Effect of particle size on the biological availability of reduced iron.

A sample of reduced iron was separated by air elutriation into several fractions based on particle size; and the relative biological values (RBVs) of 3 fractions containing fine, medium, and coarse particles were determined with rats and chicks, using diets containing either skim milk powder or casein as the major source of protein. The RBV of reduced iron for rats was shown to be dependent on particle size by curative and prophylactic assay procedures, with the source of protein having no marked effect. In contrast to rats, chicks utilized reduced iron to a higher degree, especially the iron from coarse particles. Prophylactic assays with rats indicated that a 3-4 week feeding period from weaning at 21 days of age gave RBVs which were not significantly different from those obtained by repletion of hemoglobin of anemic animals. After 5 weeks on the test diets, however, the rats lost their ability to distinguish between coarse and medium particles of reduced iron when fed with a diet containing casein as the source of protein.     

Effect of bread baking on the bioavailability of hydrogen-reduced iron powder added to unenriched refined wheat flour

Elemental iron powders are widely used to fortify flour and other cereal products. Our objective was to test the hypothesis that baking enhances the bioavailability of elemental iron powders by oxidizing Fe(0) to Fe(2+) or Fe(3+). An in vitro digestion/Caco-2 cell culture model and a piglet model were used to measure bioavailability. Bread flour, either unfortified or fortified with hydrogen-reduced (HR) iron powder or FeSO(4) (300 mg Fe/kg flour), was baked into bread. For the in vitro studies, bread samples were treated with pepsin at pH 2, 3, 4, 5, 6, or 7 and subsequently incubated with pancreatic enzymes at pH 7 in a chamber positioned above monolayers of cultured Caco-2 cells. Ferritin formation in the cells was used as an index of iron bioavailability. Ferritin formation in cells fed HR Fe bread was similar to cells fed FeSO(4) bread when the peptic digestion was conducted at a pH 2 but lower when the peptic phase was conducted at pH 3, 4, 5, 6, or 7 (P < 0.05). Pig diets containing 35% dried bread were prepared and fed to cross-bred (Hampshire x Landrace x Yorkshire) anemic pigs in two studies. The rate of increase in hemoglobin Fe over the feeding period was used to calculate relative biological value (RBV), an index of iron bioavailability. In the first pig study, RBV of HR Fe added to flour prior to baking was 47.9% when compared to FeSO(4) fortified flour (P < 0.05). In the second pig study, a third treatment consisting of unfortified bread with HR iron added during diet mixing (after bread baking) was included. RBVs of the HR Fe diet (Fe added after baking) and HR Fe diet (Fe added before baking) were 40.1% and 53.5%, respectively, compared to the FeSO(4) diet. Differences in RBV between the HR Fe (before and after baking) and FeSO(4) (before baking) treatment groups were significant, but the difference between the before and after HR treatment groups was not significant. We conclude that bread baking does not enhance the bioavailability of elemental iron powders.     

Iron bioavailability to piglets from red and white common beans (Phaseolus vulgaris)

Polyphenols in foods may chelate dietary Fe and lower its bioavailability. Concentrations of phenols are higher in red beans than in white beans. The aim of this study was to compare iron bioavailabilities from red and white beans in a piglet hemoglobin repletion model. Fe deficient cross bred piglets (Hampshire x Landrace x Yorkshire) were used. Nutritionally balanced diets (except for Fe) were formulated to contain 50% precooked, dehydrated beans (either small red or Great Northern white). At age 5 weeks, the piglets were assigned to two groups and fed diets containing either red or white beans for 4 weeks. Weight and hemoglobin (Hb) concentrations were monitored weekly. Feed intakes were measured daily. Hemoglobin repletion efficiency (HRE) was calculated as the gain in total body hemoglobin Fe (Hb-Fe) divided by Fe intake. Hb concentrations, Hb-Fe gains, and HRE were not different between the groups at any time point ( p > 0.05). HRE values in the red bean group were 50% in the first week and 30% over the entire 4 week period. In the white bean group, they were 56 and 26%, respectively. Proline-rich protein mRNA concentrations in parotid glands were higher in the red bean group compared to the white bean group. These results show that iron bioavailabilities from red and white beans are similar and suggest that pigs adapt to the inhibitory effects of polyphenols on iron absorption by increasing the secretion of protective proline-rich proteins in the saliva.     

