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Few studies have examined energy metabolism during prolonged, strenuous exercise. We wanted therefore to investigate energy metabolic consequences of a prolonged period of continuous strenuous work with very high energy expenditure. Twelve endurance-trained athletes (6 males and 6 females) were recruited. They performed a 7-h bike race on high work-load intensity. Physiological, biochemical, endocrinological, and anthropometric muscular compartment variables were monitored before, during, and after the race. The energy expenditure was high, being 5557 kcal. Work-load intensity (% of VO(2) peak) was higher in females (77.7%) than in men (69.9%). Muscular glycogen utilization was pronounced, especially in type I fibres (>90%). Additionally, muscular triglyceride lipolysis was considerably accelerated. Plasma glucose levels were increased concomitantly with an unchanged serum insulin concentration which might reflect an insulin resistance state in addition to proteolytic glyconeogenesis. Increased reactive oxygen species (malondialdehyde (MDA)) were additional signs of metabolic stress. MDA levels correlated with glycogen utilization rate. A relative deficiency of energy substrate on a cellular level was indicated by increased intracellular water of the leg muscle concomitantly with increased extracellular levels of the osmoregulatory amino acid taurine. A kindred nature of a presumed insulin-resistant state with less intracellular availability of glucose for erythrocytes was also indicated by the findings of decreased MCV together with increased MCHC (haemoconcentration) after the race. This strenuous energy-demanding work created a metabolic stress-like condition including signs of insulin resistance and deteriorated intracellular glucose availability leading to compromised fuelling of ion pumps, culminating in a disturbed cellular osmoregulation indicated by taurine efflux and cellular swelling.

Background and Aim: The sympathetic nervous system may be involved in the pathophysiology of insulin resistance and metabolic cardiovascular syndrome in young men. The aim was to study the effects of long-term stress on different features of the metabolic syndrome (MES) in formerly non-obese healthy young males during 5 months of defined conditions., Methods and Results: Sixteen healthy male sailors (mean age 36.5 (SD)+/-7 years) participating in a sailing race around the world were recruited for the study. Investigations were done before the start and at stop overs after finishing laps 1, 2 and 4 (1, 2(1/2) and 5 months, respectively). Anthropometric and blood pressure data as well as biochemical data associated with MES were substantiated. Food intake and exercise were chartered and largely controlled. A mean weight loss of 4.5+/-2 kg (P<0.005), comprising both fat and lean body mass, was recorded during the first lap. Subsequently after 5 months, a weight gain, mainly consisting of 1.2+/-1.1 kg body fat (P<0.05), took place, concomitantly with a protein mass drop of 0.6+/-1.1 kg (P<0.05). The body fat gain accumulated on the abdominal region. Elevated blood levels of HbA1c, insulin and the triglycerides/high-density lipoprotein ratio were also observed during the race. Likewise heart rate and systolic blood pressure increased slightly but to a statistically significant extent., Conclusions: Non-obese healthy young men exposed to long-term stress developed abdominal obesity and signs of a metabolic syndrome in embryo, also emphasized by biochemical and blood pressure alterations. It is suggested that long-term and sustained stress activation might be an additional risk factor for the development of MES, even after control of dietary and exercise habits.

Objective: A lowered energy metabolism in schizophrenia was reported already in the 1920s. However, these early investigations were case studies without control groups or statistical analysis. In this study the resting energy expenditure (REE) and relevant body composition variables were measured in patients with schizophrenia and healthy controls., Method: REE was determined in 30 patients and 17 controls. The difference between the measured and the expected level for each individual was calculated as DeltaREE. Body composition was assessed with bioelectrical impedance and calliper measurements., Results: DeltaREE was significantly lower in the patients than in the controls. A decrease was also seen in the non-medicated patients. The patients showed significantly lower percentages of water in fat free-mass and intracellular water., Conclusion: The lowering of REE and body water fractions may suggest a homeostatic aberration in schizophrenia that may be of importance for the understanding of metabolic disturbances observed in the disease.

The first results of the Women's Health Initiative dietary intervention trial were published in the USA in February. This is a colossal intervention designed to see if diets lower in fat and higher in fruits, vegetables and grains than is usual in high-income countries reduce the incidence of breast cancer, colorectal cancer, heart disease and other chronic diseases, in women aged 50-79 years. As interpreted by US government media releases, the results were unimpressive. As interpreted by a global media blitz, the results indicate that food and nutrition has little or nothing to do with health and disease. But the trial was in key respects not reaching its aims, was methodologically controversial, and in any case has not produced the reported null results. What should the public health nutrition profession do about such messes?

