The analysis of rare earth elements in food and feed

More common than expected – and full of potential

April 2026. Rare earth elements are frequently mentioned in public discourse in the context of geopolitical and economic issues. As a component of many highly innovative technical applications, rare earth elements are essential. This article describes their use in food and animal feed, and outlines the importance of analysing them – either as contaminants or as a product component.

What are rare earth elements?

The so-called 'rare earth elements' comprise a total of 17 chemical elements: the two transition metals scandium (Sc) and yttrium (Y), as well as the lanthanide series: lanthanum (La), cerium (Ce), praseodymium (Pr), neodymium (Nd), promethium (Pm), samarium (Sm), europium (Eu), gadolinium (Gd), terbium (Tb), dysprosium (Dy), holmium (Ho), erbium (Er), thulium (Tm), ytterbium (Yb), and lutetium (Lu). They are even more abundant than gold, with the largest deposits found in China. Due to their unique chemical and physical properties, they have a wide range of applications, e.g., in wind turbines, magnets, catalysts, and smartphones^[1].

Use of rare earth elements outside of technical applications

According to the European Food and Feed Information Portal Database four lanthanum containing feed additives are currently approved. These include lanthanide citrate with cerium for piglets, as well as lanthanum carbonate octahydrate for cats and dogs. Lanthanum carbonate serves as a phosphate binder in animals with kidney disease, thereby reducing the burden on the kidneys^[2]. This mechanism is also used in human medicines^[3]. In addition, lanthanum chloride is used in aquariums, where it also binds phosphates and thus improves water quality^[4].

An alternative growth promoter?

For weaner piglets, lanthanide citrate containing cerium can stabilise the microbiome during the weaning phase, which may lead to more efficient feed intake, better digestion, and improved growth. Positive effects on the microbiome and immune system have also been reported in sows^[5].

In addition, rare earth elements (cerium, lanthanum, gadolinium, and praseodymium), some of which are in nanoparticle form, are being discussed as a potential alternative to antibiotic growth promoters, for example for poultry^[6]. However, further research is required into the use of rare earth elements in poultry to improve egg production^[7].

In plant production, reports provide a mixed picture regarding the use of rare earth elements as fertilizer additives. In low concentrations, they can stimulate plant growth, for example by increasing the rate of photosynthesis and enhancing chlorophyll production. At higher concentrations, however, they can be toxic and can interfere with water uptake or disrupt the plants’ mineral balance^[8].

Influence on the environment

The mining of rare earth elements is very intensive, as they are primarily found as assembly in ores. The distribution of individual elements within ores varies greatly, which means that, in some cases, large quantities of ore must be processed to meet the demand for popular elements. On the one hand, mining is sometimes not carried out in accordance with current environmental standards, resulting in landscape destruction. On the other hand, due to practical necessity, increasing amounts of rare earths and other metals are being brought to the surface, which can lead to their accumulation in the soil and water and thus also in the food chain^[9].

Influence on animals and humans

Currently, there are no regulated limit values for rare earth elements. Implementing Regulation (EU) classifies lanthanum carbonate octahydrate for cats and dogs, as well as lanthanide citrate for weaned piglets, as safe when used as feed additives within their respective application areas. For dogs and cats, a maximum dosage of 7500 mg additive/kg feed is specified, and at least 1500 mg additive /kg feed must be used to ensure efficacy. For lanthanum citrate, it is noted that precautions should be taken to prevent prolonged exposure to dust^{[10, 11,12,13]}.

Potential mechanisms of effect

In accordance with the dose-dependent mechanism of response, either stimulatory or inhibitory effects can be triggered. For example, in maize plants, 0–25 µmol/L of La³⁺ enhances photosynthesis, whereas at concentrations above 25 µmol/L, photosynthesis is inhibited. One possible mechanism for explanation of influencing the photosynthesis is that lanthanides are capable of substituting magnesium ions (Mg²⁺) in the chlorophyll molecule. In humans, substitution of Mg²⁺ can also occur, which may disrupt enzymatic reactions. In general, salt balance, hormonal balance, interactions with other metals, and gene expression can be affected^[9].

In studies involving aquatic organisms exposed to rare earth compounds at concentrations above the stimulation threshold, accumulation of the metals and acute toxicity were observed. There is a call for further toxicological studies to be conducted to establish risk assessments^[14].

Analysis of rare earth elements

For quantifying concentrations in feed and feed additives, as well as in residue analysis, it is essential to perform a robust, accurate, and sensitive quantification of rare earth elements.

The inductively coupled plasma mass spectrometry (ICP-MS) analysis offered by our Metals and Elements Production Centre, in accordance with the modified DIN EN ISO 15763 (2010-04) standard, meets these criteria.

For analysis, the rare earth elements are first extracted through digestion under acidic conditions and high pressure. The sample material decomposes, and the elements are present in solution. After dilution, this measurement solution is injected into the plasma and analysed by mass spectrometer. Beneficial of this method is a simultaneous measurement of several elements while performing only one single sample preparation.

Questions regarding the analysis of rare earth elements

If you have any further questions regarding metal and element analysis, please feel free to contact your personal account manager or get in touch with our experts in the analysis of metals and elements.

Sources

[1]: Wissenschaftliche Dienste Sachstand WD 5 -300 -003/22 (in German)
[2]: The EFSA Journal (2007) 542, 1-15: Opinion of the Scientific Panel on Additives and Products or Substancesused in Animal Feed
[3]: Chem. Soc. Rev., 2006, 35, 524–533:The therapeutic application of lanthanides
[4]: Environments 2023, 10(2), 20: Slow-Release Lanthanum Effectively Reduces Phosphate in Eutrophic Ponds without Accumulating in Fish
[5]: Animals 2019, 9, 738: Effects of Maternal Supplementation with Rare Earth Elements during Late Gestation and Lactation on Performances, Health, and Fecal Microbiota of the Sows and Their Offspring
[6]: J. Adv. Vet. Res. (2024) 14(6): 954–958: Quality indicators of broiler chickens' meat under the influence of gadolinium and lanthanum orthovanadate nanoparticles
[7]: Molecules 2024, 29(3), 688: Rare Earths—The Answer to Everything
[8]: Acta Agriculturae Serbica, 28 (56), 87‒95, 2023: Rare earth elements application in agriculture
[9]: Environ. Rev. 29: 354–377 (2021): The potential environmental risks associated with the development of rare earth element production in Canada
[10]: Commission Implementing Regulation (EU) 2025/313 concerning the authorisation of lanthanum carbonate octahydrate as a feed additive for dogs
[11]: Commission Implementing Regulation (EU) 2025/647 concerning the authorisation of lanthanum carbonate octahydrate, respectively with identification numbers 4d1 and 4d23, as feed additives for cats
[12] Commission Implementing Regulation (EU) 2020/1370 concerning the authorisation of a preparation of lanthanide citrate as a feed additive for weaned piglets
[13]: EFSA Journal 2019;17(12):5912: Scientific Opinion - Safety of Lancer® (lanthanide citrate) as a zootechnical additive for weaned piglets
[14] Animals 2020, 10, 1663: An Updated Review of Toxicity Effect of the Rare Earth Elements (REEs) on Aquatic Organisms