Use of a rat model to evaluate tall fescue seed infected with introduced strains of Neotyphodium coenophialum

Experimental cultivars of the pasture grass tall fescue are infected with unique strains of the fungal endophyte Neotyphodium coenophialum, which produce low concentrations of ergot alkaloids. A rat model was evaluated as a tool for rapid, initial screening of experimental cultivars considered to be nontoxic. Rats were fed diets that included seed from experimental cultivars of tall fescue with introduced strains of N. coenophialum and a toxic control diet containing seed of the cultivar Kentucky 31 (KY31), with its endemic strain of N. coenophialum. Rats were preconditioned to a nontoxic diet and then fed treatment diets for 13 days with 5 days at thermoneutrality (21 degrees C) followed by 8 days under heat stress (31 degrees C). For most of the 13-day treatment period, rats fed KY31 exhibited depressed daily intake compared to those fed diets of cultivars with introduced endophytes (P < 0.05). In addition, rats fed KY31 exhibited significantly less weight than rats on other diets after heat treatment was imposed. For all initial trials and repeated trials, total intake and total gain calculated at the end of each trial were the most consistent indicators of toxicity.     

Hypolipidemic effect of oils with balanced amounts of fatty acids obtained by blending and interesterification of coconut oil with rice bran oil or sesame oil

Blended oils comprising coconut oil (CNO) and rice bran oil (RBO) or sesame oil (SESO) with saturated fatty acid/monounsaturated fatty acid/polyunsaturated fatty acid at a ratio of 1:1:1 and polyunsaturated/saturated ratio of 0.8-1 enriched with nutraceuticals were prepared. Blended oils (B) were subjected to interesterification reaction using sn-1,3 specific Lipase from Rhizomucor miehei. Fatty acid composition and nutraceutical contents of the blended oil were not affected by interesterification reaction. Male Wistar rats were fed with AIN-76 diet containing 10% fat from CNO, RBO, SESO, CNO+RBO blend (B), CNO+SESO(B), CNO+RBO interesterified (I), or CNO+SESO(I) for 60 days. Serum total cholesterol (TC), low-density lipoprotein cholesterol, and triacylglycerols (TAGs) were reduced by 23.8, 32.4, and 13.9%, respectively, in rats fed CNO+RBO(B) and by 20.5, 34.1, and 12.9%, respectively, in rats fed CNO+SESO(B) compared to rats given CNO. Rats fed interesterified oils showed a decrease in serum TC, low-density lipoprotein cholesterol (LDL-C), and TAGs in CNO+RBO(I) by 35, 49.1, and 23.2 and by 33.3, 47, and 19.8% in CNO+SESO(I), respectively, compared to rats given CNO. Compared to rats fed CNO+RBO blended oils, rats on CNO+RBO interesterified oil showed a further decrease of 14.6, 24.7, and 10% in TC, LDL-C, and TAG. Rats fed CNO+SESO interesterified oils showed a decrease in serum TC, LDL-C, and TAG by 16.2, 19.6, and 7.8%, respectively, compared to rats given blended oils of CNO+SESO (B). Liver lipid analysis also showed significant change in the TC and TAG concentration in rats fed blended and interesterified oils of CNO+RBO and CNO+SESO compared to the rats given CNO. The present study suggests that feeding fats containing blended oils with balanced fatty acids lowers serum and liver lipids. Interesterified oils prepared using Lipase have a further lowering effect on serum and liver lipids even though the fatty acid composition of blended and interesterified oils remained same. These studies indicated that the atherogenic potentials of a saturated fatty acid containing CNO can be significantly decreased by blending with an oil rich in unsaturated lipids in appropriate amounts and interesterification of blended oil.     