Physical activity has been shown to favorably affect metabolic risk markers, including blood lipids. The impact of high-energy turnover, without influencing the traditionally used markers of exercise training effects, on blood lipids is still unclear. The aim was to study the effect of high-volume low-intensity physical activity on the blood lipid pattern, with a tight control of diet and energy balance. Eight untrained men [42.5 (12.1) years, body mass index 24.2 (2.8) kg m(-2)] were tested in two different 6-week protocols. In the sedentary protocol, the subjects were instructed to limit their everyday physical activity. In the activity protocol, a 2-h physical activity bout was performed 5 days week(-1) (approximately 40% of VO(2max); equivalent of an additional 21 MJ week(-1) in energy expenditure). The diet for both protocols comprised approximately 40 energy percent (E%) fat, approximately 50 E% carbohydrates (CHO). The polyunsaturated fatty acids to saturated fatty acids ratio of the diet was approximately 0.12. There were no changes during each 6-week period or differences between the two protocols in body weight, body composition or aerobic capacity. Low-intensity physical activity did not affect lipid parameters substantially, except for a slightly lower Apo-B/Apo-A1 ratio with the activity protocol (P < 0.05). Total and low-density lipoprotein cholesterol, as well as Apo-B and Apo-A1, were increased during the beginning of each 6-week period (P < 0.05), but returned to basal levels by the sixth week. In conclusion, 6 weeks of high-volume low-intensity physical activity did not affect blood lipids substantially.

Because approximately 20% of the work force in the industrialized world have irregular working hours, it is pertinent to study the consequences of eating at irregular, especially nighttime hours. We studied the postprandial responses during nocturnal fasting vs. eating throughout a 24-h wake period. Seven healthy males were studied twice in a crossover design. After a 6-d diet adjustment period [high fat diet, 45 energy percent (en%) fat, 40 en% carbohydrates)] with sleep from 2300 to 0700 h, the men were kept awake for 24 h at the metabolic ward and given either 6 isoenergetic meals, i.e., every 4 h (N-eat) or 4 isoenergetic meals from 0800 to 2000 h followed by a nocturnal fast (N-fast), with the same 24-h energy intake. Energy expenditure, substrate utilization, activity, heat release, body temperature and blood variables were measured over 24 h. Energy expenditure and blood glucose, triacylglycerol, insulin and glucagon concentrations were lower and nonesterified fatty acids concentrations were higher during the nocturnal fast than during nocturnal eating (P < 0.05); however, no 24-h differences between the protocols were apparent. Nocturnal fasting slightly altered the secretory patterns of the thyroid hormones and cortisol (P < 0.05). We found no clear indication that it would be more favorable to ingest few larger daytime meals than smaller meals throughout the 24-h period. The body seems to be able to buffer small differences in meal size and timing provided energy balance is maintained.

Background: Night work is becoming more common and shift workers display several metabolic disturbances. Aim To study the endocrine responses in relation to time of day during a 24-h period and how dietary macronutrient composition affects these responses., Design: Seven males (26-43 y and 19.9-26.6 kg. m(-2)) were studied in a crossover design. Isocaloric diets described as high-carbohydrates (HC; 65 energy percent (E%) carbohydrates and 20E% fat) or high-fat (HF; 40E% carbohydrates and 45E% fat) were given. After a 6-day diet adjustment period, the subjects were kept awake for 24 h in a metabolic unit and were served an isocaloric meal (continuation of respective diet) every 4-h. Blood samples were taken throughout the 24-h period., Results: Insulin and leptin responses to meal intake differed with respect to time of day (p < 0.05). Time of day affected glucagon, thyroid stimulating hormone (TSH), free thyroxin (fT4), total triiodothyronine (tT3), cortisol, chromogranin A (CgA) and pancreatic polypeptide (PP) concentrations (p < 0.05). Meal intake decreased cortisol concentration after meals at 0800, 1200 and 0400 but not at 1600, 2000 and 0000 h. The PP's postprandial increase was greater during 0800-1600 h compared to 2000-0800 h. With the HC meals, lower glucagon and CgA concentrations (p < 0.05), and a tendency for lower tT3 concentrations (p = 0.053) were observed compared to the HF meals., Conclusion: Insulin, PP, TSH, fT4, cortisol and leptin responses to meal intake differed with respect to time of day. The decreased evening/nocturnal responses of cortisol and PP to meal intake indicate that nocturnal eating and night work might have health implications.

