A robust interpolation-based method for forensic soil provenancing: A Bayesian likelihood ratio approach.

Soil is a complex and spatially variable material that has a demonstrated potential as a useful evidence class in forensic casework and intelligence operations. Here, the capability to spatially constrain police search areas and prioritise resources by triaging areas as low and high interest is advantageous. Conducted between 2017 and 2021, a forensically relevant topsoil survey (0-5 cm depth; 1 sample per 1 km2) was carried out over Canberra, Australia, aiming to document the distribution of chemical elements in an urban/suburban environment, and of acting as a testbed for investigating various aspects of forensic soil provenancing. Geochemical data from X-Ray Fluorescence (XRF; for total major oxides) and Inductively Coupled Plasma-Mass Spectrometry (ICP-MS; for trace elements) following a total digestion (HF + HNO3) of the fused XRF beads were obtained from the survey's 685 topsoil samples (plus 138 additional quality control samples and six "Blind" simulated evidentiary samples). Using those "Blind" samples, we document a likelihood ratio approach where for each grid cell the analytical similarity between the grid cell and evidentiary sample is attributed from a measure of overlap between the two Cauchy distributions, including appropriate uncertainties. Unlike existing methods that base inclusion/exclusion on an arbitrary threshold (e.g., ± three standard deviations), our approach is free from strict binary or Boolean thresholds, providing an unconstrained gradual transition dictated by the analytical similarity. Using this provenancing model, we present and evaluate a new method for upscaling from a fine (25 m x 25 m) interpolated grid to a more appropriate coarser (500 m x 500 m) grid. In addition, an objective method using Random Match Probabilities for ranking individual variables to be used for provenancing prior to receiving evidentiary material was demonstrated. Our results show this collective procedure generates more consistent and robust provenance maps when applied to two different interpolation algorithms (e.g., inverse distance weighting, and natural neighbour), with different grid placements (e.g., grid shifts to the north or east) and by different theoretical users (e.g., different computer systems, or forensic geoscientists).

The secret hidden in dust: Assessing the potential to use biological and chemical properties of the airborne fraction of soil for provenance assignment and forensic casework.

The airborne fraction of soil (dust) is both ubiquitous in nature and contains localised biological and chemical signatures, making it a potential medium for forensic intelligence. Metabarcoding of dust can yield biological communities unique to the site of interest, similarly, geochemical analyses can uncover elements and minerals within dust that can be matched to a geographic location. Combining these analyses presents multiple lines of evidence as to the origin of dust collected from items of interest. In this work, we investigated whether bacterial and fungal communities in dust change through time and whether they are comparable to soil samples of the same site. We integrated dust metabarcoding into a framework amenable to forensic casework, (i.e., using calibrated log-likelihood ratios) to predict the origin of dust samples using models constructed from both dust samples and soil samples from the same site. Furthermore, we tested whether both metabarcoding and geochemical/mineralogical analyses could be conducted on a single swabbed sample, for situations where sampling is limited. We found both analyses could generate results from a single swabbed sample and found biological and chemical signatures unique to sites. However, we did find significant variation within sites, where this did not always correlate with time but was a random effect of sampling. This variation within sites was not greater than between sites and so did not influence site discrimination. When modelling bacterial and fungal diversity using calibrated log-likelihood ratios, we found samples were correctly predicted using dust 67% and 56% of the time and using soil 56% and 22% of the time for bacteria and fungi communities respectively. Incorrect predictions were related to within site variability, highlighting limitations to assigning dust provenance using metabarcoding of soil.

Characterization of Beef Coming from Different European Countries through Stable Isotope (H, C, N, and S) Ratio Analysis.

