Bioavailability of Essential Amino Acids From the Common Bean (Phaseolus Vulgaris) in Young Healthy Jamaican Adults Consuming a Typical Meal

Detailed 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.

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