Quality of Protein From the Common Bean
Condition: Nutrition Deficiency Due to A Particular Kind of Food
MeSH terms: Protein-Energy Malnutrition
Study type: Interventional

Summary: 
      Dietary Protein quality is based on digestion of proteins to amino acids and the
      bioavailability of the amino acids to maintain good health and body function. Currently,
      digestibility of proteins, which is measured as the difference between protein intake and
      faecal loss, is underestimated. This is because, in addition to loss from dietary proteins,
      faecal loss includes additional protein from gut secretions and bacteria residing in the
      large intestine. The expert committee on protein quality suggested that a minimally invasive
      accurate method based on Dual Stable Isotope Tracer approach (non-radioactive) could be
      developed. This method is based on the concept that if amino acids in proteins become
      labelled with an isotopic tracer within the food matrix, their appearance in the blood gives
      a measure of bioavailability. The Food and Agriculture Organization (FAO) of the United
      Nations and the World Health Organization (WHO) are promoting peas and beans to combat
      poverty, hunger and malnutrition because they are relatively less expensive sources of
      protein. We hypothesized that digestibility of protein in the common bean and absorption of
      amino acids is higher than current estimates.

      The aim of this proposal is to conduct a study in 12 healthy adults, aged 20 to 45 years, to
      test a novel method to assess protein quality of the common bean using the isotopic approach.
      The Scientific Research Council will grow the labelled beans by adding a tracer dose of
      deuterium to the irrigation water. The beans are prepared a typical Jamaican meal for
      consumption. The meal is mixed with a labelled reference protein (U-13C-spirulina) which is
      universally (U) labelled with stable isotope 13-Carbon (13C) to estimate digestibility; and
      the amino acid, phenylalanine, in which the 6 ring carbon atoms are labelled with 13C
      (ring-13C6- phenylalanine) to provide an index of amino acids absorption. Before and after
      consumption of the meal, samples of blood, breath and urine will be taken. These samples and
      a sample of the diet will be analysed for amino acids composition and deuterium enrichment
      using mass-spectrometry. The appearance of each labelled essential amino acid in blood from
      the bean protein will be calculated. The data will provide accurate date on amino acids
      bioavailability from the common bean that will be useful for dietary guideline for good
      health.
    

Detailed description: 
      Humans require certain minimal quantities of the indispensable amino acids (IAA) from dietary
      proteins to maintain healthy growth and body function (1). These amino acids are not made in
      the body and must be provided in the diet. Protein quality is about how dietary proteins can
      satisfy the body's demand for IAA at various stages of life (1,2) to make different body
      proteins and biomolecules. It is important to public health and has economic considerations
      with respect to national food policy, world production and trade in proteins. Uncertainty
      over the quality of diet, specifically with reference to its protein quality, does
      potentially impact a nation's health, economy, agriculture and nutrient security.
      International organizations have begun to address these issues Poor dietary quality has a
      marked negative impact on the sensitive periods of pregnancy (3) and the first two years of
      life (the first 1000 days). Furthermore, protein quality is related to stunting which is
      prevalent in may low and middle income countries because adequate protein quality is required
      for optimum linear growth. Hence, it is likely to have an impact on the WHO Global Nutrition
      Target 2025 for reducing the prevalence of stunting (low height-for-age) in children under 5
      years by 40%. Stunting has been shown to reduce capacity for learning in children, and hence
      productivity in adults (4). Of importance, also, stunting increases the risk of developing
      obesity and chronic non-communicable diseases (CNCD), and therefore plays a role in the
      impact of CNCD on increasing cost to health and the economy especially in developing
      countries (5). It is clear that to meet dietary requirements of the IAA, accurate assessment
      of their availability is essential.

      The availability of amino acids from protein sources depends on their amino acids composition
      and digestibility which have been yardsticks used in the assessment of protein quality. The
      Food and Agriculture Organization (FAO) in 2011 held an International Symposium on Dietary
      Protein for Human Health where it was recognized that the current measure of protein
      availability using oro-faecal nitrogen balance underestimate digestibility because colonic
      metabolism contributing additional nitrogen to dietary nitrogen is not taken into
      consideration in the stool loss. The committee concluded that a more robust method of
      assessing protein quality is needed. Whereas oro-ileal balance is a more accurate method of
      protein digestibility (6,7), it is an expensive and invasive method, and there is
      insufficient human data.

