Effects Of Caloric Intake Research Articles

Caloric Intake in Renal Patients: Repercussions on Mineral Metabolism.

The aim of this paper is to review current knowledge about how calorie intake influences mineral metabolism focussing on four aspects of major interest for the renal patient: (a) phosphate (P) handling, (b) fibroblast growth factor 23 (FGF23) and calcitriol synthesis and secretion, (c) metabolic bone disease, and (d) vascular calcification (VC). Caloric intake has been shown to modulate P balance in experimental models: high caloric intake promotes P retention, while caloric restriction decreases plasma P concentrations. Synthesis and secretion of the phosphaturic hormone FGF23 is directly influenced by energy intake; a direct correlation between caloric intake and FGF23 plasma concentrations has been shown in animals and humans. Moreover, in vitro, energy availability has been demonstrated to regulate FGF23 synthesis through mechanisms in which the molecular target of rapamycin (mTOR) signalling pathway is involved. Plasma calcitriol concentrations are inversely proportional to caloric intake due to modulation by FGF23 of the enzymes implicated in vitamin D metabolism. The effect of caloric intake on bone is controversial. High caloric intake has been reported to increase bone mass, but the associated changes in adipokines and cytokines may as well be deleterious for bone. Low caloric intake tends to reduce bone mass but also may provide indirect (through modulation of inflammation and insulin regulation) beneficial effects on bone. Finally, while VC has been shown to be exacerbated by diets with high caloric content, the opposite has not been demonstrated with low calorie intake. In conclusion, although prospective studies in humans are needed, when planning caloric intake for a renal patient, it is important to take into consideration the associated changes in mineral metabolism.

Effects of Caloric Intake and Aerobic Activity in Individuals with Prehypertension and Hypertension on Levels of Inflammatory, Adhesion and Prothrombotic Biomarkers-Secondary Analysis of a Randomized Controlled Trial.

Background: Cardiopulmonary fitness and low calorie diets have been shown to reduce inflammation but few studies have been conducted in individuals with elevated blood pressure (BP) in a randomized intervention setting. Thereby, adhesion biomarkers, e.g., soluble intercellular adhesion molecule (sICAM)-3, have not been examined so far. Methods: Sixty-eight sedentary prehypertensive and mildly hypertensive individuals (mean age ± SEM: 45 ± 1 years; mean BP: 141/84 ± 1/1 mmHg) were randomized to one of three 12-week intervention groups: cardio training and caloric reduction, cardio training alone, or wait-list control group. Plasma levels of inflammatory, adhesion and prothrombotic biomarkers were assessed. In a second step, intervention groups were combined to one sample and multivariate regression analyses were applied in order to account for exercise and diet behavior changes. Results: There were no significant differences among the intervention groups. In the combined sample, greater caloric reduction was associated with a larger increase of sICAM-3 (p = 0.026) and decrease of C-reactive protein (p = 0.018) as a result of the interventions. More cardio training was associated with increases of sICAM-3 (p = 0.046) as well as interleukin-6 (p = 0.004) and a decrease of tumor necrosis factor-α (p = 0.017) levels. Higher BP predicted higher plasminogen activator inhibitor (PAI)-1 (p = 0.001), and greater fitness predicted lower PAI-1 levels (p = 0.006) after the intervention. Conclusions: In prehypertensive and hypertensive patients, plasma levels of the adhesion molecule sICAM-3 and inflammatory biomarkers have different response patterns to cardio training with and without caloric reduction. Such anti-inflammatory and anti-thrombotic effects may have implications for the prevention of atherothrombotic cardiovascular disease among individuals at increased risk.

