Selenium concentration and speciation in biofortified flour and bread: Retention of selenium during grain biofortification, processing and production of Se-enriched food.

The retention and speciation of selenium in flour and bread was determined following experimental applications of selenium fertilisers to a high-yielding UK wheat crop. Flour and bread were produced using standard commercial practices. Total selenium was measured using inductively coupled plasma-mass spectrometry (ICP-MS) and the profile of selenium species in the flour and bread were determined using high performance liquid chromatography (HPLC) ICP-MS. The selenium concentration of flour ranged from 30ng/g in white flour and 35ng/g in wholemeal flour from untreated plots up to >1800ng/g in white and >2200ng/g in wholemeal flour processed from grain treated with selenium (as selenate) at the highest application rate of 100g/ha. The relationship between the amount of selenium applied to the crop and the amount of selenium in flour and bread was approximately linear, indicating minimal loss of Se during grain processing and bread production. On average, application of selenium at 10g/ha increased total selenium in white and wholemeal bread by 155 and 185ng/g, respectively, equivalent to 6.4 and 7.1µg selenium per average slice of white and wholemeal bread, respectively. Selenomethionine accounted for 65-87% of total extractable selenium species in Se-enriched flour and bread; selenocysteine, Se-methylselenocysteine selenite and selenate were also detected. Controlled agronomic biofortification of wheat crops for flour and bread production could provide an appropriate strategy to increase the intake of bioavailable selenium.

Rapid detection of sewer defects and blockages using acoustic-based instrumentation.

Sewer flooding incidents in the UK are being increasingly associated with the presence of blockages. Blockages are difficult to deal with as although there are locations where they are more likely to occur, they do occur intermittently. In order to manage sewer blockage pro-actively sewer managers need to be able to identify the location of blockages promptly. Traditional closed-circuit television (CCTV) inspection technologies are slow and relatively expensive so are not well suited to the rapid inspection of a network. This is needed if managers are to be able to address sewer blockages proactively. This paper reports on the development of an acoustic-based sensor. The sensor was tested in a full scale sewer pipe in the laboratory and it was shown that it is able to find blockages and identify structural aspects of a sewer pipe such as a manhole and lateral connection. Analysis of the received signal will locate a blockage and also provide information on its character. The measurement is very rapid and objective and so inspections can be carried out at much faster rates than using existing CCTV technologies.

In-sewer sedimentation associated with active flow control.

Active flow control using automated gates and weirs aims to utilise available dispersed storage within sewer systems to alleviate the severity and frequency of localised flooding incidents. Whilst a previous study has demonstrated its potential, a key operational concern before implementation was sedimentation. An experimental programme was designed to investigate the sediment deposition created when using a flow control device. Tests were also undertaken to examine the potential for rapid gate opening to flush away any resulting deposits. In catchments dominated by fine material in suspension, the use of an active flow control device can result in a uniformly thick deposit upstream of the gate. Rapid gate opening results in deposited material eroding in large sections starting at the gate and moving in an upstream direction. Granular sediment forms a series of discrete bedforms which are fairly uniform regardless of the flow conditions and a larger deposit further upstream. The potential for flushing granular deposits is limited and modification of the operation of the gate has shown little potential for increasing the effectiveness. Therefore, active flow control using a single downstream gate may only be suitable in systems with fine material moving in suspension during dry weather flow and not where there is significant granular sediment.

Estimation of uncertainty in long term combined sewer sediment behaviour predictions, a UK case study.

There are regulatory driven requirements for UK water companies to reduce the number of properties at risk of sewer flooding. One of the potential causes of sewer flooding is the presence of persistent sediment deposits in sewers. This is a common problem in many combined sewers. Although the regulation is risk based, there is a gap in current knowledge on how risk assessment is affected by the uncertainty in sewer solids behaviour prediction. This paper describes a UK case study exploring the possibility of estimating uncertainty in sewer sediment deposit level predictions, using Monte Carlo simulations combined with a response database.

Sewer system design moving into the 21st century--a UK perspective.

Change in external factors, such as environmental legislation and climate change, will mean the future of sewerage systems is likely to be different from the past. Combined sewerage systems comprise the vast majority of existing sewers in countries such as the UK. A study funded by UK Water Industry Research Ltd has reviewed the current state of sewerage within the UK, the likely drivers for change and the consequent future impacts over a 75 year timescale. Potential responses to address the anticipated changes have also been considered. It is concluded that due to the wide extent and value of existing sewer systems, these will continue to be used for the foreseeable future. However, in order to meet the major challenges as a result of changing external factors, these need to be operated more effectively, new ideas need to be explored and moves to develop better and more integrated water management systems need to be started if sewer systems in the UK are to provide the anticipated required levels of service well into the 21st century.

