Arsenic is a metalloid or semi-metal that can be present in the environment, in living organisms and in food in a number of chemical forms. These are also known as ‘arsenic species’ and each one has a different characteristic toxicity: inorganic arsenic is, for example, a known carcinogen while the organic arsenobetaine is known to be non-toxic. Food items that contribute the most to exposure to inorganic arsenic are, amongst others, rice and special food products, including food supplements. Data concerning arsenic concentration and speciation in food supplements are scarce in Belgium and at the European level. Regarding clay-based food supplements, the international literature contains hardly any information.
In this context, the COMPAs project aims:
- to contribute to the knowledge available on the concentration and speciation of arsenic in various types of food supplements, and
- to gain a better understanding of the risk and the actual exposure of the Belgian population to arsenic from food supplements.
In view of the existing Belgian maximum level for arsenic (As) in selected food supplements and potential future European debates on maximum levels for As in food supplements, 83 samples of food supplements were collected on the Belgian market and analyzed by ICP-MS and HPLC-ICP-MS for total As and four As species. Different types of food supplements were selected: food supplements based on algae, fish- or krill oil, or non-marine biological matrices (terrestrial plants, yeasts, etc.), food supplements containing clay, and other food supplements of mineral or synthetic origin.
Clay containing food supplements form a particular group within the project, because –certainly in case of pure clay- all arsenic in these samples is expected to be present in the most toxic inorganic form (Asi). In contrast to biological matrices however, a lower bioaccessibility of As can be expected. In terms of risk, the first question therefore is not which species are present, but rather what the bioaccessibility is of this inorganic arsenic. Therefore, the bioaccessible As fraction in these samples was determined by use of the “Unified Barge Method” protocol (UBM; Denys et al., 2012). The method was applied as well in some of the other mineral or synthetic food supplements.
Finally exposure calculations were performed and potential risks were evaluated by comparing the exposure to reference values.
Total As concentrations differed considerably between different types of food supplements and also between food supplements of the same type. The total As concentrations in food supplements decreased in the order algae-based > fish- and krill oil-based ≈ clay-based > non marine biological matrices > ‘other’ supplements of mineral or synthetic origin. The As species concentrations strongly differed among the types of food supplements and within the various types. Although the presence of arsenobetaine (AB) has been reported previously in various types of algae, the AB concentrations in all food supplement samples based on algae was not quantifiable.
To determine the bioaccessible As fraction in clay-containing, mineral and synthetic food supplements the UBM method was applied. The results revealed that bioaccessibility of Asi was 50% or less and varied among all clay based samples and approached 100% in other mineral and synthetic food supplements.
The risk evaluation revealed that consuming the tested food supplements did not result in any risk of acute toxicity due to the intake of Asi. For the general population, the intake of Asi resulting from chronic consumption of the tested food supplements was in most cases of no concern, except for several of the tested clay-containing food supplements, even when taking into account the relatively low bioaccessibility of Asi in these food supplements.
Several recommendations were formulated towards regulatory bodies based on the outcome of the project.