Abstract MP70: Habitual Sleep Variability, Mediated by Energy Intake, is Associated with Abdominal Obesity in Adolescents

Introduction: Although self-reported sleep duration has been associated with obesity, study of the association between objectively-measured habitual sleep pattern and the more metabolically relevant abdominal obesity, and the mediation factors for such an association, is limited. Hypothesis: We assessed the hypothesis that objectively-measured variability, mediated by excessive energy intake, is associated with abdominal obesity in adolescents. Methods: We used data from 421 adolescents in the Penn State Child Cohort follow-up examination. Actigraphy was used for 7 consecutive nights to calculate each participant’s mean sleep duration as habitual sleep duration (HSD) and the standard deviation of the mean as habitual sleep variability (HSV). Abdominal obesity was assessed by dual-energy x-ray absorptiometry as Android/Gynoid Fat Ratio and visceral fat area . Youth/Adolescents Food Frequency Questionnaire was used to obtain daily caloric, fat, carbohydrate, and protein intakes one year prior to the study. The R-based Mediation Effect Models were used to assess the association between sleep pattern and abdominal obesity, and quantitatively estimate the mediation effects of caloric intake and of other factors not analyzed in this report. Results: As shown in the table, after controlling for major confounders and BMI percentile, HSV was significantly and consistently associated with both abdominal obesity measures. The Mediation analysis consistently indicated a significant mediation effect of caloric intake, especially carbohydrate intake. For example, 20% of the association between HSV and visceral fat could be attributed to carbohydrate intake, while 80% by other factors not analyzed. HSD was not associated with abdominal obesity. Conclusions: Higher HSV, not HSD, is associated with abdominal obesity, which can be partially explained by increased caloric intake, especially from carbohydrate, in adolescents. More studies are needed to identify other mediation factors in the association.

Effects of Caloric Intake on Learning and Memory Function in Juvenile C57BL/6J Mice

Dietary composition may influence neuronal function as well as processes underlying synaptic plasticity. In this study, we aimed to determine the effect of high and low caloric diets on a mouse model of learning and memory and to explore mechanisms underlying this process. Mice were divided into three different dietary groups: normal control (n = 12), high-caloric (HC) diet (n = 12), and low-caloric (LC) diet (n = 12). After 6 months, mice were evaluated on the Morris water maze to assess spatial memory ability. We found that HC diet impaired learning and memory function relative to both control and LC diet. The levels of SIRT1 as well as its downstream effectors p53, p16, and peroxisome proliferator-activated receptor γ (PPARγ) were decreased in brain tissues obtained from HC mice. LC upregulated SIRT1 but downregulated p53, p16, and PPARγ. The expressions of PI3K and Akt were not altered after HC or LC diet treatment, but both LC and HC elevated the levels of phosphorylated-cAMP response element-binding protein (p-CREB) and IGF-1 in hippocampal CA1 region. Therefore, HC diet-induced dysfunction in learning and memory may be prevented by caloric restriction via regulation of the SIRT1-p53 or IGF-1 signaling pathways and phosphorylation of CREB.

Abstract B30: Indicators of energy balance and breast cancer risk among white and black women

