Understanding mental fatigue and its detection: a comparative analysis of assessments and tools.

Mental fatigue has shown to be one of the root causes of decreased productivity and overall cognitive performance, by decreasing an individual's ability to inhibit responses, process information and concentrate. The effects of mental fatigue have led to occupational errors and motorway accidents. Early detection of mental fatigue can prevent the escalation of symptoms that may lead to chronic fatigue syndrome and other disorders. To date, in clinical settings, the assessment of mental fatigue and stress is done through self-reported questionnaires. The validity of these questionnaires is questionable, as they are highly subjective measurement tools and are not immune to response biases. This review examines the wider presence of mental fatigue in the general population and critically compares its various detection techniques (i.e., self-reporting questionnaires, heart rate variability, salivary cortisol levels, electroencephalogram, and saccadic eye movements). The ability of these detection tools to assess inhibition responses (which are sensitive enough to be manifested in a fatigue state) is specifically evaluated for a reliable marker in identifying mentally fatigued individuals. In laboratory settings, antisaccade tasks have been long used to assess inhibitory control and this technique can potentially serve as the most promising assessment tool to objectively detect mental fatigue. However, more studies need to be conducted in the future to validate and correlate this assessment with other existing measures of mental fatigue detection. This review is intended for, but not limited to, mental health professionals, digital health scientists, vision researchers, and behavioral scientists.

Pure Juice Supplementation: Its Effect on Muscle Recovery and Sports Performance.

Strenuous exercise causes increased production of reactive oxygen species (ROS), creating an imbalance between ROS and antioxidants. The reduced antioxidant defence leads to defective elimination of ROS and consequently, delayed-onset muscle soreness (DOMS). DOMS due to exhaustive or prolonged exercise typically peaks between 24 h and 72 h after exercise results in soreness, inflammation, pain and decreased muscle function. As a result, muscle strength will be reduced progressively and this situation might be detrimental to one's athletic performance, especially amidst competition season. Therefore, supplementation to improve muscle recovery and sports performance has become a common practice among athletes. However, it is suggested to consume natural-based fruit-derived antioxidants as a more effective and safe nutritional strategy. Fruits containing a high amount of polyphenol protect muscle cells from excessive and harmful ROS due to their anti-inflammatory and antioxidant characteristics. To date, there are several expended studies on the consumption of supplements from various antioxidant-rich fruits to provide evidence on their effectiveness, giving better solutions and wider choices of supplementation to the athletes. Therefore, this review aims to provide a comprehensive overview of nutritional standpoint from previous literature on the effect of fruit juices supplementation on muscle recovery and sports performance.

Gut Microbiota and Gestational Diabetes Mellitus: A Review of Host-Gut Microbiota Interactions and Their Therapeutic Potential.

Gestational diabetes mellitus (GDM) is defined as impaired glucose tolerance recognized during pregnancy. GDM is associated with metabolic disorder phenotypes, such as obesity, low-grade inflammation, and insulin resistance. Following delivery, nearly half of the women with a history of GDM have persistent postpartum glucose intolerance and an increased risk of developing type 2 diabetes mellitus (T2DM), as much as 7-fold. The alarming upward trend may worsen the socioeconomic burden worldwide. Accumulating evidence strongly associates gut microbiota dysbiosis in women with GDM, similar to the T2DM profile. Several metagenomics studies have shown gut microbiota, such as Ruminococcaceae, Parabacteroides distasonis, and Prevotella, were enriched in women with GDM. These microbiota populations are associated with metabolic pathways for carbohydrate metabolism and insulin signaling, suggesting a potential "gut microbiota signature" in women with GDM. Furthermore, elevated expression of serum zonulin, a marker of gut epithelial permeability, during early pregnancy in women with GDM indicates a possible link between gut microbiota and GDM. Nevertheless, few studies have revealed discrepant results, and the interplay between gut microbiota dysbiosis and host metabolism in women with GDM is yet to be elucidated. Lifestyle modification and pharmacological treatment with metformin showed evidence of modulation of gut microbiota and proved to be beneficial to maintain glucose homeostasis in T2DM. Nonetheless, post-GDM women have poor compliance toward lifestyle modification after delivery, and metformin treatment remains controversial as a T2DM preventive strategy. We hypothesized modulation of the composition of gut microbiota with probiotics supplementation may reverse postpartum glucose intolerance in post-GDM women. In this review, we addressed gut microbiota dysbiosis and the possible mechanistic links between the host and gut microbiota in women with GDM. Furthermore, this review highlights the potential therapeutic use of probiotics in post-GDM women as a T2DM preventive strategy.

