Antifungal activity of poly(ε-caprolactone) nanoparticles incorporated with Eucalyptus essential oils against Hemileia vastatrix.

Coffee (Coffea L.) is one of the main crops produced globally. Its contamination by the fungus Hemileia vastatrix Berkeley and Broome has been economically detrimental for producers. The objective of this work was to extract and characterize the essential oils from Eucalyptus citriodora Hook, Eucalyptus camaldulensis Dehn and Eucalyptus grandis Hill ex Maiden, produce and characterize nanoparticles containing these essential oils and evaluate the in vivo and in vitro antifungal activity of free and nanoencapsulated essential oils. The principal constituent of the essential oil from E. citriodora was citronellal; that from E. grandis was α-pinene; and that from E. camaldulensis was 1,8-cineol. The in vitro antifungal activity against the fungus H. vastatrix was 100% at a concentration of 1000 µl l-1 for all the oils and nanoparticles containing these natural products. The sizes of the nanoparticles produced with the essential oils from E. citriodora, E. camaldulensis and E. grandis were 402·13 nm, 275·33 nm and 328·5 nm, respectively, with surface charges of -11·8 mV, -9·24 mV and - 6·76 mV, respectively. Fourier transform infrared analyses proved that the encapsulation of essential oils occurred in the polymeric matrix of poly(ε-caprolactone). The incorporation of essential oils into biodegradable poly(ε-caprolactone) nanoparticles increased their efficiency as biofungicides in the fight against coffee rust, decreasing the severity of the disease by up to 90·75% after treatment with the nanoparticles containing the essential oil from E. grandis.

Antifungal and antiocratoxigenic potential of Alpinia speciosa and Cymbopogon flexuosus essential oils encapsulated in poly(lactic acid) nanofibres against Aspergillus fungi.

Essential oils encapsulated in a polymeric matrix can be used as an alternative method to control fungi and mycotoxins. The essential oils were extracted by hydrodistillation and characterized by gas chromatography. The nanofibres were produced from poly (acid lactic) (PLA) containing essential oils by the Solution Blow Spinning method. The antifungal and antimicotoxygenic properties were evaluated against Aspergillus ochraceus and Aspergillus westerdijkiae by the fumigation method. Terpinen-4-ol (20·23%), sabinene (20·18%), 1·8-cineole (16·69%) and γ-terpinene (11·03%) were the principal compounds present in the essential oil from Alpinia speciosa, whereas citral (97·67%) was dominant from Cymbopogon flexuosus. Microscopy images showed that the addition of essential oils caused an increase in the diameter of the nanofibres. The infrared spectroscopy results indicated the presence of essential oils in the PLA nanofibres. Differential scanning calorimetry curves also indicated the existence of interactions between the essential oils and polymeric macromolecules through their plasticizing action. The hydrophobic character of nanofibres was revealed by the contact angle technique. An antifungal effect was observed, the mycelial growths (3·25-100%) and the synthesis of ochratoxin A (25·94-100%) were inhibited by the presence of the nanofibres. The results suggest that bioactive nanofibres hold promise for application to control toxigenic fungi.

Should thyroid-stimulating hormone goals be reviewed in patients with type 1 diabetes mellitus? Results from the Brazilian Type 1 Diabetes Study Group.

AIMS: To investigate if thyroid-stimulating hormone (TSH) levels are associated with any differences in glycaemic control or diabetes-related complications in individuals with Type 1 diabetes. METHODS: This observational, cross-sectional and multicentre study included patients with Type 1 diabetes for ≥ 5 years, with a recent TSH measurement and without a known previous thyroid disease. Patients were divided into three groups according to TSH levels: 0.4-2.5 mU/l; 2.5-4.4 mU/l; and ≥ 4.5 mU/l. RESULTS: We included 1205 individuals with a mean ± sd age of 23.8 ± 11.3 years. Seven patients had TSH levels <0.4 mU/l and were excluded from the comparison between groups. HbA1c levels, systolic and diastolic blood pressure, LDL cholesterol and disease duration were similar in all groups (P = 0.893, P = 0.548, P = 0.461, P = 0.575 and P = 0.764, respectively). The rates of diabetic retinopathy and GFR < 60/mL/min/1.73 m(2) differed between groups (P = 0.006 and P < 0.001, respectively) and were lower in those with lower TSH levels. Multivariate analysis confirmed these associations. The frequencies of retinopathy and GFR < 60 mL/min/1.73 m(2) were higher not only in patients with TSH ≥ 4.5 mU/l (odds ratio 1.878 and 2.271, respectively) but also in those with TSH levels of 2.5-4.4 mU/l (odds ratio 1.493 and 2.286, respectively), when compared with patients with TSH levels of 0.4-2.5 mU/l. CONCLUSIONS: TSH levels of 0.4-2.5 mU/l are associated with a lower risk of diabetic retinopathy and renal failure in individuals with Type 1 diabetes, independently of glycaemic control and duration of the disease.