The need to guarantee the geographical origin of food samples has become imperative in recent years due to the increasing amount of food fraud. Stable isotope ratio analysis permits the characterization and origin control of foodstuffs, thanks to its capability to discriminate between products having different geographical origins and derived from different production systems. The Framework 6 EU-project "TRACE" generated hydrogen (2H/1H), carbon (13C/12C), nitrogen (15N/14N), and sulphur (34S/32S) isotope ratio data from 227 authentic beef samples. These samples were collected from a total of 13 sites in eight countries. The stable isotope analysis was completed by combining IRMS with a thermal conversion elemental analyzer (TC/EA) for the analysis of δ(2H) and an elemental analyzer (EA) for the determination of δ(13C), δ(15N), and δ(34S). The results show the potential of this technique to detect clustering of samples due to specific environmental conditions in the areas where the beef cattle were reared. Stable isotope measurements highlighted statistical differences between coastal and inland regions, production sites at different latitudes, regions with different geology, and different farming systems related to the diet the animals were consuming (primarily C3- or C4-based or a mixed one).

The utility of dust for forensic intelligence: Exploring collection methods and detection limits for environmental DNA, elemental and mineralogical analyses of dust samples.

Environmental DNA (eDNA), elemental and mineralogical analyses of soil have been shown to be specific to their source material, prompting consideration of using the airborne fraction of soil (dust) for forensic intelligence work. Dust is ubiquitous in the environment and is easily transferred to items belonging to a person of interest, making dust analysis an ideal tool in forensic casework. The advent of Massive Parallel Sequencing technologies means metabarcoding of eDNA can uncover bacterial, fungal, and even plant genetic fingerprints in dust particles. Combining this with elemental and mineralogical compositions offers multiple, complementary lines of evidence for tracing the origin of an unknown dust sample. This is particularly pertinent when recovering dust from a person of interest to ascertain where they may have travelled. Prior to proposing dust as a forensic trace material, however, the optimum sampling protocols and detection limits need to be established to place parameters around its utility in this context. We tested several approaches to collecting dust from different materials and determined the lowest quantity of dust that could be analysed for eDNA, elemental composition and mineralogy, whilst still yielding results capable of distinguishing between sites. We found that fungal eDNA profiles could be obtained from multiple sample types and that tape lifts were the optimum collection method for discriminating between sites. We successfully recovered both fungal and bacterial eDNA profiles down to 3 mg of dust (the lowest tested quantity) and recovered elemental and mineralogical compositions for all tested sample quantities. We show that dust can be reliably recovered from different sample types, using different sampling techniques, and that fungi and bacteria, as well as elemental and mineralogical profiles, can be generated from small sample quantities, highlighting the utility of dust for forensic intelligence.

Forensic soil provenancing in an urban/suburban setting: A simultaneous multivariate approach.

Soil is a ubiquitous material at the Earth's surface with potential to be a useful evidence class in forensic and intelligence applications. Compositional data from a soil survey over North Canberra, Australian Capital Territory, are used to develop and test an empirical soil provenancing method. Mineralogical data from Fourier Transform InfraRed spectroscopy (FTIR) and geochemical data from X-Ray Fluorescence (XRF; for total major oxides) and Inductively Coupled Plasma-Mass Spectrometry (ICP-MS; for both total and aqua regia-soluble trace elements) are obtained from the survey's 268 topsoil samples (0-5 cm depth; 1 sample per km2 ). The simultaneous provenancing approach is underpinned by (i) the calculation of Spearman's correlation coefficients (rS ) between an evidentiary sample and all the samples in the database for all variables generated by each analytical method; and (ii) the preparation of an interpolated raster grid of rS for each evidentiary sample and method resulting in a series of provenance rasters ("heat maps"). The simultaneous provenancing method is tested on the North Canberra soil survey with three "blind" samples representing simulated evidentiary samples. Performance metrics of precision and accuracy indicate that the FTIR (mineralogy) and XRF (geochemistry) analytical methods offer the most precise and accurate provenance predictions. Maximizing the number of analytes/analytical techniques is advantageous in soil provenancing. Despite acknowledged limitations, it is concluded that the empirical soil provenancing approach can play an important role in forensic and intelligence applications.

A fresh scientific look at transfer and persistence: From a materials science and tribology perspective.

