Influence of gender and body composition on hydration and body water spaces.

BACKGROUND & AIMS: Hydration disorders are frequent in clinical practice and can be a life threatening issue in frail patients. Mild dehydration (1-2% loss of body weight) appears to impair cognitive and muscular performance. There is, however, no infallible indicator of correct hydration, and of hydration disorders. This study aim at describing total body water (TBW), extra-cellular water (ECW) and intracellular water (ICW) in a cohort of healthy subjects varying in age, gender and body composition. Two indicators of cellular hydration (TBW over fat free mass, and ICW over fat free mass) were studied. METHODS: The study cohort was made of 944 men and 874 women (mean age 42.7+/-13.1 yrs, BMI 24.3+/-3.5 kg/m(2)). All were volunteers for a preventive health examination. TBW, ECW, ICW were measured with bioelectrical impedance analysis. Body composition was assessed with the 3-compartment model. RESULTS: Values for TBW, ECW, and ICW differed with gender and with BMI categories (lean, overweight, and obese). The ratio of TBW over weight decreased with increasing BMI and was lower in women than in men. ECW (as a proportion of TBW) increased with BMI. The ratio of TBW over fat free mass decreased in obese subjects. The ratio of ICW over fat free mass was normally distributed, and decreased with BMI, more so in women than in men. CONCLUSIONS: This study provides reference values for body water spaces in healthy adults that are negatively correlated with BMI. Women and obese people display indicators of cellular dehydration, and are more at risk of dehydration.

Small bowel absorption of magnesium and calcium sulphate from a natural mineral water in subjects with ileostomy.

BACKGROUND: In many developed countries, magnesium and calcium intakes do not reach recommendations for a large part of the population. Mineral water may be a useful alternative source of dietary minerals, especially in groups of people at risk for developing deficiency due to low intakes. AIM: To assess if the addition of a natural and mineral-rich water increased small bowel mineral absorption in people with ileostomy. METHODS: A controlled randomised crossover study with two periods of two days each and a minimum 5 days of washout was performed in six ileostomy subjects. Apparent mineral absorption from 0.5 L of natural mineral water with either a high or a low mineral content consumed in the fasting state was compared. The daily addition of minerals corresponded to 2.3mmol magnesium, 6.9 mmol calcium and 7.7mmol sulphate. Ileostomy effluents were sampled and analysed for magnesium, calcium and total sulphate. RESULTS: When compared with the control, the median absorbed amount of magnesium increased from 0.8 (0-1.34) mmol/d to 1.2 (0.8-1.9) mmol/d,which corresponded to a 30% increase (P = 0.028). Median amount of calcium absorbed increased from 8.3 (6.7-13.6) mmol/d to 14.8 (8.3-20.4) mmol/d, i. e. a 45% increase (P = 0.027). The sulphate absorption increased from 1.9 (1.3-2.2) mmol/d to 5.1 (4.2-6.8) mmol/d,which corresponded to 197 % increase (P = 0.028). CONCLUSIONS: The mineral-rich water increased absorption of both magnesium and calcium and can therefore be used as an additional source of minerals. However, consumption with meals may be preferred.

Mild dehydration: a risk factor of constipation?

Constipation defined as changes in the frequency, volume, weight, consistency and ease of passage of the stool occurs in any age group. The most important factors known to promote constipation are reduced physical activity and inadequate dietary intake of fibres, carbohydrates and fluids. Fluid losses induced by diarrhoea and febrile illness alter water balance and promote constipation. When children increase their water consumption above their usual intake, no change in stool frequency and consistency was observed. The improvement of constipation by increasing water intake, therefore, may be effective in children only when voluntary fluid consumption is lower-than-normal for the child's age and activity level. In the elderly, low fluid intake, which may be indicative of hypohydration, was a cause of constipation and a significant relationship between liquid deprivation from 2500 to 500 ml per day and constipation was reported. Dehydration is also observed when saline laxatives are used for the treatment of constipation if fluid replacement is not maintained and may affect the efficacy of the treatment. While sulphate in drinking water does not appear to have a significant laxative effect, fluid intake and magnesium sulphate-rich mineral waters were shown to improve constipation in healthy infants. In conclusion, fluid loss and fluid restriction and thus de-or hypohydration increase constipation. It is thus important to maintain euhydration as a prevention of constipation.

