Evidence for a possible dietary effect on the isotopic composition of Zn in blood via isotopic analysis of food products by multi-collector ICP-mass spectrometry

In this work, the hypothesis of a possible dietary effect on the isotopic composition of Zn in blood from populations with different feeding habits, i.e. lacto-ovo vegetarians and omnivores, was investigated through isotopic analysis of Zn in common food products by multi-collector ICP - mass spectrometry (MC-ICP-MS). Several certified reference materials (CRMs) were also included in the sample set for comparison purposes. For these CRMs, the isotopic composition of Zn is expressed as delta-values, calculated with respect to both IRMM-3702 and JMC-Zn-Lyon, as isotopic standards. The range of delta Zn-66 values observed in food products was approximately 1.9 parts per thousand. In general, vegetables, cereals and derived products showed an enrichment of the heavier Zn isotopes, whereas a depletion was observed in products of animal origin (meat, fish, egg and semi-skimmed milk), relative to human blood samples. Mussel, however, showed a significant enrichment of the heavier isotopes, which is hypothetically attributed to its accumulation behaviour. Thus, the lower delta Zn-66 values found in food products of animal origin appear to be reflected in the lower delta Zn-66 value observed in blood from an omnivorous population compared to that for a vegetarian population.