Nonvitamin micronutrients.
Nonvitamin micronutrients encompass innumerable nutritionally active substances present in foods at low levels that may have beneficial and protective properties. These include nonvitamin carotenoids, essential fatty acids, amino acids, phospholipid components, and conditionally essential components such as carnitine, choline, inositol, and any compounds with antioxidant, growth promoting, antimicrobial, or immune potential. These analytes are grossly underrepresented in the Official Methods of Analysis (OMA). The General Referee urges that the nonvitamin micronutrients, carnitine, inositol, and nucleotides need to be strategically targeted for collaborative study because they are not covered in OMA by any technique. Carnitine is available through limited de novo synthesis, although deficiency is recognized, particularly in infants. Thus, infant formulas are commonly supplemented with carnitine, and reliable analytical techniques are needed. A published enzymatic methodology will hopefully be subjected to collaborative study in the near future. Similarly, inositol is considered a conditionally essential pseudovitamin and although microbiological, gas and liquid chromatographic techniques are generally used, these approaches have not been subjected to the highest level of validation. Nucleotides play important roles in major biochemical functions, and recent evidence suggests that dietary nucleotides are semiessential for newborns. The nucleotides and nucleosides are present in human milk at relatively high levels, so bovine milk-based infant formulas are increasingly supplemented with the 5'monophosphate nucleotides, and it is unfortunate that no current AOAC method exists for quantification of nucleotides. Colostral immunoglobulins, specifically IgG, confer passive immunity to the neonate until the immune system is developed. There has been an increase in the global availability of colostrum-based functional foods and supplements, which are claimed to improve gastrointestinal health and stimulate the immune system. In the absence of a reference analytical method, it is becoming increasingly important to standardize analysis techniques for IgG in such materials. Although commercial radial immunodiffusion (RID) kits are available, they are generally variable in response. An affinity high-performance liquid chromatography (HPLC) method based on specific binding of bovine IgG with immobilized Protein G has been validated within the laboratory of the prospective Study Director Don Otter and is currently at the protocol development stage. Biosensor technology can provide an alternative approach to IgG analysis, and an antibody-based optical method is also slated for collaborative study under Study Director Leyton Gapper. Where other organizations involved with method validation are active in these analyte areas, it may be timely to consider AOAC policy regarding joint adoption in order to avoid duplication of scarce scientific resources. Major difficulties may occur when validation protocols do not entirely meet the AOAC INTERNATIONAL, ISO 5725, and IUPAC harmonized protocols. Whether such studies need either to be repeated in full using OMA protocol, or perhaps, preferably, publish the method within OMA at a lower level of validation, requires clarification at the Official Methods Board level.
Indyk
Harvey
H
Fonterra, No. 1 Rd, PO Box 7, Waitoa, New Zealand. harvey.indyk@fonterra.com
D000818:Animals; D002417:Cattle; D002623:Chemistry Techniques, Analytical / Q000379:methods*; D002851:Chromatography, High Pressure Liquid; D005504:Food Analysis; D007136:Immunoglobulins / Q000737:chemistry; D041943:Infant Formula / Q000737:chemistry; D018977:Micronutrients / Q000032:analysis* / Q000502:physiology; D008892:Milk / Q000378:metabolism; D009711:Nucleotides / Q000737:chemistry
D007136:Immunoglobulins; D018977:Micronutrients; D009711:Nucleotides