The importance of the proportion of heme/nonheme iron in the diet to minimize the interference with calcium, phosphorus, and magnesium metabolism on recovery from nutritional ferropenic anemia.

The digestive utilization of Fe and its nutritive interaction with Ca, P, and Mg were studied in rats with nutritional ferropenic anemia. The diet contained 80% ferric citrate and 20% heme iron (80/20 diet). The weight gain, digestive utilization of Fe, and regeneration efficiency of hemoglobin and seric Fe were higher in iron-deficient rats (ID) fed the 80/20 diet than in iron-deficient rats fed the 50/50 diet (Campos et al., 1996). The phospho-calcic metabolism, which is adversely affected in ferropenic anemia, returned to normal values when iron was added to the diet. The digestive utilization of Mg, which fell with the 50/50 diet (Campos et al., 1996), returned to normal values when the ferropenic anemia was reversed with the 80/20 diet. In a state of iron deficiency, certain parameters related to the glucose and lipid metabolism are affected; the glucose and triglycerides values return to a normal range with the 80/20 diet.     

Iron tissue storage and hemoglobin levels of deficient rats repleted with iron bound to the caseinophosphopeptide 1-25 of beta-casein.

Caseinophosphopeptides (CPP) issued from enzyme digestion of caseins bind cations and keep them soluble in the digestive tract. They could be used as ligands to improve iron (Fe) bioavailability. Fe-deficient young rats were repleted with Fe (40 or 200 mg/kg of diet) bound either to the beta-CN (1-25) of beta-casein or to whole beta-casein or as FeSO(4). A control pair-fed group was given 200 mg of Fe (FeSO(4))/kg of diet for 6 weeks. After repletion, hemoglobin concentration of the control group was reached only by the ) animals fed 200 mg of Fe/kg; beta-CN (1-25) bound Fe (40 and 200 mg) produced higher Fe liver and spleen stores than FeSO(4). Binding Fe to the whole, nonhydrolyzed beta-casein gave results intermediate between the other experimental groups. Binding Fe to phosphoserine residues of low molecular weight CPP improved its ability to cure anemia and to restore iron tissue stores, as compared to Fe bound to the whole casein and to inorganic salts.     

Iron and zinc bioavailability in rats fed intrinsically labeled bean and bean-rice infant weaning food products

Beans are the core of the Latin American diet and contain iron and zinc. However, the bioavailability of these trace minerals from beans is low. The objective of this study was to determine if the bioavailability of iron and zinc could be improved with the use of fermentation and germination processing technologies. Black beans native to Costa Rica were grown hydroponically with either radioactive iron or zinc. The influence of fermentation and germination on iron and zinc bioavailability from intrinsically labeled infant weaning food products based on black beans and beans-rice was determined in rats. Mineral bioavailability was determined using whole-body (59)Fe retention for iron, and whole-body (65)Zn retention and incorporation of radiolabel into bone for zinc. Percent absorption of (59)Fe from fermented products ranged between 48.0 and 58.0. Percent absorption of (65)Zn ranged from 57.0 to 64.0. Fermentation did not increase iron bioavailability in rats fed fermented beans without rice. Fermentation of cooked beans significantly increased zinc retention. Germination significantly enhanced iron retention from cooked beans from 46 to 55% and from cooked beans-cooked rice from 34 to 48%. Germination significantly improved zinc absorption and retention from cooked beans without added rice.     

