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It is generally considered that the absorption of Mg is inversely related to the ingested dose. The objective of the present study was to determine if the mode of administration (bolus v. consumption throughout the day) could influence Mg bioavailability from Mg-rich natural mineral water comparing the same nutritional Mg amount (126 mg). Using a 2 d cross-over design, twelve healthy men were asked to drink 1·5 litres Mg-rich mineral water either as 2 × 750 ml or 7 × 212 ml throughout the day. Two stable isotopes ((25)Mg and (26)Mg) were used to label the water in order to distinguish both regimens. Fractional apparent Mg absorption was determined by faecal monitoring and Mg retention was determined by measuring urinary excretion of Mg isotopes. Higher Mg absorption (50·7 (SD 12·7) v. 32·4 (SD 8·1) %; P = 0·0007) and retention (47·5 (SD 12·9) v. 29·0 (SD 7·5) %; P = 0·0008) from Mg-rich mineral water were observed when it was consumed in seven servings compared with larger servings. Thus, regular water consumption throughout the day is an effective way to increase Mg bioavailability from Mg-rich mineral water.

Caffeine, theophylline, theobromine, and paraxanthine administered to animals and humans distribute in all body fluids and cross all biological membranes. They do not accumulate in organs or tissues and are extensively metabolized by the liver, with less than 2% of caffeine administered excreted unchanged in human urine. Dose-independent and dose-dependent pharmacokinetics of caffeine and other dimethylxanthines may be observed and explained by saturation of metabolic pathways and impaired elimination due to the immaturity of hepatic enzyme and liver diseases. While gender and menstrual cycle have little effect on their elimination, decreased clearance is seen in women using oral contraceptives and during pregnancy. Obesity, physical exercise, diseases, and particularly smoking and the interactions of drugs affect their elimination owing to either stimulation or inhibition of CYP1A2. Their metabolic pathways exhibit important quantitative and qualitative differences in animal species and man. Chronic ingestion or restriction of caffeine intake in man has a small effect on their disposition, but dietary constituents, including broccoli and herbal tea, as well as alcohol were shown to modify their plasma pharmacokinetics. Using molar ratios of metabolites in plasma and/or urine, phenotyping of various enzyme activities, such as cytochrome monooxygenases, N-acetylation, 8-hydroxylation, and xanthine oxidase, has become a valuable tool to identify polymorphisms and to understand individual variations and potential associations with health risks in epidemiological surveys.

Quercetin supplementation increases muscle oxidative capacity and endurance in mice, but its ergogenic effect in humans has not been established. Our study investigates the effects of short-duration chronic quercetin supplementation on muscle oxidative capacity; metabolic, perceptual, and neuromuscular determinants of performance in prolonged exercise; and cycling performance in untrained men. Using a double-blind, pretest-posttest control group design, 30 recreationally active, but not endurance-trained, young men were randomly assigned to quercetin and placebo groups. A noninvasive measure of muscle oxidative capacity (phosphocreatine recovery rate using magnetic resonance spectroscopy), peak oxygen uptake (Vo(2peak)), metabolic and perceptual responses to submaximal exercise, work performed on a 10-min maximal-effort cycling test following the submaximal cycling, and voluntary and electrically evoked strength loss following cycling were measured before and after 7-16 days of supplementation with 1 g/day of quercetin in a sports hydration beverage or a placebo beverage. Pretreatment-to-posttreatment changes in phosphocreatine recovery time constant, Vo(2peak,) substrate utilization, and perception of effort during submaximal exercise, total work done during the 10-min maximal effort cycling trial, and voluntary and electrically evoked strength loss were not significantly different (P > 0.05) in the quercetin and placebo groups. Short duration, chronic dietary quercetin supplementation in untrained men does not improve muscle oxidative capacity; metabolic, neuromuscular and perceptual determinants of performance in prolonged exercise; or cycling performance. The null findings indicate that metabolic and physical performance consequences of quercetin supplementation observed in mice should not be generalized to humans.

