Modelling of Usual Nutrient Intakes: Potential Impact of the Choices Programme on Nutrient Intakes in Young Dutch Adults

Introduction

The Choices Programme is an internationally applicable nutrient profiling system with nutrition criteria for trans fatty acids (TFA), saturated fatty acids, sodium, added sugar and for some product groups energy and fibre. These criteria determine whether foods are eligible to carry a “healthier option” stamp. In this paper a nutrient intake modelling method is described to evaluate these nutritional criteria by investigating the potential effect on nutrient intakes.

Methods

Data were combined from the 2003 Dutch food consumption survey in young adults (aged 19–30) and the Dutch food composition table into the Monte Carlo Risk Assessment model. Three scenarios were calculated: the “actual intakes” (scenario 1) were compared to scenario 2, where all foods that did not comply were replaced by similar foods that did comply with the Choices criteria. Scenario 3 was the same as scenario 2 adjusted for the difference in energy density between the original and replacement food. Additional scenarios were calculated where snacks were not or partially replaced and stratified analyses for gender, age, Body Mass Index (BMI) and education.

Results

Calculated intake distributions showed that median energy intake was reduced by 16% by replacing normally consumed foods with Choices compliant foods. Intakes of nutrients with a maximal intake limit were also reduced (ranging from −23% for sodium and −62% for TFA). Effects on intakes of beneficial nutrients varied from an unintentional reduction in fat soluble vitamin intakes (−15 to −28%) to an increase of 28% for fibre and 17% calcium. Stratified analyses in this homogeneous study population showed only small differences across gender, age, BMI and education.

Conclusions

This intake modelling method showed that with consumption of Choices compliant foods, nutrient intakes shift towards population intake goals for the nutrients for which nutrition criteria were defined, while effects on beneficial nutrients were diverse.     

The Feasibility of Achieving Low-Sodium Intake in Diets That Are Also Nutritious,Low-Cost,and Have Familiar Meal Components

Objective

Given the importance of high sodium diets as a risk factor for disease burden (ranked 11^th in importance in the Global Burden of Disease Study 2010), we aimed to determine the feasibility of low-sodium diets that were also low-cost, nutritious and (for some scenarios) included familiar meals.

Methods

The mathematical technique of “linear programming” was used to model eight optimized daily diets (some with uncertainty), including some diets that contained “familiar meals” for New Zealanders or were Mediterranean-, Asian- and Pacific-style diets. Data inputs included nutrients in foods, food prices and food wastage.

Findings

Using nutrient recommendations for men and a cost constraint of <NZ$9/d (US$6.84), the sodium intake levels in the eight optimized daily diets were all well below the 2300 mg/d (5.8 g salt/d) recommended maximum. The only diet to not consistently fall below the recommended “target” upper limit of 1600 mg/d included an evening meal with sausages (median  = 1640 mg/d, 95% simulation interval: 1551–1735 mg/d). Many additional nutritional aspects of these optimized low-sodium diets suggest that they would reduce cardiovascular disease risk in other ways (e.g., improved polyunsaturated to saturated fat ratio) and also reduce risk of cancer and other chronic diseases (e.g., via higher intakes of vegetables, fruits and dietary fiber). Even healthier diets (e.g., with higher intakes of fruit) occurred when the cost constraint was relaxed to $NZ15/d (US$11.40). Similar results were obtained when the modeling considered diets for women.

Conclusions

These results provide some reassurance for the feasibility of substantially reducing population sodium intake given currently available low-cost foods and while maintaining some level of familiar meals. Policy makers could consider ways to promote such optimized diets and foods, including regulations on maximum salt levels in processed foods, and taxes on alternative foods that are high in salt, sugar and saturated fat.     

Reproducibility and Relative Validity of a Food Frequency Questionnaire Developed for Adults in Taizhou,China

Objective

To evaluate the reproducibility and validity of a food frequency questionnaire (FFQ) developed to investigate the relationship between dietary factors and diseases in the adult Chinese population in East China.

