Taurine is a free amino sulfonic acid present in many tissues of mammals. In the bile, it conjugates with cholesterol to form soluble acids to facilitate excretion. Taurine also plays an important role in the functioning of cardiovascular, skeletal muscle, and nervous systems. Meat, seafood, and dairy products are rich sources, but it can also be synthesized in the body from cysteine ⁽¹⁾. Vegetarians may have lower plasma levels of taurine due to reduced intake of meats ⁽²⁾. Taurine is marketed as a dietary supplement and is also a major ingredient in many energy drinks.

In vitro and in vivo, taurine demonstrated neuroprotective effects ⁽⁶⁾, reduced diabetic-induced nephropathy ⁽⁷⁾, and improved glycemic control ⁽⁸⁾. In animal models, chronic taurine intake reversed muscle dysfunction and atrophy ⁽³⁾ and decreased oxidative stress ⁽⁴⁾, and maternal taurine ingestion conferred protection against offspring developing adult hypertension ⁽⁵⁾.

In humans, consumption of taurine-rich foods has been associated with lower cardiovascular risk ^(9) (10). Evidence on whether taurine can improve exercise performance are mixed ^{(11) (12) (13) (14)}, and although taurine increased skeletal muscle in rodents, these results have not been duplicated in humans ^(15) (16).

A few studies in overweight or obese patients suggest taurine may reduce triglycerides and improve lipid metabolism ⁽¹⁷⁾, increase adiponectin levels, and decrease inflammation and lipid peroxidation ⁽¹⁸⁾. However, long-term supplementation did not affect insulin response or blood glucose levels in patients with type 2 diabetes ⁽¹⁹⁾. Other studies suggest potential decreases in blood pressure ^{(20) (43) (44)} and benefit in older patients with congestive heart failure ^(21) (22). It may also help manage muscle cramps in patients with chronic liver disease ⁽⁴⁵⁾, improve cognitive function in dementia patients ⁽⁴⁶⁾, and reduce stroke-like episodes in patients with a rare genetic disorder ⁽⁴⁷⁾. Other preliminary data suggest taurine co-administration reduced chemotherapy-induced nausea and vomiting in acute lymphoblastic leukemia ⁽²³⁾, but more studies are needed.

Taurine has been associated with some adverse effects in animal models including increased infection risk ⁽²⁴⁾, delayed learning and memory ⁽²⁵⁾, and when coadministered with ethanol, drastic reductions in blood glucose resulting in death ⁽²⁶⁾. In humans, adverse reactions have been reported from excessive ingestion of energy drinks with taurine and caffeine, and in combination with alcohol ⁽²⁷⁾ .