Magnesium enrichment and distribution in plants.

Food products enriched with stable isotopes are used in nutrition to study the metabolic fate of nutrients in humans. This study reports on the labeling of green beans, white beans, soybeans and wheat with a stable isotope of magnesium (25Mg) obtained in greenhouse conditions for further studies on magnesium bioavailability. Soybean and green bean are the most efficient plant species to obtain large amounts of edible parts rapidly with a minimum loss of labeled Mg in other parts of the plants. The results obtained showed that a relatively high percentage of the magnesium found in seeds (grains/beans) can come from the redistribution of magnesium previously accumulated in other organs.

Contribution of mineral waters to dietary calcium and magnesium intake in a French adult population.

OBJECTIVE: To assess the contribution of mineral water containing different amounts of calcium and magnesium to the total dietary intakes of these minerals DESIGN: Matched case control study using data issued from the Supplementation en Vitamines et Minéraux Antioxydants (SU.VI.MAX) cohort. SUBJECTS: Subjects were water consumers-240 men and 424 women-divided into the following 4 groups (n=166 per group): regular drinkers of a calcium-rich and magnesium-rich mineral water (calcium, 486 mg/L; magnesium, 84 mg/ L), drinkers of a water classified as a moderately mineralized content (calcium, 202 mg/L; magnesium, 36 mg/L), drinkers of 2 low-mineralized waters (calcium, 9.9 to 67.6 mg/L and magnesium, 1.6 to 2 mg/L, respectively), and drinkers of tap waters. STATISTICAL ANALYSES: Quantitative data were compared using student's t test. Mean comparisons were performed in multivariate analysis by analysis of variance. RESULTS: Dietary calcium intake provided by the various food groups did not differ between the 4 consumer groups, except for calcium provided by mineral water. According to its calcium concentration, mineral water may contribute to one fourth of the total daily calcium intake. Subjects who regularly drink mineral-rich water have a calcium intake that is significantly higher (P< 10(-3)) than those drinking either low-mineral-content water or tap water. Dietary magnesium intake provided by the various food groups did not differ between the 4 consumer groups, except for magnesium provided by mineral water. Depending on the magnesium concentration of the mineral water, it contributed 6% to 17% of total daily magnesium intake. Drinkers of magnesium-rich mineral water and water with a moderate mineral content had magnesium intakes significantly (P< 10(-3)) higher than those of drinkers on low-mineralized or tap water. APPLICATIONS: Mineral-rich water may provide an important supplementary contribution to total calcium and magnesium intake. For dietetics professionals, it may provide-in place of the usual recommendations concerning the consumption of dairy products-a good way to improve calcium and magnesium intakes, particularly in subjects who don't like dairy products.

Effects of dehydration and rehydration on EMG changes during fatiguing contractions.

PURPOSE: This study measured the effects of sauna-induced dehydration (Dhy) and the effectiveness of rapid rehydration on muscle performance and EMG frequency spectrum changes associated with fatigue during isometric contractions. METHODS: Knee extensor muscle strength during isometric maximal voluntary contraction (MVC) and endurance time at 25% and 70% of MVC (ET25 and ET70, respectively) were measured three times in 11 healthy male subjects, under euhydration conditions (Eu), after Dhy, and after rehydration following Dhy (Rhy). RESULTS: Dhy led to a decrease in body weight by 2.95 +/- 0.05%. No significant effect of the hydration status was shown on MVC values. A 23% decrease in ET25 was recorded during Dhy (P < 0.01), whereas ET70 only tended to decrease (-13%, P = 0.06). ET25 was higher during Rhy than Dhy (8%, P < 0.05) but remained lower than during Eu (-17%, P < 0.05). The EMG root mean square (RMS) increased earlier during Dhy than Eu. Opposite changes were shown for the mean power frequency (MPF) of EMG, and Dhy resulted in an accelerated fall in MPF. However, because ET25 decreased with dehydration, RMS and MPF changes were similar during Eu and Dhy when reported to normalized contraction time, exhaustion was thus associated with similar values of RMS and MPF for all conditions. RMS and MPF changes during Rhy showed an intermediate pattern between Eu and Dhy. CONCLUSIONS: Dhy induced an increase in muscle fatigue, associated with early changes in EMG spectral parameters. It is not clear whether these alterations could be attributed to biochemical modifications, and the role of increased perception of effort when subjects were dehydrated should be clarified.