Methods

A total of 78 males and 129 females aged 30–75 years completed four inconsecutive 24-hour dietary recalls (24-HRs, served as a reference method) and two FFQs (FFQ1 and FFQ2) over a nine-month interval. The reproducibility of the FFQ was estimated with correlation coefficients, cross-classification, and weighted kappa statistic. The validity was assessed by comparing the data obtained from FFQ and 24-HRs.

Results

The median nutrient intakes assessed with FFQs were higher than the average of four 24-HRs. For the food groups, Spearman, Pearson, and intraclass correlation coefficients between FFQ1 and FFQ2 ranged from 0.23 to 0.61, 0.27 to 0.64, and 0.26 to 0.65, respectively. For total energy and nutrient intakes, the corresponding coefficients ranged from 0.25 to 0.61, 0.28 to 0.64, and 0.28 to 0.62, respectively. The correlations between FFQ1 and FFQ2 for most nutrients decreased after adjustment with total energy intake. More than 70% of the subjects were classified into the same and adjacent categories by both FFQs. For food groups, the crude, energy-adjusted, and de-attenuated Spearman correlation coefficients between FFQ2 and the 24-HRs ranged from 0.17 to 0.59, 0.10 to 0.57, and 0.11 to 0.64, respectively. For total energy and nutrient intakes, the corresponding coefficients ranged from 0.20 to 0.58, 0.08 to 0.54, and 0.09 to 0.56, respectively. More than 67% of the subjects were classified into the same and adjacent categories by both instruments. Both weighted kappa statistic and Bland-Altman Plots showed reasonably acceptable agreement between the FFQ2 and 24-HRs.

Conclusion

The FFQ developed for adults in the Taizhou area is reasonably reliable and valid for assessment of most food and nutrient intakes.     

Optimisation Modelling to Assess Cost of Dietary Improvement in Remote Aboriginal Australia

Background

The cost and dietary choices required to fulfil nutrient recommendations defined nationally, need investigation, particularly for disadvantaged populations.

Objective

We used optimisation modelling to examine the dietary change required to achieve nutrient requirements at minimum cost for an Aboriginal population in remote Australia, using where possible minimally-processed whole foods.

Design

A twelve month cross-section of population-level purchased food, food price and nutrient content data was used as the baseline. Relative amounts from 34 food group categories were varied to achieve specific energy and nutrient density goals at minimum cost while meeting model constraints intended to minimise deviation from the purchased diet.

Results

Simultaneous achievement of all nutrient goals was not feasible. The two most successful models (A & B) met all nutrient targets except sodium (146.2% and 148.9% of the respective target) and saturated fat (12.0% and 11.7% of energy). Model A was achieved with 3.2% lower cost than the baseline diet (which cost approximately AUD$13.01/person/day) and Model B at 7.8% lower cost but with a reduction in energy of 4.4%. Both models required very large reductions in sugar sweetened beverages (−90%) and refined cereals (−90%) and an approximate four-fold increase in vegetables, fruit, dairy foods, eggs, fish and seafood, and wholegrain cereals.

Conclusion

This modelling approach suggested population level dietary recommendations at minimal cost based on the baseline purchased diet. Large shifts in diet in remote Aboriginal Australian populations are needed to achieve national nutrient targets. The modeling approach used was not able to meet all nutrient targets at less than current food expenditure.     

Root cortical aerenchyma inhibits radial nutrient transport in maize (Zea mays)

Background and Aims

Formation of root cortical aerenchyma (RCA) can be induced by nutrient deficiency. In species adapted to aerobic soil conditions, this response is adaptive by reducing root maintenance requirements, thereby permitting greater soil exploration. One trade-off of RCA formation may be reduced radial transport of nutrients due to reduction in living cortical tissue. To test this hypothesis, radial nutrient transport in intact roots of maize (Zea mays) was investigated in two radiolabelling experiments employing genotypes with contrasting RCA.