Assessment of selenium bioavailability from high-selenium spirulina subfractions in selenium-deficient rats

It was previously found that the bioavailability of Se from Se-rich spirulina (SeSp) was lower than that from selenite or selenomethionine when fed to Se-deficient rats. The present study examined the bioavailability of Se from SeSp subfractions: a pellet (P) issuing from the centrifugation of a suspension of broken SeSp and a retentate (R) resulting from ultrafiltration of the supernatant through a 30 kDa exclusion membrane. Animals were fed a torula yeast based diet with no Se (deficients) or supplemented with 75 microg of Se/kg of diet as sodium selenite (controls) for 42 days. Se-deficient rats were then repleted for 56 days with Se (75 microg/kg of diet) supplied as sodium selenite, SeSp, P, or R. During this period, controls continued to receive sodium selenite. Speciation of Se in subfractions showed that the majority was present in the form of high molecular weight compounds; free selenomethionine was only a minor constituent. Gross absorption of Se from sodium selenite, P, and R was not different and was higher than from SeSp. Only retentate allowed full replenishment of Se concentration in liver and kidney (as did sodium selenite) and glutathione peroxidase (GSHPx) activity in liver, kidney, plasma, and erythrocytes. The bioavailabilities of Se in retentate, as assessed by slope ratio analysis using selenite as a reference Se, were 89 and 112% in the tissue Se content and 106-133% in the GSHPx activities. SeSp and P exhibited a gross bioavailability of <100%. These results indicate that Se in retentate is highly bioavailable and represents an interesting source of Se for food supplementation.     

Estimation of the bioavailability of iron.

Eight laboratories conducted a test for the estimation of the bioavailability of iron from 4 sources, using depleted male albino rats. Ferrous sulfate was used as the reference standard. Ferric orthophosphate was found to have a relative biological value of 11 (range 6-22), an old sample of hydrogen-reduced iron 27 (range 15-41), and ferric citrate 96 (range 75-125). Good results were obtained with a simplified basal diet prepared without ingredients that had previously contributed variable quantities of iron. There was no apparent advantage in using the change in hemoglobin during the repletion period instead of the final homoglobin value as the criterion of response to iron supplements. Several statistical treatments of the data yielded similar conclusions regarding relative biological values of the iron sources.     

Tissue iron distribution and adaptation of iron absorption in rats exposed to a high dietary level of NaFeEDTA

Although it has been shown that iron absorption from NaFeEDTA, a promising iron fortificant, is effectively down-regulated in iron-loaded rats, effects of prolonged exposure to high dietary levels of NaFeEDTA are not well understood. The objectives of this study were to determine whether rats can adapt to a high dietary level of NaFeEDTA by down-regulating iron absorption, and to determine effects on tissue iron distribution, with or without an iron absorption inhibitor. Male Sprague-Dawley rats were exposed to diets supplemented with FeSO4 or NaFeEDTA at 1200 mg of Fe/kg of diet, with or without tea, for 27 days. Iron absorption measured by whole-body counting before and after exposure showed that rats adapted to the high dietary level of FeSO4 or NaFeEDTA by down-regulating iron absorption to a similar extent. However, nonheme iron concentrations in liver and spleen were about 35-50% lower, whereas the concentration in kidney was about 300% higher in rats fed NaFeEDTA, compared to rats fed FeSO4. Tea had no major impact on iron absorption or iron status, regardless of iron source. Our results showed that although iron absorption was down-regulated similarly, body iron distribution was markedly different between rats exposed to FeSO4 and those exposed to NaFeEDTA. Further studies are warranted to determine the effects of prolonged exposure to dietary NaFeEDTA on kidney iron accumulation and kidney function.     

Iron dissociates from the NaFeEDTA complex prior to or during intestinal absorption in rats