Rapid sonic characterisation of sewer change and obstructions.

This paper reports on the development of a low-cost, rapidly deployable sensor for surveying live sewers for blockages and structural failures. The anticipated cost is an order of magnitude lower than current techniques. The technology is based on acoustic normal model decomposition, The instrument emits short coded acoustic signals which are reflected from any sewer wall defect. The acoustic signals can be short Gaussian pulses or longer sinusoidal sweeps and pseudo-random noise. The processing algorithms used on the reflected signal can predict the extent and geometry of the pipe deformation, and the locations and approximate size of common blockages. The effect of the water level on the frequency of the fundamental mode has also been investigated. It is shown that the technique can be adapted to work reliably in relatively large 600 mm diameter sewer pipes.

Estimation of iron absorption in humans using compartmental modelling.

OBJECTIVE: To evaluate whether a compartmental model could estimate iron absorption as accurately as the well-validated technique of plasma area under the curve using labelled test meals. DESIGN: The study is a randomised cross-sectional intervention. SETTING: The study was carried out at the Human Nutrition Unit at the Institute of Food Research, Norwich, UK. SUBJECTS: A total of nine female volunteers, aged 33+/-8 y. INTERVENTIONS: Volunteers were given an oral dose (approximately 5 mg) of Fe-57 as iron sulphate in an orange juice test drink and simultaneously infused Fe-58 (approximately 200 microg) as iron citrate over 90 min. Multiple blood samples were taken for the following 6 h. The samples were analysed by mass spectrometry and iron absorption was estimated using a mathematical model based on the appearance of Fe isotopes in plasma and the area under the curve technique. RESULTS: The geometric mean (-1 s.d., +1 s.d.) absorption of the model estimate is 16% (9, 31) and the area under curve estimate is 18% (8, 29). CONCLUSIONS: Results indicate that a compartmental model can be used to estimate labelled iron absorption although it is unlikely that this new method will be used in favour of an existing one. Further studies are now needed with unlabelled iron to assess whether the technique could have application in the assessment of total (haem+nonhaem) iron absorption from food.

Copper absorption from foods labelled intrinsically and extrinsically with Cu-65 stable isotope.

OBJECTIVE: To determine copper absorption from copper containing foods labelled either intrinsically or extrinsically with a highly enriched Cu-65 stable isotope label. DESIGN: A longitudinal cross-over study. SETTING: The study was conducted at the Institute of Food Research, Human Nutrition Unit, Norwich, UK. SUBJECTS: Subjects were recruited locally via advertisements placed around the Norwich Research Park. A total of 10 volunteers (nine female, one male) took part in the study, but not all volunteers completed each of the test meals. INTERVENTIONS: A highly enriched Cu-65 stable isotope label was administered to volunteers in the form of a reference dose or in breakfast test meals consisting of red wine, soya beans, mushrooms or sunflower seeds. Faecal monitoring and mass spectrometry techniques were used to estimate the relative quantities of copper absorbed from the different test meals. RESULTS: True copper absorption from the reference dose (54%) was similar to extrinsically labelled red wine (49%) and intrinsically labelled sunflower seeds (52%), but significantly higher than extrinsically labelled mushrooms (35%), intrinsically (29%) and extrinsically (15%) labelled soya beans and extrinsically labelled sunflower seed (32%) test meals. CONCLUSIONS: The use of Cu-65 extrinsic labels in copper absorption studies requires validation according to the food being examined; intrinsic and extrinsic labelling produced significantly different results for sunflower seeds.

Improved formulations for rapid erosion of diverse solids in combined sewers.

For more than a decade, research carried out in Scotland has investigated the movement of sediment in sewers and the associated pollutant release. Pollution by discharges from combined sewer overflows can adversely affect watercourses, particularly those in urban areas. Solids and dissolved contaminants, many derived from in-sewer deposits during a storm event, can be especially significant. This phenomenon can occur during events known as 'foul flushes'. In combined sewers these typically occur in the initial period of storm flows, when the concentration of suspended sediments and other pollutants is significantly higher than at other times. It has become apparent that much of the suspended load originates from solids eroded from the bed. The 'near bed solids' which are re-entrained into the flow, together with solids eroded from the bulk bed, account for large changes in the suspended sediment concentration under time varying flow conditions. This paper describes some of the methods employed to investigate the solids eroding in combined sewers during peak flow events. The work examined the potential for sediment re-suspension under high flow conditions both in the laboratory and in the field.

