Taurine

Taurine, or 2-aminoethanesulfonic acid, is an amino sulfonic acid. In humans, taurine is predominantly synthesized in the pancreas through either the cysteine sulfinic pathway or transsulfuration pathway¹. Although taurine is not incorporated into the structural building blocks of protein, it is highly abundant throughout the body and expressed in many organs, including the heart, brain, retina, muscle tissue, and kidneys. As a result, taurine plays a variety of roles ranging from regulation of ion concentrations to modulation of neurotransmitters to conjugation of bile acids.

While taurine is produced endogenously, meat and fish are excellent sources of taurine, and dietary taurine is necessary for maintaining homeostasis. Taurine is an essential amino acid in preterm and newborn infants as well as many other animal species². Indeed, taurine deficiency is often observed in premature infants and individuals who adhere to vegetarian or vegan diets, thus requiring supplementation. The mechanisms and effects of taurine have been well studied, with many reports demonstrating that taurine has protective effects against pathologies associated with mitochondrial diseases, metabolic syndrome, cardiovascular diseases, and neurological disorders.

Taurine and Metabolic Health

The effect of taurine administration on metabolic health and energy metabolism has been thoroughly investigated. For instance, one study demonstrated that plasma taurine concentrations in patients with insulin-dependent diabetes mellitus were significantly lower than controls³. Other studies examining Type 2 diabetic patients reported similar results⁴. Together, these findings suggest a role for taurine in modulating glucose metabolism and insulin resistance. Interestingly, in other experiments involving animal models of diabetes, taurine supplementation improved hyperglycemia and insulin resistance⁵.

Due to taurine’s role in modulating ion concentrations (e.g., Ca²⁺; calcium homeostasis), oxidative stress, and blood pressure regulation, it has potential protective effects against cardiovascular diseases and congestive heart failure. These benefits include the modulation of intracellular Ca²⁺ through antioxidant effects, antagonism of Angiotensin II (an important molecule for regulating blood pressure), and protection against endothelial cell dysfunction⁶.

(Figure from Bae et al., 2022)

Taurine and Gastrointestinal Health

Gastrointestinal health, the gut microbiome, and human disease are closely linked, and a wealth of literature has begun to implicate taurine as a molecule that plays an important role in gut microbiome regulation. In the intestinal tract, taurine is produced by host-derived conjugated bile acids and several gut bacteria are capable of cleaving taurine from these conjugated bile acids. Recent reports have shown that harmful alterations in the microbiome (i.e., gut dysbiosis) have a powerful impact on metabolite pathways, including reduced levels of taurine⁷.

In one study examining taurine supplementation and gut microbiome health, mice treated with antibiotics (a model of gut dysbiosis) and supplemented with taurine exhibited significant alterations in both gut microbiome and bile acid composition, including improvements in microbiome diversity and intestinal immunity⁸.  Additionally, these researchers further demonstrated that taurine supplementation also enhances intestinal pathogen resistance in pathogen-infected mice.

Taurine and Neuroscience

Taurine also plays an important role in the central nervous system where it serves a variety of functions. As a neurotransmitter, it is released from neurons in a calcium-dependent manner, eliciting physiological responses and acting on receptors in the brain9. Similar to its function in other organs of the body, taurine is critical for maintaining calcium homeostasis and can exert neuroprotective effects.

For instance, one study showed that taurine administration significantly increases cell proliferation and mediates synapse development in neural stem cells of developing mice¹⁰. Others have shown that taurine can provide neuroprotective effects against age-related cognitive decline¹¹—taurine supplementation in cognitively impaired aged mice reversed harmful impairments in excitatory-inhibitory balance in the hippocampus, a critical brain region for learning and memory.

Taurine and Kidney Health

Taurine also has several functions in regulating kidney physiology, including ion reabsorption, renal blood floor, renal vascular endothelial function, and antioxidant properties. Taurine’s protective effects extend to the kidneys and normal taurine levels are critical for stabilizing renal vascular networks, mitigating oxidative stress, and maintaining normal plasma ion concentrations. As a result, several studies have demonstrated that taurine supplementation can protect against a number of kidney diseases including diabetic nephropathy, acute kidney injury, and chronic renal failure¹².