A nutritional survey based on twelve adolescent male Kalenjin runners in Kenya during a 2-week field study was carried out in order to determine the composition of their diet and make a comparison with macronutrient recommendations for athletes. Food samples were collected for analysis of macronutrient distribution and energy content from main meals and the macronutrient distribution and energy content of additional food intake were based on the information of a 24 h recall interview and estimated from food tables. The diet of the Kalenjin runners was very high in carbohydrate (71 % 8.7 g/kg body weight per d) and very low in fat (15 %). Intake of total protein (13 %; 1.6 g/kg body weight per d) was above the daily intake recommended by the Food and Agriculture Organization/World Health Organization/United Nations University (FAO/WHO/UNU), while essential amino acid intake was estimated to be in the borderline-to-low range based on FAO/WHO/UNU recommendations for children <12 years and adults. The energy intake was mainly derived from vegetable sources (90 %) with maize and kidney beans as the staple food (81 %). The diet of the Kalenjin runners met recommendations for endurance athletes for total protein and most essential amino acid intake as well as carbohydrate intake even though it was based on a small range of food items.

Because night work is becoming more prevalent, we studied whether feeding at different times of a 24-h period would elicit different metabolic responses and whether dietary macronutrient composition would affect these responses. Seven men (26-43 y, 19.9-26.6 kg/m(2)) consumed two isocaloric diets, in a crossover design. The diets were a high carbohydrate (HC) diet [65 energy % (E%) carbohydrates, 20E% fat] and a high fat (HF) diet (40E% carbohydrates, 45E% fat). After a 6-d diet-adjustment period, the men were kept awake for 24 h and the food (continuation of respective diet) was provided as six isocaloric meals (i.e., every 4 h). Energy and substrate turnover, heart rate, mean arterial pressure (MAP), blood glucose, triacylglycerol (TAG), nonesterified fatty acid (NEFA) and glycerol were measured throughout the 24-h period. Significantly higher energy expenditure and NEFA concentration, and lower blood glucose and TAG concentrations were observed when the men consumed the HF diet than when they consumed the HC diet. Significant circadian patterns were seen in body and skin temperature (nadir, 0400-0500 h). When the men consumed the HF diet, significant circadian patterns were seen in fat oxidation (nadir, 0800-1200 h; plateau, 1200-0800 h), heat release (nadir, 0800-1200 h; plateau, 1600-0800 h), heart rate (nadir, 0000 h), blood glucose (nadir, 0800-1200 h; peak, 0000-0400 h), NEFA (nadir, 0800-1200 h; peak, 1200-2000 h) and TAG (nadir, 0800-1200 h; peak, 0400-0800 h) concentrations. Energy expenditure, carbohydrate oxidation, MAP and glycerol concentration did not display circadian patterns. Unequal variances eradicated most circadian effects in the HC-diet data. The increased TAG concentration in response to feeding at 0400 h might be involved in the higher TAG concentrations seen in shift workers. Distinct macronutrient/circadian-dependent postprandial responses were seen in most studied variables.

This article presents the nutrient composition and nutritional contribution of naturally occurring vegetables (NOV) in four villages in Vietnam. The frequency of consumption and quantities eaten were evaluated within the overall diet of 101 and 110 women in the Mekong Delta (flood period and rainy season, respectively) and of 103 women in the Central Highlands (rainy season). The concentrations of Ca, Fe and Zn were analysed in 28 species, and presence of tannins and phytic acid in 19 species. Provitamin carotenoids were determined in 11 species. Over 90% of the women consumed NOV, and they contributed 43, 72 and 75% (Central Highlands, Mekong rainy and Mekong flood period, respectively) of the total quantities of vegetables eaten. Aquatic species such as lpomoea aquatica and Limnocharis flava, and terrestrial vegetables such as Schismattoglottis calyptrata, were among the most commonly consumed vegetables. They were eaten in mean daily quantities exceeding 50 g and had high concentrations of Ca, Fe and beta-carotene. Other major aquatic vegetables included the stems of Eleocharis sp., Nelumbo nucifera and Nymphea lotus, all of which were used as salad vegetables and had relatively low nutrient density. The problems of assessing the current role of NOV due to lack of data on intakes in the context of the overall diets, as well as data on their composition, are addressed.

The effect of a "normal" (n = 8) and "high" (n = 6) protein intake (1 and 2.5 g x kg(-1) x day(-1), respectively) and of exercise on plasma amino acid (AA) concentrations, insulin, and glucagon concentrations was followed throughout a continuous 24-h period in adult male subjects at energy balance after six days on a standardized diet and exercise program. Subjects were fasting from 2100 on day 6 to 1200 on day 7 and then fed 10 identical meals hourly until 2100. Physical exercise was performed (46% maximal oxygen uptake) between 0830 and 1000 (fasting) and in a fed state (1600-1730) on each day. The normal-protein group showed fasting plasma AA concentrations that were higher (P < 0.05) than those for the high-protein group, except for leucine, methionine, and tyrosine. Glutamine, glycine, alanine, taurine, and threonine concentrations were distinctly higher ( approximately 30% or greater) throughout the 24-h period in subjects consuming the normal- vs. the high-protein diets. Exercise appeared to increase, although not profoundly, the plasma concentrations of amino acids except for glutamate, histidine, ornithine, and tryptophan. The profound diet-related differences in plasma AA concentrations are only partially explained by differences in the renal clearance of the amino acids. We speculate on the possible metabolic basis for these findings.

