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We evaluated the effects of high-Ca fat-free milk v. low-Ca control diet on adiposity and on glycaemic control. Fourteen subjects with type 2 diabetes (aged 49·5 (sd 8·6) years, BMI 29·4 (sd 4·5) kg/m2, low habitual Ca consumption (<600 mg/d)) were included in this randomised, crossover clinical trial. Subjects participated in two 12-week experimental sessions (high-Ca fat-free milk (HC) or low-Ca control (LC)) separated by 8-week washout. Subjects daily consumed in the laboratory a breakfast shake containing 700 mg (HC) or 6·4 mg (LC) of Ca. Energy-restricted diets containing 800 mg of dietary Ca/d were prescribed. Dietary records data indicated the consumption of 1200 mg of Ca/d during HC and of 525 mg of Ca/d during LC. There was a greater reduction in body weight, body fat mass, waist circumference and waist:hip ratio after HC. Serum 25-hydoxyvitamin D and homeostatic model assessment-2 β-cell function (HOMA2-%B) increased, and serum uric acid, parathormone (PTH) and glycated Hb (HbA1c) concentrations reduced after HC. In addition, changes from baseline in terms of serum uric acid, glucose, HbA1c and PTH concentrations were lower, and those of HOMA2-%B, serum Ca and 25-hydoxyvitamin D were higher after the HC than after LC. The consumption of approximately three servings of fat-free milk and 1200 mg of dietary Ca/d enhanced weight loss, improved body composition and promoted glycaemic control in subjects with type 2 diabetes and low habitual Ca consumption (<600 mg/d).
We use household scanner data, paired with rich demographics and merged with self-reported measures of obesity and body mass index (BMI), to investigate the potential effects of fruit and vegetable purchasing behavior on adult obesity and body weight. We find that increasing household fruit and vegetable expenditure shares by one percentage point decreases the multiyear incidence of adult obesity by approximately 9 percent and average adult BMI by 1.4 percent, controlling for a host of potential confounding factors and measures of lifestyle choices. The results are robust to specification choice, although estimated impacts differ by gender. Our findings help quantify the potential impacts of government efforts aimed at increasing fruit and vegetable intake.
The fenofibrate functions in mammals could be affected by many factors such as dietary nutrient levels and physiological status. However, this phenomenon has not been well studied in fish. The goal of our study was to investigate the effect of dietary protein contents on metabolic regulation of fenofibrate in Nile tilapia. An 8-week experiment was conducted to feed fish with four diets at two protein levels (28% and 38%) with or without the supplementation of fenofibrate (200 mg/kg body weight/day). After the trial, the body morphometric parameters, plasma biochemical parameters and qPCR data were examined. These results showed that fenofibrate significantly reduced the feeding intake and weight gain rate, increased the oxidative stress (increased plasma methane dicarboxylic aldehyde, MDA) and liver/body ratio (increased hepatosomatic index, HSI) in the LP (low protein)-fed fish. In contrast, fenofibrate exhibited a lipid-lowering (reduced hepatic lipid) effect and up-regulated the expressions of the genes related to lipid catabolism, transport and anabolic metabolism in the HP (high protein) fed-fish. The present study suggested that lipid-lowering effect of fenofibrate would be strengthened in the fish fed with HP diet containing high energy, but in the fish fed with the LP diet containing low energy, the fenofibrate treatment would cause adverse effects for metabolism. Taking together, our study showed that the metabolic regulation of fenofibrate in Nile tilapia was not only dependent on feed energy content, but also dependent on dietary nutrient composition, such as dietary protein and/or lipid levels.
