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Biomedical subjects

E Forsum

Publications and source records attributed to E Forsum.

At least 37 records · Page 2Linked to original sources
PubMed1992

Total energy expenditure of healthy Swedish women during pregnancy and lactation.

Total energy expenditure (TEE) was estimated in healthy Swedish women by the doubly labeled water method in a longitudinal study during pregnancy and lactation. Measurements were made before pregnancy (A); in gestational weeks 16-18 (B), 30 (C), and 36 (D); as well as 2 (F) and 6 (G) mo after delivery. When the results were interpreted, earlier published data regarding resting metabolic rate (RMR), energy intake, and energy in breast milk were also considered. TEE (MJ/d) and TEE/RMR were 10.5 +/- 2.2 (mean +/- SD) and 1.87 +/- 0.42 (n = 28), 9.6 +/- 2.8 and 1.65 +/- 0.67 (n = 22), 12.5 +/- 3.4 and 1.82 +/- 0.45 (n = 22), 12.2 +/- 4.1 and 1.66 +/- 0.52 (n = 19), 10.6 +/- 2.0 and 1.82 +/- 0.41 (n = 23), and 10.8 +/- 2.7 and 1.79 +/- 0.42 (n = 23) at A, B, C, D, F, and G, respectively. The results indicated that physical activity tended to be decreased during early pregnancy. Taking changes in body energy stores into consideration, it was estimated that subjects recorded 86% and 77% of their energy intakes at A and F respectively.

Adipose Tissue↗
PubMed1991

Energy restriction and the partitioning of energy among the costs of reproduction in rats in relation to growth of the progeny.

Compared with well-nourished controls, progeny of energy-restricted females are smaller and grow less well. The mechanisms behind these effects are frequently studied in rats but interpretation of such studies requires knowledge about the partitioning of dietary energy among the costs of reproduction and maternal needs. Energy partitioning was studied in rats fed ad libitum or 70% of ad libitum intake from 24-34 d before conception until d 14 of lactation and in virginal controls. Body composition was estimated for adult rats on d 1 of gestation, for adult rats and litters on d 1, 9 and 14 of lactation and for virginal controls after 65 d of dietary treatment. Milk production and composition were also studied. Dams in the two groups retained similar amounts of energy during pregnancy. Mobilized body energy corresponded to only 6 and 12% of the energy in milk for ad libitum-fed and restricted rats, respectively. Adult energy-restricted rats were smaller than their ad libitum-fed counterparts and thus needed less energy for maintenance. During lactation, energy-restricted rats used less energy per unit body size than ad libitum-fed rats. Pups of restricted dams were not only smaller, they also utilized milk energy less efficiently than did pups of well-fed dams.

Aging↗
PubMed1990

Composition of faeces from human subjects consuming diets based on conventional foods containing different kinds and amounts of dietary fibre.

The stool-bulking effect of dietary fibre (DF) is well-documented and believed to be important in the postulated beneficial effect of DF on human health. The aim of the present study was to investigate the digestibility of DF in relation to its stool-bulking properties and to study possible mechanisms for this effect. Four diets, based on conventional foods only, were studied in balance experiments on human subjects. Diet A contained DF mainly from whole-grain cereals while diets B1 and B2 contained DF mainly from pulses, vegetables and fruit. Diet C was a low-fibre diet. Faeces was fractionated into four fractions, each enriched in one of the following three components: undigested DF (fractions 1 + 2), faecal bacteria (fraction 3) and soluble components (fraction 4). The digestibility of DF in diets A, B1 and B2 was 0.62, 0.88 and 0.90 respectively. Subjects consuming diet A excreted slightly more fraction 3 than subjects consuming the other diets. Thus, the statement that DF of high digestibility stimulates microbial growth in the gut was not supported. The water-holding capacity of fraction 1 was studied in vitro and was found to be low. It is suggested that undigested soluble DF is important in the stool-bulking properties of DF.

Adult↗
PubMed1989

Estimation of body fat in healthy Swedish women during pregnancy and lactation.