In ovo inoculation of chicken embryos with probiotic bacteria and its effect on posthatch Salmonella susceptibility.

The feasibility of establishing probiotic bacteria in the intestine of broiler chickens by in ovo inoculation was investigated, followed by verifying possible subsequent protection against Salmonella Enteriditis infection. In a first study, 7 commercially available probiotics were screened for compatibility with in ovo inoculation. Two of these probiotics, one being a Enterococcus faecium and the other a Bacillus subtilis, were selected for colonizing the chick gut without compromising hatchability. In a second study, these 2 products were administered in ovo and in the feed to chicks reared until 18 d in comparison with noninoculated chicks and with chicks fed an antibiotic. All chicks were orally challenged with Salmonella Enteritidis at 4 d of age. Results showed reduced performance of Salmonella Enteritidis challenged chicks fed no additives compared with challenged chicks fed antibiotic, but no significant differences in mortality was observed. Probiotics offered in ovo or through the diet could only partially recover performance compared with antibiotic-fed chicks. A significant reduction in the number of Salmonella Enteritidis positive chicks was observed when chicks were in ovo inoculated with E. faecium and continued receiving it in the diet. This work establishes standards for future in ovo colonization research and emphasizes its value as a promising method to deliver individual precise dose of probiotics to poultry in mass scale at the earliest possible age based on the competitive exclusion concept. In ovo colonization with probiotic can therefore become an important ally in combination with other approaches to combat Salmonella and other intestinal bacterial infections in poultry.

Ileal microbiota composition of broilers fed various commercial diet compositions.

Microbiota plays a role in the release and absorption of nutrients from feed components, thereby affecting digesta composition and moisture content of the excreta. The objective of the current study was to determine the effects of 5 different diets varying in ingredients (medium-chain fatty acids, nonstarch polysaccharides, and starch) on the microbiota composition of ileal digesta of broiler chickens and excreta DM content. Each treatment was repeated 6 times in cages each containing 18 Ross 308 broilers, with growth performance measured from 0 to 34 d of age and excreta DM and ileal microbiota composition analyzed at 34 d of age. Microbiota composition was evaluated using a novel ribosomal RNA microarray technology containing 370 different probes covering various genera, groups of microbial species, and individual species of the chicken gut microbiota, of which 321 had a signal above the background threshold. Replacing part of the animal fat and soybean oil in the wheat-based diet with medium-chain fatty acids (MCFA; 0.3% C10 and 2.7% C12) improved feed efficiency compared with the other dietary treatments. This coincided with a suppression of gram-positive bacteria belonging to the phylum of the Firmicutes, including Lactobacillus species, and species belonging to the family of the Enterococcaceae and Micrococcaceae, whereas the gram-negative bacteria belonging to the family of the Enterobacteriaceae were promoted. None of the other diets used in the present study notably changed the ileal digesta bacteria composition. Excreta DM content was not affected by dietary treatment. The variation between individual birds per dietary treatment was more pronounced than variation caused by feed composition, with the exception of the digesta microbiota of the birds fed the MCFA diet. It is concluded that a diet with MCFA significantly changes the ileal microbiota composition, whereas the effect of the other diets on the composition of the microbiota and excreta DM content is small in broiler chickens.

Metabolic profiling of late-term turkey embryos by microarrays.