Reduced plasma vitamin D (VD) levels may contribute to excessive white adipose tissue, insulin resistance (IR) and dyslipidaemia. We evaluated the effect of chronic oral VD supplementation on adiposity and insulin secretion in monosodium glutamate (MSG)-treated rats. During their first 5 d of life, male neonate rats received subcutaneous injections of MSG (4 g/kg), while the control (CON) group received saline solution. After weaning, groups were randomly distributed into VD supplemented (12 µg/kg; three times/week) and non-supplemented (NS) rats, forming four experimental groups (n 15 rats/group): CON-NS, CON-VD, MSG-NS and MSG-VD. At 76 d of life, rats were submitted to an oral glucose tolerance test (OGTT; 2 g/kg), and at 86 d, obesity, IR and plasma metabolic parameters were evaluated. Pancreatic islets were isolated for glucose-induced insulin secretion (GIIS), cholinergic insulinotropic response and muscarinic 3 receptor (M3R), protein kinase C (PKC) and protein kinase A (PKA) expressions. Pancreas was submitted to histological analyses. VD supplementation decreased hyperinsulinaemia (86 %), hypertriacylglycerolaemia (50 %) and restored insulin sensibility (89 %) in MSG-VD rats, without modifying adiposity, OGTT or GIIS, compared with the MSG-NS group. The cholinergic action was reduced (57 %) in islets from MSG-VD rats, without any change in M3R, PKA or PKC expression. In conclusion, chronic oral VD supplementation of MSG-obese rats was able to prevent hyperinsulinaemia and IR, improving triacylglycerolaemia without modifying adiposity. A reduced cholinergic pancreatic effect, in response to VD, could be involved in the normalisation of plasma insulin levels, an event that appears to be independent of M3R and its downstream pathways.
While strong evidence from clinical studies suggests beneficial effects of carnitine supplementation on metabolic health, serious safety concerns associated with carnitine supplementation have been raised from studies in mice. Considering that the carnitine doses in these mice studies were up to 100 times higher than those used in clinical studies, the present study aimed to address possible safety concerns associated with long-term supplementation of a carnitine dose used in clinical trials. Two groups of NMRI mice were fed either a control or a carnitine-supplemented diet (1 g/kg diet) from weaning to 19 months of age, and parameters of hepatic lipid metabolism and stress signalling and skeletal muscle gene expression were analysed in the mice at 19 months of age. Concentrations of free carnitine and acetylcarnitine in plasma and tissues were higher in the carnitine than in the control group (P<0·05). Plasma concentrations of free carnitine and acetylcarnitine were higher in mice at adult age (10 and 15 months) than at advanced age (19 months) (P<0·05). Hepatic mRNA and protein levels of genes involved in lipid metabolism and stress signalling and hepatic and plasma lipid concentrations did not differ between the carnitine and the control group. Skeletal muscle transcriptome analysis in 19-month-old mice revealed only a moderate regulation between carnitine and control group. Lifelong carnitine supplementation prevents an age-dependent impairment of plasma carnitine status, but safety concerns associated with long-term supplementation of carnitine at doses used in clinical trials can be considered as unfounded.
Weaning is a critical transition phase in swine production in which piglets must cope with different stressors that may affect their health. During this period, the prophylactic use of antibiotics is still frequent to limit piglet morbidity, which raises both economic and public health concerns such as the appearance of antimicrobial-resistant microbes. With the interest of developing tools for assisting health and management decisions around weaning, it is key to provide robustness indexes that inform on the animals’ capacity to endure the challenges associated with weaning. This work aimed at developing a modelling approach for facilitating the quantification of piglet resilience to weaning. A total of 325 Large White pigs weaned at 28 days of age were monitored and further housed and fed conventionally during the post-weaning period without antibiotic administration. Body weight and diarrhoea scores were recorded before and after weaning, and blood was sampled at weaning and 1 week later for collecting haematological data. A dynamic model was constructed based on the Gompertz–Makeham law to describe live weight trajectories during the first 75 days after weaning, following the rationale that the animal response is partitioned in two time windows (a perturbation and a recovery window). Model calibration was performed for each animal. Our results show that the transition time between the two time windows, as well as the weight trajectories are characteristic for each individual. The model captured the weight dynamics of animals at different degrees of perturbation, with an average coefficient of determination of 0.99, and a concordance correlation coefficient of 0.99. The utility of the model is that it provides biologically meaningful parameters that inform on the amplitude and length of perturbation, and the rate of animal recovery. Our rationale is that the dynamics of weight inform on the capability of the animal to cope with the weaning disturbance. Indeed, there were significant correlations between model parameters and individual diarrhoea scores and haematological traits. Overall, the parameters of our model can be useful for constructing weaning robustness indexes by using exclusively the growth curves. We foresee that this modelling approach will provide a step forward in the quantitative characterisation of robustness.