Investigation of mineral waters and soft drinks in relation to dental erosion.

A range of still and sparkling mineral waters were assessed for their erosive potential together with comparator soft drinks using in vitro dissolution assays with extracted human teeth and powdered hydroxyapatite. Dissolution levels with all of the mineral waters were very low and for several still waters were undetectable. Sparkling mineral waters showed slightly greater dissolution than still waters, but levels remained low and were of the order of one hundred times less than the comparator soft drinks. De-gassing of a sparkling mineral water reduced its dissolution, but the total levels were still relatively low suggesting that carbonation of drinks may not be an important factor per se in respect of erosive potential. The complex and heterogeneous mineral compositions of mineral waters could influence the dissolution equilibrium of apatite in enamel and controlled addition of several ions to ultrapure deionized water was investigated. Calcium ions led to the greatest reduction in hydroxyapatite dissolution, but their effects were moderated by other ions including magnesium and sulphate. Thus, mineral waters appear to offer a safe alternative to more erosive acidic beverages and their complex mineral ion compositions may positively influence any dissolution processes at the tooth surface.

Free and total magnesium in lymphocytes of migraine patients - effect of magnesium-rich mineral water intake.

Dietary surveys performed in Western countries show magnesium intakes lower than the recommended dietary allowances, suggesting a large prevalence of magnesium deficiency. Low brain magnesium as well as impaired magnesium metabolism have also been reported in various diseases such as migraine. To detect these deficiencies, a non-invasive and sensitive test assessing magnesium status is needed. Because magnesium is an intracellular cation, either total or ionized magnesium (Mg(2+)) of blood cells were suggested as the most adequate tests. Total magnesium levels in plasma, erythrocytes and lymphocytes and Mg(2+) in lymphocytes were analyzed in a group of 29 migraine patients and 18 control subjects. Results show significantly lower concentrations of total magnesium in erythrocytes (50.7+/-4.7 vs. 53.5+/-2.9 mg/l; P<0.01) and of Mg(2+) in lymphocytes (12.0+/-3.5 vs. 14.2+/-3.8 mg/l; P<0.05) in migraine patients as compared to controls. While a significant difference of mean values was noted between migraine patients and controls, an overlap of individual values was observed. These analyses were repeated on migraine patients before and after a 2-week intake of a mineral water containing 110 mg/l magnesium, and a significant increase in all intracellular magnesium concentrations with no effect on plasma magnesium was observed. These increased intracellular magnesium concentrations demonstrate the bioavailability of magnesium from this mineral water. Among the analyzed parameters, Mg(2+) in lymphocytes appears to be the most sensitive index of magnesium deficiency with a 15% decrease in migraine patients when compared to controls and a 16% increase after 2 weeks of a magnesium-rich mineral water intake.

Mineral water as a source of dietary calcium: acute effects on parathyroid function and bone resorption in young men.

