Until the past decade, rare earth elements (REEs) like lanthanum were thought by the scientific community to be biologically inactive. It was recently discovered that methylotrophs have a methanol dehydrogenase XoxF that requires rare earth elements for activity (Nagawa et al., 2012). XoxF is a homolog of the methanol dehydrogenase MxaFl, which contains a calcium ion in its active site instead of an REE. The REEs that can function as a cofactor in XoxF include lanthanum, cerium, praseodyminium, neodynium, and- to some extent- samarium. Rare earth metals were also discovered to be a cofactor in multi‐carbon alcohol dehydrogenases in Methylobacterium extorquens AM1 and Pseudomonas putida. 

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Lanthanides, and in particular La and Ce, have also been classified as beneficial elements in plant and animal nutrition (Abdelnour et al., 2019; Tommasi et al., 2021). The addition of low levels of La and Ce salts has been reported to have beneficial effects for both plants and animals, but the results vary widely and many studies have found no significant benefit. Nevertheless, evidence of a beneficial effect was sufficient that a feed additive for animal husbandry that contains La and Ce citrate salts (Lancer) has been approved in the European Union (Tommasi et al., 2021).