Copper supplementation in humans does not affect the susceptibility of low density lipoprotein to in vitro induced oxidation (FOODCUE project).

The oxidative modification of low-density lipoprotein cholesterol (LDL) has been implicated in the pathogenesis of atherosclerosis. Copper (Cu) is essential for antioxidant enzymes in vivo and animal studies show that Cu deficiency is accompanied by increased atherogenesis and LDL susceptibility to oxidation. Nevertheless, Cu has been proposed as a pro-oxidant in vivo and is routinely used to induce lipid peroxidation in vitro. Given the dual role of Cu as an in vivo antioxidant and an in vitro pro-oxidant, a multicenter European study (FOODCUE) was instigated to provide data on the biological effects of increased dietary Cu. Four centers, Northern Ireland (coordinator), England, Denmark, and France, using different experimental protocols, examined the effect of Cu supplementation (3 or 6 mg/d) on top of normal Cu dietary intakes or Cu-controlled diets (0.7/1.6/6.0 mg/d), on Cu-mediated and peroxynitrite-initiated LDL oxidation in apparently healthy volunteers. Each center coordinated its own supplementation regimen and all samples were subsequently transported to Northern Ireland where lipid peroxidation analysis was completed. The results from all centers showed that dietary Cu supplementation had no effect on Cu- or peroxynitrite-induced LDL susceptibility to oxidation. These data show that high intakes (up to 6 mg Cu) for extended periods do not promote LDL susceptibility to in vitro-induced oxidation.

Effect of calcium supplementation on daily nonheme-iron absorption and long-term iron status.

The short-term effect of calcium supplements (1200 mg Ca/d) on daily nonheme-iron absorption was measured in 14 healthy adult volunteers by using stable isotope extrinsic labeling and fecal monitoring techniques. Mean (+/- SEM) nonheme-iron absorption from a low-calcium (< 320 mg/d), moderately high-iron (15 mg/d) diet was 15.8 +/- 2.1%, but in the presence of calcium (400 mg/meal) as calcium carbonate, absorption fell significantly to 4.7 +/- 1.4% (P < 0.001). The long-term effect of consuming calcium supplements with meals (1200 mg Ca/d) on body iron (functional and storage iron) was investigated in 11 iron-replete adults over a 6-mo period. An unsupplemented control group (n = 13) was also monitored to correct for any seasonal changes in the biochemical measurements. There were no changes in any of the hematologic indexes, including hemoglobin, hematocrit, zinc protoporphyrin, and plasma ferritin resulting from the calcium supplementation. The results clearly show that long-term supplementation with calcium did not reduce plasma ferritin concentrations in iron-replete adults consuming a Western-style diet containing moderate to high amounts of calcium in most meals.

Nonradioisotopic method for measuring iron absorption from a Gambian meal.

Iron absorption from a typical Gambian meal of rice with groundnut sauce was measured by the fecal balance technique in nonanemic adult males with 58Fe as an extrinsic label and neutron activation analysis and compared with ferrous sulphate. Gambian men had a higher efficiency of absorption than UK volunteers but the availability of the food Fe was approximately half that of ferrous sulphate in both groups of subjects.

Bioavailability of iron glycine as a fortificant in infant foods.

The bioavailability of iron glycine added to a vegetable infant weaning food was compared with ferrous sulfate. Stable, isotopically labeled compounds (57Fe or 58Fe) were mixed into the midday meal (1.4 mg added Fe/serving) and fed to 9-mo-old infants on alternate days for 8 d. Bioavailability, expressed as a percentage of the dose consumed, was measured from isotopic enrichment of hemoglobin 14 d after the last test meal. There was no difference between iron glycine and ferrous sulfate (x+/-SEM): 9.0+/-0.7% and 9.9+/-0.8%, respectively. The effect of chelation was examined by measuring iron bioavailability of iron glycine and ferrous sulfate added to a high-phytate (310 mg/100 g) whole-grain cereal weaning food and comparing it with a lower-phytate (147 mg/100 g) vegetable food, as used in the first study. Both iron compounds had lower bioavailability from the high-phytate food, 5.2+/-0.5% for iron glycine and 3.8+/-0.9% for ferrous sulfate, than the lower-phytate food, 9.8+/-1.5% for iron glycine and 9.1+/-1.3% for ferrous sulfate. The results showed no significant difference in bioavailability between the two forms of iron when added to infant weaning foods, suggesting that the glycine complex was fully or partially dissociated in the gastrointestinal tract. It is concluded that chelation does not improve the bioavailability of iron in the presence of dietary inhibitors.

