LAUSR

The paper by Muszyńska et al. [1] entitled “Study of biological activity of Tricholoma equestre fruiting bodies and their safety for human” published in the journal of European Food Research and Technology (https ://doi.org/10.1007/s0021 7-018-3134-0) presents the results of a study on the composition of T. equestre (syn. T. flavovirens, and syn. T. auratum) and in vitro anti-microbial and antioxidant activities of this mushroom. As reported, T. equestre can be a source of some essential minerals and has a favorable ratio of unsaturatedto-saturated fatty acids, while its extracts exhibit antioxidant effects (as shown in DPPH assay) at levels comparable to other mushroom species, but weak anti-microbial activities. Based on in vitro study using human lung carcinoma epithelial cells (A549 line), the authors suggest that ethanolic extract of T. equestre may exhibit pro-inflammatory activities. The authors conclude that consumption of this mushroom should be avoided. We raise some points contrary to this view, highlighting that existing toxicological evidence is insufficient to claim T. equestre as inedible or poisonous. The edibility of T. equestre has raised number of controversies. A small number of cases of rhabdomyolysis apparently developed following consumption of very large amounts of this mushroom. It was first reported in 2001 [2–4], and claimed to be supported by the results of in vivo experiments in rodents [2, 5–7]. This forced a number of countries (e.g., France, Spain, and Italy) to officially declare T. equestre as poisonous, releasing warnings to avoid its consumption. Prior to this, it had a long -history of consumption in many countries with no anecdotal or scientific evidence of toxic effects. It is still considered edible and widely consumed in regions such as Poland [8]. As shown in a recent study, more than half of mushroom foragers in this country have consumed T. equestre at least once in their lifetime [9]. This questionnaire survey and additional analysis of Polish registry of mushroom toxicity demonstrate that no rhabdomyolysis was reported in the last decade and that only mild gastrointestinal effects were noted, at a lower frequency than for other well-established edible wild mushrooms, such as Macrolepiota procera and Imleria badia [10, 11]. Importantly, the evidence from case reports of rhabdomyolysis lack critical information to indicate unambiguously that T. equestre was a causative factor of reported clinical effects. This has been recently extensively reviewed [8]. One possible explanation suggests that rhabdomyolysis could be triggered by consumption of morphologically related but genetically distinctive mushroom species to T. equestre. A paper by Muszyńska et al. [1] states that two varieties of T. equestre can be distinguished: one associated with Populus sp. (known as T. equestre var. populinum) and Betula sp. (known as T. equestre var. pallidifolia). However, the molecular evidence supports the view that the former belongs to T. frondosae clade and the latter is also a representative not belonging to the T. equestre species complex [11]. Tricholoma equestre is in turn a mycorrhizal group associated particularly with coniferous habitat (mainly Pinus) [12]. Rhabdomyolysis has also been reported after the consumption of other edible species including Agaricus bisporus or members of Boletus and Leccinum genera [13]. The in vivo models indicated increases in CK levels (a sensitive marker of rhabdomyolysis) at doses of T. equestre which are virtually impossible in human. For instance, in * Piotr Rzymski [email protected]