Taurine - Benefits and Mechanism of Action

Introduction:

Taurine is a sulfur-containing amino acid produced by breaking another amino acid called cysteine. It is an animal protein mainly found in muscles throughout the body. It is known for its cytoprotective activity because it processes fundamental actions in the cell. This property of taurine leads to an improvement in the nutritional and clinical health of humans. Due to the physiological effects of taurine, this is helpful in infant food items, dietary supplements, and energy drinks. Many studies have shown that humans cannot produce large amounts of taurine, but excellent retention of taurine is seen in human tissues.

Which Foods Have High Taurine Levels?

In the case of infants, they consume taurine through breast milk or infant food, but in adults, it is produced in the body. Following are the foods rich in taurine :

• Chicken - Dark meat such as the leg and thigh of chicken are rich sources of taurine. But it also contains saturated fats and calories.

• Turkey - Turkey thigh contains 334 mg of taurine, while turkey breast has only 12 mg of taurine. So the site of meat is responsible for the content of taurine.

• Salami - It is processed meat with high sodium content, and one ounce of salami contains 16 mg of taurine.

• Pork Loin - It is also a good source of phosphorus, zinc, selenium, and vitamin B. 48 mg of taurine is obtained from three ounces of pork.

• Tuna - About 23 mg of taurine is obtained from 2 ounces of tuna. It is rich in protein and low in calories. But the Food and Drug Administration (FDA) recommends one serving per week.

• Milk - Milk does not contain a large amount of taurine. Three cups per day can fulfill the daily requirements of taurine in vegetarian humans.

• Energy Drinks - It is not evident if adding taurine to energy drinks improves energy levels.

What Are the Underlying Mechanisms for the Cytoprotective Activity of Taurine?

The cytoprotective activity of taurine undergoes the following mechanisms:

• Antioxidant Activity - There are three processes to regulate it -

  • Taurine is an anti-inflammatory agent, and it neutralizes hypochlorous acid.

  • It decreases the superoxide formation by the mitochondria.

  • The mitochondria from the reactive oxygen species (ROS) can destroy antioxidant enzymes. This helps in protecting mitochondrial diseases like mitochondrial encephalopathy, lactic acidosis, and stroke-like episodes (MELAS).

• Energy Metabolism - Rise in the ratio of NADH/NAD+ (nicotinamide adenine dinucleotide hydrogen) affects energy metabolism, which is also influenced by taurine deficiency. As in the case of fatty acid oxidation, a reduction in energy levels is observed due to declined citric acid cycle flux and low levels of the transcription factor called PPAR (Peroxisome proliferator-activated receptors).

• Gene Expression - Taurine-sensitive genes are responsible for many cellular functions such as cell signaling, cell cycle regulation, cell death and survival, metabolism of amino acids, protein biosynthesis, protein folding, and aging. Different taurine levels also cause protein phosphorylation and cell signaling.

• Endoplasmic Reticulum Stress - Endoplasmic reticulum stress is a critical system to replace the functions of the endoplasmic reticulum and recreate a balance between protein degradation and protein biosynthesis. Increased stress is responsible for stimulating the pathways of cell lysis. The stress is developed due to the accumulation of defective proteins.

• Neuromodulatory Activity - The effects of taurine are seen as central nervous system toxicity. This toxicity occurs due to an imbalance between the excitatory and inhibitory neurotransmitters. Reduced gamma-aminobutyric acid (GABA) in the central nervous system is responsible for causing neuronal hyperexcitability. Taurine regulates the mechanism of GABA as acute taurine intake activates the receptors associated with GABA, and chronic information suppresses these receptors.

• Osmoregulation - The taurine content is high within many cells. Due to an increase in an osmotic load, there is an increase in intracellular taurine levels, whereas due to hypo-osmotic pressure, this level of taurine decreases. Thus the cell remains protected from getting stretched due to osmotic imbalances as the taurine acts as an organic osmolyte and regulates the concentration of other osmolytes in the body.

