Protein and energy utilization in men given a rural Guatemalan diet and egg formulas with and without added oat bran.

Healthy men were fed a fiber-free formula diet providing the FAO/WHO Safe Level of egg protein (0.57 g/kg) and a rural Guatemalan diet giving 0.0875 g of protein per kilogram, the recommended dietary allowance for Central America and Panama. For comparison an egg formula diet was fed at the higher protein level, with and without oat bran (0.6 g/kg). All diets maintained nitrogen balance over the 15-day test periods, and balance was distinctly positive at the higher intake of egg protein. Addition of bran doubled the fecal excretion of dry matter and energy; digestibility of energy and protein was reduced 3 to 4%. With the Guatemalan diet, fecal dry matter, nitrogen and energy excretions were nearly four times as high as with egg formula. Relative to egg ( = 100%), protein digestibility of the Guatemalan diet was 78% and total digestible energy was 92%. Present recommended dietary allowances of protein maintain nitrogen equilibrium at an energy intake of 40 kcal/kg in spite of the large fecal losses.

Energy requirements and energy expenditure of elderly men.

Basal metabolic rates (BMR) and energy cost of a few activities were measured in healthy men aged 63 to 77 years who were participants in a study of protein requirements (previously reported). The men were confined to a metabolic unit for 47 days and received a defined formula diet. Their body weights were 8 to 19 kg higher than that of younger men of the same heights and their whole body potassium content was 12% less than that of younger men (average 28 years of age) studied in the same unit. BMR of the older men was 1622 +/- 189 kcal/day, a figure 13% below the per diem rate of younger men but the same per unit of body potassium. Energy cost of sedentary activities was related to BMR. Expenditure while lying at rest was 1.22 X BMR and while sitting quietly, 1.30 X BMR; these values are the same as in younger men. Walking level at about 2.5 mph cost 4.51 +/- 0.34 kcal/min (about 4 X BMR) and cycling at a comfortable load (300 to 400 kpm) only slightly more. Energy intake required to maintain body weight of these men, who were sedentary except for 30 min of cycling daily, was 2554 +/- 222 kcal/day, or about 1.6 X BMR. Minimum maintenance energy requirement (i.e., ambulatory but inactive) of healthy older men appears to be 1.5 X BMR, the same as in other age groups.

Evaluation of lactational performance of Navajo women.

The effect of suboptimal maternal nutrition on lactational performance of 23 Navajo women was studied in terms of milk volume, milk composition, and infant growth. The mean milk volume produced by 10 Navajo women was 634 +/- 113 mg/24 h after approximately 1 month of lactation. The content of protein, lactose, and lipid were within normal limits. Retinol and carotene content were 32.9 +/- 15.7 and 19.7 +/- 6.3 microgram/dl, respectively. Milk folacin averaged 56.4 +/- 23.9 mg/ml. The mean contents of zinc, iron, and copper were 2.8 +/- 1.1, 0.8 +/- 0.6, and 0.3 +/- 0.2 mg/l, respectively. Despite evidence of suboptimal nutriture among these Navajo women, lactational performance was adequate in terms of infant growth, milk volume, and milk composition with the exception of vitamin A which was lower than normal.

PIP: The effect of suboptimal maternal nutrition on lactation performance of 23 Navajo women, age range 16 to 23 years, was investigated in terms of milk volume, milk composition, and infant growth. All of the women were in full lactation on the day of assessment, which varied from day 19 to 62 of lactation. 10 mothers agreed to the 24-hour test weighing session. Milk samples (n = 23) were expressed manually or extracted with a manual pump between 12:00 and 4:00 p.m. Maternal and infant health since hospital discharge were reviewed by a questionnaire. The mean milk volume produced by 10 Navajo women was 634 + or - 113 ml/24 hours after approximately 1 month of lactation. The content of protein, lactose, and lipid were all within normal limits. Retinol and carotene content were 32.9 + or - 15.7 and 19.7 + or - 6.3mc/dl, respectively. Milk folacin averaged 56.4 + or - 23.9 ng/ml. The mean contents of zinc, iron, and copper were 2.8 + or - 1.1, 0.8 + or - 0.6, and 0.3 + or - 0.2 mg/1, respectively. The mean rate of infant growth was 35.9 g/day. The rate of weight gain between birth and 1 month of age corresponded to the 75th percentile of the Iowa growth standards for females and to the 90th percentile for males. There were a few episodes of fever, diarrhea, and colds. The 1st month of life presented no grave problems for the infants. In sum, despite evidence of suboptimal nutriture among this group of Navajo women, lactational performance was adequate in terms of infant growth, milk volume, and milk composition with the exception of viatmin A which was lower than normal.

