Open Veterinary Journal, (2025), Vol. 15(7): 2919-2920

Letter to the Editor

10.5455/OVJ.2025.v15.i7.1

Reconsidering protein quality: Role of amino acid composition in diet-induced hepatorenal stress

Yves Hude^* and Yuxiao Hu

YVESH Laboratory, Paris, France

*Corresponding Author: Yves Hude. YVESH Laboratory, Paris, France. Email: yves.hude [at] yvesh.org

Submitted: 24/05/2025 Revised: 16/06/2025 Accepted: 17/06/2025 Published: 31/07/2025

Recent investigations into the physiological impact of diet on laboratory animals have brought renewed attention to the metabolic consequences of common dietary components. The research by Kapo-Dolan et al. (2025) titled “Assessment of the hematological profile and pathohistological changes in hepatic and renal tissue in adult rats exposed to different dietary components” (Open Veterinary Journal, Vol. 15, Issue 4) provides valuable insights into how distinct dietary patterns influence organ health. Specifically, the findings—highlighting hepatic steatosis and nephrocyte hypertrophy in rats fed with meat-based diets—are highly relevant, particularly in the context of clinical nutrition and metabolic rehabilitation.

While the study rigorously evaluates hematological and biochemical changes induced by different dietary patterns, we believe it would benefit from further discussion on protein and amino acid quality, not merely quantity. The source and composition of dietary proteins—especially the ratio of essential to nonessential amino acids—can significantly affect hepatic lipid metabolism and renal load.

For instance, branched-chain amino acids, such as leucine, isoleucine, and valine, influence insulin signaling and hepatic lipid synthesis via activation of the mTOR pathway, and excessive intake has been associated with insulin resistance and nonalcoholic fatty liver disease in animal models and humans alike(Lynch and Adams, 2014; Yoon, 2016). Similarly, methionine, a sulfur-containing amino acid, is essential but can promote oxidative stress and homocysteine accumulation if not balanced with folate and B-vitamins, aggravating hepatic and renal burden (Brosnan and Brosnan, 2006).

Moreover, the consumption of thermally processed meats introduces advanced glycation end-products (AGEs), which are known to contribute to endothelial dysfunction and nephropathy through increased oxidative stress and inflammatory pathways (Uribarri et al., 2010). Whether the hepatic and renal lesions observed by the authors were primarily driven by protein loading or by the presence of AGEs and oxidized lipids warrants further mechanistic exploration.

Future studies may be encouraged to include plasma amino acid profiling and oxidative stress markers (e.g., glutathione, malondialdehyde, and homocysteine) to clarify the biochemical pathways involved. Furthermore, supplementing experimental diets with L-arginine or glutamine—amino acids known for their hepatoprotective and renoprotective roles via nitric oxide and antioxidant modulation—may provide a model for therapeutic dietary correction in rehabilitation settings (Wu et al., 2009; Cruzat et al., 2018).

In summary, Kapo-Dolan et al. provided a solid foundation for investigating diet-induced metabolic pathology. A deeper focus on amino acid composition and bioactivity could enrich our understanding of dietary protein’s dual role as both building blocks and metabolic stressors, especially in the context of organ protection and recovery.

References

Brosnan, J.T. and Brosnan, M.E. 2006. The sulfur-containing amino acids: an overview. J. Nutr. 136(6), 1636S–1640S.

Cruzat, V., Macedo Rogero, M., Noel Keane, K., Curi, R. and Newsholme, P. 2018. Glutamine: metabolism and immune function, supplementation and clinical translation. Nutrients 10(11), 1564.

Kapo-Dolan, N., Kapić, D., Ćosović, E., Čičkušić, E., Bešić, A., Čović, N., Hadžiomerović, N., Zahirović, A. and Katica, M. 2025. Assessment of the hematological profile and pathohistological changes in hepatic and renal tissue in adult rats exposed to different dietary components. Open Vet. J. 15(4), 1673.

Lynch, C.J. and Adams, S.H. 2014. Branched-chain amino acids in metabolic signalling and insulin resistance. Nat. Rev. Endocrinol. 10(12), 723–736.

Uribarri, J., Woodruff, S., Goodman, S., Cai, W., Chen, X.U.E., Pyzik, R., Yong, A., Striker, G.E. and Vlassara, H. 2010. Advanced glycation end products in foods and a practical guide to their reduction in the diet. J. Am. Diet. Assoc. 110(6), 911–916.

Wu, G., Bazer, F.W., Davis, T.A., Kim, S.W., Li, P., Marc Rhoads, J., Carey Satterfield, M., Smith, S.B., Spencer, T.E. and Yin, Y. 2009. Arginine metabolism and nutrition in growth, health and disease. Amino Acids 37, 153–168.

Yoon, M.-S. 2016. The emerging role of branched-chain amino acids in insulin resistance and metabolism. Nutrients 8(7), 405.