Abstract Introduction: Physical activity has been linked to reduced breast cancer risk, especially among women diagnosed postmenopausally. Since the majority of studies of this association have been conducted in white women, we used the Nashville Breast Health Study (NBHS) to determine whether similar effects were seen in black women. Methods: The NBHS is a population-based case-control study of breast cancer among women age 25 to 75 conducted between 2001 and 2010 in and around the Nashville Metropolitan area. Telephone interviews were completed with 1,866 incident breast cancer cases ascertained through hospitals and the statewide cancer registry, and 2,306 randomly selected controls (with respective response rates of 58% and 79%). Results: A greater percentage of white (premenopausal 59%, postmenopausal 54%) than black (premenopausal 51%, postmenopausal 43%) women reported they had engaged in leisure-time physical activity or exercise in the past 10 years. Among premenopausal white and black women, there was little effect of exercise on breast cancer risk; however, occupational activity, defined as standing and walking at work, was associated with an increased risk of breast cancer. After adjusting for confounding and dividing the group of women who had engaged in exercise into tertiles (MET hours per day), there was a suggested reduction in postmenopausal breast cancer in women of both races (highest tertile relative to none - white odds ratio [OR] 0.8, 95% confidence interval [CI] 0.6-1.0, p for trend=0.058; black OR 0.7, 95% CI 0.4-1.1, p for trend=0.098). Similar point estimates were found for occupational activity. When considering the joint effects of caloric intake, obesity and weight gain since age 18 on the association of exercise and breast cancer, the greatest effect was seen for weight gain since 18 with increased risks in most categories relative to women in the highest tertile of exercise who had lost or maintained weight. This pattern was most pronounced among white women diagnosed postmenopausally, but among black women diagnosed premenopausally. Discussion: Our results indicate that although postmenopausal black women report engaging in very little leisure-time physical activity, its' effect on breast cancer risk is comparable to white women. However, the joint effect of adult weight gain on the exercise and breast cancer association may differ by race and menopausal status. White and black women should be encouraged to engage in leisure-time physical activity regardless of the amount of work- and housework-related physical activity done to help reduce their risk of breast cancer and other chronic diseases. Citation Format: Maureen Sanderson, Sandra L. Deming-Halverson, Alecia M. Fair, Martha J. Shrubsole, Alicia Beeghly-Fadiel, Sarah Nechuta, Yong Cui, David Shen-Miller, Heather O'Hara, Nia Foderingham, Xiao-Ou Shu, Wei Zheng. Indicators of energy balance and breast cancer risk among white and black women. [abstract]. In: Proceedings of the Sixth AACR Conference: The Science of Cancer Health Disparities; Dec 6–9, 2013; Atlanta, GA. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2014;23(11 Suppl):Abstract nr B30. doi:10.1158/1538-7755.DISP13-B30

The Effect of Nutritional Status in the Pathogenesis of Critical Illness Myopathy (CIM).

The muscle wasting and loss of specific force associated with Critical Illness Myopathy (CIM) is, at least in part, due to a preferential loss of the molecular motor protein myosin. This acquired myopathy is common in critically ill immobilized and mechanically ventilated intensive care patients (ICU). There is a growing understanding of the mechanisms underlying CIM, but the role of nutritional factors triggering this serious complication of modern intensive care remains unknown. This study aims at establishing the effect of nutritional status in the pathogenesis of CIM. An experimental ICU model was used where animals are mechanically ventilated, pharmacologically paralysed post-synaptically and extensively monitored for up to 14 days. Due to the complexity of the experimental model, the number of animals included is small. After exposure to this ICU condition, animals develop a phenotype similar to patients with CIM. The results from this study show that the preferential myosin loss, decline in specific force and muscle fiber atrophy did not differ between low vs. eucaloric animals. In both experimental groups, passive mechanical loading had a sparing effect of muscle weight independent on nutritional status. Thus, this study confirms the strong impact of the mechanical silencing associated with the ICU condition in triggering CIM, overriding any potential effects of caloric intake in triggering CIM. In addition, the positive effects of passive mechanical loading on muscle fiber size and force generating capacity was not affected by the nutritional status in this study. However, due to the small sample size these pilot results need to be validated in a larger cohort.

Effect of Caloric Intake on Western-Style Diet-Induced Intestinal Tumors in a Mouse Model for Hereditary Colon Cancer

Increased caloric intake has been associated with increased risk for cancer of the large intestine. We studied caloric intake effect on tumor formation in Apc1638 N/+ mice, a preclinical model for human familial adenomatous polyposis. Mice were fed a controlled AIN-76A diet or a new Western-style diet (NWD). Intestinal tumor development was evaluated after 6 mo of feeding 1) AIN-76A diet (fed ad libitum) vs. AIN-76A (caloric intake reduced 30%); 2) NWD (fed ad libitum) vs. NWD (caloric intake reduced 30%); and 3) AIN-76A (fed ad libitum) vs. NWD (paired-fed with NWD providing equal caloric intakes to AIN-76A). Intestinal tumor incidences were 78–100% with intergroup variation P > 0.05; however, tumor multiplicity responded differently to dietary treatment: 1) Tumor multiplicity was unchanged after AIN-76A (caloric intake reduced 30% vs. mice fed AIN-76A ad libitum); 2) tumor multiplicity was unchanged after NWD (caloric intake reduced 30% vs. NWD ad libitum); and 3) tumor multiplicity increased 130% after NWD was paired-fed with the same caloric intake as mice fed AIN-76A ad libitum (P < 0.05). Body weights showed no association with tumor development. Findings indicated modified nutrients in NWD were mainly responsible for increased tumors in mice fed NWD vs. AIN-76A in this preclinical mouse model for human FAP.