The aim of this study was to determine the effects of dietary rumen undegradable protein (RUP) level and rumen protected conjugated linoleic acid (rpCLA) on meat fatty acid (FA) profile, chemical compositions and color parameters of growing kids. Thirty two Kurdish goat kids (13.06±1.08 kg BW) were fed diets differing in RUP level (low = 250 vs. high = 350 g/kg of dietary CP) supplemented either with 15 g/kg rpCLA or 12 g/kg of hydrogenated soybean oil (HSO) for 80 days. Interaction of dietary rpCLA and RUP level had no effect on hot carcass weight, dressing and cut percentage and meat chemical composition and color parameters. Meat total saturated FA (SFA), monounsaturated FA (MUFA) and polyunsaturated FA (PUFA) concentrations were not influenced by experimental diets, whereas, kids fed diets supplemented with rpCLA had lower meat total SFA and higher PUFA concentrations compared to those fed diets supplemented with HSO. The concentration of meat trans-11 8:1 were not influenced by rpCLA supplementation, RUP level and their interaction. Kids fed diets containing rpCLA supplementation had higher meat total conjugated linoleic acids (CLA) and cis-9, trans-11 CLA and trans-10, cis-12 CLA isomers compared to those fed diets containing HSO supplementation. Desaturase indexes of C14, C16 and C18 were not influenced by rpCLA supplementation, RUP level and their interaction. It is concluded that supplementing growing kids diets with RUP and 15 g/kg rpCLA not only decreased meat fat content but also increased some FAs considered to be of potential benefit to human health.
Some food bioactives potentially exert anti-obesity effects. Anthocyanins (ACN), catechins, β-glucan (BG) and n-3 long chain PUFA (LCPUFA) are among the most promising candidates and have been considered as a strategy for the development of functional foods counteracting body weight gain. At present, clinical trials, reviews and meta-analyses addressing anti-obesity effects of various bioactives or bioactive-rich foods show contradictory results. Abdominal obesity is an important criterion for metabolic syndrome (MetS) diagnosis along with glucose intolerance, dyslipidaemia and hypertension. Food bioactives are supposed to exert beneficial effects on these parameters, therefore representing alternative therapy approaches for the treatment of MetS. This review summarises outcomes on MetS biomarkers in recent clinical trials supplementing ACN, catechins, BG and n-3 LCPUFA, focusing mainly on anti-obesity effects. Overall, it is clear that the level of evidence for the effectiveness varies not only among the different bioactives but also among the different putative health benefits suggested for the same bioactive. Limited evidence may be due to the low number of controlled intervention trials or to inconsistencies in trial design, i.e. duration, dose and/or the method of bioactive supplementation (extracts, supplements, rich or enriched food). At present, the question ‘Are bioactives effective in weight management and prevention of metabolic syndrome?’ remains inconclusive. Thus, a common effort to harmonise the study design of intervention trials focusing on the most promising bioactive molecules is urgently needed to strengthen the evidence of their potential in the treatment of obesity, MetS and related diseases.
Short-term feeding studies have highlighted a phenomenon in Ca regulation that raises concerns around Ca absorption in dogs that may make an impact on commercial diets near to the maximum recommended level. A recent study to determine responses in dogs fed one of two diets differing in dietary Ca over 40 weeks found no evidence to suggest a concern across a range of biological parameters hypothesised to be affected by Ca. Unforeseen consequences of dietary Ca could have occurred and metabolic profiling was deemed a suitable data-driven approach to identify effects of dietary Ca. The objectives were to compare the fasted plasma metabolome (sampled at 8-week intervals over 40 weeks) of dogs fed one of two diets, near to the minimum and maximum recommended levels of dietary Ca. Comparisons with the control diet were also investigated across the postprandial time course (1–4 h) following acute (1 d) and long-term (24 weeks) feeding of the test diet. Comparing fasted plasma samples at each time point, no significant effect (adjusted P < 0·05) of diet on metabolites was observed. In the postprandial state, only phosphate was consistently different between diets and was explained by additional dietary P to maintain Ca:P. Metabolic profiling analysis supports the view that the dietary Ca upper limit is safe. Additionally, the canine plasma metabolome was characterised, providing insights into the stability of individual profiles across 40 weeks, the response to consumption of a nutritionally complete meal over a 4 h postprandial time course and different kinetic categories of postprandial absorption.