Nitrate and nitrogen balances in men.

Nitrate is a nitrogen-containing compound that is not detected by the traditional Kjeldahl method of nitrogen analysis. Nitrate balance studies were done in order to determine if nitrate production in the human body contributes to the irrationally positive nitrogen balances that have been reported in healthy adults. Seven healthy young men, confined to a metabolic unit, received five diets for 9 days each: a mixed foods diet, a fiber-free egg formula diet, and egg formula with California small white beans, lima beans, and wheat bran added. Nitrate-nitrogen intake with the mixed foods diet was 75 mg/day and nonnitrate nitrogen intake was 19 g/day; crude Kjeldahl nitrogen balance (intake--(urinary + fecal)) was 0.64 +/- 1.23 g/day. Nitrate-nitrogen excretion exceeded intake by 0.10 +/- 0.05 g/day. With the four other diets, nitrate-nitrogen intake was almost nil (about 2 mg/day) and nonnitrate nitrogen intake was 95 mg/kg body weight; crude Kjeldahl nitrogen balances ranged from -0.63 +/- 0.73 to 0.02 +/- 0.45 g N/day. With these four diets, feces contained about 80 mg nitrate-nitrogen/day and urine contained about 8 mg. Saliva obtained before lunch had about 1 ppm nitrate-nitrogen with the formula diets and 5 ppm with the mixed foods diet. Net synthesis of nitrate is quite variable but appears to be of the order of 100 mg nitrate-nitrogen/day. Although the excess nitrate excretion increased total nitrogen excretion by less than 5%, it could account for as much as 10 to 20% of unexplained positive nitrogen balances previously reported in well-controlled studies.

Minerals in human teeth: differences between preindustrial and contemporary Hopi Indians.

Mineral elements in dentin from 17th century Hopis were compared with samples from contemporary Hopis living in the same geographic area. Less lead, zinc, and copper, and more strontium were found in the preindustrial teeth. Trace element levels in the contemporary Hopi teeth were similar to those in suburban Californian teeth.

Heart rate and energy expenditure of pregnant and lactating women.

Data on heart rate and oxygen consumption of 21 mature pregnant women, and of 16 of them postpartum, were examined for evidence of the suitability of heart rate as an index of energy expenditure during pregnancy. Energy expenditure, measured by indirect calorimetry, and heart rate were recorded with subjects at rest (lying, sitting, and standing) and working (on a treadmill and cycle ergometer) at three different levels. Energy expenditure (EE) and heart rate (HR) were highly correlated during the second half of gestation and postpartum. Both EE and HR were affected by pregnancy state, but the relationship between HR and EE was not changed. Slopes of regression of two linear components of EE/HR relationship were 0.01-0.02 for resting, and 0.05-0.06 for working measures. The slopes under resting and working conditions are significantly different from zero, and from each other. Prediction of EE from HR is unreliable in the range 80-120 beats/min where resting and working HRs overlap.

Food intake measurement: problems and approaches.

Sources of variance in dietary intake records were measured and compared. Eighteen graduate students recorded self-selected food intakes during a 30-day study. Subjects were divided into two groups and on alternating 5 consecutive day periods, one group weighted all food consumed and recorded it on tape recorders while the other group recorded estimated intake in small notebooks. An average of two, 24-h dietary recalls was also obtained from each subject and compared to previously estimated intake. The major contributions to total variance were within subject and between subject variance. There was no difference in the mean protein and energy intake recorded by weighing when compared to that recorded in household measures, but there was less variability in the records obtained by weighting intake. The 95% confidence limits were calculated both for the group's and an individual's intake for each method, these demonstrated that 1-day dietary record gave a reasonable estimate (within 15%) of the usual intake of the group. However, the 1-day record, regardless of which method used, gave a meaningless estimate of an individual's usual diet. The protein/energy ratios and the coefficient of interindividual variation are also reported.

