International cooperative study on the relationship between dietary factors and blood pressure: a preliminary report from the Cardiovascular Diseases and Alimentary Comparison (CARDIAC) Study. The CARDIAC Cooperative Study Research Group

Taurine in morning spot urine for the useful assessment of dietary seafood intake in Japanese children and adolescents

Background

Since our previous report on WHO CARDIAC Study data demonstrated that 24-hour urinary (24U) taurine (Tau) excretion was a useful biomarker of seafood (SF) intake and inversely related to the mortality rates of stroke and coronary heart diseases in the world, we determined that SF is important in the risk reduction of lifestyle related-diseases. The amounts of dietary SF intake are so far estimated from a nutritional survey or 24U Tau excretion.

The sodium/potassium ratio of spot urine (SU) and the 24U ratio were reported to be significantly correlated with. Therefore, we presently examined the relationship of Tau excretion in the morning SU with 24U Tau for simplifying the population comparison and the follow-up of SF intake changes in the process of food education program (FEP).

Methods

After informed consent was obtained, 54 children aged 6-11 years (Children) and 193 adolescents aged 13-18 years (Adolescents) participated in collecting precisely 24U and SU of the first urination on the same day and answered the questionnaire including age and height and weight measurements. The urine samples were measured for creatinine (Cre) and Tau, and the association of these between 24U and SU were analyzed.

Results

The success rates of 24U sampling were very high in Children and Adolescents, 96.4% and 82.4%, respectively. From the result of the multiple regression analysis of SU Tau/Cre and weight we obtained formulas for predicting 24U Tau excretion in Children and Adolescents as follows: Children: 24U Tau = 16.3 (weight) + 314.3 (SU Tau/Cre) -175.2; and Adolescents: 24U Tau = 20.2 (weight) + 644.7 (SU Tau/Cre) - 569.4.

Conclusions

The present study established the regression equation to estimate 24U Tau excretion from SU Tau/Cre and weight. These formulas are expected to contribute to the estimation of fish and SF intake and the follow-up of the change of the dietary behavior by FEP in Children and Adolescents.

Preventive nutritional factors in epidemiology: interaction between sodium and calcium

1. It is generally believed, though difficult to prove, that diet plays a role in the risk of various diseases. Components of difficulties include several issues such as dietary assessment method, regression dilution bias, multicolinearity and interaction among nutrients. 2. The present study focuses on colinearity and interaction between sodium and calcium, which should be cautiously examined in nutritional epidemiological studies in relation to blood pressure and bone mineral density. 3. The World Health Organization's International Cooperative Cardiovascular Diseases and Alimentary Comparison study showed significant multicolinearity among urinary sodium, calcium and urea nitrogen as well as urinary calcium and magnesium. Urinary sodium and calcium had significant correlation (r = 0.438, P < 0.05, n = 48) by cross-centre analysis. 4. Interaction between sodium and calcium on bone mineral density is studied using the data set from bone mineral density screening for 1658 females, aged 20-40 years, in Yokohama, Japan. Among those who have lower calcium intake (< 600 mg/day), higher calcium intake (%) from small fish, which is likely to be associated with a high salt diet, related to significantly lower mineral bone density. 5. Interaction between sodium and calcium on bone mineral density among young Japanese females is suggested. Moderate sodium restriction is needed for prevention of not only cardiovascular diseases but also osteoporosis.

Implication of hypertensive rat models for primordial nutritional prevention of cardiovascular diseases

1. Various substrains maintained during selective sib-mating contributed to the establishment of spontaneously hypertensive rats (SHR) with a variety of clinical features. 2. Stroke-prone SHR (SHRSP), developing haemorrhagic and/or ischaemic stroke spontaneously, are regarded as a model for osteoporosis. 3. The genetic mechanisms of spontaneous hypertension have been attributed pathophysiologically to neural and structural vascular alterations. 4. The mechanisms of stroke are ascribed to the limited regional oxygen and nutrient supplies to the brain areas fed by perforating arteries. 5. The genome-wide linkage analysis on the F2 obtained by crosses of SHRSP with normotensive strains has demonstrated different gene loci contributing to the development and maintenance of hypertension during the ageing process and also genes influencing the susceptibility to stroke without any effect on blood pressure. 6. Experimental studies in SHRSP revealed that stroke could be prevented by protein, Ca- or Mg-supplemented diets, particularly if given in the early stage, indicating the importance of primordial nutritional prevention of cardiovascular diseases (CVD). 7. Experimental findings in SHRSP as well as epidemiological studies on nutrition and CVD indicate the future avenue towards 'predictive-preventive medicine' for CVD.