Knowledge of the mechanisms governing transfer, persistence, and recovery of trace evidence, together with background prevalence in the population of interest, and other task relevant information, is key for the forensic interpretation and reconstruction of what happened at the activity level. Up to now, this informational "toolkit" has largely been developed through empirical forensic studies on specific trace materials such as glass, textile fibers, and soil. Combined with the identified systemic siloing between disciplines, while valuable, such research tends to be very material-dependent, introducing specific parameters and interpretations that may have actually impeded the recognition of underlying foundational factors applicable to most material types. In Australia, there has been a renewed interest in developing a discipline-independent framework for the interpretation and/or reconstruction of trace evidence to interpret specific circumstances in casework. In this paper, we present a discipline agnostic "way of thinking" that has been anchored in foundational science underpinning the trace evidence discipline. Physical and mechanical material properties such as material geometry and surface topography, strength, stiffness, and hardness collectively influence contact interactions through underlying friction, wear, and lubrication cause and effect mechanisms. We discuss how these fundamental factors and parameters stemming from materials science and tribology may be adopted and adapted by forensic practitioners and researchers to contribute to a better understanding of transfer, persistence, and recovery mechanisms irrespective of evidence discipline and material type. Examples are provided to demonstrate the practical significance to real-life casework and academic research.

Forensic soil provenancing in an urban/suburban setting: A sequential multivariate approach.

Compositional data from a soil survey over North Canberra, Australian Capital Territory, are used to develop and test an empirical soil provenancing method. Mineralogical data from Fourier transform infrared spectroscopy (FTIR) and magnetic susceptibility (MS), and geochemical data from X-ray fluorescence (XRF; for total major oxides) and inductively coupled plasma-mass spectrometry (ICP-MS; for both total and aqua regia-soluble trace elements) are performed on the survey's 268 topsoil samples (0-5 cm depth; 1 sample per km2 ). Principal components (PCs) are calculated after imputation of censored data and centered log-ratio transformation. The sequential provenancing approach is underpinned by (i) the preparation of interpolated raster grids of the soil properties (including PCs); (ii) the explicit quantification and propagation of uncertainty; (iii) the intersection of the soil property rasters with the values of the evidentiary sample (± uncertainty); and (iv) the computation of cumulative provenance rasters ("heat maps") for the various analytical techniques. The sequential provenancing method is tested on the North Canberra soil survey with three "blind" samples representing simulated evidentiary samples. Performance metrics of precision and accuracy indicate that the FTIR and MS (mineralogy), as well as XRF and total ICP-MS (geochemistry) analytical methods, offer the most precise and accurate provenance predictions. Inclusion of PCs in provenancing adds marginally to the performance. Maximizing the number of analytes/analytical techniques is advantageous in soil provenancing. Despite acknowledged limitations and gaps, it is concluded that the empirical soil provenancing approach can play an important role in forensic and intelligence applications.

A δ2H Isoscape of blackberry as an example application for determining the geographic origins of plant materials in New Zealand.

In this investigation, two previously reported precipitation δ2H isoscapes for New Zealand were used to develop a δ2H isoscape for blackberry (Rubus sp.) leaf. These isoscapes were calibrated using the measured δ2H values of 120 authentic blackberry leaf samples collected from across the country. A regression model based on environmental variables available for New Zealand was also determined to predict δ2H values measured from blackberry leaves without initially modelling the precipitation δ2H values. The three models were compared for their accuracy and precision when assigning 10 samples of blackberry leaves for their geographic location based on their measured δ2H values. One of the models based on a precipitation isoscape was similar in accuracy and precision of assignment to the model determined from the environmental variables and provides an approach for determining valid isoscapes for future plant materials.

Spatial variability of 2H and 18O composition of meteoric freshwater lakes in Scotland.

