Taurine vs Betaine: What's the Difference

Taurine and betaine have similar names, both occur in pre-workout complexes and neither is a “classic” amino acid from which protein is built. That is largely where the similarity ends. The editorial team broke down the chemical nature, physiological roles and evidence base of both substances, and also showed where their metabolic pathways unexpectedly intersect.

Chemical nature and sources

Taurine is 2-aminoethanesulfonic acid. Instead of the carboxyl group characteristic of ordinary amino acids, it has a sulfonic group and therefore is not part of proteins. Taurine is present free in tissues, especially in high concentrations in the heart, skeletal muscle, retina of the eye and brain.

Betaine is trimethylglycine, that is, glycine with three methyl groups attached to its nitrogen atom. It is also not used for protein synthesis. In the body, betaine is formed from choline by oxidation, mainly in the liver and kidneys, and also comes from food.

The dietary sources differ. Taurine is contained mainly in animal products: meat, fish, seafood, dairy products, whereas in plants it is practically absent. Betaine, on the contrary, is rich in plant products: beet (from which the name comes - Lat.Beta vulgaris), spinach, wheat bran and germ, as well as in seafood.

Taurine can be synthesized in the human body from cysteine, but the rate of synthesis is limited, so part of the requirement is provided by food. For infants, taurine is considered conditionally essential, and that is why it is added to infant formula.

Functions of taurine

The classic review by Huxtable (1992) describes taurine as a substance with an extremely broad spectrum of action. One of the best-studied functions is the conjugation of bile acids in the liver: tauro-conjugated bile acids participate in the digestion and absorption of fats.

The second function is osmotic regulation. Taurine is an organic osmolyte, that is, it helps cells maintain volume and stability when the salt concentration in the surrounding environment changes. This is important for cells of the kidneys, brain and muscle.

The third function concerns excitable tissues. In the heart and skeletal muscle, taurine participates in the regulation of calcium metabolism and contractility, and in the nervous system it interacts with receptors of inhibitory neurotransmitters. It is precisely the muscular functions that the sporting interest in taurine is linked to.

Finally, taurine has antioxidant and membrane-stabilizing properties, although on its own it is not a classic “scavenger” of free radicals. A review by Schaffer and Kim (2018) summarizes the results of studies of taurine as a potential therapeutic agent, while emphasizing that much of the data is obtained in animals and cell models.

Functions of betaine

The main metabolic role of betaine is as a methyl group donor. In the liver and kidneys, the enzyme betaine-homocysteine methyltransferase (BHMT) transfers a methyl group from betaine to homocysteine, converting it into methionine. This is one of the two pathways of homocysteine remethylation, alongside the folate- and B12-dependent pathway.

Thanks to this, betaine lowers the level of homocysteine in plasma. A study by Schwab et al. (2002) and other controlled works showed that regular betaine intake lowers homocysteine concentration in healthy people. A review by Craig (2004) describes in detail the role of betaine in human nutrition.

The second function of betaine, like taurine, is as an osmolyte. It accumulates in the cells of the kidneys and other tissues and protects proteins and cell structures from osmotic stress. The sporting hypothesis is that this property may help muscle cells during intense exertion and dehydration.

Interestingly, taurine and betaine are linked through homocysteine metabolism. Homocysteine has two fates: remethylation into methionine (including with the participation of betaine) or transsulfuration to form cysteine, from which taurine can subsequently be synthesized. So both substances are located on different “branches” of the same metabolic node.

What sports research says

For taurine, the most interesting data concern endurance. A meta-analysis by Waldron et al. (2018) concluded that a single intake of taurine may moderately improve endurance measures, and the effect did not clearly depend on the dose within the range used in the studies. The authors emphasized the small number and heterogeneity of the studies.

For betaine, more work concerns strength and speed-strength measures and body composition. A review by Cholewa, Guimarães-Ferreira and Zanchi (2014) describes ambiguous results: in some studies betaine improved work volume or power, in others there was no effect.