The last stages of embryonic development are crucial for turkeys as their metabolism shifts to accommodate posthatch survival and growth. To better understand the metabolic change that occurs during the perinatal period, focused microarray methodology was used to identify changes in the expression of key genes that control metabolism of turkey embryos from 20 d of incubation (E) until hatch (E28). Gene expression patterns were evaluated in liver, pectoral muscle, and hatching muscle and were associated with measured embryonic growth and tissue glycogen concentration. Within the studied period, the expression of 60 genes significantly changed in liver, 53 in pectoral muscle, and 51 in hatching muscle. Genes related to lipid metabolism (enoyl-CoA hydratase, 3-hydroxyacyl-CoA dehydrogenase, 3-hydroxymethylglutaryl-CoA reductase, acetyl-CoA carboxylase, lipoprotein lipase, and thyroxine deiodinase) had reduced expression between E22 and E26, corresponding to the period of expected limited oxygen supply. In contrast, genes related to opposing pathways in carbohydrate metabolism, such as glycolysis and gluconeogenesis (hexokinases, glucose-6 phosphatase, phosphofructokinases, glucose 1-6 phosphatase, pyruvate kinase, and phosphoenolpyruvate carboxykinase), or glycogenesis and glycogenolysis (glycogen synthase and glycogen phosphorylase) had rather static expression patterns between E22 and E26, indicating their enzymatic activity must be under posttranscriptional control. Metabolic survey by microarray methodology brings new insights into avian embryonic development and physiology.

Assessment of arterial stiffness in women with gestational diabetes.

AIMS: Gestational diabetes mellitus may precede development of Type 2 diabetes and may be related to cardiovascular disease. Pulse wave velocity measurement is the gold-standard method to evaluate arterial stiffness, a preclinical cardiovascular risk marker. However, the relationship between aortic stiffness and gestational diabetes is unclear. The aim of this study was to evaluate aortic pulse wave velocity in women with gestational diabetes in comparison with a matched control group of healthy pregnant women. METHODS: This case-control study included 24 women with gestational diabetes and 27 matched control subjects. Clinical, demographic and laboratory variables were obtained and aortic pulse wave velocity were measured. RESULTS: Both groups had similar age, gestational age, BMI, ethnicity, smoking status and blood pressure levels. Women with gestational diabetes had aortic pulse wave velocity comparable with control subjects: 7.2 ± 0.9 vs. 7.3 ± 1.2 m/s (P = 0.79). When categorized according to the median value of pulse wave velocity (7.3 m/s), age (P < 0.001), diastolic blood pressure (P = 0.03) and heart rate (P = 0.02) were associated with increased arterial stiffness. In the group with gestational diabetes, there was a non-significant trend towards higher 1-h postprandial glycaemia in patients with higher (above the median) pulse wave velocity (6.5 ± 0.8 vs. 7.1 ± 1.3 mmol/l, P = 0.22) and a lower prevalence of patients with good glycaemic control (38.5 vs. 72.7%, P = 0.09). CONCLUSIONS: Although gestational diabetes may be a risk factor for development of cardiovascular disease, women with gestational diabetes do not have higher aortic stiffness than healthy pregnant women. Time of exposure to hyperglycaemia may have been insufficient to increase central arterial stiffness in women with gestational diabetes.

Prehatch intestinal maturation of turkey embryos demonstrated through gene expression patterns.

Some of the challenges faced by neonatal turkeys include weakness, reduced feed intake, impaired growth, susceptibility to disease, and mortality. These symptoms may be due to depleted energy reserves after hatch and an immature digestive system unable to replenish energy reserves from consumed feed. To better understand enteric development in turkeys just before hatch, a new method was used to identify the patterns of intestinal gene expression by utilizing a focused microarray. The duodenums of 24 turkey embryos were sampled on embryonic day (E)20, E24, E26, and hatch (E28). The RNA populations of 96 chosen genes were measured at each time point, from which 81 significantly changed (P < 0.01). These genes were clustered by gene expression pattern similarity into 4 groups. The expression pattern of hormone receptors revealed that intestinal tissues may be less responsive to growth hormone, insulin, glucagon, and triiodothyronine during the last 48 h before hatch, when developmental emphasis switches from cell proliferation to functional maturation. Based on gene expression patterns, we concluded that at hatch, poults should have the capacity to 1) digest disaccharides but not oligopeptides, due to increased expression of sucrase-isomaltase but decreased expression of aminopeptidases and 2) absorb monosaccharides and small peptides due to high expression of sodium-glucose cotransporter-4 and peptide transporter-1.

Focused microarrays as a method to evaluate subtle changes in gene expression.