This pilot randomised controlled study evaluated the effects of a nutrient-supported intermittent energy restriction nutrition programme to prevent weight gain in healthy overweight adults during the 6-week winter holiday period between Thanksgiving and New Year. For 52 d, twenty-two overweight adults (mean age 41·0 years, BMI 27·3 kg/m2) were assigned to either the nutrition programme (n 10; two fasting days of 730 kcal/d (3050 kJ/d) of balanced shake and dietary supplements to support weight management efforts, followed by 5 d of habitual diet) or a control group (n 12; habitual diet). A significant weight loss from baseline (pre-holiday 10 d before Thanksgiving) to day 52 (post-holiday 3 January) was observed in the nutrition programme (75·0 (sd 9·8) v. 76·3 (sd 9·8) kg; P < 0·05). Body weight did not significantly change in the control group and there was no between-group difference. Increases from baseline in fasting insulin (42·9 %; P = 0·0256), updated homoeostasis model assessment (HOMA2) (43 %; P = 0·025), LDL-cholesterol (8·4 %; P = 0·0426) and total cholesterol (7·1 %; P = 0·0154) levels were also reported in the control group. In the nutrition programme group, baseline HDL-cholesterol and TAG levels measured after two fasting days increased (13 %; P = 0·0245) and decreased (22·8 %; P = 0·0416), respectively. There was no significant change in HOMA2. Between-group differences in changes in insulin levels (P = 0·0227), total cholesterol:HDL-cholesterol ratio (P = 0·0419) and HOMA2 (P = 0·0210) were significant. Overall compliance rate was 98 % and no severe adverse events were reported. These preliminary findings suggest that this intermittent energy restriction intervention might support weight management efforts and help promote metabolic health during the winter holiday season.
Zn plays an important role in maintaining the anti-oxidant status within the heart and helps to counter the acute redox stress that occurs during myocardial ischaemia and reperfusion. Individuals with low Zn levels are at greater risk of developing an acute myocardial infarction; however, the impact of this on the extent of myocardial injury is unknown. The present study aimed to compare the effects of dietary Zn depletion with in vitro removal of Zn (N,N,N′,N′-tetrakis(2-pyridinylmethyl)-1,2-ethanediamine (TPEN)) on the outcome of acute myocardial infarction and vascular function. Male Sprague–Dawley rats were fed either a Zn-adequate (35 mg Zn/kg diet) or Zn-deficient (<1 mg Zn/kg diet) diet for 2 weeks before heart isolation. Perfused hearts were subjected to a 30 min ischaemia/2 h reperfusion (I/R) protocol, during which time ventricular arrhythmias were recorded and after which infarct size was measured, along with markers of anti-oxidant status. In separate experiments, hearts were challenged with the Zn chelator TPEN (10 µm) before ischaemia onset. Both dietary and TPEN-induced Zn depletion significantly extended infarct size; dietary Zn depletion was associated with reduced total cardiac glutathione (GSH) levels, while TPEN decreased cardiac superoxide dismutase 1 levels. TPEN, but not dietary Zn depletion, also suppressed ventricular arrhythmias and depressed vascular responses to nitric oxide. These findings demonstrate that both modes of Zn depletion worsen the outcome from I/R but through different mechanisms. Dietary Zn deficiency, resulting in reduced cardiac GSH, is the most appropriate model for determining the role of endogenous Zn in I/R injury.
