Clinical Pharmacist and Master’s student in Clinical Pharmacy with research interests in pharmacovigilance, behavioral interventions in mental health, and AI applications in clinical decision support. Experience includes digital health research with Bloomsbury Health (London) and pharmacovigilance practice in patient support programs. Published work covers drug awareness among healthcare providers, postpartum depression management, and patient safety reporting. 
Clinical Pharmacist and Master’s student in Clinical Pharmacy with research interests in pharmacovigilance, behavioral interventions in mental health, and AI applications in clinical decision support. Experience includes digital health research with Bloomsbury Health (London) and pharmacovigilance practice in patient support programs. Published work covers drug awareness among healthcare providers, postpartum depression management, and patient safety reporting. What was reviewed?
This review article, focused on cadmium and other metallic contaminants in cacao, provides an extensive synthesis of recent research regarding the occurrence, sources, transfer mechanisms, and mitigation strategies for cadmium (Cd) in Theobroma cacao. The review covers the geogenic and anthropogenic origins of soil Cd, the variability of Cd accumulation in beans, and the influence of soil, plant genetics, and environmental factors on Cd bioaccumulation. It also assesses the effectiveness of mitigation interventions such as post-harvest treatments, soil amendments, bioremediation, breeding programs, and grafting. Furthermore, the review addresses knowledge transfer to stakeholders and briefly examines the presence and regulatory context of other metals, notably nickel (Ni), in cacao and chocolate products. The synthesis draws heavily on studies published since 2021, highlighting evolving scientific understanding and regulatory responses in the cacao sector, especially in relation to new EU and Codex Alimentarius limits and their socioeconomic implications for major producing regions.
Who was reviewed?
The review synthesizes findings from a wide array of research conducted on cacao plantations primarily in Latin America and the Caribbean, with comparative references to Africa and Asia. The reviewed populations include cacao producers, smallholder farmers, and exporters—especially those in regions where cacao beans often exceed international cadmium limits. Studies reviewed encompass nationwide and regional surveys of soil and bean Cd content, pot and field experiments on cacao genotypes, and research on farm management practices. The review also incorporates data from various international research collaborations, genebanks, and breeding programs. Stakeholders further include chocolate manufacturers, regulatory authorities, and supply chain actors impacted by cadmium regulations and mitigation strategies.
Most important findings
| Critical Points | Details |
|---|---|
| Sources and variability of Cd in cacao | Cd in Latin American cacao is mainly geogenic, linked to sedimentary rocks; anthropogenic sources (mining, fertilizers) are sometimes relevant. Large regional and field-level variability in bean Cd exists, with some areas consistently exceeding EU and Codex limits. |
| Influence of soil and environmental factors | Total soil Cd, pH, and organic carbon are principal predictors for bean Cd; low pH increases Cd uptake. Soil amendments (lime, gypsum, biochar) show inconsistent or limited effectiveness in reducing bean Cd in real-world field conditions. |
| Genetic variation and breeding potential | Cacao genotypes exhibit large variability in Cd uptake and accumulation; some cultivars, like CCN-51, accumulate less Cd. Breeding for low-Cd genotypes is promising, but widespread adoption and systematic phenotyping are needed. Grafting with low-uptake rootstocks may reduce bean Cd. |
| Mitigation strategies: post-harvest and bioremediation | Post-harvest interventions—optimized fermentation and removal of testa—can reduce bean Cd by up to 30–60%. Bioremediation with Cd-tolerant microorganisms is promising in vitro, but field efficacy is unproven. Blending beans to achieve compliance is practiced, but it affects traceability. |
| Socio-economic and regulatory impacts | Post-harvest interventions—optimized fermentation and removal of testa—can reduce bean Cd by up to 30–60%. Bioremediation with Cd-tolerant microorganisms is promising in vitro, but field efficacy is unproven. Blending beans to achieve compliance is practiced, but affects traceability. |
| Knowledge transfer and research gaps | Initiatives for practical guidance and digital tools have begun, but require ongoing updates. Major research needs include field validation of mitigation, understanding environmental interactions, and leveraging genetic diversity under realistic conditions. |
Key implications
The findings underscore that heavy metal certification programs must address large variability and primarily geogenic origins of cadmium in cacao, prioritize genetic and post-harvest mitigation strategies, and recognize the limitations of soil amendments. Systematic screening of genotypes and robust knowledge transfer to stakeholders are essential for sustained compliance with evolving international regulations.
Citation
Letort F, Chavez E, Cesaroni C, Castillo-Michel H, Sarret G. Cadmium and other metallic contaminants in cacao: Update on current knowledge and mitigation strategies. OCL. 2025;32:22. https://doi.org/10.1051/ocl/2025019
Cadmium is a persistent heavy metal that accumulates in kidneys and bones. Dietary sources include cereals, cocoa, shellfish and vegetables, while smokers and industrial workers receive higher exposures. Studies link cadmium to kidney dysfunction, bone fractures and cancer.