Recent studies using microarray technologies for the chicken have reported information regarding the effects of specific experimental treatments on gene expression levels often resulting in large gene lists and limitations on the statistical significance levels detected. In most cases, with these limitations, along with thresholds of +/-2-fold differences in expression levels, that are used to create these gene lists, much of the biological information may have been overlooked. In this study, a focused 70-mer oligonucleotide microarray was developed to address the apparent limits of detection and issues with multiple testing resulting from the use of microarrays that include only a single spot (probe) for each gene. Gene expression was assayed across the development of the chicken embryonic heart from d 7 to 20 of incubation. When using a mixed-model approach and ANOVA with Bonferroni correction for multiple testing, including replicates within the focused array significantly increased the sensitivity with which differences could be detected across sample groups, as compared with single-spot data. By incorporating replication into the focused array, 50 genes were detected as being differentially expressed in the embryonic heart across the time points sampled. This compares with only 7 genes detected as being differentially expressed when a more typical, less statistically stringent single-spot analysis is conducted. Based on our observations, the use of focused microarrays allows for the thorough investigation of gene expression patterns, with detection of significant changes in gene expression of +/-7%. This limit of detection is far superior to that of real-time PCR, which is able to detect significant changes in expression from +/-33 to 55%, depending on the specific application. The ability to detect small differences in expression will allow investigators to identify subtle effects that have perhaps been overlooked in many prior assays, including single-spot arrays. Subtle shifts in gene expression are exactly those that occur during embryonic development, nutritional manipulation, and the initial stages of disease before clinical signs appear.

Midarm computerized tomography fat, muscle and total areas correlation with nutritional assessment data.

BACKGROUND AND OBJECTIVES: Correlated nutritional assessment data (anthropometric, bioimpedance and biochemical) with computerized tomography (CT) of total, muscle and fat midarm areas. Total body fat and fat-free mass were estimated using bioimpedance. Daily urinary urea and creatinine were also quantified. In all, 28 subjects (13 males, 15 females) were evaluated and, they were clinically divided in obese, malnourished and control subjects. DESIGN: Quantification of total, fat muscle midarm areas by tomography and anthropometry and total body fat and free-fat mass by bioimpedance. RESULTS: CT values were 29% higher for fat area and 4-5% lower for total and muscle midarm areas compared against anthropometric data. The midarm skinfold thickness highly correlated with CT fat midarm area. Total body fat and free-fat mass bioimpedance data showed significant correlation with CT midarm data. Urinary creatinine correlated with CT muscle midarm area. CONCLUSION: Utilization of anthropometry can lead to error estimation of fat and fat-free arm areas and that bioimpedance gives fair correlation between total body and CT midarm measurements.

Obese women on a low energy rice and bean diet: effects of leucine, arginine or glycine supplementation on protein turnover.

This study examined if leucine, arginine or glycine supplementation in adult obese patients (body mass index of 33 +/- 4 kg/m(2)) consuming a Brazilian low energy and protein diet (4.2 MJ/day and 0.6 g protein/kg) affects protein and amino acid metabolism. After four weeks adaptation to this diet, each subject received supplements of these amino acids (equivalent to 0.2 g protein kg(-1) day(-1)) in random order. On the seventh day of each amino acid supplementation, a single-dose 15N-glycine study was carried out. There were no significant differences in protein flux, synthesis or breakdown. The protein flux (grams of nitrogen, gN/9 h) was 55 +/- 24 during the nonsupplemented diet intake and 39 +/- 10, 44 +/- 22 and 58 +/- 35 during the leucine-, glycine- and arginine-supplemented diet intake, respectively; protein synthesis (gN/9 h) was 57 +/- 24, 36 +/- 10, 41 +/- 22 and 56 +/- 36, respectively; protein breakdown (gN/9 h) was 51 +/- 24, 34 +/- 10, 32 +/- 28 and 53 +/- 35, respectively; kinetic balance (gN/9 h) was 3.2 +/- 1.8, 4.1 +/- 1.7, 3.4 +/- 2.9 and 3.9 +/- 1.6. There was no difference in amino acid profiles due to leucine, arginine or glycine supplementation. The present results suggest that 0.6 g/kg of dietary protein is enough to maintain protein turnover in obese women consuming a reduced energy diet and that leucine, arginine or glycine supplementation does not change kinetic balance or protein synthesis.