BACKGROUND: Calcium is a major component of mineralized tissues and is required for normal growth and maintenance of bone. Epidemiologic studies showed that a large percentage of the population fails to meet the currently recommended guidelines for optimal calcium intake. OBJECTIVE: The present study was designed to determine whether high-calcium mineral water is an efficient additional source of dietary calcium. DESIGN: Twelve healthy young men (mean +/- SD age: 21.1 +/- 1.2 y) ingested in a randomized order either 0.5 L of a mineral water containing 344 mg Ca/L or 0.5 L of a mineral water with a very low concentration of calcium (<10 mg/L) as a control. Blood samples were drawn before and 1, 2, 3, and 4 h after intake of the water. Urine was collected for 2 h before and every 2 h for 4 h after ingestion of the water. Serum concentrations of intact parathyroid hormone (iPTH) and serum concentrations and urinary excretion of a recently developed biochemical marker of bone resorption, type 1 collagen cross-linked C-telopeptide (CTx), were measured. RESULTS: Serum iPTH was significantly (P < 0.002) lower after ingestion of high-calcium water than after ingestion of the control. There was a significant (P = 0.01) progressive decrease in urinary CTx after ingestion of the high-calcium water, whereas after ingestion of low-calcium water the changes were modest and not significant. The fall in serum CTx concentrations was 34.7% 3 h after ingestion of high-calcium water, compared with 17.6% with the control. The decreases in serum CTx concentrations were significantly (P < 0.05) lower 1, 2, 3, and 4 h after ingestion of high-calcium water than after ingestion of the control. CONCLUSION: The present study showed that one oral intake of water containing a very moderate dose of calcium (172 mg) acutely inhibited iPTH secretion and bone resorption.

Comparison of the effect of medium-chain and long-chain triacylglycerols on calcium absorption in healthy subjects.

BACKGROUND: The absorption efficiency of calcium in humans is low. Some studies in infants have shown that calcium absorption can be increased by adding medium-chain triacylglycerols to the formula diet. OBJECTIVE: The effect of medium- and long-chain triacylglycerols on calcium absorption was studied in 18 healthy, young men. The results were compared with data obtained from calcium ingestion of a protein-carbohydrate formula devoid of triacylglycerols. DESIGN: Calcium absorption was measured by using a double-isotope technique and the kinetic parameters were obtained by using a deconvolution method. RESULTS: The total fractional calcium absorption measured in the presence of medium-chain triacylglycerols (0.236 +/- 0.016) or from a protein-carbohydrate formula without triacylglycerols (0.235 +/- 0.012) was not significantly different. The same result was observed with long-chain triacylglycerols (0.309 +/- 0.026) and the protein-carbohydrate formula (0.275 +/- 0.012). No kinetic parameters were significantly different regardless of the diet (protein-carbohydrate, medium-chain triacylglycerol, or long-chain triacylglycerol). This suggests that the same mechanism for calcium absorption was operative. CONCLUSIONS: Triacylglycerols had no direct effect on calcium absorption from a protein-carbohydrate formula in healthy subjects. These data do not support the use of medium-chain triacylglycerols as adjuvants to increase the absorption of calcium in healthy adults.

Effects of caffeine on energy metabolism, heart rate, and methylxanthine metabolism in lean and obese women.

The magnitude of coffee-induced thermogenesis and the influence of coffee ingestion on substrate oxidation were investigated in 10 lean and 10 obese women, over two 24-h periods in a respiratory chamber. On one occasion the subjects consumed caffeinated coffee and on the other occasion, decaffeinated coffee. The magnitude of thermogenesis was smaller in obese (4.9 +/- 2.0%) than in lean subjects (7.6 +/- 1.3%). The thermogeneic response to caffeine was prolonged during the night in lean women only. The coffee-induced stimulation of energy expenditure was mediated by a concomitant increase in lipid and carbohydrate oxidation. During the next day, in postabsorptive basal conditions, the thermogenic effect of coffee had vanished, but a significant increase in lipid oxidation was observed in both groups. The magnitude of this effect was, however, blunted in obese women (lipid oxidation increased by 29 and 10% in lean and obese women, respectively). Caffeine increased urinary epinephrine excretion. Whereas urinary caffeine excretion was similar in both groups, obese women excreted more theobromine, theophylline, and paraxanthine than lean women. Despite the high levels of urinary methylxanthine excretion, thermogenesis and lipid oxidation were less stimulated in obese than in lean subjects.

Caffeine demethylation measured by breath analysis in experimental liver injury in the rat.

