The dietary composition of pre-fast meals and its effect on 24 hour food and water fasting.

BACKGROUND: Fasting is required by the Jewish and Islamic religions, and may sometimes be necessary for non-religious reasons as well. Very little empiric data are available on the effect of 24 hours of food and water deprivation. OBJECTIVES: To compare the effects of the dietary composition of different pre-fast meals on subjective discomfort and various other parameters of a 24 hour food and water fast. METHODS: Thirteen volunteers of both genders participated in a non-randomized crossover study. Each consumed three different equicaloric pre-fast meals in which the main source of calories was protein (49% of calories), carbohydrate (86%), or fat (69%). Weight, heart rate, blood pressure, blood and urine were tested before and after 24 hours of fasting, and the subjective evaluations of the discomfort during the three fasts were compared. RESULTS: After the protein-rich meal greater discomfort and more side effects were reported. Weight and blood pressure decreased at the end of the fasts that followed each of the three meals; heart rate increased after the high fat and carbohydrate meals but not after the protein meal. The main laboratory findings were a 40% increase in blood urea nitrogen and higher urine osmolarity after the protein-rich meal than after the other meals. CONCLUSION: A protein-poor pre-fast meal is likely to be followed by easier fasting.

Effect of food palatability on early (cephalic) phase of diet-induced thermogenesis in nonobese and obese man.

OBJECTIVE: To study the effect on the early (cephalic) phase of diet-induced thermogenesis (EDT) of palatable vs unpalatable food, in nonobese and obese man. SUBJECTS: Twenty-four nonobese volunteers and 19 obese clinic patients. DESIGN AND MEASUREMENTS: A palatable, liquid formula meal of Ensure (1048 KJ, 450 ml), and of Ensure made unpalatable by addition of aqueous KCl, were sipped on nonconsecutive mornings. O2 consumption (ml/min) was measured before, and starting 30, 60 and 90 min after beginning the test meal, from which EDT was calculated as KJ/min. RESULTS: Palatability of the test meal significantly increased EDT (palatability effect, P = 0.004) but obesity status per se, did not affect EDT. Nevertheless, the effect of palatability on EDT was dependent on obesity status, being seen only in the nonobese. EDT was significantly greater in the nonobese after the palatable than the unpalatable meal: (mean +/- s.e.m.) 2.45 +/- 0.14 vs 1.83 +/- 0.14; P < 0.0001, but not in the obese: 1.93 +/- 0.28 vs 1.73 +/- 0.20; P < 0.21. Therefore only after the palatable meal was EDT less in the obese compared with the nonobese: P < 0.05. The threshold for the unpleasant taste of added KCI was 31% higher in the obese than the nonobese: 4.2 +/- 0.4 vs 3.2 +/- 0.2 [g KCI]; P < 0.025. CONCLUSIONS: The early (cephalic) phase of dietary thermogenesis (EDT) is significantly increased in the nonobese by palatability, but not in the obese, so that only after a palatable meal is EDT less, or 'deficient,' in the obese compared with the nonobese. Also, the obese have a higher threshold for the unpleasant taste of KCI (in Ensure) than the nonobese.

Does religious observance promote health? mortality in secular vs religious kibbutzim in Israel.

OBJECTIVES: This study assessed the association of Jewish religious observance with mortality by comparing religious and secular kibbutzim. These collectives are highly similar in social structure and economic function and are cohesive and supportive communities. METHODS: In a 16-year (1970 through 1985) historical prospective study of mortality in 11 religious and 11 matched secular kibbutzim in Israel, 268 deaths occurred among 3900 men and women 35 years of age and older during 41347 person-years of observation. RESULTS: Mortality was considerably higher in secular kibbutzim. Cox proportional hazards analysis was used to adjust for age and the matched design; rate ratios were 1.67 (95% confidence interval [CI]=1.17, 2.39) for men, 2.67 (95% CI=1.55, 4.60) for women, and 1.93 (95% CI=1.44, 2.59) overall. Kaplan-Meier survival analysis of birth cohorts confirmed the association. The lower mortality in religious kibbutzim was consistent for all major causes of death. CONCLUSIONS: Belonging to a religious collective was associated with a strong protective effect not attributable to confounding by sociodemographic factors. Elucidation of mechanisms mediating this effect may provide etiologic insights and leads for intervention.