Some aspects of bile acid and urobilinogen excretion and fecal elimination in men given a rural Guatemalan diet and egg formulas with and without added oat bran.

Six healthy men were fed a formula diet with and without oat bran and a natural food diet typical of rural Guatemala. No significant difference in dye transit time was found between diets but the Guatemalan diet significantly decreased dye retention time and increased stool frequency. Serum cholesterol and triglyceride levels showed no significant differences among dietary treatments. Excretion of fecal bile acids significantly increased on the Guatemalan and oat bran diets, but fecal bile acid concentration was significantly lower only on the Guatemalan diet. Urinary urobilinogen excretion and fecal urobilinogen concentration were significantly lower with the Guatemalan diet.

Lactation and pregnancy in Iran. III. Hormonal factors.

Lactation failure is common in urban areas of industrially developing countries, but little is known about its epidemiology and causality. The study reported here was undertaken to investigate the serum levels of some hormones other than prolactin that have been shown in animal studies to play a role in lactation, and to examine their relationship to adequacy of lactation and to nutritional and socioeconomic status in urban Iranian women. Serum levels of placental lactogen, growth hormone, cortisol, and thyroid hormones were measured under standard conditions in two groups of pregnant women from low and low middle socioeconomic areas of Teheran, 1 or 2 weeks before parturition and the latter three hormones again in the 3rd month postpartum. Significant differences were found in the biochemical parameters between socioeconomic groups. Hemoglobin and serum albumin values were lower and all the globulin fractions (except alpha 2 globulin during pregnancy), growth hormone and cortisol were higher in the low than the middle socioeconomic subjects, both during pregnancy and postpartum. The discrepancies between the socioeconomic groups were greater postpartum. Growth hormone level was significantly lower in subjects with adequate lactation than inadequate or ceased, and cortisol values show the same trend. No correlations were found between the measured parameters of nutritional status nor free thyroxine values and lactation adequacy. In view of the role of growth hormone and cortisol in stress and malnutrition and some evidence of a reciprocal relationship between growth hormone and prolactin, these hormones may be a link in the chain between the urban environment, malnutrition and lactation failure.

Lactation and pregnancy in Iran. II. Diet and nutritional status.

Dietary intake in the third month postpartum and nutritional status during pregnancy close to term were assessed in Iranian urban uomen of low and middle socioeconomic status as part of a study investigating nutrition, hormonal status, and lactation in a population where lactation failure is a serious problem. Dietary intake was assessed by the 24-hr-recall method. The greatest differential in food groups consumed was in animal products, fruit, and vegetables. Intake of nutrients equal to or less than 80% of recommendations in both socioeconomic groups were energy, vitamin B6, folacin, calcium, iron, and zinc. In the low socio-economic group, only average intakes of vitamin C, thiamin and protein met the standards. Significant differences were found between the socioeconomic groups in hemoglobin, hematocrit, serum total protein, and protein fractions, but not in weight and height. The only parameters of nutritional status significantly correlated with adequacy of lactation were postpartum weight and percent of standard weight for height in the low socioeconomic group, and hematocrit values in the middle socioeconomic group. Differences between pregnant and postpartum individual values of the blood parameters were in general greater in the middle socioeconomic group than the low socioeconomic group.

PIP: Dietary intake in the 3rd month postpartum and nutritional status during pregnancy close to term were assessed in Iranian urban women of (LSE) low socioeconomic status and (MSE) middle socioeconomic status as part of a study investigating nutrition, hormonal status, and lactation in a population where lactation failure is a serious problem. Dietary intake was assessed by the 24-hour recall method. The greatest differential in food groups consumed was in animal products, fruit, and vegetables. Intake of nutrients = or than 80% of that recommended to both socioeconomic groups were energy, vitamin B6, folacin, calcium, iron, and zinc. In the LSE group, only average intakes of vitamin C, thiamin, and protein met the standards. Significant differences were found between the socioeconomic groups in hemoglobin, hematocrit, serum total protein, and protein fractions, but not in weight and height. The only parameters of nutritional status significantly correlated with adequacy of lactation were postpartum weight and % of standard weight for height in the LSE group, and hematocrit values in the MSE group. Differences between pregnant and postpartum individual values of the blood parameters were in general greater in the MSE group than the LSE group.