To assess the effects of experimental liver injury on caffeine metabolism, 1 muCi/kg b.w. of [3-methyl 14C]-caffeine (together with 5 mg/kg b.w. of the cold compound) was injected i.p. to four different experimental groups and respective controls of unanesthetized male Sprague-Dawley rats. Exhaled 14CO2 was completely collected during 4 h and peak exhalation rate and fraction of dose recovered were calculated. 1/3 hepatectomy affected 14CO2 exhalation to a limited extent, decreasing solely peak exhalation rate (p < 0.05 compared to sham-operated controls). 2/3 hepatectomy, on the other hand, resulted in significant reduction (p < 0.01) in both peak exhalation rate (by 59%) and fraction of dose recovered (by 47%), that were proportionate to the loss of liver mass (59%). End-to-side portocaval shunt led to the well-documented hepatic "atrophy", liver weight being diminished on average to 50% within 2 weeks of surgery; however, reductions in peak exhalation rate (by 75%) and fraction of dose recovered (by 64%) were even more pronounced. Finally, 48 h bile duct ligation was equivalent to "functional 2/3 hepatectomy", peak exhalation rate (by 65%) and fraction of dose recovered (by 56%) being markedly diminished despite increased liver weight. These results indicate that 14CO2 exhalation curves following administration of specifically labelled caffeine are quantitative indicators of acute or chronic loss of functioning liver mass. In addition, the 3-demethylation pathway appears to be particularly sensitive to the inhibitory effects of cholestasis on microsomal function.

Metabolism and pharmacokinetics of [14C]-deoxyfructosylserotonin creatinine sulfate administered orally and intravenously to rats and mice.

Deoxyfructosylserotonin (DFS) has been shown in in vitro tests to inhibit L-DOPA-oxidase and also to suppress the multiplication of Mycobacterium leprae. The possible therapeutic use of DFS makes necessary the study of its metabolic fate in animal models. Labelled [14C]-DFS was synthesized by condensation of serotonin and [14C]-glucose and administered per os or intravenously to rats and mice. After oral administration, some of the radioactivity transited through the intestinal tract to be excreted in feces (20-60% of the dose) and some was destroyed in the pH conditions of the intestine and further metabolized by the flora, producing 14CO2 in the expired air (10-40% of the dose). Radioactivity excreted in the urine amounted to 8-15% after 24 h. After intravenous administration, 60-90% of the dose had already been excreted in the urine after 8 h. Feces and CO2 accounted for 5-10% each. In the urine, for both routes of administration, beside DFS, half of the radioactivity corresponded to the glucuronide conjugate, while in the feces all the radioactivity found was unchanged DFS. Whole animal body autoradiography showed the presence of radioactivity in all the organs (1-2% of the dose) mainly resulting from the incorporation of labelled carbon from glucose and CO2. These results, obtained in healthy rats, demonstrate poor intestinal absorption of DFS (10% of the dose) and when it is absorbed, rapid urinary excretion. For its possible therapeutic use as an anti-leprosy drug in humans, derivatives with higher bioavailability must be attained.

Effect of acute acidosis and alkalosis on leucine kinetics in man.

The effects of acute pH changes on whole body leucine kinetics (1-13C-leucine infusion technique) were determined in normal subjects. Plasma insulin, glucagon, and growth hormone concentrations were kept constant by somatostatin and replacement infusions of the three hormones. When acidosis was produced by ingestion of NH4Cl (4 mmol kg-1 p.os; n = 8) arterialized pH decreased within 3 h from 7.39 +/- 0.01 to 7.31 +/- 0.01 (P less than 0.001) and leucine plasma appearance increased by 0.13 +/- 0.04 mumol kg-1 min-1 (P less than 0.02); in contrast, when alkalosis was produced by intravenous infusion of 4 mmol kg-1 NaHCO3 (n = 7, pH 7.47 +/- 0.01), leucine plasma appearance decreased by -0.09 +/- 0.04 mumol kg-1 min-1 (P less than 0.01 vs. acidosis). Whole body leucine flux also increased during acidosis compared to alkalosis (P less than 0.05), suggesting an increase in whole body protein breakdown during acidosis. Apparent leucine oxidation increased during acidosis compared to alkalosis (P = 0.05). Net forearm leucine exchange remained unaffected by acute pH changes. Plasma FFA concentrations decreased during acidosis by -107 +/- 67 mumol l-1 (P less than 0.05) and plasma glucose increased by 1.90 +/- 0.25 mmol l-1 (P less than 0.02); in contrast, alkalosis resulted in an increase in plasma FFA by 83 +/- 40 mumol l-1 (P less than 0.02; P less than 0.01 vs. acidosis), suggesting an increase in lipolysis; plasma glucose decreased compared to acidosis (P less than 0.01). The data demonstrate that acute metabolic acidosis and alkalosis, as they occur in clinical conditions, influence protein breakdown, and in the opposite direction, lipolysis.