Sodium iron ethylenediaminetetraacetate (NaFeEDTA) has superior iron bioavailability especially in foods containing iron absorption inhibitors. However, mechanisms involved in the absorption and subsequent partitioning of iron complexed with EDTA are poorly understood. Our objectives were to compare retention and tissue distribution of iron administered to rats either as FeSO4 or NaFeEDTA, either orally (OR) or subcutaneously (SC). Weanling rats were fed semipurified diets supplemented with either FeSO4 or NaFeEDTA for 7 days. They were then given a meal containing 59Fe-labeled FeSO4 or NaFeEDTA, or they were injected SC with these two forms of radiolabeled Fe. 59Fe retention was measured by whole body counting. Urine was collected and counted at 24 h intervals throughout the counting period. Tissue samples were analyzed for nonheme iron and 59Fe activity. Absorption of iron from FeSO4 or NaFeEDTA was similar (57.7 and 53.4%, respectively). Seventy-seven percent of the injected Na59FeEDTA was excreted in the urine within 24 h, whereas only 0.5, 0.8, and 1.4% of the injected 59FeSO4, oral 59FeSO4, and oral Na59FeEDTA, respectively, was excreted in the urine. The nonheme iron content was lower in the liver and spleen, by 56.8 and 28.4%, respectively, among rats consuming the NaFeEDTA diet as compared to rats fed FeSO4. We conclude that iron is dissociated from EDTA prior to or during intestinal absorption and that some fraction of the dissociated EDTA is absorbed separately from the iron.     

Food matrix effects on bioactivity of broccoli-derived sulforaphane in liver and colon of F344 rats

Sulforaphane (SF) is considered to be the major anticarcinogenic component in broccoli. The effects of feeding rats purified SF (5 mmol/kg of diet), broccoli containing SF formed in situ during laboratory hydrolysis (broccoli-HP; 20% freeze-dried broccoli diet, 0.16 mmol of SF/kg of diet), and broccoli containing intact glucosinolates (broccoli-GS; 20% freeze-dried broccoli diet, 2.2 mmol of glucoraphanin/kg of diet) were compared. Rats (male F344 rats, five per group) were fed control (modified AIN-76 B-40), SF, broccoli-HP, or broccoli-GS for 5 days. In rats fed broccoli-GS, quinone reductase activities (QR) in the colon and liver were greater (4.5- and 1.4-fold over control, respectively) than in rats fed broccoli-HP (3.2- and 1.1-fold over control, respectively). Broccoli-GS and SF diets increased QR to the same extent, even though the broccoli-GS diet contained far less SF (as the unhydrolyzed glucosinolate, glucoraphanin) than the purified SF diet. In a second experiment, rats were fed one of six diets for 5 days: (1) control; (2) 20% broccoli-GS; (3) diet 2 + low SF (0.16 mmol/kg of diet); (4) diet 2 + high SF (5 mmol/kg of diet); (5) low SF (0.32 mmol/kg of diet); or (6) high SF (5.16 mmol/kg of diet). In both liver and colon, QR was increased most by high SF plus broccoli-GS; individually, high SF and broccoli-GS had similar effects, and adding the low-dose SF to broccoli-GS had either no effect or a negative effect. In both experiments, urinary SF-mercapturic acid correlated with QR activity, not with dietary intake. It was concluded that all diets were substantially more effective in the colon than in the liver and that broccoli-GS was more potent than SF or broccoli-HP.     

Nutritional quality of sesame seed protein fraction extracted with isopropanol

The nutritional effect of diet containing decorticated sesame seed extracted with isopropanol (DSS-Iso) was evaluated on growth performance, food efficiency ratio, plasma and tissue lipid profile, plasma protein content, and erythrocyte membrane lipid profile of rats on a comparative basis with diets containing casein (control), soybean meal, and decorticated sesame seed extracted with hexane (DSS-Hex). Rats fed a DSS-Iso-based diet showed body weight gain and food efficiency ratio similar to those of the control groups fed diets prepared with casein, soybean meal, and DSS-Hex. However, dietary proteins exerted a separate effect on plasma lipid concentrations of the rats. Rats fed a DSS-Iso-based diet showed significant decreases in plasma total cholesterol (p < 0.01), triglyceride (p < 0.01), and VLDL+LDL cholesterol (p < 0.01) concentrations in comparison to the rats fed diet containing casein. No significant differences in plasma lipid concentrations were observed for the rats fed diets prepared with soybean meal, DSS-Hex, and DSS-Iso. Rats fed the different dietary proteins did not show much variation in plasma proteins, liver lipids, and erythrocyte membrane lipid concentrations, which suggests that DSS-Iso could be a suitable edible protein like casein or soybean meal.     