Aims: In this study, the effects of four single nucleotide polymorphisms (SNPs), -3860G>A, -2467delT, -739T>G and -163C>A, of CYP1A2 gene on lung cancer were evaluated in Tunisian population., Main Methods: Four polymorphisms of CYP1A2 gene were analysed in 109 healthy smokers and in 101 lung cancer cases, including 63 with squamous cell carcinoma (SCC) and 41 with adenocarcinoma (AD). The genotyping for the SNPs -3860 G>A, -2467delT, -739T>G and -163C>A was performed by polymerase chain reaction (PCR)-restriction fragment length polymorphism analysis., Key Findings: The results showed that smokers with CYP1A2 gene polymorphisms were associated with an increased risk for the development of lung AD. There was however no significant increased risk of developing lung SCC in smokers having CYP1A2 gene polymorphisms. An increased risk of developing AD was observed in smokers who are carriers of at least one copy of -3680A or -739G giving a significant odds ratio (OR) of 6.02 (CI=2.91-12.9) and 3.01 (CI=1.54-5.98), respectively., Significance: These genotyping data are consistent with the hypothesis that tobacco-specific-N-nitrosamines (TSN) such as 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) are major contributors to the development of lung AD and that CYP1A2 gene product plays an important role in the metabolic activation of NNK. This study suggests that SNPs of CYP1A2 could be considered as promising biomarkers in the aetiology of lung AD in smokers.

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.

Magnesium (Mg) is the fourth most abundant mineral in the body and the most abundant intracellular divalent cation, with essential roles in many physiological functions. Consequently, the assessment of Mg status is important for the study of diseases associated with chronic deficiency. In spite of intense research activities there is still no simple, rapid, and accurate laboratory test to determine total body Mg status in humans. However, serum Mg < 0.75 mmol/l is a useful measurement for severe deficiency, and for values between 0.75 and 0.85 mmol/l a loading test can identify deficient subjects. The loading test seems to be the gold standard for Mg status, but is unsuitable in patients with disturbed kidney and intestinal functions when administered orally. There is also a need to reach a consensus on a standardized protocol in order to compare results obtained in different clinical units. Other cellular Mg measurements, such as total or ionized Mg, frequently disagree and more research and systematic evaluations are needed. Muscle Mg appears to be a good marker, but biopsies limit its usefulness, as is the case with bone Mg, the most important but heterogeneous Mg compartment. The development of new and non invasive techniques such as nuclear magnetic resonance (NMR) may provide valuable tools for routinely analysing ionized Mg in tissues. With the development of molecular genetics techniques, the recent discovery of Transient Receptor Potential Melastatin channels offers new possibilities for the sensitive and rapid evaluation of Mg status in humans.

Increasing incidence of lung adenocarcinoma (Ad) is observed for the last two decades in all over the world and may become the most frequent lung cancer subtype in the next years. Its increasing prevalence has been well documented in United States for the last two decades. Geographical differences in the increase of Ad prevalence was also reported in Europe where the Squamous Cell Carcinoma (SCC) still predominates but the increase of Ad incidence was shown in the beginning of 1980s. In Tunisia, the incidence of Ad was relatively low in 1990 when compared to western countries and was shown to continue to increase with a more important rise of Ad incidence over SCC type. In this study the time-dependent increased incidence of Ad is reported between USA, Europe and Tunisia. A lag-time period of 10 years is observed between Tunisia and Europe for this increased incidence in smokers and about 20 years between USA and Tunisia. According to the literature, changes in the types of cigarettes smoked as well as modifications in time and geographical trends seem to explain partly the increased incidence of Ad lung cancer.

The present study investigated pharmacokinetic and electroencephalographic responses to caffeine (140 mg) in two groups of healthy volunteers reporting, or not, caffeine-related sleep disturbances. Significant differences in caffeine consumption and smoking habits were observed between the two groups. Plasma samples were taken from each subject before (T0) and after caffeine intake at 0.5, 1, 2, 4, 6 and 24 h. Three pharmacokinetic parameters: half-life (t1/2), maximum time (Tmax) and maximum plasma concentration (Cmax) were calculated from caffeine plasma concentration measurements determined by reversed phase HPLC analysis. Caffeine-sensitive subjects showed significantly greater half-life values when calculated on 24 h after the administration than tolerant subjects (p<0.05). Since the elimination kinetics were similar on the first 6 h after caffeine administration, the increased caffeine clearance observed overnight, when smoking was resumed in the control group, may indicate a short delay for the induction of hepatic cytochrome, reported here for the first time. Electrophysiological responses to caffeine, including vigilance and cortical activity, were assessed by ambulatory electroencephalographic (EEG) recorded during a period of 6 h before and after caffeine consumption. Following caffeine intake, the caffeine-intolerant subjects presented an increase in vigilance levels with faster peak alpha, beta frequency and lower delta and theta power when compared to tolerant subjects. Pharmacokinetic parameters and EEG data showed significant differences between sleep-sensitive and control subjects. These variations may be, in part, explained by cigarette smoking and the higher caffeine intake observed in the subjects of the control groups while caffeine sleep-sensitive subjects have a significantly lower caffeine intake, as already reported in previous studies on patients with sleep disturbances.