      Following the symposium in 2011, FAO in 2013 convened a expert consultation meeting and
      released a report , 'Dietary protein quality evaluation in human nutrition', (8) as part of
      the call from the United Nations to promote sustainable diets and health and influenced by
      the 2012 WHO technical note on foods for the management of moderate acute malnutrition in
      children(9) This report was motivated mainly by advances in methods available to measure the
      quality of nutritional proteins with more accuracy. It was suggested that a minimally
      invasive method based on Dual Stable Isotope Tracer approach could be developed to accurately
      assess protein quality. The IAEA held a Consultants' Meeting in October 2013 to discuss
      stable isotopic methods to measure protein quality in humans, followed by a FAO Expert
      Working Group Meeting in March 2014 in Bangalore, to specifically define the most appropriate
      research methodologies to measure protein digestibility and utilization in humans (10).Hence,
      the International Atomic Energy Agency (IAEA) has established a Co-ordinated Research Project
      (CRP) with the aim to develop and validate a novel Dual Stable Isotope Tracer method that is
      minimally invasive to assess protein digestibility and utilization from plant based diets, as
      they are consumed by vulnerable populations, in regions habitually relying on plant based
      diets. Generally, the method is based on the concept that if IAA become labeled with isotope
      within the food matrix, their appearance in the blood gives a measure of bioavailability,
      which is independent of other proteins in the food and independent of endogenous body
      proteins. Comparative tracer appearance in blood of labelled test and reference proteins
      gives a direct measure of digestion and bioavailability of the test protein. Also, when the
      reference protein is accompanied by a trace quantity of a differently labelled amino acid
      such as 13C6-phenylalanine, it will provide an index of amino acids absorption following
      digestion. We have been awarded an IAEA grant as part of the CRP and proposing to conduct
      studies in healthy human adults to assess the availability of the IAA from intrinsically
      labelled common bean (Phaseolus vulgaris) which is among the eight species regarded as global
      priorities by the Consultative Group for International Agricultural Research (CGIAR, 2012)
      (11) The research Program includes leveraging legumes to combat poverty, hunger, malnutrition
      and environmental degradation. Our collaborator from the Scientific Research Council will
      grow the beans. The amino acids in the bean will be labelled with deuterium, by adding a
      bolus dose of deuterium oxide to the irrigation water. They have successfully produced
      labelled beans in a pilot study. To accurately measure IAA availability and protein quality
      in the common bean will be useful to inform dietary choices consistent with good health The
      main aim of this study is to develop a minimally invasive method to accurately measure
      protein quality in the common bean to inform dietary choices consistent with good health. We
      also, aim to establish an absorption index relative to phenylalanine for use in future
      studies and to assess utilisation of the protein by measuring protein oxidation and urinary
      amino acids.

      Specific aims are:

        1. to characterize the bean protein for isotopic enrichment

        2. to quantify bean amino acids made available to the body when the bean and a reference
           protein are consumed by healthy adults, aged 20 to 45 years.

        3. to establish an index for amino acids absorption

        4. to determine digestible indispensable amino acids scores
    

Intervention name(s): Using intrinsically labelled bean protein to assess bioavailability of amino acids in healthy adults
Intervention type(s): Other
Intervention description(s): The intervention comprises a test meal of intrinsically deuterium labelled stewed common bean with rice. The meal is mixed with a reference protein (Universally labelled 13C-spirulina, 12 mg/kg) and 13C6-Phenylalanine (0.05mg/kg) which is divided into equal mini meals and fed hourly over 8 hours. Protein in the total meal provides 15% of the energy intake with the labelled bean contributing >50% of the protein.
Other intervention name(s): Testing quality of bean protein in a feeding trial
Intervention model: Single Group Assignment
Intervention model description: The model is based on the concept that if amino acids in protein become labelled with an isotopic tracer within the food matrix, their appearance in the blood gives a measure of their bioavailability following digestion and absorption of the protein; which is independent of other proteins in the food and independent of endogenous body proteins and gut bacterial proteins. Amino acids in the common bean were labelled with deuterium, by adding a bolus dose of deuterium oxide (2H2O) to the irrigation water. Then a dual tracer technique is used to measure the bioavailability of amino acids in the bean. After consuming a diet prepared with the mature bean, comparative tracer appearance in blood of the deuterium labelled amino acids from the bean and amino acids derived from a reference protein labelled within another tracer (U-13C- spirulina) gives a direct measure of bioavailability of the bean amino acids.
Masking: None (Open Label)
Primary purpose: Basic Science
Keywords: protein quality, legume