Taurine: Research on healthspan and supplements

Key takeaways:
~ Increasing taurine levels may be beneficial for healthspan and healthy longevity.
~ Taurine helps mitochondrial energy production, acts as an antioxidant, balances calcium in cells, interacts with bile acids, and is neuroprotective.
~ Your cells can synthesize some taurine, but you also need to get taurine from food. Supplemental taurine may be helpful in aging for some people.

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What is taurine and why is it important?

Taurine is a sulfur-containing amino acid found throughout the body. The liver can make a small amount of taurine by metabolizing cysteine. However, humans get most of their taurine from foods such as beef, shellfish, and poultry dark meat.[ref]

Taurine is used in many ways throughout the body. It supports nerve growth, muscle function, and bile acid production, and it is important for brain function. It is also involved in a number of cellular processes, including regulating minerals and helping with healthy vision.[ref][ref]

Rabbit trail: The name taurine comes from the Latin word, taurus, meaning bull, because the amino acid was first isolated from bulls.

Setting the stage: Taurine and Increased Lifespan

Recently, a longevity study published in Science caught my eye. The researchers discovered that taurine deficiency is a driving factor in aging. The study looked at taurine levels in mice, monkeys and humans and found that levels decline with age. The researchers then used laboratory mice to determine if supplemental taurine could increase lifespan. The results showed that the median lifespan increased by 10 to 12%.[ref]

Healthspan improved: The study showed that taurine supports overall health during aging. Beginning taurine supplementation in midlife “improved functioning of bone, muscle, pancreas, brain, fat, gut, and immune system, indicating an overall increase in health span.”[ref]

This has prompted me to look at the research on taurine: why it may be a linchpin in healthy longevity, as well as how important it is for overall health at any age.

Let’s start with how taurine is synthesized in the body, and then we’ll get into all the clinical studies that use taurine to promote various aspects of wellness.

Taurine Synthesis Pathways:

Taurine is synthesized in cells through the conversion of cysteine. First, cysteine is oxidized to cysteine sulfinic acid. This reaction is catalyzed by the enzyme cysteine dioxygenase (CDO gene). Next, cysteine sulfinic acid (or cysteine sulfinate) is decarboxylated by cysteine sulfinic acid decarboxylase (CSD gene) to form hypotaurine. Finally, hypotaurine is enzymatically oxidized to taurine by hypotaurine dehydrogenase.[ref]

Cysteine is a semi-essential amino acid that is used throughout the body for a variety of purposes. You get cysteine from eating foods that contain protein (meat, dairy, eggs, lentils, seeds, whole grains). It can also be synthesized in cells from serine and homocysteine.[ref]

In addition to being used to make taurine, cysteine can be used to synthesize glutathione, which is an important intracellular antioxidant. Cysteine can also be used as a source of sulfur (hydrogen sulfide) or as a building block for other proteins in a cell.

The pathway that creates cysteine from serine and then eventually taurine is the transsulfuration pathway. Within the methylation cycle, homocysteine is usually recycled back to methionine, but in some circumstances, it can go down the transsulfuration pathway to become cysteine. This pathway begins with the conversion of homocysteine to cystathionine. Cystathionine is then converted to hypotaurine through the sequential action of three enzymes: cystathionine gamma-lyase, cysteine dioxygenase, and cysteine sulfinic acid decarboxylase. Hypotaurine is then oxidized to taurine.

Related article: Homocysteine: Understanding Genetic Connections

As with most essential molecules, there are multiple pathways for the synthesis of taurine.

In addition to the main pathway of synthesis from cysteine, the degradation of coenzyme A to cysteamine can lead to the formation of hypotaurine via another pathway. [ref]

Vitamin B6 is a cofactor in several steps in the pathways that produce taurine. A vitamin B6 deficiency can lead to depleted taurine levels.

Taurine absorption, transport, and uptake:

While taurine can be synthesized in cells (mainly in the liver) from cysteine, most of our taurine comes from the foods we eat.

Taurine must be transported into cells by a taurine-specific transporter, called TauT, which is encoded by the SLC6A6 gene. The same TauT transporter is also used for absorption in the intestines.