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.

Whether mental performance is affected by slowly progressive moderate dehydration induced by water deprivation has not been examined previously. Therefore, objective and subjective cognitive-motor function was examined in 16 volunteers (8 females, 8 males, mean age: 26 yr) twice, once after 24 h of water deprivation and once during normal water intake (randomized cross-over design; 7-day interval). Water deprivation resulted in a 2.6% decrease in body weight. Neither cognitive-motor function estimated by a paced auditory serial addition task, an adaptive 5-choice reaction time test, a manual tracking test, and a Stroop word-color conflict test nor neurophysiological function assessed by auditory event-related potentials P300 (oddball paradigm) differed (P > 0.1) between the water deprivation and the control study. However, subjective ratings of mental performance changed significantly toward increased tiredness (+1.0 points) and reduced alertness (-0.9 points on a 5-point scale; both: P < 0.05), and higher levels of perceived effort (+27 mm) and concentration (+28 mm on a 100-mm scale; both: P < 0.05) necessary for test accomplishment during dehydration. Several reaction time-based responses revealed significant interactions between gender and dehydration, with prolonged reaction time in women but shortened in men after water deprivation (Stroop word-color conflict test, reaction time in women: +26 ms, in men: -36 ms, P < 0.01; paced auditory serial addition task, reaction time in women +58 ms, in men -31 ms, P = 0.05). In conclusion, cognitive-motor function is preserved during water deprivation in young humans up to a moderate dehydration level of 2.6% of body weight. Sexual dimorphism for reaction time-based performance is present. Increased subjective task-related effort suggests that healthy volunteers exhibit cognitive compensating mechanisms for increased tiredness and reduced alertness during slowly progressive moderate dehydration.

Background: Several previous epidemiological studies have shown a relation between drinking water quality and death in cardiovascular disease whereas others have not found such a relationship. An intervention study was undertaken to evaluate the effect of water with added magnesium and natural mineral water on blood pressure., Methods: A group of 70 subjects with borderline hypertension was recruited and consumed 1) a water low in minerals, 2) magnesium enriched water or 3) natural mineral water, in a random, double blind fashion during four weeks., Results: Among persons with an initial low excretion of magnesium or calcium in the urine, the urinary excretion of magnesium was increased in the groups consuming the two waters containing magnesium after 4 weeks. A significant decrease in blood pressure was found in the group consuming mineral water at 2 and 4 weeks., Conclusion: The results suggest that minerals taken in water are significant for the body burden and that an intake of mineral water among persons with a low urinary excretion of magnesium or calcium may decrease the blood pressure. Further studies should investigate the extent of mineral deficiency in different populations and the efficiency of different vehicles for supplying minerals, particularly magnesium and calcium.

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.

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.

The aim of this study was to build a compartmental model of magnesium (Mg) kinetics by using data collected from six healthy adult men after oral administration of 26Mg and intravenous administration of 25Mg. Blood, urine, and feces were collected for 12 days after administration of the isotopes. Isotopic ratios were determined by inductively coupled plasma-mass spectrometry. Data were analyzed for each subject using SAAMII. We began with a compartmental model previously proposed (Avioli LV and Berman M. J Appl Physiol 21: 1688-1694, 1966) and developed an alternative approach to resolve the discrepancy between model-predicted curves and experimental data. This analysis enables the exploration of 25% of total body Mg that exchanges rapidly from plasma compartment with two extraplasma pools. One of the extraplasma compartments contains 80% of the exchangeable Mg with a transport rate of 48 +/- 13 mg/h. The second exchanges 179 +/- 88 mg of Mg/h. The model permitted estimation of kinetic parameters as well as fractional Mg absorption and fecal endogenous excretion.