Training Induced Oxidative Stress-Derived DNA and Muscle Damage in Triathletes.

OBJECTIVE: Regular moderate-intensity exercise has beneficial health effects, whereas regular strenuous exercise increases the production of oxidants that may lead to DNA, skeletal, and cardiac muscle damages. Triathletes experience strenuous muscular activity both during competition and training, being at risk of developing these tissue damages. The objective of the present study was to estimate DNA, skeletal, and cardiac muscle damages using blood biomarkers, 8-hydroxy-2'-deoxyguanosine (8-OHdG), myoglobin, and cardiac troponin I (cTnI) among young triathletes. MATERIALS AND METHODS: Age-matched seven male and seven female triathletes were recruited for the study. They were on a standardized training regimen and on average competed in at least one endurance event every month for the past 3-4 years. Serum biomarkers were measured using enzyme-linked immunosorbent assay at the start and at end of the racing season. RESULTS: Both male and female triathletes showed a statistically significant increase in 8-OHdG. A similar pattern of increase was seen with serum myoglobin, which was not statistically significant in both male and female triathletes. cTnI levels did not show any change in both sexes. CONCLUSION: Our study shows that there could be an increased evidence of DNA damage among triathletes. However, similar effects were not observed with skeletal and cardiac muscle biomarkers.

Effect of gender specific anthropometric characteristics on lung function in young competitive triathletes from Malaysia.

BACKGROUND: Anthropometric and lung function characteristics of triathletes are important for the implementation of individual specific training and recovery recommendations. However, limited data are available for these parameters in triathletes. Hence, the aim of this study was to characterize and examine the gender differences of lung function and anthropometry parameters in competitive triathletes from Malaysia. METHODS: Body composition assessment and lung function tests were performed on sixteen competitive triathletes (nine male and seven female). The subject's body composition profile including muscle mass (kg), fat free mass (kg), and percent body fat was measured using a bio-impedance segmental body composition analyzer. Forced vital capacity (FVC) and forced expiratory volume in one second (FEV1) were measured by Quark PFT2 spirometer. RESULTS: The anthropometric measurements revealed that male triathletes were significantly taller than female triathletes and had significantly more protein and skeletal muscle mass. The female triathletes, however, had significantly higher percent body fat. Male triathletes had statistically significant higher FVC and FEV1 than female triathletes. Both the male and female triathletes showed a positive correlation between height, fat free mass and the lung function markers FVC and FEV1. This association was not seen with Body Mass Index (BMI) in female triathletes. CONCLUSIONS: The data from our study shows that anthropometric parameters are directly linked to lung function of a triathlete. We also found the relationship between BMI and lung function to be gender specific in triathletes and is dependent on the body protein and fat content. Hence, body composition characterization is essential and provides valuable information for developing individual specific training modules.

Melatonin ameliorates the adverse effects of leptin on sperm.