Trans-unsaturated fatty acids in margarines and human subcutaneous fat in Israel.

Representative Israeli dietary fats were analysed by capillary gas chromatography, with emphasis on the trans-fatty acid (FA) content. The percentages of trans-monoenes were relatively high: 28.5-30.4 in three hard margarines, 13.4 in both of two soft margarines, but 0 in both of two cooking oils and 27.6 for a sample of commercial cookies. The corresponding percentages of trans-dienes were 0.4-0.5, trace-0.9, 0-0.1 and 0 (one oil sample had 0.6 had 0.6 per cent trans-triene). For cis-polyunsaturated FA the percentages were 26.4-28.7, 39.7-41.6, 60.6 and 18.2 respectively. P/S ratios for the hard margarines were 1.69-2.01, higher than those of American margarines, which are about 1.40. When trans-FA were included with the saturated FA, the ratios were almost equal, 0.52-0.60 versus 0.53, respectively. In the subcutaneous fat of 8 Israelis of various ethnic origins and dietary habits, total trans-FA averaged 4.5 per cent (range 1.9-6.6), similar to that in the US and UK. However, the percentages of polyunsaturated FA in the Israelis were very high, 27.2 (20.3-32.3) for linoleic acid and 1.5 (1.0-1.8) for linolenic acid. The average P/S ratio was also very high, 1.19 (0.80-1.60) and P/(S+trans) was 0.98 (0.67-1.37).

Effect of 24-hour food-and-water deprivation on biochemical variables in blood.

In 38 subjects, 24-h food-and-water deprivation during the Jewish fast day, Tisha b'Av, led to a 2.5-fold increase in plasma free fatty acids and to a doubling of the bilirubin concentration. There were also significant increases in serum sodium, chloride, total proteins, albumin, uric acid, phosphorus and alkaline phosphatase and aspartate aminotransferase activity. Serum glucose and triglycerides decreased in concentration. There were no changes in concentrations of urea, potassium, cholesterol or calcium. The marked increases in free fatty acids might constitute a hazard for those with impaired myocardial function.

Polyunsaturation of subcutaneous fat and concentration of serum lipids of Israeli Beduin Arabs.

In 55 Israeli Beduin Arabs the ratio of polyunsaturated to saturated fatty acids in subcutaneous fat (which reflects the degree of unsaturation of dietary fat) and serum cholesterol and triglyceride concentrations were all significantly lower in men and women leading the typical seminomadic Beduin life than in men doing western-type work and in housewives of a fixed Beduin settlement. The values were 0.76, and 159 and 72 mg/dl, respectively, compared with 0.93, 187 and 108; P less than 0.001, less than 0.01 and less than 0.02, respectively. In the group as a whole there was a paradoxically positive correlation between P/S ratio and cholesterol (r = 0.37, Pr = 0.025) and P/S ratio and triglycerides (r = 0.46, Pr less than 0.01). The expected cholesterol-lowering effect of the polyunsaturated Israeli diet (P/S ratio about 1.0) was apparently swamped by other factors, dietary and/or non-dietary, involved in acculturation to a western life style of Beduin, among whom coronary heart disease has only recently begun to appear.

Influence of physical activity on the thermic effect of food in young men.

Oxygen consumption and heart rate of young fasting men were examined at rest and during 2 h following food intake (400 or 1,200 kcal mixed or 1,200 kcal high-protein diet). In a series of experiments, this procedure was carried out after complete recovery from moderate exercise (10 min at 50% maximal aerobic power) performed immediately after the meal. The calorigenic effect of food was exhibited by all subjects. The magnitude of the postprandial rise in oxygen consumption was related to the caloric content of food, being similar after mixed and protein-rich diets. Moderate exercise after meals augmented dietary thermogenesis.

Bilirubin binding and neonatal acidosis.

Plasma of neonates with severe metabolic acidosis secondary to fetal hypoxia bound less bilirubin than that of neonates without acidosis, as determined by Sephadex gel filtration. There was a significant correlation between the amount of bilirubin adsorbed by Sephadex and the base deficit. The method used ruled out any influence of plasma pH per se on binding. Our results suggest that organic anions that accumulate in the plasma of asphyxiated acidotic neonates may compete with bilirubin for binding sites on albumin.