Background: The double-labeling (DL) method for determining magnesium absorption is less cumbersome than is the fecal monitoring method, which has been used most often, but it has not been validated., Objective: The aim of this study was to compare methods and several sampling protocols for determining magnesium absorption to establish a simple and reliable alternative to the fecal monitoring approach. Fecal monitoring was used as the standard against which the DL methods based on urine data (DLU), plasma data (DLP), and plasma kinetics with the use of a deconvolution analysis (DP) were compared., Design: Six healthy adult men received 70 mg (26)Mg orally and 30 mg (25)Mg intravenously. Multiple blood samples and complete urine and fecal samples were collected over 12 d. Stable-isotope ratios were determined by inductively coupled plasma mass spectrometry., Results: Results from DLU were not significantly different from the fecal monitoring reference value (0.48 +/- 0.05; +/- SD) when based on 3-d urine pools from 72 to 144 h (0.54 +/- 0.04) and when based on the 24-h urine pools from 48 to 72 h (0.49 +/- 0.06), 72 to 96 h (0.51 +/- 0.11), and 96 to 120 h (0.50 +/- 0.06). Results with the DLP method 72 h after isotope administration also compared well with those with the fecal monitoring method (0.54 +/- 0.09). Magnesium absorption was 0.47 +/- 0.06 with the DP method, which also agreed with the fecal monitoring value., Conclusions: The DL methods are an alternative to fecal monitoring when applied within the appropriate time intervals. Therefore, DLU-the simplest and least invasive approach-is recommended for determining magnesium absorption.

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.

Background: Magnesium intakes in many industrialized countries are below recommended daily allowances. Magnesium-rich mineral water may contribute to coverage of magnesium requirements by providing significant amounts of natural, energy-free, bioavailable magnesium., Objective: The objectives were to determine magnesium bioavailability from magnesium-rich (110 mg/L) mineral water in healthy subjects when consumed alone and to evaluate the effect of simultaneous meal consumption., Design: Magnesium bioavailability was measured in 10 healthy women with the use of a crossover design. Stable magnesium isotopes ((25)Mg and (26)Mg) were administered orally with mineral water, which was consumed with or without a meal. Apparent magnesium absorption was determined by fecal monitoring, and magnesium retention was determined from urinary excretion of magnesium isotopes., Results: The mean (+/-SD) magnesium absorption from mineral water consumed alone was 45.7 +/- 4.6% (range: 40.2-55.5%) and was significantly greater (P = 0.0001) when it was consumed with a meal (52.3 +/- 3.9%; 46.2-60.2%), a relative difference of 14.4%. Magnesium retention also was significantly greater (P = 0.0004) when mineral water was consumed with a meal (41.5 +/- 4.2%; 35.2-50.6%) than when consumed alone (37.4 +/- 4.0%; 33.1-47.0%), a relative difference of 11.0%., Conclusions: In healthy young women, approximately 50% of the magnesium from magnesium-rich mineral water was absorbed when consumed alone. Magnesium bioavailability from mineral water is enhanced when the water is consumed with a meal, perhaps because of a slower gastrointestinal transit time, the presence of digestion products from the meal, or both. Regular consumption of magnesium-rich mineral water could make a valuable contribution to magnesium requirements.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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)