Chemopreventive effects of taurine on diethylnitrosamine and phenobarbital-induced hepatocarcinogenesis in male F344 rats

Modifying effects of taurine, a naturally occurring organosulfur compound, on diethylnitrosamine (DEN) and phenobarbital (PB)-induced hepatocarcinogenesis were examined in rats. Male F344 rats, 5 weeks old, were divided into 8 groups. Rats of groups 1 through 5 were given i.p. injections of DEN (100 mg/kg body weight) once a week for 3 weeks from one week after the start of the experiment. Of them, animals of group 2 received taurine mixed in a basal diet at a concentration of 2000 ppm for the initial 4 weeks, and those of groups 3 and 5 were given the agent starting 4 weeks after the beginning of the experiment until the end (24 weeks). Rats in groups 1, 4, 7 and 8 were kept on the basal diet throughout the experiment (24 weeks). Group 6 was given taurine throughout the experiment and group 8 was treated as a vehicle control. Animals of groups 1,2, 3 and 7 received PB in drinking water at a dose of 500 ppm from one week after the end of carcinogen or vehicle treatment. Liver neoplasms were recognized only in DEN-treated groups. The incidence and average number of liver neoplasms of group 3 were significantly lower than those of group 1. The number of glutathione S-transferase placental form (GST-P)-positive foci of group 2 or 3 was significantly smaller than that of group 1 (P < 0.01 or P < 0.005). The average and unit areas of GST-P-positive foci in groups 2 and 3 were also significantly smaller than those in group 1 (P < 0.005 and P < 0.0001 and P < 0.0001, respectively). In this study, the level of ornithine decarboxylase activity in non-neoplastic liver tissue was reduced by taurine treatment in both the initiation and postinitiation phases. These results suggest that taurine could be a chemopreventive agent for liver neoplasia.

Effects of oral taurine supplementation on lipids and sympathetic nerve tone

OBJECTIVES

To assess effects of oral taurine supplementation on lipids and sympathetic nerve tone in healthy young men on experimental high fat and cholesterol diets.

METHODS

Twenty-two healthy male volunteers, aged 18-29 years, were recruited for this randomized control trial after informed consent according to the Ethical Committee of Shimane Medical University. Volunteers were randomly allocated into 2 study groups and given experimental diet of identical regimen [total calorie 2500 kcal, cholesterol 1000 mg, polyunsaturated fat/saturated fat (P/S) ratio 0.52, fat 40% of total energy intake (%E), protein 14%E, carbohydrate 46%E] to raise serum cholesterol (CHO) level for 3 weeks. Alcohol intake, smoking and strenuous physical activities were prohibited. Taurine powder (6 g/day) was supplied to one group (T-group, N = 11) and placebo capsules to the other (C-group, N = 11), by a single-blind approach. Blood samples and 24 h urine specimens were obtained once every week. Two men in the C-group dropped out due to upper respiratory infection. There were no difference in age, body mass index (BMI) or blood pressure (BP) between the groups. Statistical analysis was performed by analysis of variance (ANOVA, repeated measurement) and Student's t-test.

RESULTS

There were no changes in BMI and BP in either group during the period. Significant increases in total CHO (25.4 +/- 17.5 mg/dl, mean +/- SD), LDL-CHO (17.1 +/- 14.5) and LDL (43.9 +/- 37.6) were observed in C-group but were attenuated in the T-group. The T-group showed significant increases in VLDL-CHO, VLDL and TG. The T-group had significantly lower urinary norepinephrine excretion than the C-group in the last week.

CONCLUSION

Oral taurine supplementation attenuated increases in T-CHO, LDL-CHO and LDL in healthy men on high fat cholesterol diets but induced significant increases in VLDL-CHO, VLDL and TG, which could be explained by a possible effect of taurine on lipoprotein lipase. Significantly lower urinary norepinephrine excretion observed by the taurine administration implies the suppression of the sympathetic nervous system.

Nutritional improvement, cardiovascular diseases and longevity in Japan

1. Nutritional conditions have improved remarkably for the past 40 years in Japan; major improvements are increases in protein intake (69.7 in 1955 to 79.2g/day per capita in '88), and fat intake (20.3 in '55 to 58.3 g/day per capita in '88), both of which are significantly related statistically to the gradual reduction of stroke mortality (r = -0.74, not significant; r = -0.78, p < 0.05) and to a remarkable extension of average life span (r = 0.91, p < 0.01; r = 0.98, p < 0.001) in the Japanese. 2. Average heights of 12-year old male and female children, correlating significantly with these nutritional improvements, are significantly positively correlated with average life spans (men and women respectively; r = 0.97, p < 0.001). 3. Thus, general nutritional improvements among the Japanese are regarded as the major contributory factor to the recent achievement of top-ranked position for longevity in the world.