All lifeforms need iron to function, but often struggle to get enough of it despite it being the fourth most abundant element on Earth. Plants get their iron from the soil. The problem is that some soils tend to bind up iron in relatively insoluble ferric (Fe³⁺) compounds, and most plants (grasses are the exception) need to have it reduced ferrous (Fe²⁺) ions that their roots can absorb. They achieve this by secreting #coumarins that make the iron easier to reduce and absorb. The plants can do this themselves but their coumarins also allow soil bacteria to participating in mobilising iron for plant use.

Humans and other animals do not need coumarins to help them get enough iron, but coumarins from plants can have strong effects on their cells. One particularly interesting coumarin is called #osthol and in accumulated in the fruits of the Cnidium plant. What it does there is unclear, but osthol has a number of interesting medicinal properties. One application is in treating skin ailments, where osthol seems to relieve itching (#pruritis) by inhibiting TRPV3 calcium channels that participate in the itch response.

So maybe pumping iron in the gym is not for you. Nevertheless, it is entirely possible that the lotions you use to relieveyour itchy skin contain coumarins similar to those used by plants to extract ironfrom the soil.

Sources:

Grillet L, Schmidt W. The multiple facets of root iron reduction. J Exp Bot. 2017;68(18):5021-5027. https://doi.org/10.1093/jxb/erx320

Harbort CJ et al. Root-Secreted Coumarins and the Microbiota Interact to Improve Iron Nutrition in Arabidopsis. Cell Host Microbe. 2020;28(6):825-837.e6. doi:10.1016/j.chom.2020.09.006 https://doi.org/10.1016/j.chom.2020.09.006

Sun XY, et al. Antipruritic Effect of Natural Coumarin Osthole through Selective Inhibition of Thermosensitive TRPV3 Channel in the Skin. Mol Pharmacol. 2018;94(4):1164-1173. https://doi.org/10.1124/mol.118.112466

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