Taurine is a derivative of the amino acid cysteine that is present in bile and plays several roles in the body. It is synthesized from cysteine in the pancreas and testes. In the brain, taurine is involved in neural cell volume regulation and is released during cell swelling to help protect against excitotoxicity. Under conditions of neural cell damage such as hypoxia or ischemia, taurine release from brain cells is enhanced. The liver plays a key role in regulating cysteine and taurine levels in the body by metabolizing dietary sulfur amino acids and increasing taurine synthesis when cysteine levels rise. Taurine is considered a conditionally semi-essential amino acid in humans and may have

1. Taurine in human
nutrition
Dr. Yousef Elshrek

2. Taurine
• Definition :Taurine is an oxidized sulfur-containing
amine occurring conjugated in the bile, usually as
cholyltaurine (a bile salt, the taurine conjugate of
cholic acid) or chenodeoxycholyltaurine (A bile salt formed in
the liver by conjugation of chenodeoxycholate* with taurine, usually as the
sodium salt. It acts as detergent to solubilize fats in the small intestine and is
itself absorbed. It is used as a cholagogue* and choleretic**); it may also
be a central nervous system neurotransmitter or
neuromodulatora derivative of the amino acid
cysteine.
• It is present in bile in combination with cholic
acid.
• It is used in the synthesis of bile salts.
______________________________________
• *An agent that promotes the flow of bile into the intestine, especially as a result of contraction of the gallbladder.
• **An agent, usually a drug, that stimulates the liver to increase output of bile.

3. • 0r It is a colorless crystalline substance formed by
the hydrolysis of taurocholic acid and found in the
fluids of the muscles and lungs of many animals
• 0r It is an amino acid often found in nerve and
muscle tissues.
• Has been reported as an adjuvant treatment for
congestive heart failure, viral hepatitis, alcoholism,
cataracts, cerebrovascular accidents, diabetes,
gallbladder conditions, high blood pressure,
multiple sclerosis, psoriasis, and seizure disorders.
• No known precautions.
• Also called L-taurine.

4. Taurine structure
• Taurine is a derivative of cysteine, an amino acid which
contains a thiol group.
• Taurine is one of the few known naturally occurring
sulfonic acids.
• In the strict sense, it is not an amino acid, as it lacks a
carboxyl group, but it is often called one, even in
scientific literature
• It does contain a sulfonate group and may be called an
amino sulfonic acid.
• Small polypeptides have been identified which contain
taurine, but to date no aminoacyl tRNA synthetase has
been identified as specifically recognizing taurine and
capable of incorporating it into a tRNA

5. Taurine, or 2-aminoethanesulfonic acid

6. Taurine Biosynthesis
• Within the body, taurine is
synthesized within the
pancreas through a pathway in
which cysteine is oxidized to
create cysteine sulphuric acid.
• Positioned behind the
stomach, the pancreas is a
gland which manufactures
hormones and digestive
enzymes.
• In adult males, taurine is also
produced within the testes
(testicles)

8. Taurine synthesis and physiological roles in mammalian cells

9. Role of taurine in neural cell volume
regulation
• Release of taurine and other amino acids was monitored
from cultured astrocytes and neurons under isomotic and
hyposmotic conditions as well as during exposure of the
cells to 56 mM KCl.
• The release was correlated with swelling, as determined by
the 3-O-methylglucose method.
• It was shown that release of taurine from astrocytes
cultured from cerebral cortex and cerebellum of rats and
mice regardless of the stimulating agent is a consequence of
cell swelling. The release is unrelated to depolarization.
• This conclusion is also valid regarding release of taurine
from cerebellar granule neurons.

10. • Comparison of release of different
amino acids showed that not only .
• On the other hand, glutamine is
not released under these
conditions.
• Studies of uptake of taurine under
isosmotic and hyposmotic
conditions as well as the
dependency of the release on
sodium and temperature strongly
suggest that the release process is
mediated by diffusional forces and
not by a reversal of the high-
affinity carrier.
• It is proposed that taurine may
play an important role as an
osmotically active substance in the
brain involved in cell volume
regulation.
• Taurine but also to some extent
glutamate, aspartate, and glycine are
released during cell swelling
• Nowadays, you will often find taurine
added to creatine or amino acid
preparations in bodybuilding supplements
for a heightened effect. The best time to
consume these combinations might be 30
minutes before training and again
immediately after.