Coastal regions, and in particular islands where precipitation from clouds formed out at sea occurs for the first time, are prime candidates for regions where 2H and 18O composition of precipitation will deviate significantly from the global mean geographic and physiographic trends of vapour-transport patterns. The results reported here are the outcome of a study that aimed to test this hypothesis by 'isotopographically' mapping the characteristic δ2H and δ18O signatures of Scottish freshwaters. The resulting isotope abundance landscapes or 'isoscapes' will underpin studies aiming to authenticate origin of Scottish produce but may also offer a baseline against which environmental changes could be assessed. Between April 2011 and May 2012 freshwater samples were collected from 127 different freshwater lochs and reservoirs across Scotland, and analysis results were compared to precipitation data provided by the British Geological Survey. Here we present the results of the 2H and 18O analyses of these water samples as well as the first detailed Scotland freshwater isoscapes with a grid resolution of about 5 × 5 km (0.05 degrees).

Bioavailable 87Sr/86Sr in European soils: A baseline for provenancing studies.

We present 87Sr/86Sr isotope ratios for ~1200 selected soil samples, collected by the GEMAS consortium from grazing (Gr) and agricultural (Ap) soils in Europe with the aim to better understand the strontium isotope distribution in the bioavailable fraction of the top-soil and its potential for provenancing applications. Spatial analysis shows that there is a clear distinction between coastal (<100 km) and non-coastal (>100 km) samples in their variance and that this variance is mirrored in the sodium concentration, suggesting an important but highly variable contribution from seaspray. We present two 87Sr/86Sr maps at 25 km × 25 km scale: one based solely on the measured data using a classical kriging approach and one based on a Random Forest model using complementary GEMAS data to predict the strontium isotope composition at the remaining 3000+ GEMAS sampling locations, including appropriate uncertainty assessment. Using a forensic Bayesian likelihood ratio approach, a tool was developed in R to create provenancing likelihood ratio maps. The maps delineate areas of high and low likelihood and allow investigators to direct their resources to areas of interest. For actual forensic case work either the measured or the modelled data can be used as reference data for the overall distribution of 87Sr/86Sr values in Europe.

Distribution of toxic elements and transfer from the environment to humans traced by using lead isotopes. A case of study in the Sarno River basin, south Italy.

The results of a large geochemical study on various environmental media (soil, stream sediment, groundwater, surface water, lettuce and human hair) of the Sarno River basin, which is one of the most polluted areas in Italy, are presented. Further, it aims to deepen our understanding of the distribution of Pb and its isotope composition for the differentiation between natural and anthropogenic metal sources. Our results show the environmental media to be significantly enriched in Cr, Cu, Pb, Hg, Zn, and to a lesser extent in Sb, Cd and Ni compared to the natural local background variation. The numerous industrial activities (mainly tanneries) have caused environmental pollution especially Cr and Hg in soils and sediment samples. Such contamination is also evident in lettuce and in the hair of the resident population, which shows particularly high values for both Cr and Hg. The unusually high As, Be and Sn concentrations arise mostly from natural sources due to the volcanic nature of the investigated area. Lead isotope measurements indicate a trend suggesting mixing between two end-members, one of clear natural origin (geogenic) and another related to human activities (anthropogenic). Lead isotope results demonstrate that Pb in hair of inhabitants is similar to those in the local topsoil and that gasoline is one of the main, but not the only source of metal pollution. The most important exposure risks within the study area are associated with toxic elements levels in topsoil and stream sediment, and the ingestion of locally grown lettuce. The high concentrations of these elements in hair are a further confirmation of this exposure pathway.

Gunshot residue preservation in seawater.

Little is known about the persistence of gunshot residue (GSR) in soft tissue and bones during decomposition in marine environments. For a better understanding, qualitative and quantitative data were obtained on GSR retention on soft tissue and bony gunshot wounds (GSWs). A quantity of 36 fleshed and 36 defleshed bovine ribs were shot at contact range with 0.22 calibre hollow point ammunition using a Stirling 0.22 calibre long rifle. Bone specimens in triplicate were placed in three environments: submerged, intertidal and in supralittoral zone. Sets of triplicates were recovered on day 3, 10, 24 and 38, and analysed with scanning electron microscopy with energy dispersive X-ray spectrometry (SEM-EDX), and inductive coupled plasma mass spectrometry (ICP-MS). The SEM-EDX recorded GSR-indicative particles surrounding the bullet entrance on all bone types (fleshed and defleshed) in all environments throughout the study. GSR-unique particles were only detected on the supralittoral bones. The ICP-MS analysis showed faster GSR loss on submerged than intertidal and supralittoral defleshed specimens. Fleshed specimens showed a faster GSR loss on intertidal than submerged and supralittoral specimens. In conclusion, the GSR disappeared faster from submerged and intertidal than non-submerged specimens. The difference of detection of GSR between analysed specimens (defleshed versus fleshed) disappeared upon defleshing. This study highlights the potential of finding evidence of GSR in a submerged body and the potential of microscopic and analytical methods for examining suspected GSW in highly decomposed bodies in marine habitats.