Zinc absorption in infants fed iron-fortified weaning food.

The effect of fortification iron (reduced iron) on zinc absorption from a commercial vegetable-based weaning food was assessed in 11 9-mo-old infants. Each infant was fed a test meal of unfortified or iron-fortified product, labeled extrinsically with 1 mg 67Zn or 70Zn (as citrate), and the next day was fed the second product labeled with the other isotope. A complete fecal collection was carried out for 3-4 d, and the amount of unabsorbed isotope measured by thermal-ionization quadrupole mass spectrometry. Apparent zinc absorption (isotope intake minus fecal excretion, expressed as the % of dose administered) was 31.1 +/- 8.3% (x +/- SD) from the iron-fortified food and 28.6%28.6 +/- 10.5% from the unfortified food. These values were not significantly different, thus iron fortification of the weaning food did not reduce zinc absorption.

Iron and zinc absorption in human subjects from a mixed meal of extruded and nonextruded wheat bran and flour.

The effect of extrusion cooking of a bran-flour mixture on iron and zinc retention was measured in normal adults. The stable isotopes 58Fe (1.253 mg) and 67Zn (5.13 mg) were administered with 40 g nonextruded or extruded cereal with milk and isotopic retention was measured from fecal excretion over the next 4-7 d by neutron-activation analysis (Fe) and fast-atom-bombardment mass spectrometry (Zn). 58Fe retention was 15.1 +/- 2.4% (means +/- SEM) with the nonextruded meal and 16.5 +/- 2.7% with the extruded meal. 67Zn retention was 18.9 +/- 1.7% with the nonextruded meal and 18.3 +/- 1.5% with the extruded meal. Extrusion cooking had no effect on 58Fe or 67Zn retention.

Rare earth elements as nonabsorbable fecal markers in studies of iron absorption.

The use of rare earth elements as nonabsorbable fecal markers for studies of iron absorption from sources labeled extrinsically with stable isotopes was evaluated. On 3 successive days 13 healthy fasting adults were given different stable isotopes of iron with samarium, ytterbium, or dysprosium. On day 1, three meals were given with 57Fe (1 mg per meal) plus samarium (0.33 mg per meal); on day 2, identical meals (taken with a calcium supplement to reduce iron bioavailability) were given with equivalent amounts of 58Fe-labeled iron and ytterbium; on day 3, a well-absorbed reference dose of 54Fe (3 mg) was given with 1 mg Dy. A complete fecal collection was carried out for 5-9 d and each stool was analyzed for rare earth elements by inductively coupled plasma-mass spectrometry and iron isotopes by thermal ionization quadrupole mass spectrometry. Mean recovery of rare earth elements was 101%, indicating that they are totally unabsorbed. The excretory pattern of the iron isotopes and the rare earth elements was very similar; the correlation coefficients between samarium and 57Fe, ytterbium and 58Fe, and dysprosium and 54Fe were 0.992, 0.989, and 0.988, respectively (P < 0.001). Iron absorption was calculated as the difference between isotope dose and fecal excretion. Mean (+/-SEM) iron absorption was 16.7 +/- 2.4%, 4.3 +/- 1.6%, and 40.3 +/- 3.1% on days 1-3, respectively. Predicted values estimated from the first 4 d of pooled feces, using the rare earth element recovery data to produce corrected figures for unabsorbed isotope, were in close agreement: 19.1 +/- 2.1%, 4.6 +/- 1.7%, and 40.8 +/- 3.1%, respectively (P < 0.001). With the diet of medium iron bioavailability and with the highly bioavailable reference dose it was possible to predict iron absorption accurately from only one or two stools, provided that they were sufficiently enriched with isotope and a rare earth element.

Oral ferrous sulfate supplements increase the free radical-generating capacity of feces from healthy volunteers.