To cross the blood-brain barrier, taurine is thought to use the GABA transporter 2 (GAT2). Animal studies also show that the GAT2 transporter is important for moving taurine into liver cells.[ref][ref]

When cells are damaged or there is a need for changes in osmolality, taurine transporters increase, allowing more taurine to enter the cell. Oxidative stress and high blood glucose can also alter the number of transporters available.[ref]

Getting taurine from foods:

Taurine is considered a conditionally essential amino acid in children and adults. Humans (and most mammals) can synthesize some taurine, but we also need to get taurine from our diet.

This is especially important for infants, who can’t synthesize taurine and have to get it from breastmilk or formula. Taurine is essential for brain development by activating GABA receptors to stimulate neuronal growth.[ref]

Foods high in taurine include shellfish, red meat, beef, and seaweed. See the Lifehacks section for more details.[ref]

What does taurine do in the body?

Taurine is used in many different physiological actions including:[ref]

• regulation of plasma glucose levels
• bile acid conjugation
• detoxification
• membrane stabilization
• blood pressure regulation
• osmoregulation
• neurotransmission
• modulation of mitochondrial function
• modulation of cellular calcium levels

Let’s look at these in more detail:

In the mitochondria:

Mitochondria produce the energy needed in a cell through a multi-step process called the electron transport chain. Taurine helps to increase the expression of a subunit of complex I, which is the first step in the electron transport chain. This, in turn, reduces the production of reactive oxygen species (ROS) in the mitochondria. [ref]

In addition, taurine is thought to exert antioxidant activity by promoting the activity of Cu/Zn superoxide dismutase (SOD1), which is a potent intracellular antioxidant. Studies show that taurine increases SOD activity.[ref][ref]

In the brain:

Taurine is abundant in the brain; it is synthesized at higher concentrations in the brain than in the rest of the body.

A basic function of taurine is to act as an osmolyte, maintaining osmotic pressure in cells as ion concentrations fluctuate in the brain. In this way, taurine keeps brain cells from swelling or shrinking and prevents cell death.[ref]

Taurine can also bind to the GABA-A and glycine receptors in a concentration-dependent manner. In animals, moderate concentrations of taurine activate the glycine receptor, while high concentrations act as a weak GABA-A receptor agonist in certain brain regions. Thus, taurine is neuroprotective in the brain.[ref] Similarly, the taurine transporter Taut (SLC6A6 gene) can also transport GABA, but with a low affinity for it.[ref]

Taurine levels decrease in aging, and this may be part of the picture for age-related cognitive problems.

In neurodegenerative diseases, taurine is thought to be helpful by reducing calcium ions and suppressing ER (endoplasmic reticulum) stress. Taurine also improves mitochondrial function in the brain.[ref]

Animal studies show that taurine has an antidepressant effect which is thought to involve improved neuronal survival and growth in the hippocampus.[ref]

In bile acids:

Taurine can be conjugated, or bound, to bile acids. Bile acids secreted by the liver and into the intestines can undergo several different reactions to create what are known as secondary bile acids or bile salts.  When bile acids are conjugated with taurine, they become more water soluble and have increased polarity.

Quick science background: Bile acids are produced in the liver and then transported to the gallbladder where they are stored as bile until needed. Bile is released in response to eating foods containing fat and then emulsifies that fat for absorption by the intestines. Bile acids are a component of bile, that I like to think of as acting like detergent to break down fat from food.

Taurine deficiency in animals results in impaired bile acid synthesis.[ref] When taurine-conjugated bile acids reach the intestine, taurine can interact with bacteria and promote the production of short-chain fatty acids. Animal studies also show that supplemental taurine can affect the gut microbiome in positive ways, especially after antibiotics.[ref]

In the heart:

Taurine also plays an important role in heart health, both in the muscle tissue of the heart and in blood vessels. In the heart, taurine makes up about 60% of the free amino acid pool.[ref]

If cats and dogs don’t get enough taurine in their pet food, they will develop cardiomyopathy. Additionally, when the genes involved in taurine transport are knocked out in mice, it leads to cardiomyopathy. This early research in animals showed that the taurine synthesized in cells is not enough to meet the needs of the heart muscle cells.[ref]

But what about taurine in humans? In the 1980s, clinical trials using supplemental taurine showed benefits for heart failure patients. One way taurine interacts with the heart is by regulating osmosis in the endothelial cells that line the blood vessels. This can directly alter membrane permeability and lead to the relaxation of the blood vessels.  Additionally, taurine can act as an antioxidant when oxidative stress is high. In this way, taurine modulates inflammation, including protection against atherosclerotic plaque formation.[ref]