The quantitative relationships between nitrogen (N) intake, urea production, excretion and amino acid oxidation are currently a matter of debate. Some investigators have proposed that urea production is essentially constant over a wide range of N intakes and that urea hydrolysis is regulated according to the N needs of the organism. We have assessed this proposal by compiling results from four separate experiments in healthy young adults (n = 34) carried out in our laboratories and all at the end of the respective diet periods using an identical 24-h continuous intravenous infusion of [(15)N, (15)N]urea and L-[1-(13)C]leucine. The N intakes were: expt. 1; protein-free diet for 5 d; expt. 2; N at 44 mg N. kg(-1). d(-1) from a balanced L-amino acid mixture for 13 d; expt. 3; N at 161 mg. kg(-1). d(-1) from egg protein for 6 d; expt. 4 -one group received 157 mg. kg(-1). d(-1) and the other 392 mg. kg(-1). d(-1) from milk-protein-based diets for 6 d. Urea production and excretion were linearly correlated with N intake (r = 0.98 and 0.94, respectively; P < 0.01). Urea hydrolysis increased linearly with N intake (r = 0.7; P < 0.05), with considerable variation in the rate among individuals, especially at the N intake of approximately 160 mg N. kg(-1)d(-1). These findings are consistent with the generally accepted view that a control of body N balance is via a regulation of urea production. They do not support the concept that urea hydrolysis is the more important site in the control of body N loss.

Background: Deficiencies of iodine, iron, and vitamin A are the 3 most common micronutrient deficiencies in developing countries, although control programs, when properly implemented, can be effective., Objective: We investigated these deficiencies and their possible interaction in preschool children in the southern Blue Nile area of Sudan., Design: Goiter, signs of vitamin A deficiency, and biochemical markers of thyroid, vitamin A, and iron status were assessed in 984 children aged 1-6 y., Results: The goiter rate was 22. 3%. The median urinary iodine concentration was 0.79 micromol/L and 19.3% of the children had a concentration >1.57 micromol/L. Although serum thyroxine and triiodothyronine concentrations were within reference ranges, the median thyrotropin concentration was 3.78 mIU/L and 44% of the children had thyrotropin concentrations above normal. The mean urinary thiocyanate concentration was high (259 +/- 121 micromol/L). The prevalences of Bitot spots and night blindness were 2.94% and 2.64%, respectively, and 32% of the subjects had serum retinol binding protein concentrations <15 mg/L. A significant positive correlation was observed between thyrotropin and retinol binding protein. Whereas 88% of the children had hemoglobin concentrations <1.86 mmol/L, only 13.5% had serum ferritin concentrations below the cutoff of 12 microg/L and 95% had serum transferrin concentrations above the cutoff of 2.50 g/L., Conclusions: Our results indicate that goiter is endemic in this region of Sudan despite iodine sufficiency and that both anemia and vitamin A deficiency are health problems in the area. Moreover, consumption of millet, vitamin A deficiency, and protein-energy malnutrition are possible etiologic factors in this endemic area.

Effects of moderate physical activity (90 min at 45-50% of maximal O2 uptake 2 times daily) and "high" (2.5 g protein. kg-1. day-1, n = 6) or "normal" protein intake (1.0 g protein. kg-1. day-1, n = 8) on the pattern and rate of 24-h macronutrient utilization in healthy adult men were compared after a diet-exercise-adjustment period of 6 days. Energy turnover (ET) was determined by indirect and direct (suit) calorimetry, and "protein oxidation" was determined by a 24-h continuous intravenous infusion of [1-13C]leucine. Subjects were in slight positive energy balance during both studies. Protein contributed to a higher (22 vs. 10%) and carbohydrate (CHO) a lower (33 vs. 58%) proportion of total 24-h ET on the high- vs. normal-protein intake. The highest contribution of fat to ET was seen postexercise during fasting (73 and 61% of ET for high and normal, respectively). With the high-protein diet the subjects were in a positive protein (P < 0.001) and CHO balance (P < 0.05) and a negative fat balance (P < 0.05). The increased ET postexercise was not explained by increased rates of urea production and/or protein synthesis.

