PURPOSE OF REVIEW: Taurine, a free amino acid, is found in millimolar concentrations in most mammalian tissues. Mammals are able to synthesize taurine endogenously, but some species such as humans are more dependent on dietary sources of taurine. A growing body of evidence suggests that taurine plays a preponderant role in many physiological processes, which will be summarized in this review. RECENT FINDINGS: Evidence for the requirement of taurine in the human diet has been obtained in many studies involving animal models and a few clinical trials. Recent and past studies suggested that taurine might be a pertinent candidate for use as a nutritional supplement to protect against oxidative stress, neurodegenerative diseases or atherosclerosis. Taurine has demonstrated promising actions in vitro, and as a result clinical trials have begun to investigate its effects on various diseases. SUMMARY: Taurine appears to have multiple functions and plays an important role in many physiological processes, such as osmoregulation, immunomodulation and bile salt formation. Taurine analogues/derivatives have recently been reported to have a marked activity on various disorders. Taken together, these observations actualize the old story of taurine.

Is taurine a functional nutrient

Gut commensal Bacteroides acidifaciens prevents obesity and improves insulin sensitivity in mice

Taurine: a critical nutrient for future fish feeds

To investigate the effect of including seafood and fish oils, as part of an energy-restricted diet, on weight loss in young overweight adults. Randomized controlled trial of energy-restricted diet varying in fish and fish oil content was followed for 8 weeks. Subjects were randomized to one of four groups: (1) control (sunflower oil capsules, no seafood); (2) lean fish (3 × 150 g portions of cod/week); (3) fatty fish (3 × 150 g portions of salmon/week); (4) fish oil (DHA/EPA capsules, no seafood). The macronutrient composition of the diets was similar between the groups and the capsule groups, were single-blinded. A total of 324 men and women aged 20–40 years, BMI 27.5–32.5 kg/m2 from Iceland, Spain and Ireland. Anthropometric data were collected at baseline, midpoint and endpoint. Confounding factors were accounted for, with linear models, for repeated measures with two-way interactions. The most important interactions for weight loss were (diet × energy intake), (gender × diet) and (gender × initial-weight). An average man in the study (95 kg at baseline receiving 1600 kcal/day) was estimated to lose 3.55 kg (95% CI, 3.14–3.97) (1); 4.35 kg (95% CI, 3.94–4.75) (2); 4.50 kg (95% CI, 4.13–4.87) (3) and 4.96 kg (95% CI, 4.53–5.40) on diet (4) in 4 weeks, from baseline to midpoint. The weight-loss from midpoint to endpoint was 0.45 (0.41–0.49) times the observed weight loss from baseline to midpoint. The diets did not differ in their effect on weight loss in women. Changes in measures of body composition were in line with changes in body weight. In young, overweight men, the inclusion of either lean or fatty fish, or fish oil as part of an energy-restricted diet resulted in ∼1 kg more weight loss after 4 weeks, than did a similar diet without seafood or supplement of marine origin. The addition of seafood to a nutritionally balanced energy-restricted diet may boost weight loss.

Randomized trial of weight-loss-diets for young adults varying in fish and fish oil content.

L-Cysteine is a nutritionally semiessential amino acid and is present mainly in the form of L-cystine in the extracellular space. With the help of a transport system, extracellular L-cystine crosses the plasma membrane and is reduced to L-cysteine within cells by thioredoxin and reduced glutathione (GSH). Intracellular L-cysteine plays an important role in cellular homeostasis as a precursor for protein synthesis, and for production of GSH, hydrogen sulfide (H(2)S), and taurine. L-Cysteine-dependent synthesis of GSH has been investigated in many pathological conditions, while the pathway for L-cysteine metabolism to form H(2)S has received little attention with regard to prevention and treatment of disease in humans. The main objective of this review is to highlight the metabolic pathways of L-cysteine catabolism to GSH, H(2)S, and taurine, with special emphasis on therapeutic and nutritional use of L-cysteine to improve the health and well-being of animals and humans.

L-Cysteine metabolism and its nutritional implications.

The relation between blood taurine (2-aminoethanesulfonic acid) concentrations and obesity was investigated. Taurine is supplied to the body by dietary ingestion as well as by de novo synthesis; it is anabolized by cysteine dioxygenase (CDO), which is abundantly expressed in liver and white adipose tissue. Overexpression of CDO in 3T3-L1 preadipocytes caused a decrease in the level of cysteine (precursor of taurine) and an increase in the level of taurine in the culture medium, suggesting that CDO is involved in biosynthesis and secretion of taurine in white adipose tissue. In high-fat diet-induced and/or genetically obese mice, a decrease in the blood taurine concentration was observed along with a decrease in CDO expression in adipose tissue but not in liver. Dietary taurine supplementation prevented high-fat diet-induced obesity with increased resting energy expenditure. Thus, taurine deficiency observed in association with obesity may create a vicious circle promoting obesity. Dietary taurine supplementation interrupts this vicious circle and may prevent obesity.

Taurine (2-Aminoethanesulfonic Acid) Deficiency Creates a Vicious Circle Promoting Obesity

Uncoupling protein 2 (UCP2) is a possible target molecule for energy dissipation. Many dietary fats, including safflower oil and lard, induce obesity in C57BL/6 mice, whereas fish oil does not. Fis...

https://www.physiology.org/doi/pdf/10.1152/ajpendo.00551.2007

Studies of UCP2 transgenic and knockout mice reveal that liver UCP2 is not essential for the antiobesity effects of fish oil.

We examined the effects of fat intake and dietary fish oil on the development of obesity in mice. C57BL/6J mice were assigned to one of five groups. The first group was fed with a high-carbohydrate control diet (10% safflower oil by energy), the second group was fed with a moderate-fat diet (30% safflower oil), and the third group was fed with a high-fat diet (60% safflower oil) for 16 weeks. The other two groups were fed with fish oil instead of safflower oil as a moderate-fat diet (30% fish oil) or a high-fat diet (60% fish oil) for 16 weeks. The mice fed with the 60% by energy safflower oil diet developed marked obesity, hyperinsulinemia and hyperleptinemia, while the mice fed with the 30% safflower oil diet developed slight adiposity in the retroperitoneal adipose tissue compared to the control group. The body fat, blood leptin and insulin levels were lower in the two fish oil groups than in the 60% safflower oil group. No significant differences in blood lipids, body weight and fat were apparent between the 30% and 60% fish oil groups, and both fish oil groups showed lower blood lipid levels than the respective safflower oil groups.These results indicate that the long-term intake of safflower oil might cause slight obesity in mice, even at a 30% by energy fat intake. Replacing all this dietary fat with fish oil effectively inhibited any body fat increase and improved the blood lipid profile in mice.

Kayo Sano

Papers

Taurine (2-Aminoethanesulfonic Acid) Deficiency Creates a Vicious Circle Promoting Obesity

Studies of UCP2 transgenic and knockout mice reveal that liver UCP2 is not essential for the antiobesity effects of fish oil.

Effect of Fat Intake on the Accumulation of Body Fat in Mice Fed with Fish Oil