Nutritional and Health-Related Environmental Studies (NAHRES)

Using nuclear techniques to assess the role of nutrition-sensitive agri-food systems in improving diet, health and nutritional status of vulnerable populations.

Brief summary

Malnutrition is a significant public health problem in low- and middle-income countries. It includes both undernutrition, especially among women and children, as well as overnutrition, leading to overweight and obesity. Improving health and nutrition of vulnerable populations will require not only direct “nutrition-specific” interventions, but also indirect “nutrition-sensitive” action addressing the underlying determinants of nutrition and inputs from multiple sectors. Nutrition-sensitive, biodiverse, and sustainable agri-food systems improve nutritional status through increased access to and consumption of high quality diets; however there is a need for further research in this area that includes rigorous design and appropriate measurement techniques for assessing health and nutritional impacts. Body composition divides weight into fat mass and fat-free mass and, compared to total body weight, will provide a more sensitive means of assessing changes in nutritional status in response to nutrition-sensitive agricultural interventions and changes in consumption. It can thus help to improve or optimize intervention strategies and understand the impact of dietary transitions. The deuterium dilution stable isotope technique, which will be used in this CRP, is among the most accurate techniques for assessing body composition. It involves the estimation of fat-free mass by measuring total body water (TBW) and provides reliable information on changes in body composition in individuals. This CRP will provide important information on the role of structural outcome measures such as body composition in understanding the link between agriculture and nutrition and in strengthening the evidence in support of nutrition-sensitive agricultural policies and practices. Studies to be included in this CRP may be stand-alone projects, or, perhaps more appropriately, build on existing research agendas (e.g. added on to a larger study). Doctoral students are encouraged to participate. The CRP will contribute to better understanding of the effect of nutrition-sensitive agri-food systems on the diet, health, and nutritional status of vulnerable populations. These findings will inform stakeholders influencing public health and agricultural policies in the design of effective interventions to combat malnutrition in all its forms.

Background
The burden of malnutrition

Undernutrition remains a highly prevalent and pervasive problem in low- and middle-income countries, particularly among women and children. The direct or immediate causes of undernutrition include inadequate dietary intake and disease [1], which can lead to such consequences as poor growth and micronutrient deficiencies. These immediate nutrition-related factors account for approximately 35% of preventable deaths among children less than 5 years of age, and 11% of the total global disease burden [2]. Alongside the burden of undernutrition, rates of overweight and obesity, as well as chronic and non-communicable diseases (NCDs) are increasing rapidly [3, 4]. This dual burden of over- and undernutrition is particularly prevalent in low- and middle-income countries undergoing a “nutrition transition” – that is, a rapid shift in dietary and lifestyle patterns toward consumption of foods that are micronutrient poor and higher in calories from fat and sugar, as well as decreased physical activity levels [5, 6]. Adequate access to nutritious foods is only one of several underlying determinants of adequate nutrition. Healthy environments, access to quality health services, and adequate care practices for children and mothers [2, 7] are also required. As such, improving nutrition requires a multi-sectoral approach that targets the underlying determinants of nutrition (“nutrition-sensitive” development), in addition to approaches that directly affect the immediate determinants of nutrition such as food intake and disease (“nutrition-specific”) [7].

The role of agriculture and agri-food systems in malnutrition

Agricultural policies and interventions can impact both the underlying and immediate determinants of nutrition by altering the availability and accessibility of nutrient-rich foods at the household, community and national level. At the household level, agricultural strategies can directly affect food and nutrition security through alterations in the production of nutrient-dense foods and/or income derived through agricultural livelihoods [8]. Indeed recent systematic reviews of the effects of agricultural interventions to increase household food production on the nutrition and health outcomes of women and young children documented significant improvements in dietary patterns and nutrient intakes but not nutritional status. However, the evidence base for household food production interventions is of relatively poor quality, largely consisting of heterogeneous studies with significant methodological and design limitations [8, 9]. On a larger scale, agricultural practices and policies, including for example, subsidies, industrialized food production and processing, and redirecting of staples to livestock feed or ethanol production, affect local and global market supplies and food prices. Agricultural growth is also strongly associated with poverty reduction [10], and the importance of agricultural biodiversity and sustainable food systems for improving nutrition and health is increasingly recognized. The notion of “sustainable diets” acknowledges the interdependencies of food production and consumption with food requirements, nutrient recommendations, and the environment [11]. For example, in order to address the food and nutrition needs of a wealthier, more urbanized, and growing world population, while preserving natural and productive resources, food systems must become more efficient in terms of resource use and food consumption. Sustainable diets have lower water and carbon footprints, and can facilitate the transition to agricultural practices that are more sensitive to nutritional needs and seasonal climate changes. Dietary sustainability also promotes the use of food biodiversity, including traditional and local foods, which can improve nutrient intakes, and counterbalance current diet trends of low diversity and high energy that are contributing to the escalating problems of obesity and chronic diseases [11, 12].