Methods

In the first experiment, time-course dynamics of phosphate loading into the xylem were measured from excised nodal roots that varied in RCA formation. In the second experiment, uptake of phosphate, calcium and sulphate was measured in seminal roots of intact young plants in which variation in RCA was induced by treatments altering ethylene action or genetic differences.

Key Results

In each of three paired genotype comparisons, the rate of phosphate exudation of high-RCA genotypes was significantly less than that of low-RCA genotypes. In the second experiment, radial nutrient transport of phosphate and calcium was negatively correlated with the extent of RCA for some genotypes.

Conclusions

The results support the hypothesis that RCA can reduce radial transport of some nutrients in some genotypes, which could be an important trade-off of this trait.     

Effects of soil nutrient heterogeneity on intraspecific competition in the invasive, clonal plant Alternanthera philoxeroides

Background and Aims

Fine-scale, spatial heterogeneity in soil nutrient availability can increase the growth of individual plants, the productivity of plant communities and interspecific competition. If this is due to the ability of plants to concentrate their roots where nutrient levels are high, then nutrient heterogeneity should have little effect on intraspecific competition, especially when there are no genotypic differences between individuals in root plasticity. We tested this hypothesis in a widespread, clonal species in which individual plants are known to respond to nutrient heterogeneity.

Methods

Plants derived from a single clone of Alternanthera philoxeroides were grown in the greenhouse at low or high density (four or 16 plants per 27·5 × 27·5-cm container) with homogeneous or heterogeneous availability of soil nutrients, keeping total nutrient availability per container constant. After 9 weeks, measurements of size, dry mass and morphology were taken.

Key Results

Plants grew more in the heterogeneous than in the homogeneous treatment, showing that heterogeneity promoted performance; they grew less in the high- than in the low-density treatment, showing that plants competed. There was no interactive effect of nutrient heterogeneity and plant density, supporting the hypothesis that heterogeneity does not affect intraspecific competition in the absence of genotypic differences in plasticity. Treatments did not affect morphological characteristics such as specific leaf area or root/shoot ratio.

Conclusions

Results indicate that fine-scale, spatial heterogeneity in the availability of soil nutrients does not increase competition when plants are genetically identical, consistent with the suggestion that effects of heterogeneity on competition depend upon differences in plasticity between individuals. Heterogeneity is only likely to increase the spread of monoclonal, invasive populations such as that of A. philoxeroides in China.     

A multivariate analysis of serum nutrient levels and lung function

Background

There is mounting evidence that estimates of intakes of a range of dietary nutrients are related to both lung function level and rate of decline, but far less evidence on the relation between lung function and objective measures of serum levels of individual nutrients. The aim of this study was to conduct a comprehensive examination of the independent associations of a wide range of serum markers of nutritional status with lung function, measured as the one-second forced expiratory volume (FEV₁).

Methods

Using data from the Third National Health and Nutrition Examination Survey, a US population-based cross-sectional study, we investigated the relation between 21 serum markers of potentially relevant nutrients and FEV₁, with adjustment for potential confounding factors. Systematic approaches were used to guide the analysis.

Results

In a mutually adjusted model, higher serum levels of antioxidant vitamins (vitamin A, beta-cryptoxanthin, vitamin C, vitamin E), selenium, normalized calcium, chloride, and iron were independently associated with higher levels of FEV₁. Higher concentrations of potassium and sodium were associated with lower FEV₁.

Conclusion

Maintaining higher serum concentrations of dietary antioxidant vitamins and selenium is potentially beneficial to lung health. In addition other novel associations found in this study merit further investigation.     

Dietary Fiber and Saturated Fat Intake Associations with Cardiovascular Disease Differ by Sex in the Malm? Diet and Cancer Cohort: A Prospective Study

Background

The aim of the study was to examine associations between intake of macronutrients and dietary fiber and incident ischemic cardiovascular disease (iCVD) in men and women.