11. Taurine and neural cell damage
• The inhibitory amino acid taurine is an osmoregulator and
neuromodulator, also exerting neuroprotective actions in
neural tissue.
• The involvement of taurine in neuron-damaging conditions,
including hypoxia, hypoglycemia, ischemia, oxidative stress,
and the presence of free radicals, metabolic poisons and an
excess of ammonia.
• The brain concentration of taurine is increased in several
models of ischemic injury in vivo.
• Cell-damaging conditions which perturb the oxidative
metabolism needed for active transport across cell
membranes generally reduce taurine uptake in vitro,
immature brain tissue being more tolerant to the lack of
oxygen.

12. • In ischemia non saturable diffusion increases
considerably.
• Both basal and K+-stimulated release of taurine
in the hippocampus in vitro is markedly
enhanced under cell-damaging conditions,
ischemia, free radicals and metabolic poisons
being the most potent.
• Hypoxia, hypoglycemia, ischemia, free radicals
and oxidative stress also increase the initial
basal release of taurine in cerebellar granule
neurons, while the release is only moderately
enhanced in hypoxia and ischemia in cerebral
cortical astrocytes.

13. • The taurine release induced by ischemia is for the
most part Ca2+-independent , a Ca2+ -dependent
mechanism being discernible only in hippocampal
slices from developing mice.
• Moreover, a considerable portion of hippocampal
taurine release in ischemia is mediated by the
reversal of Na+-dependent transporters.
• The enhanced release in adults may comprise a
swelling-induced component through Cl− channels,
which is not discernible in developing mice.
• Excitotoxic concentrations of glutamate also
potentiate taurine release in mouse hippocampal
slices.

14. • The ability of ionotropic glutamate receptor
agonists to evoke taurine release varies under
different cell-damaging conditions, the N-methyl-
D-aspartate-evoked release being clearly
receptor-mediated in ischemia.
• Neurotoxic ammonia has been shown to provoke
taurine release from different brain
preparations, indicating that the ammonia-
induced release may modify neuronal excitability
in hyperammonic conditions.

15. • Taurine released simultaneously with an
excess of excitatory amino acids in the
hippocampus under ischemic and other
neuron-damaging conditions may constitute
an important protective mechanism against
excitotoxicity, counteracting the harmful
effects which lead to neuronal death.
• The release of taurine may prevent excitation
from reaching neurotoxic levels.

16. Role of the Liver in Regulation of
Body Cysteine and Taurine Levels
• The first-pass metabolism of dietary sulfur amino acids by the
liver and the robust up regulation of hepatic cysteine
dioxygenase activity in response to an increase in dietary
protein or sulfur amino acid level gives the liver a primary role
in the removal of excess cysteine and in the synthesis of
taurine.
• Hepatic taurine synthesis is largely restricted by the low
availability of cysteinesulfinate as substrate for
cysteinesulfinate decarboxylase, and taurine production is
increased when cysteinesulfinate increases in response to an
increase in the hepatic cysteine concentration and the
associated increase in cysteine dioxygenase activity.
• The up regulation of cysteine dioxygenase in the presence of
cysteine is a consequence of diminished ubiquitination of
cysteine dioxygenase and a slower rate of degradation by the
26S proteasome.

17. Taurine and human nutrition
• Taurine (2-aminoethane sulphonic acid), a ubiquitous β-
amino acid not incorporated into proteins but found either
free or in some simple peptides is considered as a
conditionally semi-essential amino acid in man.
• Once thought of as no more than an innocuous end
product of cysteine metabolism, taurine has in recent
years generated much interest due to research findings
indicating a role in numerous physiological processes.
• These roles are varied and include membrane
stabilization, detoxification, antioxidation,
osmoregulation, maintenance of calcium homeostasis,
and stimulation of glycolysis and glycogenesis.

