proposed that this review will address this deficit, by focusing on:</jats:p> <jats:p>The focus of this review is the effectiveness of nutritional interventions. Participants' perspectives and experiences of the interventions will have a strong impact on adherence and sustainability of any treatment plans. Therefore, the qualitative perceptions and experiences of older people exposed to a nutritional interventional will also be included as a secondary outcome in this review. A scoping search identified a large number of relevant existing systematic reviews, indicating the need for an overview of reviews, otherwise known as an 'umbrella review'.25 </jats:p> </jats:sec>