Linking soil, water, and honey composition to assess the geographical origin of argentinean honey by multielemental and isotopic analyses.

The objective of this research was to investigate the development of a reliable fingerprint from elemental and isotopic signatures of Argentinean honey to assess its geographical provenance. Honey, soil, and water from three regions (Córdoba, Buenos Aires, and Entre Ríos) were collected. The multielemental composition was determined by ICP-MS. δ(13)C was measured by isotopic ratio mass spectrometry, whereas the (87)Sr/(86)Sr ratio was determined using thermal ionization mass spectrometry. The data were analyzed by chemometrics looking for the association between the elements, stable isotopes, and honey samples from the three studied areas. Honey samples were differentiated by classification trees and discriminant analysis using a combination of eight key variables (Rb, K/Rb, B, U, (87)Sr/(86)Sr, Na, La, and Zn) presenting differences among the studied regions. The application of canonical correlation analysis and generalized procrustes analysis showed 91.5% consensus between soil, water, and honey samples, in addition to clear differences between studied areas. To the authors' knowledge, this is the first report demonstrating the correspondence between soil, water, and honey samples using different statistical methods, showing that elemental and isotopic honey compositions are related to soil and water characteristics of the site of origin.

Elemental and isotopic fingerprint of Argentinean wheat. Matching soil, water, and crop composition to differentiate provenance.

The aim of this study was to investigate if elemental and isotopic signatures of Argentinean wheat can be used to develop a reliable fingerprint to assess its geographical provenance. For this pilot study we used wheat cultivated at three different regions (Buenos Aires, Córdoba, and Entre Ríos), together with matching soil and water. Elemental composition was determined by ICP-MS. δ(13)C and δ(15)N were measured by isotopic ratio mass spectrometry, while (87)Sr/(86)Sr ratio was determined using thermal ionization mass spectrometry. Wheat samples from three sampling sites were differentiated by the combination of 11 key variables (K/Rb, Ca/Sr, Ba, (87)Sr/(86)Sr, Co, Mo, Zn, Mn, Eu, δ(13)C, and Na), demonstrating differences among the three studied regions. The application of generalized Procrustes analysis showed 99.2% consensus between cultivation soil, irrigation water, and wheat samples, in addition to clear differences between studied areas. Furthermore, canonical correlation analysis showed significant correlation between the elemental and isotopic profiles of wheat and those corresponding to both soil and water (r(2) = 0.97, p < 0.001 and r(2) = 0.96, p < 0.001, respectively). To our knowledge, this is the first report demonstrating the correspondence between soil, water, and wheat samples using different statistical methods, showing that wheat elemental and isotopic compositions are mainly related to soil and irrigation water characteristics of the site of growth.

How much do soil and water contribute to the composition of meat? A case study: meat from three areas of Argentina.