This study examined the effects of melatonin on leptin-induced changes in sperm parameters in adult rats. Five groups of Sprague-Dawley rats were treated with either leptin or leptin and melatonin or melatonin for 6 weeks. Leptin was given daily via the intraperitoneal route (60 µg kg-1 body weight) and melatonin was given in drinking water (10 mg kg-1 or 20 mg kg-1 body weight per day). Upon completion, sperm count, sperm morphology, 8-hydroxy-2-deoxyguanosine, Comet assay, TUNEL assay, gene expression profiles of antioxidant enzymes, respiratory chain reaction enzymes, DNA damage, and apoptosis genes were estimated. Data were analyzed using ANOVA. Sperm count was significantly lower whereas the fraction of sperm with abnormal morphology, the level of 8-hydroxy-2-deoxyguanosine, and sperm DNA fragmentation were significantly higher in rats treated with leptin only. Microarray analysis revealed significant upregulation of apoptosis-inducing factor, histone acetyl transferase, respiratory chain reaction enzyme, cell necrosis and DNA repair genes, and downregulation of antioxidant enzyme genes in leptin-treated rats. Real-time polymerase chain reaction showed significant decreases in glutathione peroxidase 1 expression with increases in the expression of apoptosis-inducing factor and histone acetyl transferase in leptin-treated rats. There was no change in the gene expression of caspase-3 (CASP-3). In conclusion, the adverse effects of leptin on sperm can be prevented by concurrent melatonin administration.

Brain-derived neurotrophic factor delivered to the brain using poly (lactide-co-glycolide) nanoparticles improves neurological and cognitive outcome in mice with traumatic brain injury.

Currently, traumatic brain injury (TBI) is the leading cause of death or disabilities in young individuals worldwide. The multi-complexity of its pathogenesis as well as impermeability of the blood-brain barrier (BBB) makes the drug choice and delivery very challenging. The brain-derived neurotrophic factor (BDNF) regulates neuronal plasticity, neuronal cell growth, proliferation, cell survival and long-term memory. However, its short half-life and low BBB permeability are the main hurdles to be an effective therapeutic for TBI. Poly (lactic-co-glycolic acid) (PLGA) nanoparticles coated by surfactant can enable the delivery of a variety of molecules across the BBB by receptor-mediated transcytosis. This study examines the ability of PLGA nanoparticles coated with poloxamer 188 (PX) to deliver BDNF into the brain and neuroprotective effects of BNDF in mice with TBI. C57bl/6 mice were subjected to weight-drop closed head injuries under anesthesia. Using enzyme-linked immunosorbent assay, we demonstrated that the intravenous (IV) injection of nanoparticle-bound BDNF coated by PX (NP-BDNF-PX) significantly increased BDNF levels in the brain of sham-operated mice (p < 0.001) and in both ipsi- (p < 0.001) and contralateral (p < 0.001) parts of brain in TBI mice compared to controls. This study also showed using the passive avoidance (PA) test, that IV injection of NP-BDNF-PX 3 h post-injury prolonged the latent time in mice with TBI thereby reversing cognitive deficits caused by brain trauma. Finally, neurological severity score test demonstrated that our compound efficiently reduced the scores at day 7 after the injury indicating the improvement of neurological deficit in animals with TBI. This study shows that PLGA nanoparticles coated with PX effectively delivered BDNF into the brain, and improved neurological and cognitive deficits in TBI mice, thereby providing a neuroprotective effect.

Effects of Ramadan fasting on glucose homeostasis and adiponectin levels in healthy adult males.

BACKGROUND: Adiponectin is a hormone secreted by adipocytes during the fasting phase of the fast-fed cycle. Ramadan fasting involves prolonged fasting for up to twelve hours and thus could lead to increased secretion of adiponectin by adipocytes. However, studies on the role of adiponectin on glucose and body weight homeostasis during Ramadan fasting is still a matter of controversy. Thus the specific aim of this study was to assess the effect of fasting during Ramadan on the adiponectin levels, body weight and glucose homeostasis in healthy male Malaysian subjects. METHODS: Twenty healthy male (19-23 years) Muslim subjects were followed up during the fasting month of Ramadan. Anthropometry and blood samples were taken one week before and during the fourth week of fasting. Plasma glucose, insulin and adiponectin were estimated and insulin sensitivity indices were estimated using the Homeostasis Model Assessment. RESULTS: Subjects experienced a significant decrease in body weight (2.4 %, p < 0.001) and body mass index (5.5 %, p < 0.01). There was also a significant decrease of 12.3 %, 52.8 % and 45.6 % of plasma glucose, insulin and adiponectin respectively (p < 0.01). The drop in adiponectin was positively correlated with the decrease in body weight (r = 0.45, p < 0.05). There was also a significant increase in insulin sensitivity and a decrease in insulin resistance (p < 0.01). CONCLUSIONS: These results indicate that Ramadan fasting in young healthy individuals has a positive impact on the maintenance of glucose homeostasis. It also shows that adiponectin levels dropped along with significant loss in weight. We feel caloric restriction during the Ramadan fasting is in itself sufficient to improve insulin sensitivity in healthy individuals.