Fe seems to be the only nutrient deficiency that industrialized and low-income countries have in common. Thus, Fe is one of the most critical nutrition requirements to be met in most diets in human subjects. Fe deficiency is caused not only by too low an intake, but is also the result of low bioavailability, as well as an increased Fe requirement due to physiological variables or clinical problems which are not met by an increased dietary intake of Fe. In low-income countries poor dietary quality rather than Fe intake seems to be the key determinant of impaired Fe status. Sometimes the Fe intake even exceeds that in populations of industrialized countries. The interaction of all enhancers (e.g. ascorbic acid and meat), as well as inhibitors (such as bran, polyphenols, egg yolk, soyabean products, Ca, Ca3(PO4)2 and phytic acid (or phytate)) is what determines the bioavailability of non-haem-Fe in the meal. Dietary composition seems to be particularly important when Fe reserves are low, or in the presence of Fe deficiency. Furthermore, the development of anaemia as a result of Fe deficiency, secondary to Fe-stress situations, is dependent on the Fe balance in the host. With respect to the dietary intake of Fe, other products in the food consumed as well as previous treatment of the product (e.g. heat treatment and processing) may also influence bioavailability. Despite all efforts to counteract Fe deficiency it still represents one of the dominant problems in the micronutrient sphere. It is apparent that there is no simple solution to the problem, and the fact that Fe deficiency still occurs in affluent societies consuming a mixed diet speaks for itself a more holistic view of total dietary composition and the role of enhancers and inhibitors is needed.

In healthy adult men adapted to a diet/exercise regimen for 6 days, the effects of small, frequent meals supplying daily protein intakes of 1 (n = 8) or 2.5 g . kg-1 . day-1 (n = 6) on leucine oxidation, urea production, and whole body protein synthesis (PS) and degradation (PD) have been compared with the use of a 24-h continuous intravenous [13C]leucine and [15N,15N]urea infusion protocol. Two 90-min periods of exercise (approximately 50% maximal O2 consumption) were included during the fasting and the fed periods of the 24-h day. Subjects were determined to be at approximate energy, nitrogen, and leucine balances on both diets. Increased protein intake raised the urea production rate; the absolute rate of urea hydrolysis was the same on both diets. When the first-pass splanchnic uptake of leucine was taken to be 25% of intake, PS was stimulated by feeding (after an overnight fast) at both protein intake levels (P < 0.05 and P < 0.01), whereas PD declined significantly (P < 0.01) at both protein levels. Protein gain at a high protein intake appears to be the result of both a stimulation of PS and a marked decline in PD, whereas at a less generous intake, the gain appears to be a result of a fall in PD with a less evident change in PS. Exercise moderately decreased PS during and/or immediately after exercise at each protein level, and there was a postexercise-induced increase (P < 0.01) in PD, which was more dramatic when feeding was at the higher protein intake level.

Epidemiological evidence suggests that millet might play a role in the etiology of endemic goiter. Recently, we showed that a traditional fermentation procedure of two pearl millet (Pennisetum americanum L. Lecke) cultivars grown in Sudan modified their effects on the weight of the thyroid gland and thyroid hormone profile in rats. In the present study, we report that this fermentation procedure reduced the ash contents of millet by about 40% and removed considerable amounts of Mg (>50%), Zn (27-39%) and K (45%). Other minerals (Ca, Fe, Cu) were not affected. Feeding of one fermented cultivar resulted in significant reduction in bone Mg and Zn contents, whereas feeding of the other fermented cultivar resulted in reduction of bone Mg only. Dietary Mg intake and bone Mg contents correlated negatively with serum T3. Groups fed the millet diets had higher serum Se level compared to those fed wheat or casein diets and feeding of fermented millet resulted in a further increase in serum Se level. Thus our data indicate that in rats the enhanced effects of millet on the thyroid induced by fermentation is likely related to removal of minerals from millet and/or chemical transformation of the goitrogens contained in millet.

Short-term metabolic experiments have revealed that physical exercise increases the oxidation of leucine, which has been interpreted to indicate an increased requirement for dietary protein in physically active subjects. Because it may be inaccurate to extrapolate measurements of amino acid oxidation made over a few hours to the entire day, we have carried out a continuous 24-h intravenous [1-13C]leucine/[15N]urea tracer study in eight healthy adult men. Their diet supplied 1 g protein.kg-1.day-1, and exercise (mean maximal O2 consumption 46%) was for 90 min during the 12-h fast and 12-h fed periods of the day. Subjects were adapted to the diet and exercise regimen for 6 days. Then, on day 7, they were dressed in the University of Uppsala energy metabolic unit's direct calorimeter suit, were connected to an open-hood indirect calorimeter, and received the tracers. Exercise increased leucine oxidation by approximately 50 and 30% over preexercise rates for fast and fed periods, respectively. This increase amounted to approximately 4-7% of daily leucine oxidation. Subjects remained in body leucine equilibrium (balance -4.6 +/- 10.5 mg.kg-1.day-1; -3.6 +/- 8.3% of intake; P = not significant from zero balance). Therefore, moderate exercise did not cause a significant deterioration in leucine homeostasis at a protein intake of 1 g.kg-1.day-1. These findings underscore the importance of carrying out precise, continuous, 24-h measurements of whole body leucine kinetics; this model should be of value in studies concerning the quantitative interactions among physical exercise, energy/protein metabolism, and diet in humans.