BACKGROUND: Most dietary iron remains unabsorbed and hence may be available to participate in Fenton-driven free radical generation in conjunction with the colonic microflora, leading to the production of carcinogens or direct damage to colonocytes. OBJECTIVE: Our aims were to measure the proportion of fecal iron available to participate in free radical generation and to determine the effect of an oral supplement of ferrous sulfate on free radical generation. DESIGN: Eighteen healthy volunteers recorded their food intake and collected fecal samples before, during, and after 2 wk of supplementation (19 mg elemental Fe/d). Total, free, and weakly chelated fecal iron were measured and free radical production was determined by using an in vitro assay with dimethyl sulfoxide as a free radical trap. RESULTS: Fecal iron increased significantly during the period of supplementation and returned to baseline within 2 wk. The concentration of weakly bound iron in feces (approximately 1.3% of total fecal iron) increased from 60 micromol/L before to 300 micromol/L during supplementation, and the production of free radicals increased significantly (approximately 40%). Higher-carbohydrate diets were associated with reduced free radical generation. CONCLUSION: Unabsorbed dietary iron may increase free radical production in the colon to a level that could cause mucosal cell damage or increased production of carcinogens.

Iron deficiency in infancy; easy to prevent--or is it?

Despite major advances in our knowledge of iron nutrition in infancy, iron deficiency remains a significant problem in the UK. The precise size of the problem is unknown, but there appears to be a higher risk amongst certain ethnic groups. Nutritional iron deficiency appears after the age of 6 months and is undoubtedly linked to inappropriate feeding practice. High bioavailability of iron in weaning foods is of paramount importance in preventing iron deficiency, whether using family foods or commercially available products, and further information about different foods and diets is needed. The long-term detrimental effect on mental development makes prevention of iron deficiency a high priority public health objective for the 1990s.

High bioavailability of calcium in fortified Horlicks.

OBJECTIVE: To compare the bioavailability of calcium carbonate-fortified Horlicks with calcium naturally present in milk. DESIGN: Randomised crossover within-subject comparison using a double label stable isotope technique. SETTING: Institute of Food Research, Human Nutrition Unit. PARTICIPANTS: Sixteen pre-menopausal women aged 23-40 y, habituated to a high-calcium diet (mean 1240 mg/day). RESULTS: Mean true fractional calcium absorption was 38.8% (s.d.+/-14.5) from Horlicks and 21.2% (s.d.+/-4.6) from milk. Significantly more calcium was absorbed from a serving of Horlicks than from the same quantity of calcium present in 420 g semi-skimmed milk (P<0.001). CONCLUSIONS: Fortified Horlicks is a highly bioavailable source of calcium. A single serving, containing at least 500 mg calcium, provides half the reference nutrient intake for the population sub-group with the highest requirement (adolescent boys) and more than half for all others. SPONSORSHIP: SmithKline Beecham funded this research project.

Factors affecting iron stores in infants 4-18 months of age.

OBJECTIVES: To determine the effects of dietary, physiological or environmental factors on body iron levels in infants aged 4-18 months. DESIGN: The daily iron intake of the infants was measured from a diet history obtained by interview using a standardised question sheet, previously validated against weighed intake (minimum 3 days) in an independent sample of 8 and 18 month old infants. Capillary blood samples were analyzed for haemoglobin, mean cell volume, haematocrit, zinc protoporphyrin and plasma ferritin concentration. Ferritin values were log-transformed prior to analysis to give a better approximation to the normal distribution and forward stepwise multiple linear regression was carried out using SPSS. SETTING: The city of Norwich, UK and some of its suburbs. SUBJECTS: One hundred and eighty-one healthy infants in age groups 4, 8, 12 and 18 months. RESULTS: Main determinants of iron stores in the 4 month old infants were birth weight (+ve (P < 0.001)) and body weight (-ve (P < 0.005)). In the 8 month old infants intake of cow's milk (-ve (P < 0.05)), belonging to a smoking household (-ve (P < 0.05)) and quantity of commercial babyfood consumed (+ve (P < 0.05)) were significant. In this age group there was a gender effect (girls > boys (P < 0.01)) and the gender effect remained at 12 months (girls > boys (P < 0.05)), but at 18 months only non-haem iron intake was a significant factor (-ve (P < 0.05)). CONCLUSIONS: At 4 months of age birth weight and body weight exert the greatest influence on iron stores, whereas by 8 months components of the weaning diet have an effect (commercial babyfood (+ve), cow's milk (-ve)); there is also a gender effect (girls > boys), possibly reflecting the different growth rate between boys and girls. At 12 and 18 months the only significant factors are gender (girls > boys) and non-haem iron intake (-ve) respectively.