Behind the Scenes: Proteins in Antioxidant Action

Did you know that the proteins in your diet do more than just build muscles? They are essential warriors in your body's antioxidant defense system!

Glutathione Synthesis

Proteins are essential in the body's antioxidant production, mainly for glutathione synthesis. The amino acids crucial for glutathione synthesis are cysteine, glycine, and glutamate. These three form the tripeptide glutathione, which is a key molecule in the body's antioxidant defense system. Cysteine is particularly important due to its sulfur group, which gives glutathione its antioxidant properties. If the body lacks these specific amino acids, glutathione production can be significantly hindered, reducing the body's capability to fend off oxidative stress effectively.

Some of the critical functions of glutathione are:

→ Neutralization of radicals

→ Cofactor for several antioxidant enzymes

→ Regeneration of vitamins C and E

→ Transportation of mercury out of cells and the brain

→ Regulation of cellular proliferation and apoptosis

→ Vital to mitochondrial function and maintenance of mitochondrial DNA

Glutathione is distinct from other antioxidants in that its unique structure allows it to function effectively in both its reduced (GSH) and oxidized (GSSG) forms. Unlike other antioxidants, glutathione can regenerate itself and other antioxidants, amplifying its protective capabilities. Studies have shown its critical role in neutralizing free radicals, detoxifying harmful substances, and maintaining immune system health.

Furthermore, it is crucial for nutrient metabolism, cellular functions including gene expression, cell growth, and death, signaling pathways, protein folding, and protein modification. Its deficiency is linked via increased oxidative stress, to aging and various diseases such as neurological disorders, liver conditions, cystic fibrosis, blood diseases, cancer, cardiovascular incidents, and diabetes.

Some of our daily need for glutathione is supplied by our diet, but the vast majority is produced by the body. Glutathione is found in cells in very high concentrations: equal to the concentration of glucose and of cholesterol!

Diets low in some of the essential amino acids needed for glutathione synthesis, such as vegan diets if they are not carefully balanced, or generally low protein intake as common in older age, can significantly influence glutathione levels. This reduction can impact the body's overall antioxidant capacity, underscoring the importance of a well-formulated diet for maintaining optimal glutathione levels and antioxidant defense.

Enzymatic Antioxidants

Proteins are crucial in the formation of enzymatic antioxidants such as superoxide dismutase and catalase. These enzymes play a vital role in neutralizing various reactive oxygen species (ROS), which can cause cellular damage. Superoxide dismutase converts the superoxide radical into hydrogen peroxide, which is then broken down by catalase into water and oxygen. This process is essential for protecting cells from oxidative stress, thus maintaining cellular integrity and function. The presence and activity of these enzymes reflect the body's ability to defend against oxidative challenges.

Regeneration of? Antioxidants

Proteins play a critical role in the regeneration of antioxidants, a key aspect of the body's defense against oxidative stress. They assist in converting oxidized forms of antioxidants back to their active, reduced states. This process is essential in maintaining the balance and effectiveness of antioxidants like vitamin C and E, which protect cellular components from oxidative damage. Through this regeneration mechanism, proteins significantly enhance the overall antioxidant capacity of the body, ensuring continuous protection against cellular damage caused by free radicals and other reactive species.

Protein Repair and Maintenance

Proteins play a key role in repairing and maintaining other proteins that have been damaged by oxidative stress, which is crucial for preserving cellular function and integrity. This repair mechanism involves identifying and rectifying oxidatively modified amino acids, thereby preventing the accumulation of dysfunctional proteins. This process is vital for the overall health and longevity of cells, ensuring that they continue to operate efficiently and effectively in the face of oxidative challenges.

To summarize, it’s important to bolster your body's antioxidant defense and ensure optimal health by maintaining a diet with adequate quantity and high-quality protein intake! Proteins are crucial for their role in producing glutathione and other critical enzymes, the regeneration of other antioxidants, and protein repair and maintenance!

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References and Further Reading:

Wu, G., Lupton, J. R., Turner, N. D., Fang, Y. Z., & Yang, S. (2004). Glutathione Metabolism and Its Implications for Health. The Journal of Nutrition, 134(3), 489-492. https://doi.org/10.1093/jn/134.3.489

McCarty, M.F., DiNicolantonio, J.J. An increased need for dietary cysteine in support of glutathione synthesis may underlie the increased risk for mortality associated with low protein intake in the elderly. AGE 37, 96 (2015). https://doi.org/10.1007/s11357-015-9823-8

Pizzorno J. Glutathione! Integr Med (Encinitas). 2014 Feb;13(1):8-12. PMID: 26770075; PMCID: PMC4684116.

Averill-Bates, D. A. (2023). Chapter Five - The antioxidant glutathione. In G. Litwack (Ed.), Vitamins and Hormones (Vol. 121, pp. 109-141). Academic Press. https://doi.org/10.1016/bs.vh.2022.09.002

Lu, S. C. (2013). Glutathione synthesis. Biochimica et Biophysica Acta (BBA) - General Subjects, 1830(5), 3143-3153. https://doi.org/10.1016/j.bbagen.2012.09.008

Aoyama K. Glutathione in the Brain. International Journal of Molecular Sciences. 2021; 22(9):5010. https://doi.org/10.3390/ijms22095010

Lu, J., & Holmgren, A. (2014). The thioredoxin antioxidant system. Free Radical Biology and Medicine, 66, 75-87. https://doi.org/10.1016/j.freeradbiomed.2013.07.036

Bumrungpert, A., Pavadhgul, P., Nunthanawanich, P., Sirikanchanarod, A., & Adulbhan, A. (2018). Whey Protein Supplementation Improves Nutritional Status, Glutathione Levels, and Immune Function in Cancer Patients: A Randomized, Double-Blind Controlled Trial. Journal of Medicinal Food, 21(6), 612-616. https://doi.org/10.1089/jmf.2017.4080

Nwachukwu, I. D., & Aluko, R. E. (2019). Structural and functional properties of food protein-derived antioxidant peptides. Journal of Food Biochemistry, https://doi.org/10.1111/jfbc.12761

Mainigi, K. D., & Campbell, T. C. (1981). Effects of low dietary protein and dietary aflatoxin on hepatic glutathione levels in F-344 rats. Toxicology and Applied Pharmacology, 59(2), 196-203. https://doi.org/10.1016/0041-008X(81)90190-3

Wierzbicka GT, Hagen TM, Tones DP. Glutathione in food. J Food Compos Anal. 1989;2(4):327-337. https://doi.org/10.1016/0889-1575(89)90004-5

Wu G, Fang YZ, Yang S, Lupton JR, Turner ND. Glutathione metabolism and its implications for health. J Nutr. 2004 Mar;134(3):489-92. doi: 10.1093/jn/134.3.489. PMID: 14988435. https://doi.org/10.1093/jn/134.3.489