Methods

We used data from 8,139 male and 12,535 female participants (aged 44–73 y) of the Swedish population-based Malmö Diet and Cancer cohort. The participants were without history of CVD and diabetes mellitus, and had reported stable dietary habits in the study questionnaire. Diet was assessed by a validated modified diet history method, combining a 7-d registration of cooked meals and cold beverages, a 168-item food questionnaire (covering other foods and meal patterns), and a 1-hour diet interview. Sociodemographic and lifestyle data were collected by questionnaire. iCVD cases, which included coronary events (myocardial infarctions or deaths from chronic ischemic heart disease) and ischemic strokes, were ascertained via national and local registries. Nutrient-disease associations were examined by multivariate Cox regressions.

Results

During a mean follow-up of 13.5 years, we identified 1,089 male and 687 female iCVD cases. High fiber intakes were associated with lower incidence rates of iCVD in women and of ischemic stroke in men. In post-hoc analysis, we discovered statistically significant interactions between intake of fiber and saturated fat; these interactions also differed between men and women (p<0.001).

Conclusions

In this well-defined population, a high fiber intake was associated with lower risk of iCVD, but there were no robust associations between other macronutrients and iCVD risk. Judging from this study, gender-specific nutrient analysis may be preferable in epidemiology.     

Effect of trans Fatty Acid Intake on LC-MS and NMR Plasma Profiles

Background

The consumption of high levels of industrial trans fatty acids (TFA) has been related to cardiovascular disease, diabetes and sudden cardiac death but the causal mechanisms are not well known. In this study, NMR and LC-MS untargeted metabolomics has been used as an approach to explore the impact of TFA intake on plasma metabolites.

Methodology/Principal Findings

In a double-blinded randomized controlled parallel-group study, 52 overweight postmenopausal women received either partially hydrogenated soybean oil, providing 15.7 g/day of TFA (trans18:1) or control oil with mainly oleic acid for 16 weeks. Subsequent to the intervention period, the subjects participated in a 12-week dietary weight loss program. Before and after the TFA intervention and after the weight loss programme, volunteers participated in an oral glucose tolerance test. PLSDA revealed elevated lipid profiles with TFA intake. NMR indicated up-regulated LDL cholesterol levels and unsaturation. LC-MS profiles demonstrated elevated levels of specific polyunsaturated (PUFA) long-chain phosphatidylcholines (PCs) and a sphingomyelin (SM) which were confirmed with a lipidomics based method. Plasma levels of these markers of TFA intake declined to their low baseline levels after the weight loss program for the TFA group and did not fluctuate for the control group. The marker levels were unaffected by OGTT.

Conclusions/Significance

This study demonstrates that intake of TFA affects phospholipid metabolism. The preferential integration of trans18:1 into the sn-1 position of PCs, all containing PUFA in the sn-2 position, could be explained by a general up-regulation in the formation of long-chain PUFAs after TFA intake and/or by specific mobilisation of these fats into PCs. NMR supported these findings by revealing increased unsaturation of plasma lipids in the TFA group. These specific changes in membrane lipid species may be related to the mechanisms of TFA-induced disease but need further validation as risk markers.

Trial registration

Registered at clinicaltrials.gov as {"type":"clinical-trial","attrs":{"text":"NCT00655902","term_id":"NCT00655902"}}NCT00655902     

1H-NMR-based metabolic profiling of maternal and umbilical cord blood indicates altered materno-foetal nutrient exchange in preterm infants

Background

Adequate foetal growth is primarily determined by nutrient availability, which is dependent on placental nutrient transport and foetal metabolism. We have used ¹H nuclear magnetic resonance (NMR) spectroscopy to probe the metabolic adaptations associated with premature birth.

Methodology

The metabolic profile in ¹H NMR spectra of plasma taken immediately after birth from umbilical vein, umbilical artery and maternal blood were recorded for mothers delivering very-low-birth-weight (VLBW) or normo-ponderal full-term (FT) neonates.