Agricultural programs and policies may also negatively impact health and nutritional status, for example by causing a shift in food consumption toward micronutrient poor, energy dense diets [13]. Increases in agricultural income are associated with increased overweight and obesity rates, even among the rural poor [14]. Agricultural intensification may also adversely affect women’s and children’s health by increasing energy expenditures of women without concomitant increases in food intakes or by reducing the time women are able to allocate to child care, including breastfeeding. Intensification of agriculture may also increase exposure to agri-chemicals and zoonotic diseases, as well as environmental degradation and loss of biodiversity, regardless of advances in agricultural practices and technologies. Investments in agriculture and poverty reduction strategies should thus not only lead to improvements in food production, food variety and biodiversity, and enhanced agricultural practices [1, 11, 12], but also be cognizant of the variation in nutritional vulnerabilities across communities, particularly in contexts where the dual burden of malnutrition exists [7, 13].

The role of agriculture and agri-food systems in improving the health and nutritional status without contributing to the later development of NCDs is not yet fully understood. However, ongoing multi-sectoral programs have the potential to contribute to our understanding of these pathways, such as the Leveraging Agriculture for Nutrition in South Asia (LANSA) Research Programme [15], and the Consultative Group on International Agricultural Research (CGIAR) Research Program on Agriculture for Improved Nutrition and Health (A4NH) [16]. Another example is the global project of the Global Environment Facility (GEF) to mainstream biodiversity conservation and sustainable use for improved human nutrition and wellbeing into national and global policies and programs in Brazil, Kenya, Sri Lanka and Turkey that will provide evidence on the nutritional value of agricultural biodiversity, influence policies using the evidence generated and raise awareness including the identification of best practices for scaling-up (http://www.bioversityinternational.org/.../Biodiversity_for_Food_and_Nutrition.pdf). To foster more nutrition-sensitive agricultural and rural development projects, The World Bank suggests the following guiding principles: 1) Incorporate nutritional concerns into the design and implementation of agricultural policies, projects, and investments; 2) Target nutritionally vulnerable groups; 3) Invest in women; 4) Increase year-round access to diverse, nutrient-dense foods; 5) Protect health through water management; 6) Design poverty-reduction strategies explicitly to benefit nutrition; 7) Create enabling environments for good nutrition through knowledge and incentives; 8) Seek opportunities to work across sectors [13].

Future considerations for agriculture and nutrition research

Reviews of the research linking agriculture with nutrition outcomes commonly identify several limitations in the body of evidence and these limitations should be heeded when planning future programs and evaluations [8, 9, 13]. Authors stress the need for more rigorous design and monitoring and evaluation strategies including for example, 1) selecting appropriate counterfactuals, 2) assessment and control for confounding and clustering, 3) allowing sufficient implementation time to observe change in desired nutrition outcomes, 4) adequately powering evaluations for nutrition outcomes, 5) including indicators that span the impact pathway for nutrition outcomes (i.e. production, income, food expenditures, dietary intakes, body composition, micronutrient status), and 6) collecting information on costs to enable assessment of cost-effectiveness [13].