The main goal of this study was to propose a reliable method to verify the geographical origin of meat, establishing the influence of soil and water on its isotopic and elemental composition. Thus, beef meat, soil, and water samples were collected from three major cattle-producing regions of Argentina (Buenos Aires, Córdoba, and Entre Ríos). Multielemental composition was determined on these three matrices by inductively coupled plasma mass spectrometry (ICP-MS), δ(13)C and δ(15)N by isotope-ratio mass spectrometry (IRMS), and the (87)Sr/(86)Sr ratio by thermal ionization mass spectrometry (TIMS). Soil and drinking water samples could be characterized and clearly differentiated by combining the isotopic ratios and elements, demonstrating differences in geology and climatic conditions of three regions. Similarly, meat originating at each sampling area was characterized and differentiated using only five key variables (Rb, Ca/Sr, δ(13)C, δ(15)N, and (87)Sr/(86)Sr). Generalized procrustes analysis (GPA), using the three studied matrices (soil, water, and meat) shows consensus between them and clear differences between studied areas. Furthermore, canonical correlation analysis (CCA) demonstrates significant correlation between the chemical-isotopic profile of meat with those corresponding to both soil and water (r(2) = 0.93, p < 0.001; and r(2) = 0.83, p < 0.001, respectively). So far, there are clear coincidences between the meat fingerprint and those from soil/water where cattle grew, presenting a good method to establish beef provenance. To the authors' knowledge this is the first report linking the influence of soil and water all together on the composition of beef, presenting the basis for the authentication of Argentinean beef, which could be extended to meat from different provenances.

Fingerprints for main varieties of argentinean wines: terroir differentiation by inorganic, organic, and stable isotopic analyses coupled to chemometrics.

Our main goal was to investigate if robust chemical fingerprints could be developed for three Argentinean red wines based on organic, inorganic, and isotopic patterns, in relation to the regional soil composition. Soils and wines from three regions (Mendoza, San Juan, and Córdoba) and three varieties (Cabernet Sauvignon, Malbec, and Syrah) were collected. The phenolic profile was determined by HPLC-MS/MS and multielemental composition by ICP-MS; (87)Sr/(86)Sr and δ(13)C were determined by TIMS and IRMS, respectively. Chemometrics allowed robust differentiation between regions, wine varieties, and the same variety from different regions. Among phenolic compounds, resveratrol concentration was the most useful marker for wine differentiation, whereas Mg, K/Rb, Ca/Sr, and (87)Sr/(86)Sr were the main inorganic and isotopic parameters selected. Generalized Procrustes analysis (GPA) using two studied matrices (wine and soil) shows consensus between them and clear differences between studied areas. Finally, we applied a canonical correlation analysis, demonstrating significant correlation (r = 0.99; p < 0.001) between soil and wine composition. To our knowledge this is the first report combining independent variables, constructing a fingerprint including elemental composition, isotopic, and polyphenol patterns to differentiate wines, matching part of this fingerprint with the soil provenance.

Application of laser ablation (LA-ICP-SF-MS) for the elemental analysis of bone and teeth samples for discrimination purposes.

Human bone and teeth fragments can be useful evidence when found in crime scenes and/or mass burials sites. The elemental and isotopic composition of these samples can provide information about environmental exposure events and could also be used to distinguish different individuals. The development and application of robust analytical methods for the quantification of trace elements in these biological matrices may lead to a better understanding of the potential utility of these measurements in forensic analyses. In this paper, we demonstrate the possibility of conducting quantitative analysis of trace metals found in bone remains and suggest a strategy to discriminate between individuals, based on this information. A LA-ICP-SF-MS method using non-matrix matched standard calibration was developed and optimized with bone standard reference materials (SRMs) and subsequently applied to the analysis of real samples. The developed method requires micrograms amount of sample (vs. milligrams required for solution-based analysis) while also reducing the analysis time and resulting in good accuracy (typically <10% bias) and precision (<15% RSD). Additionally, laser ablation allowed using spatial resolution analysis to assess the biogenic elemental composition in buried bone samples. Elemental analysis of bone samples from 12 different individuals provided better discrimination between the individuals when the femur and humerus bones were considered separately (42.7% correct classification with all bones vs. 75.2% and 63.1% for femur bones and humerus bones, respectively). Separation of individuals was achieved by elemental composition of whole teeth samples from 14 individuals, except one case where not all the teeth from the same individual were associated together. Separation of individuals was improved when using elemental composition of the enamel and dentine+cementum layers separately in a set of samples from 7 individuals. These are promising results for the use of elemental analysis by laser ablation ICP-MS for discrimination purposes.