• Regulation of Calcium Ions - Taurine helps in protecting the cell from calcium ions by reducing the number of ions by following three mechanisms:

  • In ischemic conditions, there is a loss of taurine following the loss of sodium ions, as there will be less sodium available for the entry of calcium ions leading to a reduced concentration of calcium ions.

  • The sarcoplasmic reticulum calcium channel that maintains calcium homeostasis is also regulated by taurine.

  • Glutamate-induced calcium ions flux is also modulated by taurine.

What Are the Effects of Taurine on Human Health?

Taurine affects the central nervous system, cardiovascular system, and metabolic and inflammatory diseases in the following ways :

• Stroke - Taurine is secreted from many central nervous system cells and acts as a neuroprotective agent. During conditions like ischemic stroke and hypo-osmotic stress, taurine is released from the cells. A release of glutamate also causes hyperexcitability associated with calcium overloading, oxidative stress, depletion of adenosine triphosphate, and mitochondrial dysfunction. But the release of taurine declines the effects of glutamate by reducing the calcium ion concentration and suppressing the endoplasmic reticulum stress.

• Epilepsy - The condition arises due to imbalances between the excitatory and inhibitory neurotransmitters. Taurine acts as an inhibitory neurotransmitter as it is found in large amounts in the brain cells. Thus taurine is responsible for the suppression of certain types of seizures.

• Congestive Heart Failure - Taurine treats diseases like congestive heart failure in many countries like Japan as it reduces the symptoms like breathlessness on exertion and edema and also diminishes the need to administer heart failure medications like Digoxin. In addition, it also reduces the activity of norepinephrine and angiotensin II.

• Hypertension - Taurine helps reduce blood pressure by decreasing the activity of calcium ions, oxidative stress, and sympathetic and inflammatory activity.

• Atherosclerosis - Taurine helps treat atherosclerosis by suppressing serum cholesterol, platelet-derived growth factor-BB that causes vascular smooth muscle proliferation, and protecting endothelial cells from glucose-induced toxicity.

• Ischemia-Reperfusion Injury - Taurine is responsible for altering the effects of ischemia-reperfusion injury by acting as an antioxidant, modulation of calcium ions, osmoregulation, protein phosphorylation, and phosphate regulation.

• Myocardial Arrhythmia - Taurine affects many arrhythmic agents like Digoxin and Epinephrine by modulating sodium, potassium, and calcium ions. It is thus proved to be an effective antiarrhythmic agent.

• Diabetes Mellitus - Taurine helps increase the production of adenosine triphosphate, respiratory functions by pancreatic cell activity, and insulin secretion and thus prevents hyperglycemia-induced insulin resistance and oxidative stress.

Taurine also plays an essential role in preventing the following conditions:

1. Myotonic dystrophy (progressive muscle loss and weakness).

2. Duchenne muscular dystrophy (a genetic disease marked by the progressive loss of muscle).

3. Sarcopenia (gradual loss of muscle mass, strength, and function).

4. Muscle contractions.

5. Arthritis (swelling and inflammation of one or more joints).

6. Obesity.

7. Mitochondrial diseases like MELAS (myopathy, encephalopathy, lactic acidosis, and stroke-like episodes) (a rare genetic condition that begins in childhood).

Conclusion:

Taurine is an endogenous end metabolite found in many tissues in higher concentrations. It is known as 2-aminoethanesulfonic acid, synthesized from cysteine, and affects the skeletal muscle, the cardiovascular system, and the central nervous system. The cytoprotective activity of taurine improves humans' clinical and nutritional health through antioxidation, energy production, calcium homeostasis, neuromodulation, and osmoregulation. In addition, taurine therapy improves cardiac and skeletal muscular dystrophy and helps in conditions like congestive heart failure, diabetes mellitus, stroke, sarcopenia, reduced muscle contraction, and myotonic dystrophy. Thus taurine is an effective nutritional supplement and a therapeutic agent as well.