Common misconceptions and future intention to smoke among secondary school students in Malaysia.

BACKGROUND: The prevalence of smoking among secondary school children continues to remain unchanged over the last 3 decades even though awareness regarding the health effects of smoking is increasing. Common misconceptions about smoking and parental influence could be factors influencing future intentions to smoke among these students. Hence, we looked at the common misconceptions as well as student perceptions about their future intention to smoke among Form 4 students in Shah Alam, Malaysia. MATERIALS AND METHODS: This study was conducted by distribution of a questionnaire developed as part of the Global Youth Tobacco Survey to Form 4 student in 3 schools at Shah Alam. RESULTS: Prevalence of smoking (current smokers) was 7.5%. Almost half of the children came from families where one or both parents smoked and a third of the parents had no discussion regarding consequences of smoking with them. A large number of students were classified as "triers" as they had tried smoking and were unsure of whether they would not be smoking in the future. Contrary to our expectations, students generally felt smoking did make one feel more uncomfortable and helped one to reduce body weight. Most students seemed to be aware of the ill-effects of smoking on health. They felt they had received adequate information from school regarding the effects on smoking on health. CONCLUSIONS: Our study showed that even though Form 4 students in Shah Alam were knowledgeable about ill-effects of smoking and were taught so as part of their school curriculum, the prevalence of smoking was still high. Students in the "trier group" represent a potential group of future smokers and strategies targeting tobacco control may be aimed at tackling these vulnerable individuals. Efforts are also needed to help educate secondary school children about common misconceptions and dispel myths associated with cigarette smoking.

Dysregulation of Glucose Homeostasis Following Chronic Exogenous Administration of Leptin in Healthy Sprague-Dawley Rats.

INTRODUCTION: Impaired glucose utilization is seen in chronic hyperleptinaemia associated conditions such as obesity and type 2 diabetes mellitus. It is unclear if this impaired glucose utilization is due to the effect of persistent hyperleptinaemia on insulin secretion from the beta cells of pancreas. AIM: To examine the effects of chronic leptin administration on plasma glucose regulation in rats. MATERIALS AND METHODS: Glucose challenge curves were plotted for male Sprague-Dawley rats treated with either normal saline (Control; n=8) or subcutaneous leptin injection for 42 days (60 µg/kg body weight/day; n=8). Plasma glucose and plasma insulin levels were measured at 0, 5, 10, 15, 20 and 25 minutes after glucose challenege. Skeletal muscle tissue was collected at the end of a glucose challenge for glucose transporter-4 protein content, insulin receptor and glucose transporter-4 mRNA expression. Data were analysed using repeated measures and one-way ANOVA with post-hoc analysis. RESULTS: Chronic leptin treatment caused significantly higher fasting insulin level. Post glucose challenge, there was a significant increase in blood glucose levels and insulin level in the leptin treated rats. There was no significant difference in the skeletal muscle glucose transporter-4 content. However, leptin treated rats showed decreased mRNA expression of Insulin Receptor and glucose transporter-4 in the skeletal muscle. CONCLUSION: Leptin administration for 42 days caused hyperinsulinaemia and decreased the expression of insulin receptors in insulin sensitive tissues leading to the development of an insulin resistance-like state in the rats.

Prediction equations for lung function in healthy, life time never-smoking Malaysian population.

