Folates
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Discussion of folates within the Component Thesaurus can be based on the updates and policy issues described in the report for version 1.1, with a minor revision in version 1.2. These descriptions are available in the attached document .
Mode of expression
Compositional values for individual folates and folate totals should be expressed as monoglutamates. The term dietary folate equivalents is not required in the EuroFIR thesauri, either as a component identifier or as a unit, as it is represented by the code FOL (folate, total) plus the method indicator MI0453 (Folate by factored calculation from intrinsic folic acid and added folic acid).
Conventions for identifiers
All codes for folate component start with the letters FOL Uninverted forms such as THF for tetrahydrofolate are avoided as these make codes hard to find in an alphabetical listing, as well as being potentially ambiguous with other acronyms widely used in chemistry (e.g. THF = tetrahydrofuran).
The next structural detail specified is the level of saturation, with dihydrofolates and tetrahydrofolates having codes beginning FOLH2 and FOLH4, respectively. Then any substitution is indicated using a two-letter representation of the substituent, followed by its locant. The substituted folates currently in the thesaurus are 10-formyldihydrofolate [FOLH2FM10], 10-formylfolic acid [FOLFM10], 5-formyltetrahydrofolic acid [FOLH4FM5], 5-methyldihydrofolic acid [FOLH2ME5] and 5-methyltetrahydrofolate [FOLH4ME5].
Conjugated and bound folates
A conjugated folate has a polyglutamate moiety usually consisting of 2 to 6 glutamic acid residues. Bound folates are mono- or polyglutamates bound to proteins, etc. The component terms for "folate, bound" [FOLB] and "folate, free" [FOLFRE] have been inactivated as they are incompatible with the expression of values as monoglutamate.
Synthetic folic acid
The term for "folic acid" (i.e. pteroylmonoglutamic acid) is compatible with the standard mode of expression, but is specific to synthetic folic acid used to fortify foods. This form is considered to be more active than intrinsic (i.e. naturally occurring) folate and thus its compositional value in a fortified food is necessary information for the calculation of the total folate value. For version 1.1 of the thesaurus, the identifier for folic acid has been changed from FOLACID to FOLAC to correspond to the INFOODS tagname and the descriptor changed to “folic acid, synthetic” so that it is specific for added folic acid.
Comments related to the above issues are welcome within the Folates topic, together with any suggestions for additional folate terms, including terms for extra individual folates.
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