Lactation and pregnancy in Iran. I. Social and economic aspects.

Adequacy of lactation was assessed in Teheran women of low (LSE) and lower-middle (MSE) socioeconomic status in the third month postpartum, as part of a study linking nutrition, hormonal status, and lactation. Methods of assessment of nutritional adequacy are discussed. Characteristics of the socioeconomic groups, infant mortality, food beliefs related to lactation, and supplemental feeding practices are described. Of the LSE mothers 15 to 30% and of the MSE mothers 40 to 55% had a fully adequate milk supply in the third month. Substitutes used and affordable by the LSE were nutritionally inadequate. LSE mothers were traditional in their food beliefs. MSE mothers demonstrate the influence of scientific nutrition knowledge. The low percentage of lactation adequacy even in the MSE indicates that other social or health factors associated with urban living conditions may be just as important as economic and nutritional factors in lactation failure.

PIP: Adequacy of lactation was assessed in Teheran, Iran, among women of low (LSE) and lower-middle (MSE) socioeconomic status in the 3rd month postpartum as part of a study linking nutrition, hormonal status, and lactation. Subjects were selected randomly from women with uncomplicated pregnancies who attended 2 clinics in Teheran within 2 weeks of the expected date of birth. Subjects were interviewed, anthropometric data were obtained, and a blood sample was taken for hormonal and nutritional evaluation. Socioeconomic data, medical history, and dietary intake information were obtained. Characteristics of the socioeconomic groups, infant mortality, food beliefs related to lactation, and supplemental feeding practices are described. The criteria of lactation adequacy used were based primarily on the classification of nutritional status in early childhood as proposed by McLaren and Read. 15-30% of the LSE and 40-55% of the MSE mothers had a fully adequate milk supply in the 3rd month. Substitutes used and affordable by the LSE mothers were nutritionally inadequate, and this group of mothers was traditional in their food beliefs. MSE mothers demonstrated the influence of scientific knowledge. The low percentage of lactation adequacy even among the MSE mothers indicates that other social or health factors associated with urban living conditions may be as important as economic and nutritional factors in lactation failure.

Menstrual cycle and voluntary food intake.

The relationship of food intake and the human menstrual cycle has not been well quantified. In this study, voluntary energy and sucrose intake of seven women, aged 24-43 y, were evaluated by the weighed-intake method over one entire menstrual cycle. Portable tape recorders facilitated the recording of food intake. Although daily fluctuations of energy intake were large, analysis of variance showed intake during the luteal phase to be significantly greater than during the periovulatory and follicular phases (p less than 0.05). From 95% simultaneous (Bonferoni) confidence intervals, the estimate of difference was 283 kcal greater during the luteal phase than the periovulatory phase; the estimate of difference was 214 kcal greater during the luteal phase than during the follicular phase. No significant differences in energy intake were found among the menstrual, follicular, and periovulatory phases. No significant relationship was found between sucrose intake and the menstrual cycle.

Estimated vitamin intakes of toddlers: predicted prevalence of inadequacy in village populations in Egypt, Kenya, and Mexico.

Vitamin intakes of 255 toddlers (aged 18-30 mo) were estimated from food consumption recorded during 1 y at sites in Egypt, Kenya, and Mexico. Mean intakes were compared with requirements standards by using a probability approach to estimate the prevalence of inadequate intakes. There were predicted inadequacies for vitamin A (32%) and riboflavin (20%) in Egypt, vitamins A (68%) and C (63%) and riboflavin (52%) in Mexico, and vitamin B-12 (44%) in Kenya. Vitamin E was inadequate in all diets, but in relation to polyunsaturated fatty acids only the intake in Mexico was low. No diet provided the recommended amount of vitamin D, but its dietary requirement is uncertain. Correlations among nutrient intakes suggest factors that may contribute to reported associations of consumption of animal products with improved growth or development among these children: provision of vitamin B-12 and available minerals, displacement of fiber and phytate-rich energy sources, and increased energy density.