A double-blind, randomised, placebo controlled study on the influence of carbohydrate solution intake during labour

Objective Although there has been much debate on whether women should be allowed to eat and drink during labour, little scientific data are available on the effects of caloric intake on the course of labour. Design Double-blind, randomised, placebo controlled. Setting Leyenburg Hospital, The Hague, The Netherlands. Population Two hundred and one consecutive nulliparous women, pregnant of a single fetus in cephalic presentation. Methods All women were included in early labour (2cm–4cm of cervical dilatation) and were allowed to drink at will. Main outcome measures The duration of labour, the need for augmentation and pain medication and the incidence of abdominal and vaginal instrumental deliveries. Results Drinking of carbohydrate solutions was well tolerated, but did not show any beneficial effects regarding labour outcome when compared with the control group. In the carbohydrate group, a higher caesarean section rate was observed (RR 2.9, 95% CI 1.29–6.54). Conclusions Women in the carbohydrate group had worse labour outcome. It is unclear whether a statistical coincidence, a negative effect of the carbohydrate intake or an incorrect carbohydrate intake strategy is responsible for these results. Further studies are necessary before any definite conclusion can be drawn.

Caloric intake stimulates growth hormone secretion in food-deprived rats with anterolateral deafferentation of the medial basal hypothalamus or administered antiserum to somatostatin.

In rats, food deprivation inhibits episodic growth hormone (GH) secretion. On the basis of previous studies, we hypothesized that during a recovery from prolonged fasting, caloric intake stimulates the release of GH-releasing factor (GRF) and this process does not depend on the specific macronutrients in the meal, while protein in the meal acts to restore characteristic ultradian rhythmicity of GH secretion. To test this hypothesis, the effect of caloric intake on GH secretion was examined in fasted adult male Wistar rats devoid of somatostatin (SS) influence on GH secretion either by anterolateral deafferentation (ALC) of the medial basal hypothalamus (MBH) or administration of anti-SS goat serum (ASS). Rats were provided with an indwelling right atrial cannula and were deprived of food for 72 h. ALC was performed 2 weeks prior to the study. ASS was given i.v. 8 h and 7 h prior to refeeding, respectively. Serial blood specimens were collected every 10 min. In rats with ALC (ALC rats) or rats given ASS (ASS rats), the blood GH level revealed irregularly occurring small fluctuations, instead of the usual high bursts and low trough level. The baseline GH level and the mean GH level of fasted ALC rats or fasted ASS rats were significantly lower than those of fed ALC rats or fed ASS rats. Feeding the isocaloric mixed meal, the protein meal or the protein-deficient meal increased the GH pulse frequency, the pulse amplitude, the baseline GH level and the mean GH level in 72-h fasted ALC rats. These changes in GH secretory pattern persisted during the period of observation and were independent of the type of meal ingested. Following feeding the mixed meal, similar changes in the GH secretory pattern demonstrated in 72-h fasted ALC rats were also observed in 72-h fasted ASS rats, suggesting that the stimulation of GH secretion following caloric intake is not limited to ALC rats. Since the influence of SS on GH secretion has been largely eliminated in ALC or ASS rats, it is highly unlikely that the augmentation of GH secretion following feeding after prolonged food deprivation was the consequence of inhibition of SS secretion. Although GRF measurement was not performed, it is conceivable that the signal of caloric intake is conveyed to the MBH and acts to stimulate GRF release.

Modulation of oxidative DNA damage levels by dietary fat and calories.