Principal Findings

Clear distinctions between maternal and cord plasma of all samples were observed by principal component analysis (PCA). Levels of amino acids, glucose, and albumin-lysyl in cord plasma exceeded those in maternal plasma, whereas lipoproteins (notably low-density lipoprotein (LDL) and very low-density lipoprotein (VLDL) and lipid levels were lower in cord plasma from both VLBW and FT neonates. The metabolic signature of mothers delivering VLBW infants included decreased levels of acetate and increased levels of lipids, pyruvate, glutamine, valine and threonine. Decreased levels of lipoproteins glucose, pyruvate and albumin-lysyl and increased levels of glutamine were characteristic of cord blood (both arterial and venous) from VLBW infants, along with a decrease in levels of several amino acids in arterial cord blood.

Conclusion

These results show that, because of its characteristics and simple non-invasive mode of collection, cord plasma is particularly suited for metabolomic analysis even in VLBW infants and provides new insights into the materno-foetal nutrient exchange in preterm infants.     

Docosahexaenoic Acid for Reading, Cognition and Behavior in Children Aged 7-9 Years: A Randomized, Controlled Trial (The DOLAB Study)

Background

Omega-3 fatty acids are dietary essentials, and the current low intakes in most modern developed countries are believed to contribute to a wide variety of physical and mental health problems. Evidence from clinical trials indicates that dietary supplementation with long-chain omega-3 may improve child behavior and learning, although most previous trials have involved children with neurodevelopmental disorders such as attention-deficit/hyperactivity disorder (ADHD) or developmental coordination disorder (DCD). Here we investigated whether such benefits might extend to the general child population.

Objectives

To determine the effects of dietary supplementation with the long-chain omega-3 docosahexaenoic acid (DHA) on the reading, working memory, and behavior of healthy schoolchildren.

Design

Parallel group, fixed-dose, randomized, double-blind, placebo-controlled trial (RCT).

Setting

Mainstream primary schools in Oxfordshire, UK (n = 74).

Participants

Healthy children aged 7–9 years initially underperforming in reading (≤33^rd centile). 1376 invited, 362 met study criteria.

Intervention

600 mg/day DHA (from algal oil), or taste/color matched corn/soybean oil placebo.

Main Outcome Measures

Age-standardized measures of reading, working memory, and parent- and teacher-rated behavior.

Results

ITT analyses showed no effect of DHA on reading in the full sample, but significant effects in the pre-planned subgroup of 224 children whose initial reading performance was ≤20^th centile (the target population in our original study design). Parent-rated behavior problems (ADHD-type symptoms) were significantly reduced by active treatment, but little or no effects were seen for either teacher-rated behaviour or working memory.

Conclusions

DHA supplementation appears to offer a safe and effective way to improve reading and behavior in healthy but underperforming children from mainstream schools. Replication studies are clearly warranted, as such children are known to be at risk of low educational and occupational outcomes in later life.

Trial Registration

ClinicalTrials.gov {"type":"clinical-trial","attrs":{"text":"NCT01066182","term_id":"NCT01066182"}}NCT01066182 and Controlled-Trials.com ISRCTN99771026     

Mineral nutrient stoichiometric variability in Hedera helix (Araliaceae) seeds

Background and Aims

The analysis of variability in mineral allocation to seeds has rarely been considered in relation to allometric patterns and deviations from the allometric trajectory. Here, I examine the scaling of carbon (C), nitrogen (N), phosphorus (P) and sulfur (S) with seed mass in field-collected seeds of Hedera helix, taking into account that brood size might influence the allocation patterns.

Methods

C, N and S contents of 56 individual seeds of different sizes were analysed by combustion using a standard automated CNHS procedure. P content was determined for 200 individual seeds using spectrophotometry after acid digestion of ashed samples. This sample included seeds from different brood sizes.