Isotopic and elemental data for tracing the origin of European olive oils.

H, C, and O stable isotope ratios and the elemental profile of 267 olive oils and 314 surface waters collected from 8 European sites are presented and discussed. The aim of the study was to investigate if olive oils produced in areas with different climatic and geological characteristics could be discriminated on the basis of isotopic and elemental data. The stable isotope ratios of H, C, and O of olive oils and the ratios of H and O of the relevant surface waters correlated to the climatic (mainly temperature) and geographical (mainly latitude and distance from the coast) characteristics of the provenance sites. It was possible to characterize the geological origin of the olive oils by using the content of 14 elements (Mg, K, Ca, V, Mn, Zn, Rb, Sr, Cs, La, Ce, Sm, Eu, U). By combining the 3 isotopic ratios with the 14 elements and applying a multivariate discriminant analysis, a good discrimination between olive oils from 8 European sites was achieved, with 95% of the samples correctly classified into the production site.

Relative bioavailability of micronized, dispersible ferric pyrophosphate added to an apple juice drink.

BACKGROUND: Food iron fortification is a sustainable and relatively simple strategy to reduce/prevent iron deficiency but is a challenge for the food industry because of possible adverse organoleptic changes caused by the added iron. A micronized dispersible ferric pyrophosphate, trademarked as SunActive Fe, has recently been developed. SunActive Fe has a small particle size, is water soluble and may be suitable for fortifying liquid products. AIM OF THE STUDY: To determine the relative bioavailability of SunActive Fe and its suitability for addition to pure apple juice. METHODS: Iron absorption from SunActive Fe added to pure apple juice (Minute Maid) was compared with absorption from ferrous sulphate, a highly bioavailable form of iron, in 15 women with relatively low iron stores. Both forms of iron were enriched with an iron stable isotope and iron absorption from the apple juice drinks was calculated from the isotopic enrichment of red blood cells 14 days after the last test meal. RESULTS: Although mean absorption of iron from SunActive Fe was significantly lower than from ferrous sulphate (5.5% compared with 9.1%), the mean bioavailability of SunActive Fe iron relative to ferrous sulphate was 0.6, indicating that it is a good source of bioavailable iron. Iron Absorption from SunActive Fe was positively correlated (r = 0.97, P = 0.01) with absorption from ferrous sulphate, and negatively correlated with serum ferritin concentration (ferrous sulphate r = -0.81, P < 0.001; SunActive Fe r = -0.76, P = 0.01). CONCLUSIONS: SunActive Fe was well absorbed from apple juice and is a potentially useful fortificant for liquid food products.

Sodium and bone health: impact of moderately high and low salt intakes on calcium metabolism in postmenopausal women.

High salt intake is a well-recognized risk factor for osteoporosis because it induces calciuria, but the effects of salt on calcium metabolism and the potential impact on bone health in postmenopausal women have not been fully characterized. This study investigated adaptive mechanisms in response to changes in salt and calcium intake in postmenopausal women. Eleven women completed a randomized cross-over trial consisting of four successive 5-wk periods of controlled dietary intervention, each separated by a minimum 4-wk washout. Moderately low and high calcium (518 versus 1284 mg) and salt (3.9 versus 11.2 g) diets, reflecting lower and upper intakes in postmenopausal women consuming a Western-style diet, were provided. Stable isotope labeling techniques were used to measure calcium absorption and excretion, compartmental modeling was undertaken to estimate bone calcium balance, and biomarkers of bone formation and resorption were measured in blood and urine. Moderately high salt intake (11.2 g/d) elicited a significant increase in urinary calcium excretion (p = 0.0008) and significantly affected bone calcium balance with the high calcium diet (p = 0.024). Efficiency of calcium absorption was higher after a period of moderately low calcium intake (p < 0.05) but was unaffected by salt intake. Salt was responsible for a significant change in bone calcium balance, from positive to negative, when consumed as part of a high calcium diet, but with a low calcium intake, the bone calcium balance was negative on both high and low salt diets.