This paper contributes to explaining the obesity epidemic and finding a potential remedy. We build a theoretical model of food consumption decisions that accounts for social influence. In our model, individuals’ rationality is affected by an endogenous social weight norm, which influences their calorie consciousness and perceived survival chances. Individuals are conformist, and the degree of conformism describes the extent to which individuals’ discounted utility is influenced by the social weight norm. With an endogenous social weight norm reflecting a heavier and heavier average body weight, we show that a high degree of conformism to the social norm could explain the obesity epidemic. In this environment, a government intervention decreasing energy density is ineffective at reducing steady-state body weight. This result could explain why this type of government dietary intervention seems to have had no effect on obesity, and suggests that the same type of intervention through the Food Stamps Program would be ineffective on its own. We also find that in the steady state, individuals can be overweight or underweight depending on their degree of conformism relative to the education they receive about the healthy weight. While education programs focusing on either diet or exercise have had moderate success, we show that focusing on healthy weight education could combat social influence and reduce obesity.
This study aimed to examine in vivo starch digestion kinetics and to unravel the mechanisms of starch hydrolysing enzymes. Ninety pigs (23 (sd 2·1) kg body weight) were assigned to one of nine treatments in a 3×3 factorial arrangement, with starch source (barley, maize, high-amylose (HA) maize) and form (isolated, within cereal matrix, extruded) as factors. We determined starch digestion coefficients (DC), starch breakdown products and digesta retention times in four small-intestinal segments (SI1–4). Starch digestion in SI2 of pigs fed barley and maize, exceeded starch digestion of pigs fed HA maize by 0·20–0·33 DC units (P<0·01). In SI3–4, barley starch were completely digested, whereas the cereal matrix of maize hampered digestion and generated 16 % resistant starch in the small intestine (P<0·001). Extrusion increased the DC of maize and HA maize starch throughout the small intestine but not that of barley (P<0·05). Up to 25 % of starch residuals in the proximal small intestine of pigs was present as glucose and soluble α(1–4) maltodextrins. The high abundance of glucose, maltose and maltotriose in the proximal small intestine indicates activity of brush-border enzymes in the intestinal lumen, which is exceeded by α-amylase activity. Furthermore, we found that in vivo starch digestion exceeded our in vitro predictions for rapidly digested starch, which indicates that the role of the stomach on starch digestion is currently underestimated. Consequently, in vivo glucose release of slowly digestible starch is less gradual than expected, which challenges the prediction quality of the in vitro assay.
Age- and sex-based BMI cut-offs are used to define overweight and obesity, but the relationship between BMI and body composition has not been very well studied in children or compared between children of different ethnic groups. Body size and composition in childhood are also influenced by size at birth. Our aim was to compare body size and composition at 2 years in children with different ethnicity and size at birth. We prospectively followed a multi-ethnic cohort of 300 children born with risk factors for neonatal hypoglycaemia (infants of diabetics, large or small at birth or late preterm) to 2 years corrected age. Complete data on weight, height and head circumference and body composition using bioelectrical impedance 24±1 months corrected age were available in 209 children. At birth, compared with European children, Chinese, Indian and other ethnicity children were lighter, and Indian children had smaller head circumferences, but birth lengths were similar in all ethnic groups. At 2 years, Pacific children were heavier and had higher BMI z scores, and Indian children had smaller head circumferences and lower BMI z scores than those from other ethnic groups. However, fat mass and fat-free mass indices were similar in all groups. At median BMI, fat mass:fat-free mass ratio was 23 % lower in Pacific than in Indian children (0·22 v. 0·27, P=0·03). BMI is not a good indicator of adiposity in this multi-ethnic cohort of 2-year-old New Zealand children.
To assess the reliability and validity of body weight (BW) and body image (BI) perception reported by parents (in children) and by adolescents in a South American population.
Cross-sectional study. BW perception was evaluated by the question, ‘Do you think you/your child are/is: severely wasted, wasted, normal weight, overweight, obese?’ BI perception was evaluated using the Gardner scale. To evaluate reliability, BW and BI perceptions were reported twice, two weeks apart. To evaluate validity, the BW and BI perceptions were compared with WHO BMI Z-scores. Kappa and Kendall’s tau-c coefficients were obtained.