Two groups of six male Sprague-Dawley hypophysectomized rats (operated on day 0), 8 weeks old, treated by sc tetracosactid (ACTH, 10 micrograms every 24 hr), thyroxine (5 micrograms/100 g every 24 hr) and desmopressin (240 ng/kg/24 hr continuous infusion) received SC either saline (group I) or human growth hormone (hGH, 120 micrograms/24 hr) (group II) continuous infusion. ACTH and thyroxine were administered on days 7-19 and desmopressin and hGH on days 8-19, after surgery. They received po caffeine 4 mg/kg as citrate salt on day 15. The 0-12, 12-24 and 24-48 hr urine samples were collected after caffeine administration. Caffeine and metabolites concentrations in urines were determined using HPLC. Effect on hGH on caffeine metabolism was assessed comparing group I and group II. In 0-48-hr urine, 1-methylxanthine (154 +/- 169 pmol/g) and 3-7-dimethyluric acid (5.57 +/- 19.3 pmol/g) in group II were significantly lower than in group I (391 +/- 340 pmol/g and 262 +/- 338 nmol/g, respectively) (p less than 0.05). Other metabolites (6-amino-5-(N-methyl formylamino)-1,3-dimethyluracil included) excretion was not altered. Total, N3-, N7- and N1-demethylation ratios on 0-48 hr urine were not modified by hGH treatment. However, demethylation ratios on 12-24 and 24-48 hr (N3 + N7 + N1) and on 24-48 hr urine samples (N3 and N7) were significantly reduced in group II (p less than 0.05) suggesting an increase in the rate of appearance of demethylated metabolites during hGH treatment.(ABSTRACT TRUNCATED AT 250 WORDS)

The metabolism of maltitol (4-alpha-D-glucosylsorbitol) was assessed in fasting conventional (C) rats, C mice and germ-free (GF) mice, using [U-14C]maltitol. The radiorespirometric patterns of 14CO2 collected for 48 h after the administration of labelled maltitol were characterized by a constant rate of 14CO2 production lasting 4 h for both C rats and mice. The pattern for the GF mice showed a peak at the second hour followed immediately by a slow decrease. The percentage recovery of 14CO2 was significantly lower for the GF mice (59%) compared with C animals (72-74%). Urine, faeces and intestinal contents after 48 h totalled 19% of the administered radioactivity in the C rats and mice and 39% in the GF mice. The digestibility of maltitol and the absorption of sorbitol in GF mice was also assessed. The caecum and small intestine of GF mice, 3 h after administration of equimolar quantities of maltitol (140 mg/kg body-weight) or sorbitol (70 mg/kg body-weight), contained 39 and 51% of the ingested dose respectively, present mostly in the caecum as sorbitol. The alpha-glucosidase (maltase) (EC3.2.1.20) activity of the small intestine was appreciably higher (1.5-1.7 times) in the GF mice than in the C mice. These results suggest that the enzymic activities in the small intestine of mice and rats are sufficient to hydrolyse maltitol extensively. Consequently, the slow absorption of sorbitol seems to be an important factor limiting the overall assimilation of maltitol in the small intestine.

Adding ammonium ferric hexacyanoferrate (AFCF) to cows' fodder produced after the Chernobyl nuclear accident prevented milk contamination by increasing the faecal elimination of 137Cs. Synthesis of ammonium ferric hexa[14C]-cyanoferrate (AF14CF) and its purification were performed for the study of the metabolic fate of this complex, and the evaluation of the possible release of cyanide. The stability of this colloidal product, tested by anaerobic incubation in rumen juice in vitro, showed no release of free cyanide from AF14CF, but hexacyanoferrate was identified in the rumen juice and 0.13% of the added radioactivity was converted to labelled CO2. AF14CF administered per os to two cows showed a nearly quantitative excretion of radioactivity in faeces during the first 3 d (91-95%). A very low but significant level of radioactivity appeared in plasma, blood cells, expired CO2 and was detected in organs taken 9 d after administration. Total cumulative radioactivity in urine and milk amounted to 0.19-0.47% and 0.068-0.071% respectively for the two cows. Labelled hexacyanoferrate and thiocyanate were identified in the urine and also in faeces. In spite of this relative instability of AFCF in the rumen of cows, the poor absorption of AF14CF degradation products showed that AFCF constitutes an efficient and safe food additive to prevent the absorption of radioactive caesium from ruminant feed and its secretion in milk.