Reliable estimates of changes in body fat are important in studies of energy requirements during human reproduction. It is not known if current methods for the estimation of total body fat (TBF) are adequate for this purpose. In this paper earlier reported data from 29 women are used to show how methodology affects estimates of changes in TBF during reproduction. Skinfold thicknesses are also reported and equations relating these measurements to TBF were developed and used to demonstrate how well the skinfold technique could estimate such changes. No correlation was found between changes in body weight and body fat during early pregnancy or between the maternal changes in body weight and body fat over the complete pregnancy. These findings are tentatively explained by changes in the degree of hydration of the body.

Adipose Tissue↗
PubMed1988

Resting metabolic rate and body composition of healthy Swedish women during pregnancy.

Body weight, resting metabolic rate (RMR), total body potassium (TBK), and total body water were measured and total body fat (TBF) was calculated in a longitudinal study of 22 pregnant, healthy Swedish women. Measurements were made before pregnancy, at gestational weeks 16-18, 30, and 36, and 5-10 d and 6 mo postpartum. RMR increased more during pregnancy than previous estimates on well-nourished women showed and the increase was significantly correlated with the birth weight of the baby. TBK decreased during the first part of pregnancy; measurements at weeks 16-18 and 30 were significantly lower than the prepregnancy value and changes in TBK and RMR were significantly correlated. TBF gain during pregnancy was 5.8 +/- 4.0 kg and 60% was already gained by gestational weeks 16-18. Gain in fat was not correlated with birth weight.

Adipose Tissue↗
PubMed1988

Energy metabolism, body composition, and milk production in healthy Swedish women during lactation.

Variables of relevance to energy requirements during reproduction were studied in 23 healthy lactating Swedish women. Body composition and resting metabolic rate (RMR) were studied before pregnancy and three times postpartum. Energy intake was studied before pregnancy and, together with breast-milk production, 2 mo postpartum. The women gained 5.8 +/- 4.2 kg fat during pregnancy and their average fat content was unchanged during the first 2 mo of lactation whereas a slight loss (1.7 +/- 4.2 kg) occurred during the following 4 mo. RMR increased slightly during lactation in spite of a decrease in fat-free body weight 2 and 6 mo postpartum. Energy intake increased during lactation (280 +/- 440 kcal/d). The women produced 740 +/- 150 g breast milk/d containing 0.64 +/- 0.08 kcal/g. The results indicate that current estimates of energy needs during lactation may be too high.

Adipose Tissue↗
PubMed1987

Metabolizable energy in humans in two diets containing different sources of dietary fiber. Calculations and analysis.

The metabolizable energy (ME) of two high fiber diets, providing between 33 and 74 g dietary fiber (DF) per day, was calculated by application of Atwater's general factors (4, 9 and 4 kcal/g protein, fat and carbohydrate, respectively), Merrill and Watt's specific factors, and the British approach in which ME from carbohydrates is calculated by multiplication of the monosaccharide equivalent by 3.75 kcal/g. These factors were applied to the intakes of fat, protein and carbohydrate of 20 human subjects in two balance experiments. ME estimated by Merrill and Watt's factors agreed better with ME estimated in the balance experiment than did ME calculated by Atwater's factors or by the British approach. It was calculated that the DF in diet A, derived mainly from cereals, contributed 2.5 +/- 1.4 kcal/g to ME of the diet. The corresponding figure for DF in diet B, derived mainly from beans, vegetables and fruits, was 3.1 +/- 1.2 kcal/g. It was concluded that Merrill & Watt's factors represent the best system in current use for calculation of ME in DF-rich diets.

Adult↗
PubMed1986

Growth, body composition and breast milk intake of Swedish infants during early life.

The growth and breast milk intake of 22 healthy completely breast fed Swedish infants (9 girls, 13 boys) during the first 10 wk of life are reported and were found to be similar to those of other healthy breast fed populations of infants. Also the body composition (body fat and lean body tissue) was estimated by an anthropometric method at the age of about 10 and 65 days. It was found that the breast milk intake correlated significantly with weight and fat gain but not with gain in lean body tissue or with gain in length. These findings suggest that energy rather than protein intake limited growth in this group of infants. Also the results confirm the fact that the capacity for fat retention is high during early life and show that the size of fat stores is related to breast milk intake.