Key Results

C and N content both varied isometrically with seed mass and this variable explained most of the variation in their content in seeds. P and S, however, varied allometrically with seed mass. Additionally, seed mass only explained 37·3 % and 37·6 % of the total variance in P and S content, respectively. Seeds with higher mass contained proportionately more P and, furthermore, the seeds from small broods contained proportionally more P than those from large broods.

Conclusions

Although seed mass in this species can be used as a surrogate of investment in C and N, it does not account for variability in allocation of nutrients such as P and S. The fact that larger seeds increased their P concentration when found in smaller broods might be a consequence of intense competition for this nutrient among developing seeds. Then, brood size may influence the mineral nutrient concentration of seeds.     

Prevalence and risk factors for vitamin C deficiency in north and south India: a two centre population based study in people aged 60 years and over

Background

Studies from the UK and North America have reported vitamin C deficiency in around 1 in 5 men and 1 in 9 women in low income groups. There are few data on vitamin C deficiency in resource poor countries.

Objectives

To investigate the prevalence of vitamin C deficiency in India.

Design

We carried out a population-based cross-sectional survey in two areas of north and south India. Randomly sampled clusters were enumerated to identify people aged 60 and over. Participants (75% response rate) were interviewed for tobacco, alcohol, cooking fuel use, 24 hour diet recall and underwent anthropometry and blood collection. Vitamin C was measured using an enzyme-based assay in plasma stabilized with metaphosphoric acid. We categorised vitamin C status as deficient (<11 µmol/L), sub-optimal (11–28 µmol/L) and adequate (>28 µmol/L). We investigated factors associated with vitamin C deficiency using multivariable Poisson regression.

Results

The age, sex and season standardized prevalence of vitamin C deficiency was 73.9% (95% confidence Interval, CI 70.4,77.5) in 2668 people in north India and 45.7% (95% CI 42.5,48.9) in 2970 from south India. Only 10.8% in the north and 25.9% in the south met the criteria for adequate levels. Vitamin C deficiency varied by season, and was more prevalent in men, with increasing age, users of tobacco and biomass fuels, in those with anthropometric indicators of poor nutrition and with lower intakes of dietary vitamin C.

Conclusions

In poor communities, such as in our study, consideration needs to be given to measures to improve the consumption of vitamin C rich foods and to discourage the use of tobacco.     

The loss of metabolic control on alcohol drinking in heavy drinking alcohol-dependent subjects

Background

Most physiological studies interested in alcohol-dependence examined ethanol as a pharmacological agent rather than a nutrient. We conducted two studies, which assessed the metabolic and endocrine factors involved in the regulation of alcohol and nutrient intake in alcohol-dependent (AD) subjects. We also examined the potential role of a disruption in energy balance in alcohol-dependence.

Methods and Results

In Study-1, quantitative dietetic interviews of eating and drinking habits were conducted with 97 AD subjects. The population was split around a median alcohol intake value of 12.5 kcal/kg/day. The results showed that the “low alcohol” drinking AD subjects had high Body Mass Index (BMI) and Fat Mass (FM) and alcohol intake was compensated for by a decrease in non-alcoholic intakes. “High alcohol” drinking AD subjects, on the other hand, had low BMI and FM and the total caloric intakes were largely above norms. In Study-2, 24 AD inpatients were submitted to dietetic interviews, calorimetry and blood samplings for the measurement of biomarkers of the regulation of metabolism and satiety, on day 2, 5 and 16 of abstinence. These patients were compared with 20 controls matched for age and gender. We observed in AD patients an increase in cortisol, leptin and PYY plasma levels and a decrease in ghrelin, which might explain the observed decrease in non-alcoholic intakes. However, alcoholic and non-alcoholic intakes correlated positively with basal metabolism and negatively with leptin and leptin/BMI.