Theobromine disposition was measured twice in 12 normal men, once after 14 days of abstention from all methylxanthines and once after 1 week of theobromine (6 mg/kg/day) in the form of dark chocolate. Mean theobromine t 1/2, apparent volume of distribution, and clearance after abstinence from all methylxanthines were 10.0 hours, 0.76 L/kg, and 0.88 ml/min/kg. High daily doses of chocolate for 1 week did not change these values. After subjects abstained from methylxanthines, urinary radioactivity over 72 hours after a single, oral dose of [8-14C]theobromine consisted of 42% 7-methylxanthine, 20% 3-methylxanthine, 18% theobromine, 10% 7-methyluric acid, and 10% 6-amino-5[N-methylformylamino]-1-methyluracil. A week of daily theobromine consumption in the form of dark chocolate also did not alter this urinary profile of theobromine and its metabolites. Although these results might appear to differ from other reports of inhibition of theobromine elimination after five consecutive daily doses of theobromine in aqueous suspensions, both the rate and extent of absorption of theobromine in chocolate were less than that of theobromine in solution. Relative bioavailability of theobromine in chocolate was 80% that of theobromine in solution. This reinforces the fundamental principle that both the metabolic and the therapeutic consequences of a particular chemical can differ when that chemical is given in the pure compared with the dietary form.

To examine the rates of whole body protein synthesis and energy expenditure during the rapid growing period, premature infants of very low birth weight (VLBW) (less than 1500 g), appropriate for gestational age were kept under standard thermoneutrality conditions and received a formula diet providing 110 kcal/kg.d metabolisable energy (ME) and 3.3 g protein/kg.d. Their energy expenditure was measured by open circuit indirect calorimetry. Nitrogen turnover and whole body protein synthesis and catabolism were determined using repeated oral administration of 15N-glycine for 60-72 h followed by the analysis of 15N-enrichment in urinary urea. These VLBW infants grew at an average rate of 15 g/kg.d. About half of the ME intake (i.e. 50 kcal/kg.d) was invested in weight gain while the remainder (i.e. 60 kcal/kg.d) was oxidised. The energy equivalent of the weight gain (i.e. the amount of energy stored per g weight gain) and the N balance indicated that lean tissue made up approximately 2/3 of the weight gained and fat tissue the remaining 1/3. The plateau value for 15N enrichment reached on the third day of administration allowed us to calculate a rate of protein synthesis of 14 g/kg.d and protein breakdown of 12 g/kg.d in five VLBW fed a formula diet. The elevated energy expenditure of the very low birth weight infant seems to be related to its rapid rate of weight gain which is accompanied by a high rate of body protein synthesis. More than 20% of the total energy expenditure of the VLBW infants was accounted for by whole body protein synthesis.

The effects of liver disease on caffeine plasma clearance (Cl) and on exhalation of 14CO2 following i.v. injection of 2 mu Ci of [3-methyl-14C]caffeine together with 125 mg of the unlabeled compound were measured in 15 patients with cirrhosis, 11 subjects with miscellaneous liver disease, and 10 normal volunteers. Compared to mean values for Cl (2.02 +/- S.D. 0.68 ml per min per kg) and t1/2 (3.8 +/- 0.9 hr) in normal volunteers, cirrhotics were characterized by highly significant reductions in Cl (to 0.76 +/- 0.40) and prolongation in t1/2 (to 13.7 +/- 13.0), whereas the volume of distribution (VD) remained relatively unchanged (0.57 +/- 0.16 vs. 0.64 +/- 0.13 liter per kg in normals). Cumulative 14CO2 production and specific activity of 14CO2 in breath decreased in parallel (r = 0.83) with Cl. Patients with miscellaneous liver disease exhibited only small changes in Cl and t1/2; however, 14CO2 parameters in breath appeared more sensitive in indicating the slight functional derangement. In view of the correlation (Rs = 0.83) of cumulative 14CO2 excretion with the initial disappearance constant for bromosulfophthalein, the caffeine breath test may be considered as a quantitative measure of hepatic microsomal activity; based on a surprisingly close, hyperbolic relationship between Cl and fasting caffeine plasma concentrations, the latter might serve as a simple guide to severity of liver disease.