PIP: Data on 255 children, 18-30 months old, in Kalama village on the Nile delta in Egypt, the Embu district in Kenya, and the Solis Valley in Mexico were analyzed over a 1-year period to study the relationships of energy and animal protein intakes with vitamins, minerals, and two factors that affect bioavailability, dietary fiber and phytate. The researchers used the probability approach to determine the prevalence of inadequate intakes. Estimated intake inadequacies were 32% for vitamin A and 20% for riboflavin in Egypt; 68% for vitamin A, 63% for vitamin C, and 52% for riboflavin in Mexico, and 44% for vitamin B12 in Kenya. All the diets were deficient in vitamin E. Yet, when researchers compared vitamin E in relation to polyunsaturated fatty acids, the vitamin E intake was low only in Mexico. None of the diets had the recommended amount of vitamin D, but actual dietary requirements were unknown. Further, the researchers had no information on solar exposure. Provision of vitamin B12 and available minerals, displacement of fiber and phytate-rich energy sources, and increased energy density were associated with improved growth or development among children ingesting animal products (p 0.05). Intakes of folacin, niacin, and thiamin were negatively related to animal protein intake (p 0.05).

Estimated mineral intakes of toddlers: predicted prevalence of inadequacy in village populations in Egypt, Kenya, and Mexico.

Intakes of minerals and factors that might affect their bioavailability were estimated for 255 toddlers aged 18-30 mo living in villages in Egypt, Kenya, and Mexico. Mean intakes over 1 y were compared with international-requirement estimates by using a probability approach. The prevalence of iron intakes likely to be inadequate to prevent anemia was estimated as 35% in Egypt, 13% in Kenya, and 43% in Mexico. The prevalence of zinc intakes likely to be inadequate to meet basal requirements was estimated as 57% and 25% in Kenya and Mexico, respectively, but only 10% in Egypt, where the use of yeast-leavened breads was judged to have improved zinc availability. There was no suggestion that estimated copper or magnesium intakes were inadequate, but calcium intakes in Kenya and Egypt were well below recommended amounts. Studies of factors affecting mineral bioavailability in the diets of these countries' populations could suggest dietary changes that might improve effective mineral intake with minimal cost.

Estimated protein intakes of toddlers: predicted prevalence of inadequate intakes in village populations in Egypt, Kenya, and Mexico.

This paper presents a probability assessment of the adequacy of protein intakes of toddlers (aged 18-30 mo) in study communities in Egypt, Kenya, and Mexico judged in relation to FAO/WHO/UNU estimates of requirements. Effects of supplementing amino acid intakes, or of assuming lower bioavailability for lysine are also considered. In Egypt and Mexico existing protein intakes of toddlers were adequate. In Kenya existing intakes were marginal. Total protein intake was low and often lysine or tryptophan concentration was low. If Kenyan intakes met estimated energy requirements, protein intakes would be adequate. We conclude that protein intake is unlikely to be a primary limiting factor for toddler growth and development, and the benefit to be expected from increasing the intake of limiting amino acids is marginal. Reported associations of animal-source protein and energy with growth, size, and psychologic function of these toddlers are unlikely to be causally attributable to inadequacy of protein intakes.

Integumentary loss of calcium.

Integumentary calcium loss was studied in 16 healthy young men. The daily loss by the 16 ambulatory but relatively sedentary young men in 52 determinations of 6-day periods each was 8.7 +/- 1.9 mg/m2 per day (average 15.8 mg/man per day). The amount lost was not influenced by calcium intake (0.1 to 2.3 g/day). In contrast to urinary calcium excretion, which is directly related to protein intake, there was no significant change in integumentary calcium loss with varying protein intakes (1 to 96 g nitrogen per day). No compensatory relationship between urinary and integumentary calcium excretion was noted. During strenuous exercise calcium loss increased to an average of 25 mg in 40 min. There was no compensatory decrease in urinary excretion on the day of strenuous exercise. It was also noted that integumentary calcium loss was not affected by general calcium balance.

Effects of marginally negative energy balance on insulin binding to erythrocytes of normal men.