Several equations have been used to predict lung function standard results for different populations. It is important lung function evaluations use appropriate standards for the study population. The objective of this study was to develop a prediction equation for lung function test results for the Malaysian population. Spirometry was performed among 5,708 subjects and 1,483 healthy, lifetime never smoked subjects (386 males and 1,097 females). Prediction equations were derived for both men and women for FVC and FEV1 results. The equations were validated on new subjects (n = 532, 222 males and 310 females) who met the same inclusion and exclusion criteria as the main cohort. There was a positive correlation between the measured values and the values derived from the new prediction equations (0.62 for FEV1 and between 0.66 and 0.67 for FVC; both p < 0.05) for both men and women with a smaller bias and limit of agreement compared to the published reference equations of ECCS, Knudson, Crapo and NHANES III. The reference equations derived from local spirometry data were more appropriate than generally used equations based on data from previous studies in different population.

The daily phenylalanine requirement of healthy Indian adults.

BACKGROUND: The daily requirement for phenylalanine is not known with certainty. Earlier 24-h tracer studies have suggested that the requirement is between 30 and 40 mg . kg(-1) . d(-1). OBJECTIVE: The objective was to assess the phenylalanine requirement in healthy well-nourished Indians with the use of 8 test phenylalanine intakes (19, 23, 27, 31, 35, 38, 43, and 47 mg . kg(-1) . d(-1)) and the 24-h indicator amino acid oxidation (24-h IAAO) and 24-h indicator amino acid balance (24-h IAAB) methods. DESIGN: Thirty-two healthy, well-nourished Indian men were studied during each of 2 randomly assigned 6-d diet periods in which phenylalanine intakes of 19, 23, 27, 31, 35, 38, 43, and 47 mg . kg(-1) . d(-1) were supplied; the diet was devoid of tyrosine. A 24-h [13C]leucine tracer infusion was used to measure 24-h IAAO and 24-h IAAB on day 7. The breakpoint in the relation between these values and the phenylalanine intake was determined. RESULTS: Two-phase linear regression of daily leucine oxidation and balance against phenylalanine intake estimated a breakpoint in the response curve at phenylalanine intakes of 37 and 38 mg . kg(-1) . d(-1) (95% CI for both: 31, >47 mg . kg(-1) . d(-1)), respectively. CONCLUSION: On the basis of the 24-h IAAO and 24-h IAAB methods, a mean phenylalanine requirement of 38 mg . kg(-1) . d(-1) is proposed for healthy well-nourished Indian adults in the absence of tyrosine intake. This finding is similar to that in Western adults.

Branched-chain amino acid requirements in healthy adult human subjects.

There is now an expanding body of evidence to recommend, in the case of adult humans, the use of revised indispensable amino acid requirement values; these are approximately 2 to 3 times higher than the current international recommendations. The earlier methodologies for determining amino acid requirements, based on nitrogen balance, were criticized because of their design and the associated high energy intakes. The 1985 World Health Organization/Food & Agriculture Organization/United Nations University requirement for leucine has been demonstrated to be too low by short- and long-term (24-h) tracer-derived estimates of leucine oxidation and balance. The best values for leucine requirements come from 24-h direct amino acid oxidation (DAAO) and direct amino acid balance (DAAB) studies. Finally, we also collated all available data from studies on fed-state leucine oxidation with an adequate dietary adaptation period to assess the inflection on the leucine oxidation-leucine intake curve. The mean requirements for leucine, valine, and isoleucine are likely to be 40, 17-25, and 19 mg . kg(-1) . d(-1), respectively. This adds up to a total of approximately 84 mg . kg(-1) . d(-1), which is much lower than the lowest estimate of the total BCAA requirement of approximately 110 mg . kg(-1) . d(-1) made by the short-term indicator amino acid oxidation (IAAO) method, which determined the BCAA requirement from the pattern of oxidation of an indicator amino acid (phenylyalanine) at different levels of BCAA intake. An additional estimate of the leucine requirement was also made by a meta-analysis of all available 24-h DAAO/DAAB data from different studies. This resulted in a higher value for the leucine requirement than that obtained by the specific studies that utilized the 24-h DAAO/DAAB approach; however, even adding this value to the total BCAA requirement does not account for the difference in the total BCAA requirement estimates and the summed individual BCAA estimates.

The daily valine requirement of healthy adult Indians determined by the 24-h indicator amino acid balance approach.