Decreased dietary intake of fat and/or calories generally results in a lower incidence of mammary gland tumors in rodents. Feeding of either low-fat or calorie-restricted diets to rats also has been shown to result in decreased levels of oxidative DNA damage. Since oxidative DNA damage is suggested to have a role in carcinogenesis, this may be one mechanism by which dietary change can reduce cancer risk. The effects of calorie-restricted diets on both oxidative DNA damage levels and mammary gland tumor incidence are generally more pronounced than that of low-fat diets. There is, however, some difficulty in defining what amount of fat should be used to prepare 'low-fat' and 'high-fat' rodent diets as well as what a suitable fat intake for control diets should be in studies that examine the effects of dietary fat and/or calories on tumorigenesis. In particular, the promoting effects of dietary fat may be exerted only up to a certain level of fat, above which no further effect is observed. Another difficulty in the interpretation of the results is that there may be a time-dependent effect of high fat diets on oxidative damage, with increased damage resulting only when the diets are fed for longer periods of time. The appropriate experimental approach to model human dietary exposures therefore remains to be determined. Although the effects of caloric intake on mammary gland tumorigenesis appear to be more pronounced than that of fat intake, low-fat diets still may be useful as a preventive measure in human populations to reduce breast cancer risk for individuals who cannot safely reduce their caloric intake.

Effects of diet and body fat content on cold-induced anestrus in Syrian hamsters

Mammalian reproduction is inhibited by food shortages, increased foraging requirements, and other factors that decrease the energy available for biological processes. Cold-induced inhibition of reproduction may result from a depletion of available metabolic energy due to the increased requirements for thermogenesis or, alternatively, from mechanisms unrelated to energy expenditure. We examined the relationship between energy availability (in the diet and the body fat stores) and cold-induced anestrus in Syrian hamsters. In experiment 1, hamsters were housed in the cold (5 degrees C) and fed diets that differed in the amount of effort required to ingest them. The number of consecutive estrous cycles was positively correlated with caloric intake and negatively correlated with body weight loss in the cold. In experiment 2, hamsters were fed these diets for several weeks, so that they differed dramatically in body weight and fat content before cold exposure. Half of each group retained the same diet during cold exposure, whereas the other half were fed a regular chow diet. The effects of body weight before cold exposure were less pronounced than the effects of caloric intake during cold exposure. In experiment 3, females were fed different diets before cold exposure, then, during cold exposure, all were fed in a manner that decreased food intake and increased the effort required to obtain food. This energetic challenge exaggerated the effect of prior body weight on the latency to cold-induced anestrus. Thus the latency to cold-induced anestrus in Syrian hamsters is primarily a function of the availability of metabolic energy.(ABSTRACT TRUNCATED AT 250 WORDS)

The Effects of Altered Nutritional Status upon Insulin-Like Growth Factors and their Binding Proteins in Neonatal Rats

To investigate the role of nutrition in the regulation of IGFs during the perinatal period, 10-d-old rats were infused intravenously with various concentrations of nutrients for 24 h. Breast-fed litter mates served as controls. The effect of caloric intake on concentrations of IGF-I and IGF-II as well as IGF-binding proteins in serum, liver, and brain of neonatal rats was studied. A total of 45 rats from 10 litters was infused with solutions ranging from a caloric intake of 0 (saline) to 75% (glucose, amino acids, and lipids) of the estimated intake of control rats. In serum, both IGF-I and -II concentrations fell markedly in response to fasting. Serum IGF-II levels were linearly related to caloric intake in the pooled data from all groups. Concentrations of IGF-II, but not IGF-I, in liver and brain were depressed by caloric restriction. In contrast to the fall in IGF concentrations, activity of IGF-associated binding proteins rose in serum and in liver cytosol 2- to 4-fold in response to decreased nutrient intake. In serum, but not liver, the rise in binding protein activity was inversely related to to caloric intake. In liver, cytosol, but not serum, the rise in binding protein activity was inversely related to total serum amino acid concentration. Thus, IGF concentrations in preweanling rats change in response to alterations of nutrient intake. The fasting induced decrements in IGF levels, as well as the elevations in IGF-associated binding protein activity, may serve as a protective mechanism to depress growth in times of caloric restriction.

