Author: András S. Szabó
Because many investigations proved, that the concentration-distribution of essential and non-essential microelements within the healthy organisms shows significant difference, this fact can be used for clarification of the biological role of the given elements. In case of essential elements the concentration-range is narrow, the distribution is normal, in case of non-essential elements the interval is wide, the distribution is lognormal. Based on the measurements of Ni content of radish samples the conclusion was the following: for higher plants the nickel is not essential.
As a reference element Zn was used, which is definitely an essential element, and to the measurements the concentration range was narrow, the distribution normal. So, the trace element investigation of different foodstuffs can really help for determination of biochemical role of micro elements. However for human beings Ni is essential, in the paper information is given about the Ni-content of some foodstuffs, as well. In case of normal, well-balanced nutrition there is no risk of Ni-deficiency, the daily Ni-need is maximum 0.1 mg.
In the 2013/3 issue of the Journal of Food Investigation – Essentiality of trace elements and food investigations – detailed analysis was given about the concept of trace and micro elements, classification of trace elements, based on the physiological role, analytical techniques for determination of trace elements and the concentrationdistribution of essential and non-essential microelements . It was established, that the distribution of the various microelements in case of healthy organisms – for plants, animals and human beings, as well – shows huge differences in the tissues. In case of essential elements the concentration-range is narrow, the difference between the arithmetical and geometrical means is small , , , , . However in case of non-essential microelements the range can be really huge, the difference between arithmetical and geometrical means is significant. The former paper  was dealing with investigation of Li-, Sr- and Zn-contents of radish samples (representing different agricultural lands in Hungary) and distribution-analysis of the measured concentrations. We could establish, that Zn – this was measured as a reference element, concerning the investigation of the biochemical role, based on the distribution – is of course biologically necessary element, so the concentration range was narrow. The situation was similar in case of Sr, as well. However for Li the conclusion was on the contrary, the range was wide, the difference between arithmetical average and geometrical mean was significant, so there is no control mechanism for concentration-regulation, the element should be taken
as non-essential. This paper informs about the measurement data for nickel (heavy metal trace element, belonging to the iron group) in case of radish samples and information is given about the Ni-content of some foodstuffs. Let me mention, that for higher animals (e.g. mammals) and of course for human beings nickel is an essential microelement, known since the 70-ies , , , . But for plants the essentiality is not proven resp. the position is controversial , . read more ...