In a study by Cholewa et al. (2013), trained men were given 2.5 g of betaine per day over six weeks during a resistance program. The authors reported an improvement in body composition and in the volume of work performed compared with placebo, but the sample was small and the results require replication.

So both substances have a limited and heterogeneous evidence base. Taurine is more often associated with endurance, betaine with strength work and body composition. Neither can be considered a supplement with a reliably proven ergogenic effect at the level of creatine or caffeine.

• Taurine: moderate data on endurance, single intake.
• Betaine: ambiguous data on strength, power and body composition, course intake.
• Both: small studies, need for confirmation.

Safety and medical aspects

Taurine is considered safe in dietary amounts. A risk assessment by Shao and Hathcock (2008) set an observed safe level (OSL) of 3 g per day for supplemental intake. The EFSA panel (2009) concluded that consumption of taurine at levels typical of energy drinks raises no safety concern. At the same time, energy drinks themselves contain caffeine and sugar, which have their own risks.

Betaine in dietary doses is also generally well tolerated. However, in a number of studies with intake of a few grams per day an increase in total cholesterol and LDL cholesterol was observed, so people with lipid metabolism disorders should discuss intake with a doctor.

Anhydrous betaine is a registered medicinal product for the treatment of homocystinuria - a rare hereditary metabolic disorder. In patients with certain forms of this disease, cases of severe elevation of methionine and brain edema have been described during treatment, so in medicine betaine is used under the control of laboratory indicators.

For people who consume several products at once, it is important to count the total amount: taurine is contained in energy drinks and many pre-workout complexes, betaine in a number of pre-workout and “fat-burning” formulas.

Editorial conclusions

Taurine and betaine are two substances that differ in chemistry: a sulfonic amino acid that is not part of proteins, and a trimethylated derivative of glycine. What unites them is their role as osmolytes and their belonging to the common metabolic node of homocysteine.

Taurine is linked primarily to bile acids, calcium regulation and the function of excitable tissues; betaine to the transfer of methyl groups and the lowering of homocysteine.

In sport, both substances have only a limited and heterogeneous evidence base, and safety depends on the dose and the person's state of health.

About who and for what goals each of the substances may suit, read the material “Taurine vs betaine: what to choose and for whom.” We also recommend our reviews “CLA vs L-carnitine: what's the difference” and “Glutamine vs BCAA: what's the difference.”

References

1. Huxtable RJ. Physiological actions of taurine. Physiol Rev. 1992;72(1):101–163.
2. Schaffer SW, Kim HW. Effects and mechanisms of taurine as a therapeutic agent. Biomol Ther (Seoul). 2018;26(3):225–241.
3. Waldron M, Patterson SD, Tallent J, Jeffries O. The effects of an oral taurine dose and supplementation period on endurance exercise performance in humans: a meta-analysis. Sports Med. 2018;48(5):1247–1253.
4. Craig SA. Betaine in human nutrition. Am J Clin Nutr. 2004;80(3):539–549.
5. Cholewa JM, Guimarães-Ferreira L, Zanchi NE. Effects of betaine on performance and body composition: a review of recent findings and potential mechanisms. Amino Acids. 2014;46(8):1785–1793.
6. Cholewa JM, Wyszczelska-Rokiel M, Glowacki R, et al. Effects of betaine on body composition, performance, and homocysteine thiolactone. J Int Soc Sports Nutr. 2013;10(1):39.
7. Schwab U, Törrönen A, Toppinen L, et al. Betaine supplementation decreases plasma homocysteine concentrations but does not affect body weight, body composition, or resting energy expenditure in human subjects. Am J Clin Nutr. 2002;76(5):961–967.
8. Shao A, Hathcock JN. Risk assessment for the amino acids taurine, L-glutamine and L-arginine. Regul Toxicol Pharmacol. 2008;50(3):376–399.