Influence of caloric intake on experimental carcinogenesis: a review.

The effect of caloric intake on tumor growth has been recognized for over 70 years. Inhibition of tumor growth depends primarily on the extent of caloric restriction, but tumor type, animal strain, and dietary composition all exert some influence. Caloric restriction is most effective when maintained during both initiation and promotion, but if limited to one of these phases, restriction during promotion appears to be the more effective modality. The types of tumor that have been studied include spontaneous mammary and lung tumors as well as tumors induced by organ-specific carcinogens or irradiation with ultraviolet light. Numerous investigators have studied the effects of fat, and a diet low in calories but high in fat is generally significantly more effective in inhibiting carcinogenesis than is a diet high in calories but low in fat. Mice fed high fat, low calorie diets exhibited 48% fewer chemically induced skin tumors and 61% fewer tumors induced by ultraviolet irradiation than did mice fed low fat, high calorie diets. Mice fed a diet containing 2% fat exhibited a 66% incidence of skin tumors, whereas mice fed an isocaloric diet containing 61% fat showed a 78% incidence. Rats whose diet was restricted in calories by 40% exhibited no mammary tumors (coconut oil as primary dietary fat) or 75% fewer tumors (corn oil as dietary fat) compared to ad libitum-fed controls; they also exhibited 47% fewer colonic tumors. The mechanism by which caloric restriction exerts its tumor-inhibiting effects remains to be elucidated.

THE RELATIONSHIP BETWEEN INFANT TEMPERAMENT AND ADIPOSITY IN HEALTHY INFANTS

The effect of caloric intake, 24 hour heart rate and infant temperament (Carey Scale) on adipose tissue deposition was studied in two groups of healthy 18 month old infants: Group I (N=10) had weight by length (W/L) and triceps skinfold thickness (TSF) above the 75%ile and Group II (N=11) had W/L and TSF between 25-75%ile of the growth chart. The caloric intake in infants in group I and II was comparable (mean ± SEM 102.3 ± 7.8 vs. 121.5 ± 10.7 kcal/kg/day). No significant differences in heart rate during awake and asleep periods were seen between the two gorups. The number of infants in Group I and II classified into four temperament categories varying from easy, intermediate low, intermediate high, and difficult were respectively 1 vs 3, 4 vs 3, 2 vs 5 and 2 vs 0. Multiple linear regression analysis applied to this data showed that an increse in scores for difficult temperament in infants in Group II correlated positively with caloric intake (r2 = 0.41), and heart rate awake (r2 = 0.54), and negatively with five skinfold thickness (r2 = -0.71). Conversely, an increase in scores for difficult temperament in infants in Group I correlated negatively with caloric intake (r2 = 0.66), positively with five skinfold thickness (r2 = 0.94) and it was unrelated to changes in heart rate. This study shows that: 1) increased adiposity in infants studied was not explained by differences in caloric intake; 2) decreased adiposity observed in infants with difficult temperament was associated with elevations in heart rate suggesting either increased metabolic and/or physical activity of those infants; 3) the findings of increased adiposity in infants with difficult temperament warrant further investigation.

Small Intestine of Artificially Reared Rat Pups: Effect of Caloric Intake and Dietary Composition on Growth and Disaccharidase Activities

When rats were fed a cow milk formula (CMF) from 12 to 16 days of age at a caloric intake sufficient to support a body weight gain equal to mother-fed (MF) rats, their small intestine outweighed that of MF rats by 40%. If the caloric intake was reduced by approximately 40%, artificially reared (AR) rats exhibited intestinal weights similar to MF rats, but their body weight was lower than MF rats. Sucrase specific activity was precociously increased in all AR rats; this increase was higher in rats with low caloric intake than rats with high caloric intake. Conversely, lactase specific activity was significantly decreased in the ileum of all AR rats. As compared to MF rats, the total lactase activity was significantly lower only in rats with low caloric intake. When AR rats were fed a modified Ross Carbohydrate-Free formula (RCF) containing the same caloric density of protein, fat, and carbohydrate as rat milk, the intestinal growth and disaccharidase activities were the same as those of AR rats fed CMF. It is concluded that the weight gain of small intestine depends on the caloric intake of AR rats and both CMF and RCF are nutritionally equal in supporting intestinal growth. Changes in sucrase and lactase activities in AR rats appear to have no relation to compositional differences in CMF and RCF.