Body Composition↗
PubMed1985

Casein content of human milk.

Three methods for estimating the casein content of human milk were tested; isoelectric precipitation with washing and correction for co-precipitating proteins, sedimentation by ultracentrifugation, and indirect analysis (ie analyzing for the content of the major whey proteins and subtracting these from the total protein content). Gel electrophoresis and amino acid analysis were used to confirm some of the results. The casein content (mg/ml) of mature human milk (n = 9) was 2.33 +/- 1.69 by isoelectric precipitation, 1.80 +/- 0.48 by sedimentation and 2.96 +/- 1.08 by the indirect approach. A probable partition of nitrogen in breast milk would be casein N: whey protein N: non-protein N of 20:50:30; ie the correct ratio of casein nitrogen: whey nitrogen is approximately 20:80. Analysis of trace elements and minerals demonstrates that of total Ca 10%, Mg 5%, Zn 28%, Cu 17%, and Fe 27% is bound to casein when prepared by ultracentrifugation while isoelectric precipitation causes a redistribution of some of these elements. Since the protein ratio of human milk is considered a guideline when manufacturing infant formulas, these findings should be considered with regard to infant nutrition.

Amino Acids↗
PubMed1985

Effect of reduced energy intake versus increased physical activity on the outcome of nitrogen balance experiments in man.

The effects of energy deficiency created by a reduced energy intake versus an increased physical activity on urinary nitrogen excretion, nitrogen balance and the biological value of the dietary protein (0.57 g/kg/day from a mixed diet) are reported. Two experiments, 21 and 27 days respectively, designed to even out possible effects of time on nitrogen balance, were conducted on 12 young adult men and women. During energy deficiency, urinary nitrogen increased while nitrogen balance and biological value decreased. No significant differences between the two kinds of energy deficiency were found but the effect on the parameters studied tended to be less pronounced the longer the subjects had been on the experimental diets.

Adult↗
PubMed1983

Calculation and determination of metabolizable energy in mixed diets to humans.

Several approaches are currently in use for calculating metabolizable energy of mixed diets from the foods and nutrients they contain. This study compares the metabolizable energy content of six low fiber and one high fiber diet as calculated by conventional procedures (ie, using Atwater's general factors, Merrill and Watts specific factors, and the British procedure where the monosaccharide equivalent of available carbohydrates is multiplied by 3.75 kcal/g) with values for metabolizable energy measured in balance experiments on human subjects. For the low fiber diets, the conventional procedures for calculation of metabolizable energy showed an average deviation between calculated and measured values of up to about 6% of the value obtained in balance experiments. For the high fiber diet Merrill and Watts specific factors and Atwater's general factors were superior to the British approach for calculation of metabolizable energy. Fecal energy content in relation to intake of undigestible energy is discussed.

Adult↗
PubMed1982

Protein evaluation of mixed diets in young adults, growing pigs, and growing rats.

The protein quality of mixed diets was tested using the nitrogen balance technique with a slope-ratio approach in adults, growing pigs, and rats. For diet A (milk, cereals, potatoes, meat, fish, and vegetables) and diet B (milk, cereals, and potatoes) the slope of the regression line, nitrogen balance = f (nitrogen intake) was calculated and expressed in percentage of the slope obtained for diets containing egg white protein. In man, diet A was significantly better than the egg white protein diet which was similar to diet B. In pigs, diets A and B were significantly better than egg white protein. In rats, egg white protein was significantly better than diets A and B. The results are of interest in relation to the recommendations by FAO/WHO regarding adjustment of protein allowance in relation to dietary protein quality.

Adult↗
PubMed1981

Effect of energy restriction on total heat production, basal metabolic rate, and specific dynamic action of food in rats.

