Given the recent focus on taurine and the association between feeding a grain-free diet and the development of dilated cardiomyopathy in dogs, I thought it would be interesting to review a few lesser-known facts about taurine and its role in both normal body function and the treatment of various diseases.
1) In many studies, seafood products have been found to contain the highest concentrations of taurine. Clams, mussels and squid are particularly rich sources, as is the water contained within a can of salmon or tuna. Poultry products, especially turkey and duck, also contain high concentrations of taurine. All fruits, grains, legumes, nuts, seeds and vegetables that have been tested contain no detectable taurine.
However, some plants do contain taurine. Kawasaki et al. (2017) found that the taurine content in seaweed varied according to the species. The authors measured the taurine content of 29 different types of seaweed and found that red algae contained relatively high concentrations of taurine. In contrast, the taurine content was low or undetectable in brown and green algae. McCusker et al. (2014) also found that some red algae species contained a significant amount of taurine; Chondracanthus spp. yielded an average taurine concentration of 6·3 mg/g DM, similar to concentrations reported for some seafood items, and Mazzaella spp. had a similar taurine concentration to that of animal tissue. Both exceeded the AAFCO and FEDIAF feline requirement for taurine for canned foods (0·2, 0·25 % DM, respectively).
As part of the same study, the authors also measured the taurine content of various insect species. With the exception of soldier fly larvae, all insects analysed yielded crude protein, essential amino acid and taurine concentrations in excess of the National Research Council's minimum requirement for dogs and cats. Another reason why insects seem promising as the alternate protein source of the future!
As is the case with many nutrients, research has demonstrated that the taurine content of beef, pork and poultry liver can vary enormously. Different diets, husbandry practices, breeds and environments may significantly affect the taurine content, and liver taurine stores may be depleted before other storage sites in the body, because of conjugation with bile acids. This is another reminder why relying on liver to meet essential nutrient requirements can be a risky strategy.
2) Taurine is suggested to have an important role in brain development. Research by Arnold et al. (2007) provided evidence that the proportion of spiders in the diet of nestling blue tits, Cyanistes caeruleus, varies significantly with the age of chicks, but is unrelated to either the timing of breeding or spider availability. Moreover, this parental prey selection supplies nestlings with high levels of taurine (spiders are particularly rich in taurine), particularly at younger ages.
The authors also compared the behaviours and development of birds fed a taurine-supplemented diet to a control diet and found that juveniles that were fed taurine-rich diets as neonates were larger risk takers and more adept at spatial learning tasks. This is a fascinating example that illustrates how diet in early life can have a long-term effect on behavioural characteristics, which could affect survival by influencing foraging and competitive performance.
3) In 1984, Dietrich Mateschitz co-founded Red Bull GmbH company. He currently holds 49% of the company's shares and as of June 2019, his net worth was estimated to be $19.5 billion USD, making him the 51st richest person in the world.
But does the drink really increase your physical endurance, concentration, reaction speed and emotional wellbeing, as the company claims? While Red Bull is composed of many different ingredients, the two compounds promoted as the key components responsible for Red Bull’s proposed effects are taurine (1000 mg) and glucuronolactone (600 mg). However, Red Bull also contains a hefty amount of caffeine, and because the drink is often consumed quite quickly, it seems likely that this is what's responsible for the energising effect of the drink.
Taurine does play an important role in energy metabolism though. Schaffer et al. (2013) demonstrated that mitochondrial taurine content regulates the biosynthesis of mitochondria encoded proteins, and hence the activity of respiratory chain complexes. Taurine plays a critical role not only in excitation-contraction coupling and organelle structure, but also in the regulation of skeletal muscle energy metabolism during exercise. So while taurine is not likely to be responsible for the immediate "lift" provided by Red Bull, it may still have beneficial effects for some individuals.
4) An important property of taurine is its high water solubility. Most of the taurine contained in meat or seafood will be dissolved into any cooking water, therefore, how a diet is prepared will significantly affect the taurine that remains in the food ingredient, for consumption by the animal.
Raw ingredients have the highest taurine content, followed by pan-frying with juices retained, pan-frying without juices retained, baking and lastly, boiling.
Boiling results in the most taurine loss because the food is surrounded by water, thereby leeching the taurine from the product. Unless all the water is included in the meal, the animal is likely to be consuming much less taurine than predicted. This is important to keep in mind when home-preparing your dog or cat's diet - it's not just the ingredients that matter, but also the method of preparation.
5) We still have a lot to learn about the therapeutic use of taurine for different diseases in dogs and cats, however research in other species is very interesting. In 1995, Trachtman et al. administered streptozotocin to male rats, which subsequently developed a diabetic nephropathy characterised by elevated glomerular filtration rate, glomerular hypertrophy and proteinuria and albuminuria. Administration of taurine (1% in the drinking water) reduced proteinuria by 50%, and dramatically suppressed glomerular hypertrophy and tubulointerstitial fibrosis. The authors attributed the protective effects of taurine to suppression of oxidative stress and advanced glycosylation. It would be interesting to know if taurine supplementation had a similar effect on proteinuria in dogs and cats, particularly given that a low protein diet is a standard nutritional approach to this problem.
As you can see, taurine is a really interesting amino acid, and I'm sure we will learn a lot more about its potential uses in the future. If you would like more information on taurine, or your dog or cat's diet, please contact us: firstname.lastname@example.org
Read the full paper by Spitze et al here: https://www.ncbi.nlm.nih.gov/pubmed/12864905
Read the full paper by McCusker et al here: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4473169/
Read the full paper by Arnold et al here: https://www.ncbi.nlm.nih.gov/pubmed/17698490
Read the full paper by Trachtman et al here: https://www.ncbi.nlm.nih.gov/pubmed/7573492