BACKGROUND: The 1985 FAO/WHO/UNU requirement for valine was set at 10 mg x kg(-1) x d(-1) on the basis of nitrogen balance studies carried out in Western subjects. It is likely that the requirement is higher, however, because the requirement of another branched-chain amino acid, leucine, was found to be about 3 times as high (40 mg x kg(-1) x d(-1)) as the 1985 FAO/WHO/UNU value (14 mg x kg(-1) x d(-1)). OBJECTIVE: We assessed the valine requirement in healthy, well-nourished Indians by using 7 test valine intakes (5, 10, 15, 20, 25, 30, and 35 mg x kg(-1) x d(-1)) and the 24-h indicator amino acid oxidation (24-h IAAO) and balance (24-h IAAB) method, with phenylalanine as the indicator amino acid, while maintaining leucine intake at 40 mg x kg(-1) x d(-1). DESIGN: Eighteen healthy, well-nourished Indian men were studied during each of 3 randomly assigned 7-d diet periods supplying valine intakes that were equally placed on either side of a putative mean valine requirement of 20 mg x kg(-1) x d(-1). Twenty-four-hour IAAO and 24-h IAAB were measured on day 7 by use of a 24-h [13C]phenylalanine tracer infusion. The breakpoint in the relation between these values and the valine intake was determined. RESULTS: Two-phase linear regression of daily phenylalanine oxidation or balance against valine intake estimated a breakpoint in the response curve at a valine intake of 17 mg x kg(-1) x d(-1) (95% Fieller's CI: 11, > 35 and 11, 28 mg x kg(-1) x d(-1), respectively). CONCLUSION: From the 24-h IAAO/IAAB approach, a mean valine requirement of 17 mg x kg(-1) x d(-1) is proposed for healthy, well-nourished Indian adults.

Effect of cystine on the methionine requirement of healthy Indian men determined by using the 24-h indicator amino acid balance approach.

BACKGROUND: The 1985 FAO/WHO/UNU requirement for methionine in healthy adults consuming a cystine-free diet is 13 mg.kg(-1).d(-1). It is unclear whether this daily requirement is influenced by dietary cystine. OBJECTIVE: We assessed the effect of 2 intakes of cystine (5 and 12 mg.kg(-1).d(-1)) on methionine requirements in well-nourished Indian men by using 7 test methionine intakes (3, 6, 9, 13, 18, 21 and 24 mg.kg(-1).d(-1)) and the 24-h indicator amino acid oxidation (24-h IAAO) and balance (24-h IAAB) methods. We combined these data with those from an experiment with zero cystine intake and in which the exact same method was used. DESIGN: Two studies were performed in which a diet containing either 5 or 12 mg cystine.kg(-1).d(-1) was fed to 21 well-nourished Indian men over three 7-d periods. The 24-h IAAO and 24-h IAAB values were measured on day 7 with the use of a 24-h intravenous [13C]leucine tracer infusion. The breakpoints in the relation between these values and methionine intake in each study were assessed by two-phase linear regression. RESULTS: Breakpoints in the response curve were obtained at methionine intakes of 20 (95% Fiellers CI: 17, 26) and 10 (95% Fiellers CI: 8, 16) mg.kg(-1).d(-1) with cystine intakes of 5 and 12 mg.kg(-1).d(-1) intakes, respectively, which suggested a sparing effect of cystine. Although the 5- and 12-mg cystine breakpoints differed from one another, they did not differ significantly from that estimated previously with 0 mg cystine. CONCLUSION: Cystine may spare the methionine requirement in healthy men, although the amount of sparing is difficult to quantify.

Daily requirement for total sulfur amino acids of chronically undernourished Indian men.