Obese women on a low energy rice and bean diet: effects of leucine, arginine or glycine supplementation on protein turnover

This study examined if leucine, arginine or glycine supplementation in adult obese patients (body mass index of 33 + or - 4 kg/m²) consuming a Brazilian low energy and protein diet (4.2 MJ/day and 0.6 g protein/kg) affects protein and amino acid metabolism. After four weeks adaptation to this diet, each subject received supplements of these amino acids (equivalent to 0.2 g protein kg-1 day-1) in random order. On the seventh day of each amino acid supplementation, a single-dose 15N-glycine study was carried out. There were no significant differences in protein flux, synthesis or breakdown. The protein flux (grams of nitrogen, gN/9 h) was 55 + or - 24 during the nonsupplemented diet intake and 39 + or - 10, 44 + or - 22 and 58 + or - 35 during the leucine-, glycine- and arginine-supplemented diet intake, respectively; protein synthesis (gN/9 h) was 57 + or - 24, 36 + or - 10, 41 + or - 22 and 56 + or - 36, respectively; protein breakdown (gN/9 h) was 51 + or - 24, 34 + or - 10, 32 + or - 28 and 53 + or - 35, respectively; kinetic balance (gN/9 h) was 3.2 + or - 1.8, 4.1 + or - 1.7, 3.4 + or - 2.9 and 3.9 + or - 1.6. There was no difference in amino acid profiles due to leucine, arginine or glycine supplementation. The present results suggest that 0.6 g/kg of dietary protein is enough to maintain protein turnover in obese women consuming a reduced energy diet and that leucine, arginine or glycine supplementation does not change kinetic balance or protein synthesis

Growth and hematological studies on Brazilian children of low socioeconomic level.

Anemia and undernutrition are common all over the world, especially in less developed countries. The relationship between low weight, short stature and iron deficiency should be better understood so that appropriate measures might be taken to prevent these problems. A total of 115 institutionalized children aged 12 to 72 months were studied in day-care institutions in the town of Pontal, Southeastern Brazil, during the second semester of 1999. Personal data, weight, height and hematological profile were obtained from all subjects. Food intake was evaluated in 20 children by a direct food-weighing method. The prevalence of low weight for age (2.6%), low weight for height (1.7%) and low height for age (4.3%) was considered low. Anemia was observed in 68.7% of the children. Diet was found to be adequate in terms of the major nutrients evaluated, but food iron supply was of low bioavailability. In conclusion, the population studied revealed a peculiar behavior i.e., the coexistence of fairly good anthropometric nutritional status along with iron-deficiency anemia. The prevention of this kind of malnutrition cannot be limited to an adequate calorie/protein supply but should also be based on the correction of the severe iron deficiency present in this low socioeconomic level preschool children in Brazil.

High-yield purification of biosynthetic human growth hormone secreted in Escherichia coli periplasmic space.

A six-step, high-yield purification procedure for the preparation of clinical grade recombinant human growth hormone (rhGH) secreted in bacterial periplasmic space is described. Particular emphasis is given to hormone recovery yields and maximum contaminant host cell elimination. The strategy adopted, in addition to using one precipitation and five chromatographic steps in a particularly efficient sequence, was also based on running E. coli proteins - immunoradiometric assay profiles right after each chromatographic elution. Thus, an overall rhGH recovery higher than 40%, with a final concentration of E. coli proteins below 10 ppm is described for the first time. The accuracy of hGH and total protein quantification, especially in the early steps of the process, and the maximum elimination of hGH-related forms were also studied in detail. For these purposes size-exclusion and reversed-phase HPLC were found to be extremely valuable analytical tools.

Enrichment of the diet with synthetic and natural sources of provitamin A.

The use of available food rich in provitamin A and retinol as well as fortification of local food are known to result in adequate vitamin A status. In Brazil, several regional foods are known to be good sources of provitamin A such as buriti, several palm oils, mango and others. Improving the consumption of these locally available natural sources of provitamin and vitamin A would cover the needs of the vulnerable population. At the same time fortification of industrialized foods with natural and/or synthetic forms of provitamin A could speed up and fill the gap between requirement and low intake of this vitamin in many parts of the country. This approach has been considered by many as the most effective intervention program to prevent micronutrient deficiencies in developing countries. Our previous studies on the subject have shown that cooking vegetable oil, mainly soybean oil, is a very good alternative vehicle to be fortified and supply vitamin A to the population. Lately we have also enriched the same soybean oil with beta-carotene. Addition of this provitamin A to the oil showed it to be stable when heated at cooking and frying temperatures (retention of 92.4 +/- 6.7% and 65.4 +/- 8.6%, respectively). When rat or human food was prepared with carotene-enriched cooking oil, its bioavailability in experimental animals and absorption in humans were shown to be adequate. An alternative for Brazil, besides adding chemical forms of the vitamin to the cooking oil, would be to mix available carotene-rich palm oil to the soybean oil. There are already regional uses of carotenoid-rich palm oils in the preparation of local dishes in some parts of Brazil and this would facilitate its acceptance by the population. Enrichment of common foods in Brazil, such as soybean oil, with chemical forms of beta-carotene or mixing rich sources of provitamin A can be a good alternative to improve the intake of vitamin A by the Brazilian population.