Beneficial effect of pollen and/or propolis on the metabolism of iron, calcium, phosphorus, and magnesium in rats with nutritional ferropenic anemia

There has been considerable debate regarding the nutritional benefits of pollen and the propolis produced by bees, although most contributions have lacked scientific soundness. This paper describes the possible beneficial effect of their use in pharmacological products in cases of anemic syndrome. We studied the effect of these two natural products on the digestive utilization of iron, calcium, phosphorus, and magnesium, using control rats and rats with nutritional ferropenic anemia. The addition of these products to the diet produced a positive effect on weight gain; this fact could constitute a scientific basis for the application of pollen and propolis as fortifiers. They improve the digestive utilization of iron and the regeneration efficiency of hemoglobin, especially during recovery from an anemic syndrome. They also have a positive effect on phosphocalcic metabolism and maintain an appropiate level of magnesium metabolism. Furthermore, in iron-deficient rats, these natural products palliate, to a large extent, the adverse effects of iron deficiency on calcium and magnesium metabolism as a result of the improvement in the digestive utilization of these minerals.     

Bocaiuva (Acrocomia aculeata (Jacq.) Lodd) improved Vitamin A status in rats

Carotenoid bioavailability is influenced by various factors including the food matrix. The release of those molecules from the food matrix is the initial and most important step in the absorption process. The relative bioavailability of bocaiuva pulp beta-carotene in relation to pure beta-carotene was assayed by a hepatic retinol store, in vitamin A deficient Wistar rats. After the depletion period, the vitamin A deficient rats were separated into two groups and fed an AIN-93G modified diet, which contained 14 400 microg of pure beta-carotene (beta-carotene diet) or 13 475 microg of beta-carotene from 275 g of bocaiuva pulp (bocaiuva diet) per 1 kg of the diet as a vitamin A source. Both experimental diets resulted in similar body weight gains. The bioavailability, estimated as Retinol Accumulation Factor, was 7.3 and 3.5 for the beta-carotene and the Bocaiuva group, respectively. These results show that in spite of the matrix of the bocaiuva pulp, the beta-carotene bioavailability from this fruit was higher than the pure beta-carotene.     

Inulin effects on bioavailability of soy isoflavones and their calcium absorption enhancing ability

The effect of inulin on isoflavone absorption and the effect of isoflavones and synergy with inulin on calcium absorption in rats was investigated. Rats (n = 48) were divided into three groups and fed inulin (50 mg/g), isoflavone (8 mg/g) or inulin + isoflavone (50 mg/g + 8 mg/g) diets for 21 days. After a 2-h fast, rats were given (45)Ca orally or intraperitoneally, together with 25 mg of calcium as calcium acetate. Blood and femurs were collected 4 days later. Sera were analyzed for isoflavones using HPLC-MS, femurs for (45)Ca by beta-scintillation counting, and total femoral calcium by atomic absorption spectroscopy. Both groups fed isoflavones had similar and significantly higher weight-adjusted total femoral calcium content compared to the inulin-fed group (p < 0.0001). (45)Ca absorption was significantly higher (p < 0.01) when isoflavones were added to the diet, and serum equol was significantly lower (p < 0.01) when inulin was added to the diet containing isoflavones. We conclude that isoflavones enhance calcium absorption, without synergy from inulin, and that inulin decreases equol production.     