BACKGROUND: Earlier studies of the requirement for total sulfur amino acids (SAAs; methionine in the absence of cystine) in healthy, well-nourished Indians indicated a value of 15 mg.kg(-1).d(-1), but it is unknown whether this estimate is applicable to chronically undernourished subjects. OBJECTIVE: We assessed the total SAA requirement in otherwise clinically healthy, young, chronically undernourished adult Indians by using 7 test methionine intakes (3, 6, 9, 13, 18, 21, and 24 mg.kg(-1).d(-1)), without cystine, and by using both the 24-h indicator amino acid oxidation (24-h IAAO) and the 24-h indicator amino acid balance (24-h IAAB) methods. DESIGN: Twenty-one men were studied during each of 3 randomly assigned 7-d diet periods supplying methionine intakes (diet devoid of cystine) above and below the putative total 1985 FAO/WHO/UNU SAA requirement of 13 mg.kg(-1).d(-1). Twenty-four-hour IAAO and IAAB were measured on day 7 by use of a 24-h [(13)C]leucine tracer infusion. The breakpoint in the relation between these values and methionine intake was determined. RESULTS: Two-phase linear regression of daily leucine oxidation or the daily leucine balance against methionine intake estimated a breakpoint in the response curve at a methionine intake of 16 mg.kg(-1).d(-1) (95% Fiellers CI: 13, 22 mg.kg(-1).d(-1)). CONCLUSIONS: On the basis of the 24-h IAAO-IAAB approach, a mean total SAA requirement of 16 mg.kg(-1).d(-1) is proposed for undernourished Indian adults. This is not significantly different from that determined in Western and Indian well-nourished adults.

Intestinal parasites increase the dietary lysine requirement in chronically undernourished Indian men.

BACKGROUND: We previously used the 24-h indicator amino acid balance method to show that the lysine requirement in undernourished Indian men from low socioeconomic and unsanitary environments is approximately 50% higher than the mean requirement of 30 mg lysine. kg(-1). d(-1) in well-nourished men. OBJECTIVE: It is possible that this higher lysine requirement in persons with chronic undernutrition is due to environmental influences, including the presence of intestinal parasites. We assessed this possibility by using 24-h indicator amino acid balance (with leucine) at both the "normal" requirement for lysine intake and the higher requirement, before and after successful treatment to eradicate intestinal parasites in affected, undernourished men. DESIGN: Fourteen chronically undernourished men were studied before and after treatment for intestinal parasites, during each of two 7-d (6-d dietary adaptation plus 1-d tracer experiment) diet periods supplying either 30 (n = 7) or 45 (n = 7) mg lysine. kg(-1). d(-1) from an L-amino acid diet. Twenty-four-hour indicator amino acid balance was estimated on day 6 by [(13)C]leucine tracer infusion. RESULTS: Before the parasite treatment, subjects were in neutral 24-h leucine balance at both lysine intakes. After the eradication of intestinal parasites, there was a significant (P < 0.001) improvement in 24-h leucine balances, which were positive at both lysine intakes. CONCLUSIONS: On the basis of the 24-h indicator amino acid balance approach, it appears that intestinal infestation with parasites increases the requirement for lysine and that this may be one factor responsible for the higher lysine requirement observed in persons with chronic undernutrition.

Daily methionine requirements of healthy Indian men, measured by a 24-h indicator amino acid oxidation and balance technique.

BACKGROUND: The 1985 FAO/WHO/UNU upper requirement for the sulfur-containing amino acids in healthy adults, which was set at 13 mg . kg(-)(1) . d(-)(1), is based on nitrogen balance studies in Western subjects. Short-term tracer-based studies also estimated a mean requirement of 13 mg . kg(-)(1) . d(-)(1), but whether this estimate is applicable to healthy populations worldwide is unknown. OBJECTIVE: Using a 24-h indicator amino acid oxidation and balance method with 7 test methionine intakes (3, 6, 9, 13, 18, 21, and 24 mg . kg(-)(1) . d(-)(1)), we assessed methionine requirements in healthy, well-nourished Indians. DESIGN: Twenty-one healthy, well-nourished Indian men were studied during each of 3 randomly assigned 7-d diet periods in which methionine intakes (diet devoid of cysteine) were equally placed on either side of the putative mean methionine requirement of 13 mg . kg(-)(1) . d(-)(1). Twenty-four-hour indicator amino acid oxidation and balance were measured on day 7 by using a 24-h [(13)C]leucine tracer infusion. The breakpoint in the relation between these values and the methionine intake was determined. RESULTS: Two-phase linear regression of daily leucine oxidation against methionine intake estimated a breakpoint in the response curve at a methionine intake of 14 mg . kg(-)(1) . d(-)(1) (95% CI: 11, 23 mg . kg(-)(1) . d(-)(1)). The breakpoint estimated from the leucine balance-methionine intake relation was 15 mg . kg(-)(1) . d(-)(1) (95% CI: 11, 27 mg . kg(-1) . d(-1)). CONCLUSIONS: From the 24-h indicator amino acid oxidation and balance approach, a mean methionine requirement, in the absence of cysteine intake, of 15 mg . kg(-1) . d(-1) is proposed for healthy, well-nourished Indian adults. This requirement is similar to that established in Western adults.