Effects of caloric intake and dietary composition on the development of proteinuria, age-associated renal disease and longevity in the male rat.

The development of age-associated proteinuria and renal disease was studied in groups of male Wistar rats fed 12.5, 25, 50 and 75 kcal of food/day, respectively, and in calorie-restricted (40 kcal/day) rats receiving diets rich in fat, protein or carbohydrate. Proteinuria developed faster, kidneys were larger and the incidence of glomerular lesions and proteinaceous casts was greater in rats eating high calorie diets of 50 kcal/day or more. High protein diets, even when calorie-restricted, increased protein excretion and the incidence of glomerular lesions. In old rats acute food restriction (25 kcal/day) decreased protein excretion by 40% in 1 week, with no further reduction in the 2 week. Life duration was greatest in rats fed 50 kcal/day.

The effect of caloric intake on nitrogen balance in chronic renal failure.

1. Nitrogen balance in uraemic patients on similar nitrogen intakes improves with increasing caloric intake in the range of 36–55 cal/kg body weight. 2. The degree of improvement in nitrogen balance is compatible with increased utilization of endogenous nitrogen probably as a result of increased dietary calories.

Effects of Caloric Intake and Feeding Frequency on Carbohydrate Metabolism of the Rat

The relationship between quantitative nutrient intake and periodicity of food ingestion on the adaptations of carbohydrate metabolism was studied. Glucose and insulin tolerance tests were conducted on animals that had eaten ad libitum (controls), were pair-force-fed or force-fed 80% of the nutrient intake of the others. It was found that, compared with the controls, a) the underfed rat was more reactive, the fully-force-fed animal less responsive, to the hypoglycemic effects of insulin and b) the undernourished rat disposed of a glucose load at a faster rate, the pair-forcefed rat at a slower or equal rate. The results of glucose tolerance tests performed on relatively undernourished rats “trained” to eat for 2 hours/day or pair-fed animals eating aliquots of their ration hourly were similar. In vitro studies with diaphragms and epididymal fat pads (glucose uptakes and insulin sensitivities) of animals that had eaten ad libitum or were force-fed either 100% or 80% of the nutrient intake of the controls yielded data that do not appear to account fully for the in vivo findings. It is concluded that in studies of metabolic adaptations to altered feeding frequency, one should use pair-fed animals given “optimal” amounts of nutrients, which in this case required force-feeding to equalize intake at the ad libitum level.

Effect of Dietary Fat, Protein and Cholesterol on Atherosclerosis in Swine

Three trials involving 48 pigs each were conducted to study the effects of high and low levels of energy intake from 2 fat sources (soybean oil versus tallow), protein level (18 versus 12%) and the addition of 1% cholesterol to the above fat sources, on serum cholesterol levels and the incidence of atherosclerotic lesions in the thoracic and abdominal aortas and coronary arteries. The feeding of diets containing tallow generally resulted in a trend toward higher serum cholesterol levels and increased incidence of lesions except in trial 1, where the coronary arteries of the pigs receiving the diets containing soybean oil had the greater incidence. Serum cholesterol levels were unaffected by the levels of energy intake. The effect of caloric intake on the incidence of lesions was inconsistent. The pigs fed the diets containing 12% protein had slightly elevated serum cholesterol levels as opposed to those fed the diets containing 18% protein. The effect of protein level on the incidence of lesions was inconsistent. Cholesterol addition to the diets significantly increased serum cholesterol levels and incidence of lesions as compared with that observed in the pigs on similar diets without cholesterol addition.

Effect of caloric intake and castration on body weight in the male pheasant (Phasianus colchicus).

Effect of caloric intake and castration on body weight in the male pheasant (Phasianus colchicus).