Body composition as indicator of health and nutritional status

Body composition is an indicator of nutritional status that reflects the relative proportions of the two major body compartments, fat mass (FM) and fat-free or lean mass (FFM). The amount and distribution of body fat and lean mass change with age, and are important health outcomes throughout the life course [18]. Body composition as a structural outcome measure that characterizes the change in body mass in terms of FFM and FM can be used to evaluate the success of nutritional interventions covering the whole spectrum of the double burden of malnutrition [17]. For example, in the management of acute undernutrition it determines the nature of the weight gained and provides information on the quality of growth, i.e., lean versus fat mass accumulation. Assessing body composition in relation to dietary intake and quality can play an important role in optimizing the health benefits of nutrition intervention strategies. For example, in a recent review, Marinangeli and Jones (2012) showed that consumption of pulses was associated with reduced visceral fat deposition, and thus could modulate the risk of obesity [20]. Body fat accretion has been shown to vary across ethnicities, which is important to consider when assessing the health impact of nutrition programs implemented in different countries, as well as identifying target populations for such programs [21]. For interpretation of the obtained body composition measures of FM and FFM, it is recommended to adjust them for body size to make comparisons within and between individuals meaningful. This is especially important when children grow between 2 measurement points. The expression of FM as a proportion of weight to derive percentage fat has been used traditionally, but is influenced by the relative amount of FFM tissue in body weight. Therefore, it is proposed to normalise both FM and FFM separately for height rather than body mass, deriving a fat mass index and fat-free mass index [18]. However, research on how best to adjust body composition data for size is going on, in particular on the use of indices relating FFM to indices of height [19]. In addition, the acquisition of reference data is currently a priority and is addressed by several research groups.

Body composition measurement approaches and applications

The ‘gold standard’ for body composition analysis is chemical analysis of cadavers. No in vivo technique can meet the accuracy of cadaver analysis, as there are always assumptions involved in getting from the measured parameter to body composition. In vivo techniques do not measure body composition directly, but predict it from measurements of body properties and the application of certain assumptions that may also affect their suitability under certain conditions. Several measurement techniques exist, each with their own complexities, feasibility, and limitations. Simple measures, such as skinfold thickness, body mass index (BMI), and bioelectric impedance analysis (BIA) are generally easy to perform with minimal equipment requirements. They provide useful objective indicators in epidemiological studies, although tend to have poor accuracy in individuals and are not sensitive enough to provide reliable information on changes in body composition over time [18]. Skinfold thickness measurements are reliable indices of regional body fat, and thus can be used to rank individuals in terms of relative fatness. They are suitable for use in most age groups and are useful for monitoring growth. Skinfold measures can also be used with relevant equations to predict percent body fat; however, the accuracy is poor in individuals, and also varies in relation to body fatness, making them unsuitable for longitudinal inter-individual comparisons [18]. Body mass index (BMI), calculated as weight in kg/height in m2, is a global index of nutritional status and correlated with percent body fat. It is used to categorise overweight and obesity. It cannot, however, distinguish between fat and lean masses, and can be misleading in children suffering from inflammation or other clinical conditions, where low BMI can be associated with an increase in relative body fat and a severe decrease in lean tissue [22]. Furthermore, comparisons in adults and older children across ethnic groups are limited, due to differences in the amount of body fat for a given BMI [21, 23]. Bioelectric impedance analysis (BIA) measures impedance of the body to a small electric current. Adjustment of bioelectrical data for height allows estimation of total body water (TBW). In practice this requires empirical derivation of regression equations, which are population specific, and tend to perform poorly in individuals. Conventional single frequency BIA measurements are appropriate for assessing FFM in terms of the direction of change, though are unlikely to quantify magnitude with accuracy [18], and may also be confounded by clinical status. BIA is useful primarily as an epidemiological tool, where it is the only predictive technique that estimates lean mass.

Compared to the simpler single-compartment measures described above, multi-compartment models are more accurate for assessing body composition because there are fewer assumptions involved; however they are also more complex and have greater equipment requirements. The most commonly used four compartment model assumes the body is composed of fat, water, mineral and ‘the rest’. Total body water is measured by isotope dilution. Bone mineral mass is measured by dual energy X ray absorptiometry (DXA) and body fat is measured by densitometry. Each of these techniques can be used to assess body composition using a two compartment model (one that divides the body into FM and FFM), but isotope dilution is the only method that can be used in the field and in subjects of all ages.