Public and private schools and high schools from six countries of South America (Argentina, Peru, Colombia, Uruguay, Chile, Brazil).
Children aged 3–10 years (n 635) and adolescents aged 11–17 years (n 400).
Reliability of BW perception was fair in children’s parents (κ=0·337) and substantial in adolescents (κ=0·709). Validity of BW perception was slight in children’s parents (κ=0·176) and fair in adolescents (κ=0·268). When evaluating BI, most children were perceived by parents as having lower weight. Reliability of BI perception was slight in children’s parents (κ=0·124) and moderate in adolescents (κ=0·599). Validity of BI perception was poor in children’s parents (κ=−0·018) and slight in adolescents (κ=0·023).
Reliability of BW and BI perceptions was higher in adolescents than in children’s parents. Validity of BW perception was good among the parents of the children and adolescents with underweight and normal weight.
Favourable body composition has been associated with higher dietary protein intake. However, little is known regarding this relationship in a population of Chinese Americans (CHA), who have lower BMI compared with other populations. The aim of the present study was to assess the relationship between dietary protein intake, fat mass (FM) and fat-free mass (FFM) in CHA. Data were from the Chinese American Cardiovascular Health Assessment (CHA CHA) 2010–2011 (n 1707); dietary intake was assessed using an adapted and validated FFQ. Body composition was assessed using bioelectrical impedance analysis. The associations between protein intake (% energy intake) and BMI, percentage FM (FM%), percentage FFM (FFM%), FM index (FMI) and FFM index (FFMI) were examined using multiple linear regression adjusted for age, sex, physical activity, acculturation, total energy intake, sedentary time, smoking status, education, employment and income. There was a significant positive association between dietary protein and BMI (B = 0·056, 95 % CI 0·017, 0·104; P = 0·005), FM (B = 0·106, 95 % CI 0·029, 0·184; P = 0·007), FM% (B = 0·112, 95 % CI 0·031, 0·194; P = 0·007) and FMI (B = 0·045, 95 % CI 0·016, 0·073; P = 0·002). There was a significant negative association between dietary protein and FFM% (B = −0·116, 95 % CI −0·196, −0·036; P = 0·004). In conclusion, higher dietary protein intake was associated with higher adiposity; however, absolute FFM and FFMI were not associated with dietary protein intake. Future work examining the relationship between protein source (i.e. animal) and body composition is warranted in this population of CHA.
The passage rate of solids and liquids through the gastrointestinal tract differs. Increased dietary nutrient solubility causes nutrients to shift from the solid to the liquid digesta fraction and potentially affect digesta passage kinetics. We quantified: (1) the effect of three levels of dietary nutrient solubility (8, 19 and 31 % of soluble protein and sucrose in the diet) at high feed intake level (S) and (2) the effect of low v. high feed intake level (F), on digesta passage kinetics in forty male growing pigs. The mean retention time (MRT) of solids and liquids in the stomach and small intestine was assessed using TiO2 and Cr-EDTA, respectively. In addition, physicochemical properties of digesta were evaluated. Overall, solids were retained longer than liquids in the stomach (2·0 h, P<0·0001) and stomach+small intestine (1·6 h, P<0·001). When S increased, MRT in stomach decreased by 1·3 h for solids (P=0·01) and 0·7 h for liquids (P=0·002) but only at the highest level of S. When F increased using low-soluble nutrients, MRT in stomach increased by 0·8 h for solids (P=0·041) and 0·7 h for liquids (P=0·0001). Dietary treatments did not affect water-binding capacity and viscosity of digesta. In the stomach of growing pigs, dietary nutrient solubility affects digesta MRT in a non-linear manner, while feed intake level increases digesta MRT depending on dietary nutrient solubility. Results can be used to improve predictions on the kinetics of nutrient passage and thereby of nutrient digestion and absorption in the gastrointestinal tract.