A polymorphism of the ability to smell urinary metabolites of asparagus.

The urinary excretion of (an) odorous substance(s) after eating asparagus is not an inborn error of metabolism as has been supposed. The detection of the odour constitutes a specific smell hypersensitivity. Those who could smell the odour in their own urine could all smell it in the urine of anyone who had eaten asparagus, whether or not that person was able to smell it himself. Thresholds for detecting the odour appeared to be bimodal in distribution, with 10% of 307 subjects tested able to smell it at high dilutions, suggesting a genetically determined specific hypersensitivity.

Blood viscosity and the overnight fast.

A 12-hour overnight fast in 17 subjects did not result in a significant increase in blood viscosity, as occurs after a 24-hour fast. The usual preoperative fast does not therefore appear to have any adverse rheological effect. However, when it is necessary to prolong the fast, intravenous fluids should be given to prevent the expected increase in blood viscosity which then might have clinical effects as a result of decreased organ perfusion.

Bilirubin binding capacity of albumin isolated from cord-blood serum is less than that from serum of adults.

As estimated by Sephadex gel filtration, the bilirubin binding capacity of albumin isolated from cord-blood serum by ion-exchange chromatography is less than that of albumin isolated from serum of adults. Albumin isolated from cord-blood serum showed increased bilirubin binding as compared with the albumin in the native serum. These findings suggest that the lower bilirubin binding capacity of serum from newborns as compared with serum from adults is a result of both an intrinsic deficiency in binding capacity of neonatal albumin and the presence of substances in neonatal serum that interfere with bilirubin binding.

Effect of a 24-hour food-and-water fast on viscosity of whole blood and plasma.

As a result of abstaining from food and water for 24 h during the midsummer Tishah-b'Ab fast, blood viscosity increased by 16.5% in 27 subjects studied; plasma viscosity increased by 10.3% in nine; hematocrit, by 3.1% in 27; serum total protein, by 6.3% and albumin, by 7.7%, both in 29 subjects. These changes were statistically significant. Plasma fibrinogen did not increase significantly. Fasting-induced changes could impair blood supply to vital organs in patients with vascular insufficiency.

Unsaturated fatty acids in adipose tissue of Israeli Jews.

The ratio of polyunsaturated to saturated fatty acids in the adipose tissue of Israelis was found to be 0.88 for Ashkenazic Jews and 1.13 for non-Ashkenazic Jews, the highest reported for any population on a free-choice diet. Despite the unusually high ratios, indicating a high consumption of polyunsaturated fat, there is nevertheless, a relatively high incidence of ischemic heart disease among Israelis.

Experience with Sephadex gel filtration in assessing the risk of bilirubin encephalopathy in neonatal jaundice.

Clinical experience with Sephadex gel filtration for evaluation of the bilirubin binding affinity of serum in neonatal jaundice is reported. In serum specimens from 362 jaundiced neonates the results of the test were in most cases in good agreement with the independently determined decision to perform exchange transfusion. In all relevant cases of the 24 with bilirubin encephalopathy the Sephadex test was strongly positive. The test was positive at lower bilirubin levels and bilirubin:albumin molar ratios in preterm as compared with term neonates, especially those in poor clinical conditions. Among term infants the test indicated an increase in bilirubin binding affinity after the fifth day of life. The Sephadex test appears to be of practical value in supplementing and refining existing criteria for exchange transfusion.

Characteristics of a photoproduct of bilirubin found in vitro and in vivo, and its effect on the bilirubin binding affinity of serum.

The 430 pigment isolated from bilirubin-albumin solutions illuminated in vitro, decreased the bilirubin binding affinity of serum. This effect was demonstrated for both tightly and loosely bound bilirubin in serum, but in albumin solutions pretreated with charcoal only the binding of loosely bound bilirubin was decreased. This finding is of importance because a similar pigment has been isolated from the body fluids of an infant with Crigler-Najjar syndrome. The production and accumulation of 430 pigment during phototherapy might decrease the binding of bilirubin to albumin in the circulation.