18. • Intracellular and plasma taurine levels are high
and although cellular taurine is tightly regulated,
plasma levels are known to decrease in
response to surgical injury and numerous
pathological conditions including cancer, trauma
and sepsis.
• Decreased plasma concentrations can be
restored with supplementary taurine. Although
the importance of taurine as a physiological
agent with pharmacological properties is now
recognized, the potential advantages of dietary
supplementation with taurine have not as yet
been fully exploited and this is an area which
could prove to be of benefit to the patient.

19. • Because the role of elemental sulfur in human
nutrition has not been studied extensively, it is
the purpose to emphasize the importance of this
element in humans and discuss the therapeutic
applications of sulfur compounds in medicine.
• Sulfur is the sixth most abundant macromineral
in breast milk and the third most abundant
mineral based on percentage of total body
weight
• The sulfur-containing amino acids (SAAs) are
methionine, cysteine, cystine, homocysteine,
homocystine, and taurine.

20. • Dietary SAA analysis and protein supplementation
may be indicated for vegan athletes, children, or
patients with HIV, because of an increased risk for SAA
deficiency in these groups.
• Methylsulfonylmethane (MSM), a volatile component
in the sulfur cycle, is another source of sulfur found in
the human diet.
• Increases in serum sulfate may explain some of the
therapeutic effects of MSM, DMSO, and glucosamine
sulfate. Organic sulfur, as SAAs, can be used to
increase synthesis of S- adenosylmethionine (SAMe),
glutathione
• (GSH), taurine, and N- acetylcysteine (NAC).

21. • MSM may be effective for the treatment of allergy,
pain syndromes, athletic injuries, and bladder
disorders.
• Other sulfur compounds such as SAMe,
dimethylsulfoxide (DMSO), taurine, glucosamine or
chondroitin sulfate, and reduced glutathione may
also have clinical applications in the treatment of a
number of conditions such as depression,
fibromyalgia, arthritis, interstitial cystitis, athletic
injuries, congestive heart failure, diabetes, cancer,
and AIDS.
• The low toxicological profiles of these sulfur
compounds, combined with promising therapeutic
effects, warrant continued human clinical trails

22. Taurine in Pediatric Nutrition
• Taurine was long considered an end product of
the metabolism of the sulfur-containing amino
acids, methionine and cyst(e)ine.
• Its only clearly recognized biochemical role had
been as a substrate in the conjugation of bile
acids. Taurine is found free in millimolar
concentrations in animal tissues, particularly
those that are excitable, rich in membranes, and
generate oxidants.

23. • Various lines of evidence suggest one major
nutritional role as protecting cell membranes by
attenuating toxic substances and/or by acting as
an osmoregulator.
• The totality of evidence suggests that taurine is
nonessential in the rodent, it is an essential
amino acid in the cat, and it is conditionally
essential in man and monkey.
• from the diet of a conditionally essential
nutrient does not produce immediate deficiency
disease but, in the long term, can cause
problems.

24. • Taurine is now added to many infant formulas as
a measure of prudence to provide improved
nourishment with the same margin of safety for
its newly identified physiologic functions as that
found in human milk.
• Such supplementation can be justified by the
finding of improved fat absorption in preterm
infants and in children with cystic fibrosis, as well
as by salutary effects on auditory brainstem-
evoked responses in preterm infants.
• Experimental findings in animal models and in
human cell models provide further justification
for taurine supplementation of infant formulas.

25. Taurine Sources
• Taurine occurs naturally in food,
especially in seafood and meat.
• The mean daily intake from omnivore
diets was determined to be around 58
mg (range from 9 to 372 mg) and to be
low or negligible from a strict vegan diet
• Natural sources of taurine come from a
variety of food items. taurine levels in
vegans

26. • Foods rich in taurine include:
1. eggs
2. fish
3. meat
4. milk
5. seafood
• As foods rich in taurine include meat and fish, levels of
taurine in vegans can be lower than non-vegans who include
meat and fish in their die
• One benefit of taurine is using taurine supplements to raise