Taurine may also have benefits for arrhythmias. A case study series showed that taurine plus arginine prevented PVCs (premature ventricular contractions) and reduced premature atrial contractions by 50%.[ref] Animal studies show that taurine could reverse the fibrosis and changes in the heart due to atrial fibrillation.[ref][ref]

Taurine may help in reducing or preventing atherosclerosis. Multiple animal studies show taurine supplementation playing a beneficial role, and epidemiological studies show that high dietary consumption of taurine is associated with low levels of atherosclerosis. For example, studies in Japanese populations that eat abundant seafood, such as scallops, octopus, and white fish, show high levels of taurine and low levels of atherosclerosis and heart disease.[ref][ref]

In the muscles:

Muscle overuse can affect taurine synthesis.  Hard exercise or muscle overuse increases reactive oxygen species (ROS) in muscles. The excess ROS can end up altering the levels of cysteine, the amino acid necessary for taurine synthesis.

Without sufficient cysteine, taurine synthesis is subsequently reduced. Studies show that taurine supplementation during hard workouts may help mitigate oxidative stress.[ref]

Bones and Calcium:

Taurine is also involved in intracellular calcium regulation and bone health.

Taurine is thought to play a role in osteoporosis. Serum homocysteine levels are higher on average in people with osteoporosis, but several clinical trials have shown that lowering homocysteine with folate and B12 does not improve bone mineral density. The other pathway that can affect homocysteine levels is the transsulfuration pathway, which leads to the synthesis of taurine.

Researchers measured taurine levels in osteoporosis patients and found that they were almost twice as low as in age-matched healthy controls. This led the researchers to conclude that low taurine levels in osteoporosis cause a dysregulation of intracellular calcium and a decrease in calcium and vitamin D absorption.[ref]

More research is definitely needed on the role of taurine in osteoporosis, but in the meantime, getting sufficient taurine should be a priority for preventing osteoporosis.

Clinical trials with supplemental taurine:

Supplemental taurine is readily available in capsules or powder form. The following are just a few of the clinical trials on taurine to show some of the benefits or lack of benefits from supplemental taurine for different conditions.

Blood pressure:
Supplemental taurine (1.6 g/day) lowered systolic blood pressure by an average of 7.2 mm Hg and diastolic BP by 4.7 mm Hg after 12 weeks. The researchers found that the taurine increased hydrogen sulfide in the blood vessels, which reduced blood pressure reactivity by inhibiting TRPM3 activation.[ref]

Heart failure:
In a small placebo-controlled clinical trial, taurine at 500 mg/3x/day for 2 weeks significantly improved physical function in heart failure patients.[ref]. Other clinical trials found that taurine (at the same dose) improved exercise capacity and had anti-atherogenic effects in heart failure patients.[ref][ref]

Athletic performance:
In healthy men, taurine supplementation (3g or 6g) before exercise increased lipid oxidation.[ref]

In cyclists, taurine (50 mg/kg) increased their cycling time before exhaustion by 10%. Taurine also improved their ability to perform in the heat.[ref]

In obese women, taurine (3g/day) plus exercise reduced adipocyte size and improved inflammatory markers.[ref]

Anti-aging:
In a placebo-controlled clinical trial, taurine (1.6g/day for 16 weeks) increased antioxidant levels in women in their 60s.[ref]

The animal study I mentioned at the beginning of this article showed the beneficial effects of taurine on healthspan and longevity. The dosage used, starting in middle age, was the equivalent of an 80 kg adult taking 3 – 6 g/day.[ref]

Insulin resistance – maybe:
A clinical trial in men with type 2 diabetes found that 1g of taurine per day did not statistically improve insulin secretion or insulin sensitivity.[ref]. However, taurine (1g/day) combined with dietary changes increased insulin sensitivity more than dietary changes alone.[ref] In addition, taurine conjugated with a bile acid, TUDCA, has been shown to increase liver and muscle insulin sensitivity in a small clinical trial.[ref]

Safety and Side Effects:

As an endogenous amino acid, taurine is relatively safe to supplement with. Talk with your doctor if you have any questions about any supplement, especially if you are on medication or have a chronic illness. As with anything, at really high doses there could be negative effects from taurine.

Dosing:
One study from the 80s showed that 12g/day of taurine helped with acute viral hepatitis.[ref] (Including this to show the safety of a huge dose… not recommending it as a medical intervention.)