Conclusion

For individuals consuming below12.5 kcal/kg/day of alcohol, alcohol intake is compensated for by a decrease in non-alcoholic nutrient intakes, probably due to changes in metabolic and satiety factors. For individuals consuming above 12.5 kcal/kg/day of alcohol, alcohol accelerates metabolism and decreases fat mass and leptin levels, and the total caloric intake largely exceeds norms. A dual model for regulation of energy intake in AD subjects is proposed.     

Dietary Adequacies among South African Adults in Rural KwaZulu-Natal

Background

Food quality, determined by micronutrient content, is a stronger determinant of nutritional status than food quantity. Health concerns resulting from the co-existence of over-nutrition and under-nutrition in low income populations in South Africa have been fully recognized in the last two decades. This study aimed to further investigate dietary adequacy amongst adults in rural KwaZulu-Natal, by determining daily energy and nutrient intakes, and identifying the degree of satisfaction of dietary requirements.

Methods

Cross-sectional study assessing dietary adequacy from 24-hour dietary recalls of randomly selected 136 adults in Empangeni, KwaZulu-Natal, South Africa.

Results

Results are presented for men (n = 52) and women (n = 84) 19–50 and >50 years old. Mean energy intake was greatest in women >50 years (2852 kcal/day) and exceeded Dietary Reference Intake’s for both men and women, regardless of age. Mean daily energy intake from carbohydrates was 69% for men and 67% for women, above the Dietary Reference Intake range of 45–65%. Sodium was also consumed in excess, and the Dietary Reference Intakes of vitamins A, B12, C, D, and E, calcium, zinc and pantothenic acid were not met by the majority of the population.

Conclusion

Despite mandatory fortification of staple South African foods, micronutrient inadequacies are evident among adults in rural South African communities. Given the excess caloric intake and the rising prevalence of obesity and other non-communicable diseases in South Africa, a focus on diet quality may be a more effective approach to influence micronutrient status than a focus on diet quantity.     

Mistletoes and mutant albino shoots on woody plants as mineral nutrient traps

Background and Aims

Potassium, sulphur and zinc contents of mistletoe leaves are generally higher than in their hosts. This is attributed to the fact that chemical elements which are cycled between xylem and phloem in the process of phloem loading of sugars are trapped in the mistletoe, because these parasites do not feed their hosts. Here it is hypothesized that mutant albino shoots on otherwise green plants should behave similarly, because they lack photosynthesis and thus cannot recycle elements involved in sugar loading.

Methods

The mineral nutrition of the mistletoe Scurrula elata was compared with that of albino shoots on Citrus sinensis and Nerium oleander. The potential for selective nutrient uptake by the mistletoe was studied by comparing element contents of host leaves on infected and uninfected branches and by manipulation of the haustorium–shoot ratio in mistletoes. Phloem anatomy of albino leaves was compared with that of green leaves.

Key Results

Both mistletoes and albino leaves had higher contents of potassium, sulphur and zinc than hosts or green leaves, respectively. Hypothetical discrimination of nutrient elements during the uptake by the haustorium is not supported by our data. Anatomical studies of albino leaves showed characteristics of release phloem.

Conclusions

Both albino shoots and mistletoes are traps for elements normally recycled between xylem and phloem, because retranslocation of phloem mobile elements into the mother plant or the host is low or absent. It can be assumed that the lack of photosynthetic activity in albino shoots and thus of sugars needed in phloem loading is responsible for the accumulation of elements. The absence of phloem loading is reflected in phloem anatomy of these abnormal shoots. In mistletoes the evolution of a parasitic lifestyle has obviously eliminated substantial feeding of the host with photosynthates produced by the mistletoe.     

Complementarity in root architecture for nutrient uptake in ancient maize/bean and maize/bean/squash polycultures

Background and Aims

During their domestication, maize, bean and squash evolved in polycultures grown by small-scale farmers in the Americas. Polycultures often overyield on low-fertility soils, which are a primary production constraint in low-input agriculture. We hypothesized that root architectural differences among these crops causes niche complementarity and thereby greater nutrient acquisition than corresponding monocultures.