Methionine supplementation of soya products: effects on nitrogen balance parameters.

Soybean protein is one of the best quality foods available. Contribution of soy to human nutrition increases because of its overall positive nutritional profile, low cost, high protein and excellent functional properties. Addition of methionine to rat soybean diets improve biological value of soy protein. Few studies on methionine fortification of soya protein were carried in infants, but fortification of baby formulas with this amino acid is usually found. This study was carried out to demonstrate in malnourished children that the effect of methionine supplementation of soya milk and soy isolated protein, as well as to compare with their results to cows' milk. A total of 30 malnourished children, 1 to 3 years old, admitted to our metabolic unit and distributed in groups of 6 children were studied. They were fed experimental formulas with cows' milk, soya milk, soya milk plus methionine, soya isolated and soya isolated plus methionine. Nutrient compositions of formulas were calculated to be similar to mothers' milk. DL-methionine, 1.5 g per 100 g protein content was added to soya milk and soya isolated formulas. Two nitrogen balances, 3 days each, were carried out. Fecal and urinary nitrogen, serum proteins, creatinine and urea in serum and urine were followed during the study. Results showed differences of intake and retention of nitrogen between some of the groups, but there were no statistically significant differences on protein absorption in the groups. No differences were demonstrated in serum proteins, total nitrogen and other serum and urine parameters analyzed. Cows' milk fed children presented the highest nitrogen retention in both balance studies. The addition of methionine to the soya milk formula increased the nitrogen retention, not reaching the cows' milk levels and did not have the same effect when added to the isolate soy protein.

Absorption, by humans, of beta-carotene from fortified soybean oil added to rice: effect of heat treatment.

OBJECTIVE: This study was carried out to evaluate the absorption of beta-carotene in humans when rice is prepared with refined cooking soybean oil fortified with beta-carotene and to assess the effect of heat treatment on its bioavailability. METHODS: Sixteen healthy adults subjects participated in two experimental trials. Studies were carried out during two experimental periods of 11 days with a 12-day interval between them. Beta carotene was added to the soybean cooking oil and rice was cooked with it or it was added to the rice after cooking. Experimental diets included these two kinds of rice during the first day and fasting blood samples were collected on different days. All of the test diets were low in carotenoids. Plasma carotenoids were measured by HPLC method. beta-carotene absorption was calculated through postabsorptive peak rise in plasma beta-carotene and the total area under the absorption curve was determined by the trapezoidal method for the 11-day period. RESULTS: Absorption of carotene from heated or unheated fortified soybean oil were similar. Peak plasma carotene rise was different in men and women, p < 0.05 (0.66 +/- 0.097 vs. 1.04 +/- 0.117 mumol/l, respectively). Plasma alpha-carotene and retinol showed no variation. CONCLUSIONS: Results demonstrate that beta-carotene added to soybean oil used in the preparation of rice is absorbed, heated or not, and could be a practical source of provitamin A. Developing countries looking for strategies to increase vitamin A intake could use fortification of vegetable oils with synthetic beta-carotene as a simple method.

On the methods for studying the mechanisms and bioavailability of iron.

Studies of the molecular mechanisms involved in the absorption and bioavailability of iron are important to attempts made worldwide to control the high incidence of iron-associated disorders. The ultimate objective of these studies is to develop methods that are relevant to iron bioavailability and interactions in humans. However, a comprehensive understanding of the chemical and physiologic mechanisms that influence iron bioavailability is necessary to achieve this goal. Initial studies using in vitro and animal models offer the potential for flexibility and manipulation of experimental variables that could provide valuable information toward the understanding and improvement of food iron bioavailability.