Energy turnover during offshore sailing was studied in 11 male crew members of one team during the first three legs of the 1993-1994 Whitbread Round The World Race. The effect of racing on the energy balance of the crew members was studied by anthropometric measurements and dietary intake as calculated from food inventories before and after each leg. Energy turnover, calculated from dietary intake and release of endogenous energy as a result of changes in body composition, was higher than expected (about 18-20 MJ.d-1). These findings were confirmed using the doubly labeled water technique in six crew members during the third leg, in which mean energy turnover was found to be 19.3 MJ.d-1. Changes in body weight and composition indicated a negative energy balance during all legs.

The purpose of this study was to develop flexible and accurate multicompartment equations to calculate body composition and compare the results with methods using common two-compartment equations. Twenty-two healthy male volunteers 22-59 y of age were studied. Body volume was measured by underwater weighing (UWW) or with a skinfold caliper, bone mineral by dual-energy X-ray absorptiometry (DXA), and body water by bioelectrical impedance analysis (BIA). The percentage of water and bone mineral in fat-free mass (FFM) had a significant effect on the difference in percentage fat obtained by the two-compartment model compared with a four-compartment model. FFM density was negatively (r = -0.76, P < 0.001) and percentage water in FFM was positively correlated with age (r = 0.75, P < 0.001). The three-compartment model based on field-adapted methods (skinfold thickness + BIA) to calculate percentage body fat correlated significantly with the more complex four-compartment model (UWW + BIA + DXA; r = 0.95, P < 0.001). The advantages of three- and four-compartment equations are that they compensate for differences in body content of bone mineral and water.

Intensive cooling has been shown to increase energy expenditure (EE) during work as well as to decrease physical performance. Two different levels of moderate cooling (10 degrees C vs 15 degrees C) were studied during light endurance exercise in order to examine the effect of the increased heat loss on EE. Twelve subjects performed a 90-min low intensity exercise (100 W) on a cycle ergometer, wearing a water-cooled calorimeter suit for controlled cooling. The lower temperature resulted in a 4.3 +/- 3.8% (mean +/- SD) higher EE, increased total heat loss and lowered skin temperatures. No differences in central core body temperature, heart rate or respiratory quotient (RQ) were recorded. There was a relation between differences in the rate of heat loss and the corresponding increase in EE. Even a small increase in cooling during endurance exercise increased EE which may be a relevant problem in winter sports.

In addition to factors such as fat free mass, hormonal status, genetics and energy balance, previous physical activity has been shown to influence energy turnover during resting (RMR = resting metabolic rate) or basal conditions (BMR = basal metabolic rate). This article presents data on BMR from elite endurance athletes (4 female and 4 male), at least 39 h after their last training session, in comparison with sedentary nonathletic controls matched for sex and fat free mass (FFM). Comparisons with theoretical calculations of BMR were also made. The athletes were shown to have a significantly higher BMR than was expected from calculations based on body mass (16%, P < 0.05) or body composition (12%, P < 0.05). There were no corresponding differences found in the nonathletic control group. The athletes had a 13% higher (P < 0.001) BMR than controls if related to FFM and 16% (P = 0.001) if related to both FFM and fat mass (FM). The athletes were also found to have 10% lower R-values (P < 0.01) indicating higher fat oxidation. The conformity of these findings with the present literature and the possible mechanisms behind them as well as its influence on theoretical calculations of energy turnover (ET) based on activity factors expressed as multiples of RMR are further discussed.

To study the impact of work hours on eating habits the dietary intake of 96 male industrial workers on day work and two- and three-shift work was investigated using repeated 24 h recall. The intake of energy, 14 nutrients, and coffee and tea was computed, using a nutrient data base, for 8 h work and shifts (day, morning, afternoon, night) and for the 24-h periods including these work shifts. No changes in intake of energy, nutrients and coffee/tea were observed between 8 h morning and afternoon shifts, but there was a reduction in intake during 8 h night shifts. Night shift work caused a redistribution of food and coffee intake, but not an overall 24 h reduction. On the whole, the energy-intake and the quality of food intake (percentages of energy from macronutrients and density of micronutrients) were not affected by shift work, although the intake of carbohydrates was lower in day- and three-shift workers during days off. The intake of alcohol was higher during days off in all groups. In summary, two- and three-shift work in this study affected the circadian distribution of food intakes and coffee consumption, but not the overall 24-h consumption.