Variations in feeding behaviour between animals result from individual variations in their metabolism as affected by diet composition. The study aimed to link the within-day dynamics of voluntary feed intake and those of blood metabolites and insulin in growing pigs having ad libitum access to feed and receiving diets differing in dietary fibre levels and aleurone supplementation. A total of forty pigs (body weight: 35 kg) had access to diets provided ad libitum, which differed by fibre content (13 or 18 % neutral-detergent fibre) and aleurone supplementation (0, 2 or 4 g/kg). Feeding behaviour was individually recorded for 1 week. The kinetic of plasma metabolites and insulin was followed for 1 h after a voluntary test meal. Dietary fibre level did not affect the daily feed intake but increased meal size and meal duration. Aleurone supplementation (4 g/kg) decreased the daily feed intake and number of meals. Dietary fibre level only decreased insulin concentration measured 15 min after meal beginning. Aleurone supplementation (4 g/kg) decreased glycaemia in the first hour after the meal and insulinaemia 15 min after the meal. Free access to feed led to high variability in pre-prandial metabolites and insulin concentrations, resulting in different test meal size irrespective of diet composition. Animals were then spread over different profiles combining feeding behaviour and fasted status to explain different profiles of regulation of feed intake. Plasma metabolites and insulin kinetics were affected by diet composition but also by animal characteristics. Individual variability should be considered when diet composition is used to modulate feeding behaviour.
Life-history theory predicts a trade-off between the juvenile growth rate and adult traits related to survival. However, this hypothesized negative correlation is difficult to test robustly because many trade-offs are mild, and environmental variables, such as changes in nutrient availability, can ameliorate the trade-off or make it more pronounced. Thus, it is reasonable to expect that the expression of the trade-off can be condition-dependent. In the present study, we first examined the pre-adult life-history traits of the cotton bollworm, Helicoverpa armigera, collected from northern, central, and southern China at different temperatures. We found that the northern China population has a significantly shorter pre-adult developmental time and higher growth rate than the southern China population as a result of adaptation to the decreased seasonal length. Then, we tested for a trade-off between the juvenile growth rate and adult lifespan in different temperature and nutrient conditions. We found a negative relationship between juvenile growth rate and adult lifespan under starvation or desiccation conditions; however, a continuous supply of sugar can diminish or obviate the apparent negative relationship, in which the adult lifespan did not show a significant difference in most of the comparisons. These results suggested a resource-mediated trade-off may exist between juvenile growth rate and adult lifespan. However, the adult size may have some positive effect on the lifespan under starvation and desiccation conditions, which may affect the expression of trade-off.
Sufficient protein intake has been suggested to be important for preventing physical frailty, but studies show conflicting results which may be explained because not all studies address protein source and intake of other macronutrients and total energy. Therefore, we studied 2504 subjects with data on diet and physical frailty, participating in a large population-based prospective cohort among subjects aged 45+ years (the Rotterdam Study). Dietary intake was assessed with a FFQ. Frailty was defined according to the frailty phenotype as the presence of at least three out of the following five symptoms: weight loss, low physical activity, weakness, slowness and fatigue. We used multinomial logistic regression models to evaluate the independent association between protein intake and frailty using two methods: nutrient residual models and energy decomposition models. With every increase in 10 g total, plant or animal protein per d, the odds to be frail were 1·06 (95 % CI 0·98, 1·15), 0·87 (95 % CI 0·71, 1·07) and 1·07 (95 % CI 0·99, 1·15), respectively, using the nutrient residual method. Using the energy partition model, we observed that the odds to be frail were lower with higher vegetable protein intake (OR per 418·4 kJ (100 kcal): 0·61, 95 % CI 0·39, 0·97), however, results disappeared when adjusting for physical activity. For energy intake from any source we observed that with every 418·4 kJ (100 kcal) increase, the odds to be frail were 5 % lower (OR: 0·95, 95 % CI 0·93, 0·97). Our results suggest that energy intake, but not protein specifically, is associated with less frailty. Considering other macronutrients, physical activity and diet quality seems to be essential for future studies on protein and frailty.