Lysine Requirement of Healthy, School-Aged Indian Children Determined by the Indicator Amino Acid Oxidation Technique

Abstract

We recently reported the lysine requirement of school-aged children living in Canada consuming a mixed diet to be 35 mg.kg(-1).d(-1). Because the majority of children in the world live on cereal-based diets in developing countries, we measured the daily lysine requirement in healthy children living in India and consuming a mostly cereal-based diet. Our objective in this study was to determine the lysine requirement in healthy, school-aged children in the developing world by using the indicator amino acid oxidation method with l-[1-(13)C] phenylalanine. Six healthy, school-aged children consumed 7 levels of lysine (5, 15, 25, 35, 50, 65, and 80 mg.kg(-1).d(-1)) each in a random order along with an amino acid mixture providing energy and protein intakes of 1.7 x resting energy expenditure and 1.5 g.kg(-1).d(-1), respectively. The mean lysine requirement was determined by applying a 2-phase linear regression crossover analysis on tracer oxidation (F(13)CO(2)) data, which identified a breakpoint (requirement) at minimal F(13)CO(2) in response to the graded lysine intakes. The mean lysine requirements with the upper 95% CI for children were determined to be 33.5 and 46.6 mg.kg(-1).d(-1), respectively, by breakpoint analysis of the F(13)CO(2) data. The mean lysine requirements of Indian children were almost identical to that of Canadian children (35 mg.kg(-1).d(-1)). There is no evidence for any adaptation in lysine requirements in children from developing countries such as India.

Protein requirement of healthy school-age children determined by the indicator amino acid oxidation method

“…Therefore, tyrosine should be present in relative excess to sensitively partition the carboxyl carbon of phenylalanine between the incorporation into protein or oxidation. The amounts of phenylalanine and tyrosine in the current study were comparable to earlier childhood amino acid IAAO-requirement studies (18)(19)(20)(21)(22) and were shown to sensitively display a breakpoint in phenylalanine oxidation in response to test diet intakes.…”

“…Our studies of amino acid requirements in adult humans and children yielded requirement estimates for lysine (13,21,22), total sulfur amino acids and minimum methionine (19,20,41,42), and total branched chain amino acids (14,18) that were not different between age groups. We hypothesized that the similar results suggested that maintenance needs are similar in adults and children (6-10 y old) who are slow growing.…”

“…On the basis of adult IAAO protein-requirement data, we hypothesized that the current DRI recommendations for young children are underestimated. The IAAO method has previously been successfully applied to identify amino acid requirements in adult humans by us (12)(13)(14)(15) and others (16,17) and in children (18)(19)(20)(21)(22) and neonates (23)(24)(25). The minimally invasive IAAO method has several advantages (26)(27)(28) in the determination of requirements for amino acids and protein in vulnerable populations, such as in children because the isotope is delivered orally (13), enrichment of 13 C is measured in breath and urine (29,30), and the length of test intake adaptation is 8 h (31).…”

Recent developments in understanding protein needs – How much and what kind should we eat?

“…It had been hypothesized that these populations may be able to adapt and thrive on a lower lysine intake than that needed in the developed world. To test this question, the lysine needs of school-aged children in Toronto, Canada, and in Bangalore, India, were measured and shown to be identical (Pillai et al 2010). Moreover, the lysine requirements in moderately malnourished Indian children increased by 20% because of gut parasite infection (Pillai et al 2015).…”

An Evaluation of Protein Intake for Metabolic Demands and the Quality of Dietary Protein in Rats Using an Indicator Amino Acid Oxidation Method

“…Therefore, employing the nitrogen balance method, the metabolic demand for protein cannot be assessed in patients with a widely varying metabolic demand. The indicator amino acid oxidation (IAAO) method was originally employed to study amino acid requirements in pigs ( 8 ), and thereafter it has been widely used for studies on pigs ( 9-11 ) and humans (12)(13)(14)(15)(16)(17). Since the IAAO method does not require prior dietary adaptation ( 18 ) to each of the varying protein intake levels, it could be available when an assessment of the metabolic demand for protein is required for post-operative patients or patients with injuries or infections.…”