Objectives: The goal of this study was to examine the effect of rotating three-shift work on the circadian distribution of dietary intake and to investigate the relationships between displaced eating and nutritional status variables [blood lipids, blood glucose, body mass index (BMI)]., Methods: Dietary data were collected by 147 replicate 24-h dietary recalls from 22 male industrial workers in rotating three-shift work. The intakes of energy and nutrients were estimated by the use of a nutrient data base. The BMI was calculated, and blood glucose, serum triglycerides, high-density lipoprotein (HDL) cholesterol and low-density lipoprotein (LDL) cholesterol were measured once., Results: The dietary intakes of energy, protein, total fat, saturated fat, total carbohydrates, sucrose, and dietary fiber did not differ between 24-h periods but did differ between work shifts and were lowest during the night. Correlation analyses between dietary intakes and nutritional status parameters showed that those who redistributed their eating most to the night shift had higher levels of serum total cholesterol and LDL and a higher LDL:HDL ratio; 63% of the LDL cholesterol level was explained by carbohydrate intake during night shifts. In contrast, the total intake for whole 24-h periods or across entire shift cycles was not related to serum variables or BMI., Conclusions: Dietary intake is lower during night shifts (34-37% of 24-h intake of various nutrients) than during morning shifts (43-47%) and afternoon shifts (47-59%). The redistribution of food intake to the night may be associated with metabolic disturbances in lipid metabolism.

To establish the major determinants of bone mass, we assessed relationships between bone mineral density (BMD) and height, weight, body mass index (BMI), muscle strength, physical capacity (VO2max), body composition, serum concentrations of insulin-like growth factor I (IGF-I), growth hormone (GH), the GH-dependent IGF binding protein (IGFBP-3), testosterone, sex hormone binding globulin (SHBG), osteocalcin, and parathyroid hormone (PTH) in 38 healthy men between 25 and 59 years of age. Values of BMD at all sites (total body, lumbar spine, and hip) were strongly correlated with IGFBP-3 (r = 0.51-0.64, p < 0.001 at all sites), and total-body BMD was also significantly correlated with IGF-I (r = 0.43, p = 0.01). BMD measurements of the total body and of the different sites of the hip were negatively correlated with age and positively with weight, BMI, muscle strength, VO2max, and fat-free weight. IGF-I and IGFBP-3 were both positively related to muscle strength and VO2max. In a stepwise forward multiple-regression analysis, the best model was obtained for the femoral neck, where IGFBP-3, GH, PTH, age, IGF-I, and BMI explained 77% of the variation in BMD. The partial regression coefficients of IGFBP-3, PTH, and BMI were all positive, whereas age, GH, and IGF-I were negatively correlated with BMD. In summary, IGFBP-3 correlated better with BMD than any other study parameter. The findings indicate that GH is of importance for bone mass and suggest that IGFBP-3 not only reflects the integrated GH secretion but also has a direct role in the endocrine regulation of bone metabolism.

A modification of the suit calorimeter originally developed in 1972 was used in combination with indirect respiratory calorimetry. The modification included increased cooling capacity of the suit by means of an increased density of cooling tubes and a variable water flow pump which permitted higher flow rates. This has made the suit calorimeter a very effective heat exchanger that could be used for studies on high energy turnover during heavy exercise. Furthermore, specially designed absorption clothing made it possible to collect any sweat produced before it evaporated, thus minimizing potential error in measuring evaporative heat loss. The suit calorimeter would seem to offer a valuable tool in the analysis of the specific thermogenic responses to dietary changes and physical activity in studies on energy and protein metabolism and their interaction in humans. It also makes it possible to perform direct calorimetric measurements in metabolic balance studies using continuous parenteral infusion since the subjects do not need to be sealed in a calorimeter chamber.

Determination of body composition by dual-energy x-ray absorptiometry (DEXA) was evaluated in healthy men, by using underwater weighing (UWW), skinfold thickness measurement, and bioimpedance analysis. There were strong correlations between percent body fat obtained by all techniques, but DEXA gave significantly lower values (P < 0.001). The influence of differences in bone mineral density (BMD) on fat content determined by UWW was also studied. The individual differences between UWW and DEXA fat estimates were calculated and there was a negative correlation with BMD (r = -0.50, P < 0.05). There was also a negative correlation between body fat by UWW and BMD (r = -0.71, P < 0.01) in the subjects with lowest fat by DEXA, indicating that high or low BMD gave false values by UWW. In conclusion, DEXA and UWW provide complementary information and a combination of these techniques seems to offer new opportunities in evaluations of body composition.

