Use of a default methodology for establishment of a health-based guidance value (HBGV) resulted in a group acceptable daily intake (ADI) for glutamates (E620-625) below the normal dietary glutamate intake, and also lower than the intake of free glutamate by breast fed babies. Use of a chemical-specific adjustment factor (CSAF) may overcome this problem. The present study investigates the interindividual human variability in glutamate plasma and brain levels in order to define a CSAF for the interindividual variation in kinetics, a HKAF, for glutamates. Human clinical data on plasma glutamate levels available from different groups of subjects at Mitsui Memorial Hospital as well as literature data on plasma and brain-related glutamate levels were collected and analysed. The median HKAF value obtained amounted to 2.62–2.74 to 2.33–2.52 for plasma derived values and to 1.68–1.81 for brain derived values. Combining these values with the CSAF for the interspecies differences in kinetics of 1 and the default factors for interspecies and interindividual differences in dynamics of 2.5 and 3.16 results in an overall CSAF of 16–20. Using this CSAF will result in a HBGV for glutamate that is no longer below the acceptable range of oral intake (AROI).
- Chemical-specific adjustment factor (CSAF)
- CSAF for Interindividual variation in kinetics (HK)
- Interindividual differences