Taurine is commonly sold as adietary supplement, but there is no good clinical evidence that taurine supplements provide any benefit to human health.[11] Taurine is used as afood additive to meet essential dietary intake levels for cats,[12] and supplemental dietary support for dogs and poultry.[13]
Taurine is widely distributed in nature, particularly in animal tissues.[3][better source needed] Moreover, it is abundant in nature, including in animal organs,[19][better source needed] and further, as substrates in the biosynthesis ofbile salts.[9] Taurine concentrations in human cells may derive from at least three processes:
biosynthesis from the sulfur amino acids (e.g., cysteine);
Taurine occurs naturally in fish and meat.[11][31][15] The mean daily intake from omnivore diets was determined to be around58 mg (range9–372 mg),[32] and to be low or negligible from avegan diet.[11] Typical taurine consumption in theAmerican diet is about123–178 mg per day.[11]
Taurine is partially destroyed by heat in processes such as baking and boiling. This is a concern for cat food, as cats have a dietary requirement for taurine and can easily become deficient. Eitherraw feeding or supplementing taurine can satisfy this requirement.[33][34]
Taurine is present inbreast milk, and has been added to manyinfant formulas as a measure of prudence since the early 1980s. However, this practice has never been rigorously studied, and as such it has yet to be proven to be necessary, or even beneficial.[36]
Taurine is not regarded as anessential human dietary nutrient and has not been assigned recommended intake levels.[8] High-quality clinical studies to determine possible effects of taurine in the body or following dietary supplementation are absent from the literature.[11] Preliminary human studies on the possible effects of taurine supplementation have been inadequate due to low subject numbers, inconsistent designs, and variable doses.[11]
According to theEuropean Food Safety Authority, taurine is "considered to be a skin and eye irritant and skin sensitiser, and to be hazardous if inhaled"; it may be safe to consume up to 6 grams of taurine per day.[13] Other sources indicate that taurine is safe for supplemental intake in normal healthy adults at up to 3 grams per day.[11][38]
A 2008 review found no documented reports of negative or positive health effects associated with the amount of taurine used in energy drinks, concluding, "The amounts ofguarana, taurine, andginseng found in popular energy drinks are far below the amounts expected to deliver either therapeutic benefits or adverse events".[39]
Cats lack the enzymesulfinoalanine decarboxylase to produce taurine and must therefore acquire it from their diet.[12] A taurine deficiency in cats can lead to retinal degeneration and eventually blindness ‒ a condition known ascentral retinal degeneration[40][41] as well as hair loss and tooth decay. Other effects of a diet lacking in this essential amino acid are dilatedcardiomyopathy,[42] and reproductive failure in female cats.[12][43]
Decreased plasma taurine concentration has been demonstrated to be associated withfeline dilated cardiomyopathy. Unlike CRD, the condition is reversible with supplementation.[44]
Taurine is now a requirement of theAssociation of American Feed Control Officials (AAFCO) and any dry or wet food product labeled approved by the AAFCO should have a minimum of 0.1% taurine in dry food and 0.2% in wet food.[45] Studies suggest the amino acid should be supplied at10 mg/kg of bodyweight per day for domestic cats.[46]
A number of other mammals also have a requirement for taurine. While the majority of dogs can synthesize taurine, case reports have described a singularAmerican cocker spaniel, 19Newfoundland dogs, and a family ofgolden retrievers suffering from taurine deficiency treatable with supplementation.Foxes onfur farms also appear to require dietary taurine. Therhesus,cebus andcynomolgus monkeys each require taurine at least in infancy. Thegiant anteater also requires taurine.[47]
Taurine appears to be essential for the development ofpasserine birds. Many passerines seek out taurine-richspiders to feed their young, particularly just after hatching. Researchers compared the behaviours and development of birds fed a taurine-supplemented diet to a control diet and found the juveniles fed taurine-rich diets as neonates were much larger risk takers and more adept at spatial learning tasks. Under natural conditions, eachblue tit nestling receive1 mg of taurine per day from parents.[48]
Taurine can be synthesized by chickens. Supplementation has no effect on chickens raised under adequate lab conditions, but seems to help with growth under stresses such as heat and dense housing.[49]
Species of fish, mostly carnivorous ones, show reduced growth and survival when the fish-based feed in their food is replaced with soy meal or feather meal. Taurine has been identified as the factor responsible for this phenomenon; supplementation of taurine to plant-based fish feed reverses these effects. Future aquaculture is expected to use more of these more environmentally-friendly protein sources, so supplementation would become more important.[50]
The need of taurine in fish is conditional, differing by species and growth stage. Theolive flounder, for example, has lower capacity to synthesize taurine compared to therainbow trout. Juvenile fish are less efficient at taurine biosyntheis due to reducedcysteine sulfinate decarboxylase levels.[51]
^Irving CS, Hammer BE, Danyluk SS, Klein PD (October 1980). "13C nuclear magnetic resonance study of the complexation of calcium by taurine".Journal of Inorganic Biochemistry.13 (2):137–150.doi:10.1016/S0162-0134(00)80117-8.PMID7431022.
^Jacobson SG, Kemp CM, Borruat FX, Chaitin MH, Faulkner DJ (October 1987). "Rhodopsin topography and rod-mediated function in cats with the retinal degeneration of taurine deficiency".Experimental Eye Research.45 (4):481–490.doi:10.1016/S0014-4835(87)80059-3.PMID3428381.
^dos Santos BA, Campagnol PC, Morgano MA, Pollonio MA (January 2014). "Monosodium glutamate, disodium inosinate, disodium guanylate, lysine and taurine improve the sensory quality of fermented cooked sausages with 50% and 75% replacement of NaCl with KCl".Meat Science.96 (1):509–513.doi:10.1016/j.meatsci.2013.08.024.PMID24008059.
^Shao A, Hathcock JN (April 2008). "Risk assessment for the amino acids taurine,L-glutamine andL-arginine".Regulatory Toxicology and Pharmacology.50 (3):376–399.doi:10.1016/j.yrtph.2008.01.004.PMID18325648.the newer method described as the Observed Safe Level (OSL) or Highest Observed Intake (HOI) was utilized. The OSL risk assessments indicate that based on the available published human clinical trial data, the evidence for the absence of adverse effects is strong for taurine at supplemental intakes up to 3 g/day,glutamine at intakes up to 14 g/day andarginine at intakes up to 20 g/day, and these levels are identified as the respective OSLs for normal healthy adults.
^Clauson KA, Shields KM, McQueen CE, Persad N (2008). "Safety issues associated with commercially available energy drinks".Journal of the American Pharmacists Association.48 (3): e55–63, quiz e64–7.doi:10.1331/JAPhA.2008.07055.PMID18595815.S2CID207262028.
^Burger IH, Barnett KC (1982). "The taurine requirement of the adult cat".Journal of Small Animal Practice.23 (9):533–537.doi:10.1111/j.1748-5827.1982.tb02514.x.
^Schaffer SW, Ito T, Azuma J (January 2014). "Clinical significance of taurine".Amino Acids.46 (1):1–5.doi:10.1007/s00726-013-1632-8.PMID24337931. (abstracts of animal citations used to provide list of species)