Man and experimental animals are able to adapt to restricted levels of energy intake mainly by a reduction in basal metabolic rate (BMR) while the effects of energy restriction on the specific dynamic action (SDA) of food and the spontaneous activity are less well established. In this study, growing rats were fed ad libitum or restricted amounts of diet during 28-31 days. Then total heat production (THP) and BMR during 22 hours, as well as SDA of a test meal, were measured on individual rats by indirect calorimetry. After the calorimeter study rats were kept in metabolic cages for 6 days after which they were killed and analyzed for total body composition. The energy balance of the rats over the last 7 days of the study was calculated from changes in body composition and measurements of food intake during this period. During the calorimeter experiment an indirect estimation of the spontaneous activity of the rat was made. Results showed that THP, BMR and SDA of restricted rats were significantly lower than for ad libitum-fed rats. From body composition measurements, rats restricted in food intake before the calorimetry study were found to mobilize more protein and less fat compared to rats fed ad libitum until the calorimetry and body composition studies were carried out. No difference in spontaneous activity was observed between the two dietary treatments.

Adipose Tissue↗
PubMed1981

Protein evaluation of mixed diets. Comparative study in man and in the pig and rat of vegetable-animal and vegetable protein diets.

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.

Adult↗
PubMed1980

Effect of oral contraceptives on composition and volume of breast milk.

Nitrogen and protein composition was determined in milk from women using oral contraceptives during lactation. Total nitrogen and nonprotein nitrogen as well as lactose and the individual milk proteins lactoferrin, alpha-lactalbumin, and serum albumin were analyzed before introduction of oral contraceptives and thereafter throughout the lactation period. Twenty-four hour milk volumes were registered by weighing the infant before and after each feeding. The four oral contraceptives used consisted of different combinations of d-norgestrel, megestrolacetate, and ethinylestradiol. Significant changes were observed between groups and controls for all parameters studied. However, the changes observed were generally within the physiological variation of normal breast milk. It is suggested that the use of oral contraceptives during lactation should be limited.

Contraceptives, Oral↗
PubMed1980

Effect of protein intake on protein and nitrogen composition of breast milk.

The effect of a low and a high protein diet (approximately 8 and 20% energy from protein, respectively) on the contents of different nitrogen-containing substances in breast milk was studied on three healthy Swedish mothers in full lactation. Each experimental diet was fed during a 4-day period and milk samples were collected during the last day. The milk volume was estimated by weighing the child before and after each feeding. The 24-hr outputs as well as concentrations of total nitrogen, true protein, and nonprotein nitrogen were significantly higher when the subjects consumed the high protein rather than the low protein diet. The higher content of nonprotein nitrogen was due to increased urea levels as well as to increased levels of free amino acids. Milk urea levels were closely correlated with plasma urea levels in samples obtained after overnight fasting when the subjects had consumed the experimental diets for 4 days. The 24-hr output of lactoferrin, alpha-lactalbumin, and serum albumin were higher when the subject consumed the high protein diet as compared to the low protein diet but the differences were not significant.

Adult↗
PubMed1979

Protein evaluation in growing rats of breast milk and breast milk substitutes with special reference to the content of non-protein nitrogen.

The levels of individual proteins and other nitrogen containing substances differ considerably between cow's milk and human milk. Therefore, during manufacture of infant formulas, attempts are made to simulate the protein composition of human milk. However, the composition and nutritional characteristics of human milk protein are incompletely known. In this paper, the protein quality of breast milk protein with and without the non-protein-nitrogen (NPN) substances present in human milk was studied with growing rats and compared to two formulas, one "adapted" commercial infant formula and a suggested further modified, possibly improved, infant formula. Detailed examinations of protein and amino acid composition of the test diets are given. Breast milk protein with added NPN substances showed a lower protein quality than all other test proteins. Breast milk protein without NPN substances and the protein of the suggested infant formula were of similar quality while the protein of the commercial adapted formula was significantly better than all other test proteins. The use of rat growth assays in the evaluation of protein quality of infant formulas is discussed.

Amino Acids↗