Isotope dilution can be used to estimate FFM via the measurement of total body water (TBW). The method involves giving a dose of water labelled with deuterium (a stable isotope of hydrogen), and following equilibration, measuring the isotope enrichment of body water using saliva or urine samples [18, 24, 25]. Deuterium dilution is simple to perform and requires minimal subject cooperation, thus making it particularly suitable for infants and toddlers, as well as field studies. Isotope ratio mass spectrometry can be used to measure deuterium enrichment in either urine or saliva specimens. Saliva enrichment can also be measured using Fourier transform infrared spectrometry, which is a relatively inexpensive (but labour intensive) technique particularly suited to resource limited settings. Estimating FFM from TBW requires an assumed value of the hydration of FFM, which varies with age. Published tables of hydration values are available and relatively consistent with measured values in healthy participants. The inter-individual variability of published hydration values is relatively low; however, in certain disease states, and during the second and third trimesters of pregnancy, variation in FFM hydration may be substantially higher, owing to overhydration or underhydration, so isotope dilution should only be used where normal hydration can be assumed [24, 25]. The accuracy of deuterium dilution is comparable to other gold standard multicomponent models for measuring body composition in vivo [18, 26, 27]. In fact, it has been used to develop population-specific prediction equations for other measurement techniques, such as BIA and skinfold thickness [21, 28-30]. Over the past 20 years, it has been among the various types of stable isotope techniques that have played an increasingly vital role in monitoring the efficacy of nutrition interventions in both developed and developing countries [31-37].

Required methodological considerations for proposals

This CRP supports assessment of the effects of agriculture and agri-food systems on body composition measured using isotopic methods. Studies to be included in this CRP may be stand-alone projects, or, perhaps more appropriately, build on existing research agendas (e.g. added on to a larger study). Master or doctoral students are encouraged to participate. In either case, in the proposed design, hierarchy of evidence and methods should be fully described, including the methods (or tools) used for assessing causal or impact pathways, research hypothesis, calculating sample size, selecting participants, and managing the data. The target population should also be defined, as well as analytical plans, and any processes for obtaining ethics approval and protecting participant information. Partnerships and collaborations are encouraged and should be described, along with details regarding laboratory access or capacity (where applicable). Target groups may include (though are not limited to) the urban poor, indigenous populations/societies, young children, adolescents, or women of reproductive age. All studies must include at least the following core set of indicators:

  • Body composition measured by deuterium dilution technique, assessed longitudinally over at least 2 years with measurement time points that correspond with seasons or are a minimum of 3-4 months apart;
  • Dietary quality, including assessment of individual food intakes using recall methods;
  • Anthropometry, including weight and height/length;
  • Impact pathway-related indicators as relevant (e.g. physical activity, time-allocation, income);
  • Costs, to the project of adding body composition measures using nuclear techniques (labor, materials, logistics).

Other indicators related to agriculture, socio-economic conditions, demographics etc. will depend on the research context. Up to 7 research contracts of a total of €25,000-40,000 each will be awarded over a period of 3-4 years (yearly approval required).

Potential examples of agriculture-nutrition impact pathways that may be explored through observational or intervention research include (though are not limited to) the following:

  • Increased production and consumption of high protein and micronutrient dense foods from animal or plant sources.
  • Intensification of staples, roots, tubers, bananas, cereals, legumes, dairy, animal source foods, fruits and vegetables.
  • Unintended consequences of intensified value chains and urbanization.
  • Changing agricultural biodiversity and derangement in the food system/environment (e.g. nutritional status of adolescents consuming locally sourced foods in schools).
  • Dietary/nutrition transition, e.g. changes in consumption of low nutrient density foods (higher fat, salt, and sugar intake).
  • Environmental changes such as climate or habitat losses on indigenous food systems or practices and natural resource based livelihoods (e.g. pastoralist societies).

In conclusion, the primary focus of this CRP is the application of stable isotope methods to assess the effect of nutrition-sensitive agri-food systems (including interventions) and of dietary transition on body composition. The emphasis is on proof-of-concept in the context of whole diets, and elucidating specific impact pathways to improving nutritional status through nutrition-sensitive agriculture systems/interventions. Applying a more sensitive measure of nutritional status using stable isotope techniques will address a persistent gap in the literature regarding the amount and/or quality of evidence underlining the health effects of changes in food intake, dietary diversity, or diet quality in nutrition-sensitive agri-food systems. It will give insights on whether indicators of dietary intake and quality can predict changes in body composition. The knowledge gained will also contribute to a better understanding of sustainable food systems with improved agricultural biodiversity and dietary patterns and their potential to combat both sides of the dual burden of malnutrition. Together, this will inform stakeholders influencing public health and agricultural policies in the design of effective strategies to improve nutrition and health of vulnerable populations.