Leucine requirement and splanchnic uptake of leucine in chronically undernourished adult Indian subjects.

BACKGROUND: We showed previously by the 24-h direct amino acid balance (DAAB) method that the leucine requirement of well-nourished Western and South Asian subjects is approximately 40 mg x kg(-1) x d(-1). OBJECTIVE: It is not known whether this estimated leucine requirement is applicable in chronic undernutrition; therefore, we assessed the leucine requirement in Indian men with chronic, but stable, undernutrition. DESIGN: We studied 26 chronically undernourished men during 2 randomly assigned 7-d diet periods consisting of an L-amino acid diet (n = 20) and supplying either 14 and 30 (n = 10) or 22 and 40 (n = 10) mg leucine x kg(-1)x d(-1) or consisting of the subjects' habitual cereal-and-lentil-based diets (n = 6). The 24-h DAAB was estimated on day 6 by using a [13C]leucine tracer infusion. The splanchnic uptake of leucine was determined at an intake of 40 mg x kg(-1) x d(-1) by administering [2H3]leucine orally. RESULTS: By using mixed-models linear regression of leucine balance against leucine intake, we estimated a zero leucine balance at a leucine intake of 39.6 mg x kg(-1) x d(-1). The splanchnic first-pass uptake of [2H3]leucine was 22.7% and 11.5% of the intake in the fasted and fed phases, respectively. The subjects were in neutral leucine balance with their habitual cereal-and-lentil-based diets. CONCLUSION: On the basis of the 24-h DAAB approach, a mean leucine requirement of 40 mg x kg(-1) x d(-1) is proposed for healthy and for chronically undernourished Indian adults.

Lysine requirements of chronically undernourished adult Indian men, measured by a 24-h indicator amino acid oxidation and balance technique.

BACKGROUND: In earlier studies with well-nourished subjects that used a 24-h indicator amino acid oxidation or balance approach, we concluded that the 1985 FAO/WHO/UNU requirement for lysine (12 mg x kg(-1) x d(-1)) was inadequate for healthy South Asian subjects and proposed a tentative requirement of 30 mg x kg(-1) x d(-1). OBJECTIVE: We assessed whether chronic undernutrition, with low habitual dietary protein and lysine intakes, leads to changed lysine requirements. DESIGN: Twenty-seven otherwise clinically healthy, chronically undernourished Indian men were studied during 2 randomly assigned 7-d diet periods supplying 12 and 30, 18 and 36, or 24 and 42 mg lysine x kg(-1) x d(-1), based on an L-amino acid diet. The subjects' leucine intake was 40 mg x kg(-1) x d(-1). At 1800 on day 6, a 24-h intravenous [(13)C]leucine tracer-infusion protocol was conducted to assess leucine oxidation and daily leucine balance at each test lysine intake. RESULTS: A breakpoint was not identified in the lysine intake-leucine oxidation or balance response over the range of intakes studied. Mixed-models linear regression analysis indicated a mean requirement of 44 mg lysine x kg(-1) x d(-1) (95% CI: 36, 63) for the lysine intake-leucine balance relation. CONCLUSIONS: The mean lysine requirement in chronically undernourished men is estimated to be higher than the value of 30 mg x kg(-1) x d(-1) proposed for well-nourished individuals. This may be related to body-composition differences. It also suggests that these subjects have not elicited a metabolic adaptation in response to their habitually low lysine intakes by substantially improving their efficiency of dietary lysine utilization.