This study investigated the possibility of preventing prednisone-induced protein wasting by regular physical activity. Eight healthy untrained volunteers took prednisone (30 mg/d for nine days), once after a 4-week exercise program that consisted of jogging 2.5 miles four times a week, and once without exercise. Whole body protein turnover was measured from the 15N enrichment plateau of urinary ammonia during ingestion of 15N glycine at hourly intervals. Whole-body protein synthesis and breakdown were derived from nitrogen flux, nitrogen intake, and urinary nitrogen elimination. Muscle myofibrillar protein breakdown was explored by measuring urinary 3-methylhistidine excretion. Bone protein metabolism was studied by measuring serum bone GLA protein (BGP), a specific marker of bone protein synthesis, and urinary elimination of hydroxyproline, an index of bone resorption. Whole-body protein turnover was significantly increased by exercise and prednisone (+19% and +17%, respectively); this effect was related to increased protein synthesis during exercise training (+27%, P less than .01) and to increased protein breakdown during prednisone administration without exercise (+21%, P less than .05). In contrast, values of protein turnover, synthesis, and breakdown were not different from control when the subjects took prednisone after training. Urinary excretion of 3-methylhistidine was decreased (-15%, P less than .05) at the end of the prednisone administration period but was identical to the control value when the subjects took prednisone in association with exercise. In contrast, serum BGP was significantly decreased by prednisone, with or without exercise (-35%, P less than .001). These data suggest that moderate exercise training can prevent, at least in part, the protein loss induced by prednisone.(ABSTRACT TRUNCATED AT 250 WORDS)

5-Hydroxymethyl-2-furaldehyde (HMF), is a major product of sugar degradation found in food and solutions used in parenteral nutrition. Labeled [14C]HMF was synthesized by dehydration of [14C]fructose on ion-exchange resin and administered per os (po) and intravenously (iv) to rats. Metabolic balance of radioactivity demonstrated that HMF or its metabolites are rapidly eliminated in the urine with a recovery of 95-100% after 24 h. Literature reported, in some cases, 50% retention in the body. HMF was completely converted to two metabolites, which have been identified by nuclear magnetic resonance (NMR) and mass spectroscopy (MS) as 5-hydroxymethyl-2-furoic acid and N-(5-hydroxymethyl-2-furoyl)glycine. Administration of high doses of HMF showed a similar rapid elimination, but a proportional reduction of the amount of the glycine conjugate produced. Whole-animal-body autoradiography confirm that shortly after administration radioactive material was present in the liver but was mostly in the kidney and the bladder. The only significant difference between po and iv administration was the presence of a higher level of radioactive material in the brain of iv-treated rats.

L-[U-14C]-sorbose was administered orally as single doses to 5 normal rats. The recovery of radioactivity was 5.3% in the urine, 46% in the faeces exclusively as L-sorbose 16% as carbon dioxide. Caloric utilization was approximately 25%. A second group of 3 rats that had previously received L-sorbose in their diet showed 14C recoveries of 8.9% in the urine, 6.6% in the faeces and 59% as carbon dioxide. The time course of expired carbon dioxide suggests that a portion of L-sorbose was rapidly absorbed and partially metabolized while the principal pathway involved fermentation by the intestinal microflora to volatile fatty acids which were subsequently absorbed and metabolized. The total caloric utilization of L-sorbose was estimated to be 70%. It was observed that a human intestinal microflora also required an adaptation period in order to ferment this sugar. The efficiency of the fermentation was estimated to be 70%.

Medium-chain triglycerides (MCT) are known to be rapidly digested and oxidized. Their potential value as a source of dietary energy during exercise was compared with that of maltodextrins (MD). Twelve subjects exercised for 1 h on a bicycle ergometer (60% VO2 max), 1 h after the test meal (1MJ). The metabolism of MCT was followed using 1-13C-octanoate (Oc) as tracer and U-13C-glucose (G) was added to the 13C-naturally enriched MD. After MCT ingestion no insulin peak was observed with some accumulation of ketone bodies (KB), blood levels not exceeding 1 mM. Total losses of KB during exercise in urine, sweat and as breath acetone were small (less than 0.2 mmol X h-1). Hence, the influence of KB loss and storage on gas exchange data was negligible. The partition of fat and carbohydrate utilization during exercise as obtained by indirect calorimetry was practically the same after the MCT and the CHO meals. Oxidation over the 2-h period was 30% of dose for Oc and 45% for G. Glycogen decrements in the Vastus lateralis muscle were equal. It appears that with normal carbohydrate stores, a single meal of MCT or CHO did not alter the contribution of carbohydrates during 1 h of high submaximal exercise. The moderate ketonemia after MCT, despite substantial oxidation of this fat, led to no difference in muscle glycogen sparing between the diets.