And 16 | Amino Acid | Proteins

And 16 % for men and 22 % for women consuming unrefined, cereal-based diets (WHO low biovailability). Whether these biovailability factors are appropriate for childen, pregnant or lacting women, or the elderly has not been established. 4.8.8 development or algorithms for the other nutrients Research on factors affecting the biovailability of other nutrients in contemporary diets is urgently required. So far, steps have been take to develop algorithms to quantify the biovailability of protein, folate and vitamin a in human diets; these are considere below. Niacin is discussed in section 4.4.5 The nutrional value of proteins in diets can be estimated from a protein digestibility corred amino using procedures of schaafsma (2000). This method is recommended by FAO/WHO (1990) and is based on comparision of the concentration of the first limiting amino acid in a reference patern of essential amino acids. The reference scoring pattern is derived from the essential amino acid requirements of the preschool-age child and is given in tabel 4.16 . the chemical score derived in this way is then corrected for true fecal digestibility of the test protein. Some values for true fecal digestibility, amino acid score, and nontrunancated digestibility, amino acid score from selected foods are shown in tabel 4.17. the values for proteins with PDCAAS > 100% can be truncated to 100 % (FAO/WHO 1990). This approach has been adopted on the assumption the digestble essentialamino acid concetrations in excess of thoe in preschool-age reference pattern do not provide additional nutritional benefit. However, this assumption has been questioned because it does not take into acount the ability of high-quality proteins to balance the amino acid composition of inferior proteins. This is highly relevant because, in most cases, humans consume mixed diet containing protein from a variety of sources, rather than singel protein source (scaafasma, 2000). To apply this formula to habilitual mixed diets, first the observed intakes of the essential amino acid are calculated from food compostion data. The uncorrectd amino acid score is the computed independently for each amino acid score is then computed independently for each amino acid using the reference amino acid pattern for childern aged 2-5 y. lastly, the lowest amino acid score is selected and applied for the estimate of the (PDCAAS) (as %). Note that the digestib must ability of total protein intake must also be taken into account.