Metabolic effects in rats of a diet with a moderate level of medium-chain triglycerides.

Energy intake, weight gain, carcass composition, plasma fuels, hepatic metabolites and lipogenic enzyme activities were studied in adult rats fed either a low fat, high carbohydrate (LF) diet or one of two fat-containing diets in which 32% of the metabolizable energy was constituted by long-chain triglycerides (LCT) or medium-chain triglycerides (MCT). Compared with the LF diet, the MCT diet did not depress food and energy intake, weight gain, energy and nitrogen retention or lipid deposition and did not produce ketogenesis. The weight gain of rats fed LCT was 25% higher, and increased lipid deposition was observed. Lower lipogenic enzyme activities were observed in rats fed the LF diet containing 4% corn oil than in rats fed the MCT diet containing 1% corn oil. This effect disappeared when rats previously adapted to the LCT diet were fed LF or MCT diets containing 1% corn oil for 21 d. By d 21, in both groups, hepatic malic enzyme, ATP-citrate lyase, acetyl CoA carboxylase and fatty acid synthase activities were 2.2-, 2.0-, 2.3- and 1.8-fold higher than those of rats fed LCT. Intermediate hepatic glucose-6-phosphate dehydrogenase activities were observed in rats fed the MCT diet, compared with LCT (40% lower) and LF (1.6-fold higher) diets. These data show that in rats fed a diet in which MCT supplies 32% of metabolizable energy, a high activity of lipogenic enzymes is observed, suggesting that MCT had no inhibitory effect on the activity of these enzymes.

Protein metabolism assessed by 1-13C leucine infusions in patients undergoing bone marrow transplantation.

Patients receiving cytoreductive therapy and bone marrow transplantation (BMT) are known to develop marked protein catabolism. To assess the contribution of whole body protein breakdown, amino acid oxidation and incorporation into proteins, plasma leucine kinetics (1-13C-leucine infusion technique) were determined in six patients five times within 14 days before and after cytoreductive therapy (Cyclophosphamide and total body irradiation) and marrow transplantation. Nitrogen balance became negative (-0.20 +/- 0.04 g/Kg/24 hr) after cyclophosphamide (p less than 0.01) and was -0.25 +/- 0.05 g/Kg/24 hr 7 days after BMT in spite of total parenteral nutrition. Plasma leucine concentration increased after BMT by 67% (p less than 0.0015). Leucine plasma appearance was 1.20 +/- 0.15 mumol/kg/min before treatment, it increased slightly and transiently after cyclophosphamide, and increased again from day 5 to day 7 after BMT (p less than 0.01), suggesting increased protein break-down. Leucine oxidation increased from 0.27 +/- 0.07 before therapy to 0.97 +/- 0.16 mumol/kg/min (p less than 0.02) after cyclophosphamide and BMT. Nonoxidative leucine disappearance rate decreased slightly from 0.92 +/- 0.08 to 0.75 +/- 0.16 mumol/kg/min after BMT (ns). Leucine metabolic clearance rate decreased from 11.8 +/- 1.65 before therapy to 6.9 +/- 0.70 ml/kg/min (p less than 0.02) after cytoreductive therapy. After BMT it increased again to 9.9 +/- 1.5 ml/kg/min (p less than 0.02). The results demonstrate that patients undergoing cytoreductive therapy and bone marrow transplantation develop negative nitrogen balance due to increased protein breakdown associated with increased leucine oxidation and increased metabolic clearance rate.(ABSTRACT TRUNCATED AT 250 WORDS)