The European Food Safety Authority has set taurine safety at 1g/kg/day as the No Observable Adverse Effect Level. [ref]

Genetics and Taurine:

There are a number of genes involved in taurine transport and synthesis. However, there isn’t much research on variants in these genes that cause a significant impact on taurine levels.

This lack of variants is common in essential biochemical pathways, probably because variants would be too detrimental to be compatible with life. The human genome is varied and diverse in areas such as immune response or phenotypic traits, but there tends to be little genetic variation in essential pathways.

Taurine impacts several chronic diseases, and looking at these genetic pathways may give you an idea of whether you are likely to get more out of taurine supplementation. I want to be clear here that there isn’t necessarily direct research on taurine for these variants – instead, the link between taurine and these genes is tangential.

Lifehacks:

Talk with your doctor if you have questions about whether taurine is safe for you. While the safety studies show that it is generally safe, there may be uncommon conditions, such as ALS or cystic fibrosis, when increasing taurine is not a good idea.

Increasing taurine in your diet:

Foods high in taurine include (in order of taurine content per 100g):[ref]

• Scallops (827 mg)
• Mussels (655 mg)
• Squid (356 mg)
• Turkey, dark meat (300 mg)
• Clams (240 mg)
• Chicken, dark meat (199 mg)
• Whitefish (172 mg)
• Veal (46 mg)
• Pork loin (56 mg)
• Lamb, dark meat (44 mg)
• Ham (49 mg)
• Salami (59 mg)
• Tuna (40mg)
• Beef (39 mg)

Adding scallops, dark meat poultry, clams, or whitefish several times a week to your diet could significantly increase your taurine consumption.

Energy drinks, like Monster or Red Bull, contain a lot of taurine. So consider this as part of your daily taurine intake if you regularly drink energy drinks.

Supplement for strict vegetarians? Vegan diets are very low in taurine. One study found that after 4 years, taurine levels were more than 3-fold lower in vegans than in non-vegetarians.[ref]

Choosing a good taurine supplement:

ConsumerLab.com tests supplements to see if they contain what is on the label and to determine if the supplement has heavy metal contamination.

For taurine supplements, ConsumerLab found that the following brands passed their tests: AllMax taurine, Bulk Supplements taurine powder, Now Taurine capsules, Puritan’s Pride Taurine caplets, Solgar Taurine, and Thorne taurine. Bulk Supplements brand was the cheapest per gram.[ref]

Taurine is available in capsules or as a powder. The powder option may be more economical and easier if you want to supplement at higher doses. The taste isn’t bad, and powdered taurine is easy to mix into your smoothie, yogurt, or coffee. Taurine is fairly heat stable, so it should be okay to mix into hot beverages.[ref]

Anti-aging supplement?

Circling back healthspan and longevity study that started me down the path of reading more about taurine… Should everyone supplement with taurine when they get old? I don’t have a solid answer to that, based just on research studies. I would imagine that diet plays a big role in taurine levels, and if you eat a lot of shellfish – especially scallops – you may not need more.

Earlier studies in mice found that taurine depletion in skeletal muscle caused an increase in cellular senescence, which is when cells stop growing and start giving off inflammatory signals.

While cellular senescence is a normal part of the cell cycle, an excess of senescent cells can overwhelm the immune system’s ability to remove the cells. This is a hallmark of aging and is thought to be one cause of many diseases of aging.[ref]

Epidemiological studies tie high taurine levels in traditional Japanese diets to their longevity and healthspan.[ref]

The more recent studies showing healthspan and longevity benefits used supplemental taurine in amounts equivalent to 3-6 grams per day for an average adult.

Online reviews of taurine mention that some people initially experience a strong laxative effect at higher doses.  Clinical trials showed no significant side effects from taurine at 3g/day or 6g/day.[ref][ref]

Vitamin B6:

I mentioned above that B6 is a cofactor in a couple of steps in the pathway that produces taurine, and B6 deficiency can lead to depleted taurine levels in animal studies.[ref] If you are low in vitamin B6, you may find that supplementing with this vitamin helps your taurine levels.

Personal conclusion:

After reading hundreds of articles and studies on taurine, my takeaway is that keeping taurine levels high is an easy way to positively affect several important aspects of aging, such as heart health and bone health. There are many ways to increase taurine, including eating more taurine-rich foods. Supplementing with taurine is also inexpensive and an easy way to make sure you’re getting enough.

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