Analytical techniques to be used

All proposals are required to use the deuterium dilution stable isotope technique to measure total body water for the assessment of body composition following procedures described in references [24] and [25]. Analysis of stable isotope enrichment in saliva or urine samples need to be made by Fourier Transform Infrared spectrometry (FTIR), or where available, Isotope Ratio Mass Spectrometry (IRMS), respectively. Though not required for this CRP, other stable isotope methods may be included for the assessment of human milk intake, iron/zinc bioavailability and/or vitamin A status if they are complementary and add value to the proposal. For measuring the amount of human milk taken in by the infant the well-established deuterium oxide ‘dose-to-mother’ technique may be used. The same way as for body composition assessment, deuterium enrichment of urine and/or saliva samples of mother and infant may be analysed by FTIR or IRMS. Iron and zinc bioavailability may be measured using stable isotopes of iron and zinc. The analysis of these isotopes in biological samples may be undertaken using thermal ionization mass spectrometry (TIMS) or inductively-coupled plasma mass spectrometry (ICP-MS). The total body vitamin A pool size may be estimated using vitamin A labelled either with the stable isotope of hydrogen (deuterium, 2H) or with the stable isotope of carbon (13C). For the estimation of total body vitamin A pool size gas-chromatograph-mass spectrometry (GC-MS) or gas-chromatograph-combustion-isotope ratio mass spectrometry (GC-C-IRMS) may be used depending on whether deuterium labelled retinol or carbon-13 labelled retinol is measured.

Overall objective

To provide the evidence base of the application of stable isotope techniques to describe and assess the role of nutrition-sensitive agri-food systems in health and nutrition.

Specific research objectives (purpose)

Assess the role of stable isotope techniques to:

  1. Further understand the effects of nutrition-sensitive agriculture systems/interventions that aim to improve diet quality on nutritional status.
  2. Further the understanding of nutritional consequences (including unintended ones) of dietary shifts or changes in nutrition-sensitive agri-food systems.
  3. Further the understanding of the effect of agricultural biodiversity on nutrition.
  4. Further the understanding of the correlation between body composition and dietary diversity scores, meal frequency, and other indicators of dietary intake and quality.
  5. Improve the knowledge of additional costs and benefits of including isotopic measures of body composition as a nutritional outcome.
Expected outputs
  • New knowledge on the effects of nutrition-sensitive agri-food systems on diet, health, and nutritional status among vulnerable populations.
  • New knowledge on the nutritional consequences of dietary shifts or changes in nutrition-sensitive agri-food systems.
  • New knowledge on the role of agricultural biodiversity in nutrition.
  • New knowledge on impact measuring tools of nutrition-sensitive agriculture systems/interventions.
  • Costing information on adding isotopic measures of body composition as a nutritional outcome.
  • Publications in the form of scientific reports and peer-reviewed papers and conference presentations.
  • Technical brief or workshop presentation on lessons learned around application of isotopic methods in agricultural research.
Expected outcome

Contribute to better understanding of the role of nutrition-sensitive agri-food systems in the diet, health, and nutritional status of vulnerable populations in order to inform the design of effective strategies to combat malnutrition in all its forms.

Proposal submission forms

Research institutions in Member States interested in participating in this CRP are invited to submit proposals directly to the Research Contracts Administration Section (NACA) of the International Atomic Energy Agency: Official.Mail@iaea.org or to Ms Cornelia Loechl: C.Loechl@iaea.org

The forms can be downloaded from http://www-crp.iaea.org/html/forms.html. For more information about research contracts and research agreements, please visit our web-site: http://www-crp.iaea.org/html/faqs.html.

Deadline for submission of proposal

Proposals must be received no later than 30 September 2013. Transmission via Email is acceptable if all required signatures are scanned.

For additional information, please contact:
Cornelia Loechl
Nutrition Scientist
Nutritional and Health-related Environmental Studies Section
Division of Human Health
International Atomic Energy Agency (IAEA)
A-1400 Vienna, Austria
Phone: + 43 1 2600 21635
Fax: + 43 1 2600-7
C.Loechl@iaea.org

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