Taurine is technically not an amino acid in the classical sense — it’s a sulfonic acid — but it behaves like one and is the second most abundant amino acid in the human body after glutamate. Unlike most amino acids, taurine is not incorporated into proteins. Instead it exists free in tissues, partic

The Most Abundant Amino Acid You’ve Never Heard Of

Taurine is technically not an amino acid in the classical sense — it’s a sulfonic acid — but it behaves like one and is the second most abundant amino acid in the human body after glutamate. Unlike most amino acids, taurine is not incorporated into proteins. Instead it exists free in tissues, particularly the heart, brain, retina, and skeletal muscle, where it serves critical roles in membrane stabilisation, antioxidant defence, and neurological modulation. Vegetarians and vegans are at particular risk of taurine deficiency because plant foods contain virtually no taurine, while meat and fish are rich sources.

Cardiovascular Protection

Taurine’s best-established benefit is cardiovascular protection. It reduces blood pressure by antagonising the renin-angiotensin system and reducing sympathetic nervous system activity. A 2003 human trial found that 3g of taurine daily for 12 weeks reduced systolic blood pressure by 10mmHg and diastolic by 6mmHg in overweight adults. Taurine also reduces homocysteine levels, improves endothelial function, and reduces arterial stiffness — all independent cardiovascular risk factors.

Mitochondrial Function and Exercise Performance

Taurine is highly concentrated in mitochondria, where it regulates the electron transport chain and reduces oxidative damage to mitochondrial DNA. Exercise increases taurine requirements, and athletes supplemented with taurine show improved performance, faster recovery, and reduced muscle damage markers. The mitochondrial protection aspect is particularly relevant for brain health, as neurons are post-mitotic cells with limited regenerative capacity — protecting existing mitochondria is crucial for long-term cognitive function.

Neuroprotection and Stroke

Animal studies show that taurine administration before or immediately after ischaemic stroke dramatically reduces infarct size and improves functional recovery. Human epidemiological data suggests that higher dietary taurine intake is associated with reduced stroke risk. While these findings are preclinical, they are consistent across species and point to taurine as one of the most broadly protective nutritional compounds for neurological function.

Iron’s Role in Brain Energy Metabolism

Iron is essential for brain function far beyond its role in haemoglobin and oxygen transport. The brain consumes approximately 20% of the body’s oxygen despite accounting for only 2% of body weight, and iron is critical in this energy metabolism — particularly in the electron transport chain within mitochondria, where iron-sulfur clusters are essential components of Complexes I, II, and III. Iron is also a cofactor for tyrosine hydroxylase, the rate-limiting enzyme in dopamine synthesis, and for ribonucleotide reductase, the enzyme required for DNA synthesis. These roles mean that iron deficiency — even without frank anaemia — can impair dopaminergic signalling, reduce neural energy production, and compromise myelin formation, with measurable effects on attention, memory, and executive function.

Why Iron Deficiency Is So Common

Iron deficiency is the most common nutritional deficiency worldwide, affecting an estimated 2 billion people. In menstruating women, iron deficiency is particularly prevalent due to monthly menstrual blood loss — even a “normal” menstrual iron loss of 30-40ml per cycle can gradually deplete iron stores over months to years. In men and post-menopausal women, iron deficiency should always be investigated as it can signal occult gastrointestinal blood loss. The symptoms of iron deficiency extend well beyond fatigue and pallor: restless legs syndrome (strongly associated with brain iron deficiency), impaired thermoregulation, reduced exercise tolerance, and cognitive impairment in both children and adults.

Iron Status: Not Just Haemoglobin

The standard diagnostic marker for iron deficiency is haemoglobin — but this misses the majority of iron-deficient people, because haemoglobin only falls after iron stores (ferritin) are already significantly depleted. Ferritin is the storage form of iron, and a level below 30 ng/mL indicates depleted stores, while anything below 15 ng/mL indicates frank deficiency. Optimal ferritin for cognitive function appears to be in the range of 50-100 ng/mL. Iron supplementation should always be guided by ferritin testing, not haemoglobin alone, and excessive iron (from over-supplementation or haemochromatosis) carries its own serious risks including liver cirrhosis and increased infection risk through iron-dependent pathogen growth.

Iron’s Role in Brain Energy Metabolism

Iron is essential for brain function far beyond its role in haemoglobin and oxygen transport. The brain consumes approximately 20% of the body’s oxygen despite accounting for only 2% of body weight, and iron is critical in this energy metabolism — particularly in the electron transport chain within mitochondria, where iron-sulfur clusters are essential components of Complexes I, II, and III. Iron is also a cofactor for tyrosine hydroxylase, the rate-limiting enzyme in dopamine synthesis, and for ribonucleotide reductase, the enzyme required for DNA synthesis. These roles mean that iron deficiency — even without frank anaemia — can impair dopaminergic signalling, reduce neural energy production, and compromise myelin formation, with measurable effects on attention, memory, and executive function.

Why Iron Deficiency Is So Common

Iron deficiency is the most common nutritional deficiency worldwide, affecting an estimated 2 billion people. In menstruating women, iron deficiency is particularly prevalent due to monthly menstrual blood loss — even a “normal” menstrual iron loss of 30-40ml per cycle can gradually deplete iron stores over months to years. In men and post-menopausal women, iron deficiency should always be investigated as it can signal occult gastrointestinal blood loss. The symptoms of iron deficiency extend well beyond fatigue and pallor: restless legs syndrome (strongly associated with brain iron deficiency), impaired thermoregulation, reduced exercise tolerance, and cognitive impairment in both children and adults.

Iron Status: Not Just Haemoglobin

The standard diagnostic marker for iron deficiency is haemoglobin — but this misses the majority of iron-deficient people, because haemoglobin only falls after iron stores (ferritin) are already significantly depleted. Ferritin is the storage form of iron, and a level below 30 ng/mL indicates depleted stores, while anything below 15 ng/mL indicates frank deficiency. Optimal ferritin for cognitive function appears to be in the range of 50-100 ng/mL. Iron supplementation should always be guided by ferritin testing, not haemoglobin alone, and excessive iron (from over-supplementation or haemochromatosis) carries its own serious risks including liver cirrhosis and increased infection risk through iron-dependent pathogen growth.