Taurine-deficient diets

The functional significance of decreases in plasma taurine is uncertain. As the only known bioch nical f mction of taurine is conjugation with bile acids (Encrantz and Sjovall, 1959)> measurement of taurine pools in liver and bile could be helpful in assessing the potential functional effects of a taurine-deficient diet. Measurement of the cerebral pool of taurine might also be helpful in assessing the availability of taurine for its putative function as a neurotrans-... 

Taurine-deficient diets fed to human infants for 3- weeks (Gaull et al., 1977) and to kittens for 10 weeks (Sturman et al., 1978) have been reported to cause a decrease in plasma taurine concentrations. Because of the limited tissues available for assaying taurine in human infants, it is difficult to determine how accurately plasma taurine concentrations reflect the effect of a taurine-deficient diet on tissue taurine concentrations. In the taurine-deficient kitten, plasma was second to liver only as the most adversely affected taurine pool (sturman et al., 1978). The affect of a relatively short period of a... 

In summary, total parenteral nutrition in the beagle puppy provides a useful tool in which further to examine the consequences of taurine-deficient diets during development. These data suggest that the hepatic taurine pool is the pool most rapidly depleted during taurine deficiency. Hepatic CSAD activity in the beagle is increased in response to a taurine-deficient diet, but this response is not... 

Cats and kittens fed a synthetic diet containing partially-purified casein as the source of protein become taurine deficient and develop retinal degeneration. This degeneration, which eventually results in blindness, can be prevented or reversed by supplementing these diets with taurine but not by supplementation via ostensible taurine precursors, methionine, cysteine or inorganic sulfate (Hayes et al., 1975a,b Schmidt et al., 1976). 

In a beagle pup model of total parenteral nutrition, the liver pool of taurine decreases more rapidly than the plasma pool, whereas the bile taurocholate pool is much slower to reflect taurine deficiency (Malloy et al., in preparation). In short-term experiments in adult man (up to 9 days), the concentration of taurocholate reflected the concentration of taurine available in the liver and the diet rather than that in plasma and muscle, indicating that all taurine pools in man are not in equilibrium (Hardison 1978). 

Cats fed a taurine-free, casein diet develop retinal taurine deficiency and subsequently photoreceptor cell death. (Berson, Hayes, Rabin, Schmidt, and Watson, 1976 Schmidt, Berson and Hayes, 1976 Schmidt, Berson, Watson and Huang, 1977). Supplementation of this diet with methionine, cysteine, inorganic sulfate, vitamin B., or vitamin B plus cysteine did not prevent development of retinal taurine deficiency and retinal malfunction. A synthetic amino acid diet devoid of casein and taurine also resulted in retinal taurine deficiency and retinal malfunction. Only taurine-containing diets (i.e., chow or casein plus taurine) preserved normal retinal taurine concentrations arid electroretinogram (ERG) amplitudes. These findings have firmly established a role for exogenous taurine in maintaining normal retinal function in the cat. 

Some of these protective substances are found in the diet, such as the vitamins, the sulphur-containing amino acid taurine, and methionine which is an important precursor of proteaive thiols. The sulphur amino acids are found especially in foodstuffs containing protein and, in the case of taurine, only in meat and fish. Vegans and vegetarians are therefore deficient in this important substance. 

Stone formation appeared to depend on a deficiency of sulfur-containing amino acids. Increasing the protein content of the diet to 27 % or adding 1 % taurine to the diet increased urinary taurine excretion, increased con-... 

Sturman, Taurine pool sizes in the rat effects of vitamin B-6 deficiency and high taurine diet, J. Nutr., 103 1566 (1973). 

---