Nutritional composition assessment

Accurate assessment of supply and intake is a complex procedure. In practice, a crude estimate of intake can be obtained from a careful clinical history taken by an experienced practitioner or from a food frequency questionnaire that summarizes the content of the individuars diet over several days, depending on how frequently particular typical foods are consumed. A more accurate quantitative assessment usually requires a minimum of three days recording of a complete dietary diary, which is subsequently analyzed using a computer program with reference tables of the nutritional contents of most foods. Unfortunately, estimates of the portion size, amounts consumed, and actual nutritional composition of the food consumed may be inaccurate. In addition, the disease process also affects the amount actually consumed and absorbed, further reducing the accuracy of the estimate of nutritional intake. 

Generation of data on the nutrient content of agricultural products and foods forms the basis for estimating nutrient intakes of populations via dietary surveys, nutritional labelling for consumer protection, nutrition education for consumer food choice, home and institution menu planning and food purchase, and for research in nutrient requirements and metabolism, toxicant chemical composition is used to assess effects of farm management practices, crop culture, and food processing on chemical content and implications for human health. 

Amino acid analysis has long been of importance for nutritional purposes. Recently, there has been an increasing interest in assessing the exact amino acid composition of new protein sources, infant formulas, nutraceutical-type products, or supplements targeted at people with unusual metabolic needs. There is also a regulatory necessity to have rapid methods available for amino acid determination to verify product consistency with that declared on the label [196]. 

Metabolism is considered to be a phenotype. It integrates all the factors from nutrition to environment to genetics assessing one s current state of health. Metabolomics arose from metabolic control theory and was originally based on the metabolome, which is defined as the metabolic composition of a cell and is analogous to the genome or proteome. In metabonomics, static cellular and biofluid concentrations of endogenous metabolites are evaluated over a time-course. 

Better markers of nutrition status and methods for determining patient-specific nutrition requirements are needed to allow further refinement of estimates of individual nutrition needs. Functional tests and simple, noninvasive tests for body composition analysis hold promise for the future. However, until better methods of assessment become available clinically and are demonstrated to be cost-effective, the currently available battery of tests will continue to be the mainstay of nutrition assessment. 

Elia M, Ward LC. New techniques in nutritional assessment Body composition methods. Proc Nutt Soc 1999 58 33-38. 

Establishing links between acmal dietary iodine intake and iodine deficiency disorders relies on the availability of precise techniques to enable accurate estimation of nutritional intake. However, the evaluation of iodine intake is difficult, due to wide variations in the iodine content of food hence, obtaining an accurate assessment is not possible with food composition tables. This is particularly pertinent to vegans who consume a variety of unconventional foods not listed, or inconsistently listed, in such tables. 

Iodine intake was not assessed in the 1997 National Nutrition Survey because of inadequate food composition data. However, analysis of three-day dupficate diets collected in a 1990 study by 50 Otago residents indicated that intakes ranged from 12 to 812 (median intake, 108)pg/day (Thomson, 2004). These diets included discretionary salt used in cooking, but may not have included salt used at the table. 

Mai, K., Mercer, J. P., and Donlon, J. (1994). Comparative studies on the nutrition of two species of abalone, HaUotis tuberculata L. and Haliotis discus hannai Ino 11. Amino acid composition of abalone and six species of macroalgae with an assessment of their nutritional value. Aquaculture 128,115-130. 

The parameters of interest in body composition analysis (bioelectric impedance analysis, BIA) are total body water (TBW), extracellular/intracellular fluid balance, fat-free mass (lean body mass or muscle mass), and fat mass. Application areas are as diversified as sports medicine, nutritional assessment, and fluid balance in renal dialysis and transplantation. 

Live systems as analytical tools Different life systems have been utilized in assessing composition and nutritional quality of foods. 

The importance of amino acids, peptides, and proteins is widely know and it arises from different aspects ranging from an important role in human nutrition and health to different technological functions that can widely influence the quality of food products (mainly for peptides and proteins). Therefore, their analysis is crucial not only from the nutritional point of view (for example, to warranty and verify the content of an specific amino acids) but also for product quality assessment and product development (where information about the composition of the protein fraction is mandatory). Also important is assessment of the authenticity of foods through enantiomer separation and identification. 

Appropriate clinical studies of nutritional and safety assessment should be performed particularly for components, and combinations of components, which have not been previously included in infant fonnulas and other dietary products tor infants. Technological as well as compositional modifications to infant formulas should be assessed nutritionally. 

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