Established nutritional science methods and a new concept for meal-classification were applied to shiftworkers (rotating 3-shift) data. The frequency of meals and snacks of different nutritional quality as a function of work schedule was evaluated, as well as the content of selected nutrients (energy, fat, sucrose, dietary fibres, ascorbic acid) in these meals and snacks. The results do not indicate that rotating 3-shift work affects the nutritional quality of the diet or the frequency of different types of meals and snacks. A qualitative classification of meals and snacks might be a cost-effective strategy for data-evaluation in field studies of shift workers' eating habits when quantitative estimations of the dietary intake are to be complicated.

Iron bioavailability from species-specific milk is assumed to be high for the offspring, possibly due to species-specific iron-binding proteins in the milk. To assess this bioavailability using radioisotopes, the validity of extrinsic labeling technique needs to be proven. Using the suckling piglet as an animal model, we have compared iron bioavailability from sow's milk labeled extrinsically and intrinsically. During intrinsic labeling transfer into milk of 59Fe given intramuscularly was slow and was found to be at maximum 14 h post-injection. Recovery of isotope in the milk was only 0.00014%. Extrinsic and intrinsic labels were distributed differently among milk fractions; intrinsic iron bound primarily to the fat fraction but the extrinsic iron bound primarily to the casein fraction. Iron retention from intrinsically labeled milk was considerably higher than from extrinsically labeled milk. These results show that the extrinsic tag method is not valid for studies on iron absorption from sow's milk and suggest that the situation may be the same for human milk.

Excess mortality in a population is one of the hallmarks of an influenza epidemic. Apart from the pandemic years, 1918-1919, 1957 and 1968-1969, annual excess mortality has occurred 16 times in Sweden during the period 1911-1988. An unusually high mortality was caused by Influenza A Sichuan 2/87 (H3N2), the unexpected appearance of which at the beginning of November 1988 started an intensive epidemic in Sweden, while other European countries had a relatively mild influenza season. Swedish deaths in December totalled 10,500-2,200 more than expected; age groups over 65 years accounted for 95 per cent of the mortality, and those over 80 (N = 350,000 in Sweden) for 1,400 deaths. 0.4 percent of those over 80 died. The excess mortality is to be explained by the high proportion of the elderly in the Swedish population and the very low rate of influenza vaccination before the outbreak. As the increase in the proportion of the very elderly can be expected to continue, future influenza epidemics will result in even higher mortality unless adequate prophylactic measures are taken.

The procedure suggested by FAO/WHO to evaluate the protein quality of mixed diets has been tested using vegetable and vegetable-animal protein diets. Chemical scores were calculated and protein digestibilities were compared in human adult, growing pigs and rats. Pigs were studied as alternatives to rats in the protein evaluation of human diets. The results showed that the choice of the samples to calculate the chemical score is important; that the composition of the samples for biological evaluations must be considered in order to avoid experimental problems, and that values for true protein digestibility in human subjects, pigs and rats are in agreement, and further studies of growing pigs as an experimental model are suggested. Minor differences in protein quality of the two diets were demonstrated.

A 10-year follow-up study of 30 patients subjected to jejunoileal bypass surgery for obesity is reported. The technique used which resulted in a jejunoileal shunt length of 50-55 cm gave satisfactory weight reduction in 75 per cent of the patients. There were no serious complications. The weight loss occurred essentially during the first 12-18 months, the main cause being defective digestion and malabsorption. In some instances this was supported by initially reduced food consumption. A certain degree of steatorrhoea persists in most cases after 10 years and may be of importance in the maintenance of the new stable weight level.

The contents of total nitrogen, nonprotein nitrogen, lactose, and individual milk proteins have been determined in human milk from well-nourished Swedish mothers. Breast milk samples from 50 mothers at different stages of lactation (up to 170 days) were collected. Furthermore, three mothers gave samples repeatedly throughout the whole lactation period. The protein content in mature milk was found to be 0.8 to 0.9% by amino acid analysis. The nitrogen content and the contents of the major human milk whey proteins, alpha-lactalbumin and lactoferrin, are very high for the first few days, then decrease rapidly and reach, thereafter, the more slowly declining level of mature milk. Nonprotein nitrogen and the nonspecific milk protein serum albumin are present in constant concentrations throughout lactation. The daily milk volumes were determined and found to be 500 to 600 ml in the very early part and 700 to 800 ml in the later part of the lactation period.