Iron derivatives from casein hydrolysates as a potential source in the treatment of iron deficiency

The properties of an Fe(3+)-peptide complex containing 5.6% Fe, obtained by the reaction of ferric chloride with an enzymatic hydrolysate of casein, are described. The major site of iron binding corresponds primarily to the carboxylate groups and to a lesser extent to the peptide bonds. The Fe(3+)-peptide complex is insoluble at acid pH and completely soluble at neutral to alkaline pH. When soluble, the Fe(3+) is tightly bound to the complex peptide mixture but can be displaced and complexed by a low molecular weight ligand such as cysteine. Its efficacy in relation to iron sulfate was compared in rats. Both iron sources were administrated in Milli-Q water by gastric gavage to male Wistar rats (180-200 g) after an 18 h fast with water ad libitum. Fe(3+) from the Fe(3+)-peptide complex was transferred to the blood in a dose-dependent manner (1-8 mg of Fe/kg), and the serum iron levels were significantly higher (p < 0.001) than in a similar group of rats treated with iron sulfate. In the comparative kinetics experiments, the rats received 4 mg of Fe/kg. Both iron sources presented maximum absorption, as indicated by the elevation of serum iron levels, 30 min after administration, and the AUC(0)(-->2h) of the Fe(3+)-peptide complex was significantly higher (p < 0.05) than that observed with iron sulfate. The simultaneous administration of free peptides (0-192 mg) with the Fe(3+)-peptide complex or iron sulfate did not modify the extent of absorption of iron from both sources, suggesting that the absorption is due to the complex formed and probably not to exchange reactions in the gastrointestinal tract. In the hemoglobin repletion experiments carried out on newly weaned rats with anemia induced by a low-iron diet, supplementation of the diet with the the Fe(3+)-peptide complex was as efficient as supplementation with iron sulfate in the conversion from diet to hemoglobin iron. These results, taken together, suggest that the Fe(3+)-peptide complex is a potential compound for use as an iron source in biological situations.     

Iron bioavailability of hemoglobin from soy root nodules using a Caco-2 cell culture model

Heme iron has been identified in many plant sources-most commonly in the root nodules of leguminous plants, such as soy. Our objective was to test the effectiveness of soy root nodule (SRN) and purified soy hemoglobin (LHb) in improving iron bioavailability using an in vitro Caco-2 cell model, with ferritin response as the bioavailability index. We assessed bioavailability of iron from LHb (either partially purified (LHbA) or purified (LHbD)) with and without food matrix and compared it with that from bovine hemoglobin (BHb), ferrous sulfate (FeSO4), or SRN. Bioavailability of each treatment was normalized to 100% of the FeSO4 treatment. When iron sources were tested alone (100 ug iron/mL), ferritin synthesis by LHbD and BHb were 19% (P > 0.05) and 113% (P < 0.001) higher than FeSO4, respectively. However, when iron sources were used for fortification of maize tortillas (50 ppm), LHbA and BHb showed similar bioavailability, being 27% (P < 0.05) and 33% (P < 0.05) higher than FeSO4. Heat treatment had no effect on heme iron but had a significant reduction on FeSO4 bioavailability. Adding heme (LHbA) iron with nonheme (FeSO4) had no enhancement on nonheme iron absorption. Our data suggest that heme iron from plant sources may be a novel value-added product that can provide highly bioavailable iron as a food fortificant.     

Bioavailability and efficacy of vitamin D2 from UV-irradiated yeast in growing, vitamin D-deficient rats

New food sources are needed to bridge the gap between vitamin D intake and recommended intake. We assessed the bioavailability and efficacy of vitamin D in an 8 week dose-response study of bread made with vitamin D2-rich yeast compared to vitamin D3 in growing, vitamin D-deficient rats. Plasma 25-hydroxyvitamin D (25OHD) levels increased in a curvilinear, dose-dependent manner with both forms of vitamin D, but rats fed vitamin D2-rich yeast achieved lower levels than rats fed vitamin D3. Rats fed the highest doses of vitamin D had significantly greater (p<0.05) trabecular BMC, BMD, bone volume, and connectivity density, and greater midshaft total cross-sectional area, compared to rats on the vitamin D-deficient diets, with no significant difference due to vitamin D source. Vitamin D2-rich yeast baked into bread is bioavailable and improves bone quality in vitamin D-deficient animals.