Taurine and Drug Development

Due to taurine’s protective effects across the body, considerable research has been focused on its potential as a therapeutic. Taurine has been approved for the treatment of congestive heart failure in Japan¹³ and has the potential to treat several other diseases, such as mitochondrial diseases, metabolic diseases, and inflammatory diseases like arthritis.

For example, taurine administration not only ameliorates common symptoms of congestive heart failure (e.g., breathlessness) but also decreases the need for other heart failure medications like digoxin¹⁴. In a preliminary study examining patients with myopathy, encephalopathy, lactic acidosis, and stroke-like episodes (MELAS), application of taurine to MELAS patient-derived cells improved MELAS -induced oxygen consumption impairments and increased oxidative stress in MELAS cells¹⁵. Additionally, oral administration of taurine prevented stroke-like episodes in two MELAS patients for over nine years.

Taurine in research

As of July 2023, there are nearly 2,000 citations for “taurine” in research publications (excluding books and documents) on Pubmed. The vast number of publications linking this metabolite to metabolic, neurological, gastrointestinal, and kidney health provides a foundation for researchers interested in quantitative analyses of taurine. Due to the various effects of taurine on the human body, preclinical research may also benefit from taurine quantification for a comprehensive understanding of biomarkers, diagnosis, and disease monitoring.

References

1. Ripps H and Shen W. Review: taurine: a “very essential” amino acid. Mol Vis 2012;(18):2673-2686.
2. Perry TL, Bratty PJ, Hansen S et al. Hereditary mental depression and Parkinsonism with taurine deficiency. Arch Neurol 1975;(32):108-113.
3. Franconi F, Miceli M, Fazzini A et al. Taurine and diabetes. Humans and experimental models. Adv Exp Med Biol 1996;(403):579-582.
4. Merheb M, Daher RT, Nasrallah M et al. Taurine intestinal absorption and renal excretion test in diabetic patients: a pilot study. Diabetes Care 2007;(30):2652-2654.
5. Nakaya Y, Minami A, Harada N et al. Taurine improves insulin sensitivity in the Otsuka Long-Evans Tokushima Fatty rat, a model of spontaneous type 2 diabetes. Am J Clin Nutr 2000;(71):54-58.
6. Xu YJ, Arneja AS, Tappia PS et al. The potential health benefits of taurine in cardiovascular disease. Exp Clin Cardiol 2008;(13):57-65.
7. Levy M, Thaiss CA, Zeevi D et al. Microbiota-Modulated Metabolites Shape the Intestinal Microenvironment by Regulating NLRP6 Inflammasome Signaling. Cell 2015;(163):1428-1443.
8. Qian W, Li M, Yu L et al. Effects of Taurine on Gut Microbiota Homeostasis: An Evaluation Based on Two Models of Gut Dysbiosis. Biomedicines 2023;(11).
9. Wu JY and Prentice H. Role of taurine in the central nervous system. J Biomed Sci 2010;(17 Suppl 1):S1.
10. Shivaraj MC, Marcy G, Low G et al. Taurine induces proliferation of neural stem cells and synapse development in the developing mouse brain. PLoS One 2012;(7):e42935.
11. El Idrissi A, Shen CH, and L’Amoreaux WJ. Neuroprotective role of taurine during aging. Amino Acids 2013;(45):735-750.
12. Chesney RW, Han X, and Patters AB. Taurine and the renal system. J Biomed Sci 2010;(17 Suppl 1):S4.
13. Schaffer S and Kim HW. Effects and Mechanisms of Taurine as a Therapeutic Agent. Biomol Ther (Seoul) 2018;26(3):225-241.
14. Azuma J, Sawamura A, and Awata N. Usefulness of taurine in chronic congestive heart failure and its prospective application. Jpn Circ J 1992;(56):95-99.
15. Rikimaru M, Ohsawa Y, Wolf AM et al. Taurine ameliorates impaired the mitochondrial function and prevents stroke-like episodes in patients with MELAS. Intern Med 2012;(51):3351-3357.