Methods

A functional–structural plant model, SimRoot, was used to simulate the first 40 d of growth of these crops in monoculture and polyculture and to determine the effects of root competition on nutrient uptake and biomass production of each plant on low-nitrogen, -phosphorus and -potassium soils.

Key Results

Squash, the earliest domesticated crop, was most sensitive to low soil fertility, while bean, the most recently domesticated crop, was least sensitive to low soil fertility. Nitrate uptake and biomass production were up to 7 % greater in the polycultures than in the monocultures, but only when root architecture was taken into account. Enhanced nitrogen capture in polycultures was independent of nitrogen fixation by bean. Root competition had negligible effects on phosphorus or potassium uptake or biomass production.

Conclusions

We conclude that spatial niche differentiation caused by differences in root architecture allows polycultures to overyield when plants are competing for mobile soil resources. However, direct competition for immobile resources might be negligible in agricultural systems. Interspecies root spacing may also be too large to allow maize to benefit from root exudates of bean or squash. Above-ground competition for light, however, may have strong feedbacks on root foraging for immobile nutrients, which may increase cereal growth more than it will decrease the growth of the other crops. We note that the order of domestication of crops correlates with increasing nutrient efficiency, rather than production potential.     

How Did the TB Patients Reach DOTS Services in Delhi? A Study of Patient Treatment Seeking Behavior

Setting

Revised National Tuberculosis Control Programme (RNTCP), Delhi, India.

Objective

To ascertain the number and sequence of providers visited by TB patients before availing treatment services from DOTS; to describe the duration between onset of symptoms to treatment.

Study design

A cross sectional, qualitative study. Information was gathered through in-depth interviews of TB patients registered during the month of Oct, 2012 for availing TB treatment under the Revised National TB Control Programme from four tuberculosis diagnosis and treatment centers in Delhi.

Results

Out of the 114 patients who registered, 108 participated in the study. The study showed that informal providers and retail chemists were the first point of contact and source of clinical advice for two-third of the patients, while the rest sought medical care from qualified providers directly. Most patients sought medical care from more than two providers, before being diagnosed as TB. Female TB patients and patients with extra-pulmonary TB had long mean duration between onset of symptoms to initiation of treatment (6.3 months and 8.4 months respectively).

Conclusion

The pathways followed by TB patients, illustrated in this study, provide valuable lessons on the importance of different types of providers (both formal and informal) in the health system in a society like India and the delays in the diagnosis and treatment of tuberculosis.     

Linkage of Presumptive Multidrug Resistant Tuberculosis (MDR-TB) Patients to Diagnostic and Treatment Services in Cambodia

Setting

National Tuberculosis Programme, Cambodia.

Objective

In a cohort of TB patients, to ascertain the proportion of patients who fulfil the criteria for presumptive MDR-TB, assess whether they underwent investigation for MDR-TB, and the results of the culture and drug susceptibility testing (DST).

Methods

A cross sectional record review of TB patients registered for treatment between July-December 2011.

Results

Of 19,236 TB patients registered, 409 (2%) fulfilled the criteria of presumptive MDR-TB; of these, 187 (46%) were examined for culture. This proportion was higher among relapse, failure, return after default (RAD) and non-converters at 3 months of new smear positive TB patients (>60%) as compared to non-converters at 2 months of new TB cases (<20%). Nearly two thirds (n = 113) of the samples were culture positive; of these, three-fourth (n = 85) grew Mycobacterium tuberculosis complex (MTBc) and one-fourth (n = 28) grew non-tuberculous Mycobacteria. DST results were available for 96% of the MTBc isolates. Overall, 21 patients were diagnosed as MDR-TB (all diagnosed among retreatment TB cases and none from non-converters) and all of them were initiated on MDR-TB treatment.

Conclusion

There is a need to strengthen mechanisms for linking patients with presumptive MDR-TB to culture centers. The policy of testing non-converters for culture and DST needs to be reviewed.