Six healthy male volunteers were confined to a metabolic unit for 105 days. Energy intake (EI) and energy expenditure (EE) were varied in order to achieve either a marginally negative (-15%) or an equilibrated energy balance (EB), in different metabolic periods (MP) as follows: MP I: EE = 1, EI = 1, EB = 0; MP II: EE = 1, EI = 0.85, EB = -15%; MP III: EE = 0.85, EI = 0.85, EB = 0; MP IV: EE = 0.85, EI = 0.70, EB = -15%; MP VI: EE = 1.15, EI = 1.15, EB = 0; MP VII: EE = 1.15, EI = 1, EB = -15%. An egg protein formula diet was fed throughout the study. The amount given in MP I was sufficient to maintain body weight constant. Assigned physical activity consisted of regulated walking and cycling. During MP I, this physical activity accounted for 15% of the energy intake. Serum insulin, insulin binding to erythrocytes and body fat content were determined at the end of each MP. No significant changes were found in serum insulin level throughout the study, but specific insulin binding did change significantly. Binding increased with increased physical activity by 23% at the end of MP VI and an additional 35% at the end of MP VII. The maximum percentage of insulin binding to erythrocytes correlated inversely with the percentage of body fat in each MP. These data suggest that insulin binding to erythrocytes, in normal men, is sensitive to a small change in energy balance, and especially to physical activity.(ABSTRACT TRUNCATED AT 250 WORDS)

Menstrual cycle and basal metabolic rate in women.

Basal metabolic rate, resting metabolic rate (RMR), and energy cost of selected activities were measured in six healthy young women who were participating in a study of protein requirements. The women were confined to a metabolic unit for 92 days during which they consumed a defined formula diet. The basal metabolic rate of the women was 20.7 +/- 2.6 kcal/kg body weight/day and the caloric requirement for maintenance of weight was 38.7 kcal/kg body weight/day. Basal metabolic rate varied significantly with the menstrual cycle. Basal metabolic rate decreased at menstruation and fell to its lowest point approximately 1 wk before ovulation subsequently rising until the beginning of the next menstrual period. RMR was 0.99 +/- 0.16 kcal/kg/h. The energy expenditure while sitting was 1.06 times RMR, while walking it was 2.81 times RMR, and while performing treadmill exercise it was 3.47 times RMR.

Nutritional assessment of pregnant and lactating Navajo women.

Nutritional parameters of 87 Navajo women were assessed at term and in 23 of these women after 1 month of lactation. Serum levels of zinc, retinol-binding protein, folacin, protein, Hb, and ferritin and hair zinc content were determined. Twenty-four-hour dietary recalls were recorded for the subsample of 23 women. Median nutrient intakes were less than 60% of the Recommended Dietary Allowance of calcium, magnesium, zinc, copper, vitamins A (lactation only), D, E, and B6, biotin, and folacin. Serum zinc fell below 50 microgram/dl in 68% of the subsample at term and remained below 65 microgram/dl 43% during lactation. Serum retinol was below normal ( less than 33 microgram/dl) in 24% of these women at term and 23% at 1 month. Low serum folacin (less than 6 ng/ml) was detected in 9% at term and 24% at 1 month. Anemia was present in 15 to 20% of the women. Serum protein, retinol-binding protein, ferritin, and hair zinc were essentially normal. Biochemical findings confirmed dietary inadequacies among Navajo women and indicate needed nutritional improvement.

Hormonal changes in normal men under marginally negative energy balance.

Six men were confined to a metabolic unit for 105 days. Their assigned work and energy intake were varied throughout six metabolic periods in order to create either a marginally negative (-15%) or an equilibrated energy balance. They were fed a defined diet providing a constant amount of protein. At each metabolic period, T4, T3, reverse T3(rT3), free T3, free reverse T3, thyroid-stimulating hormone, cortisol, cortisol-binding globulin, testosterone, and testosterone/estradiol-binding globulin were measured. Free urinary cortisol was measured daily. Results show that serum thyroid hormones are sensitive to marginal changes in energy intake, expenditure, and balance. The ratio T4/T3 appears to be more sensitive to the balance itself, with the ratio T3/rT3 being more sensitive to the intake and expenditure level at which this balance is established. Regulations of T3 and rT3 production are probably distinct. Urinary cortisol did not show any variation that could be related to the energy balance. However, daily urinary cortisol was correlated to daily urinary nitrogen excretion. No change in serum testosterone was found.