Making bread with sourdough improves mineral bioavailability from reconstituted whole wheat flour in rats

OBJECTIVE: We compared the effects of different kinds of bread fermentation on mineral bioavailability. METHODS: Wistar rats were fed one of the following experimental diets for 21 d: control, reconstituted whole wheat flour (white flour plus bran), yeast bread, and sourdough bread. The apparent mineral absorption and intestinal fermentation were measured in each animal. RESULTS: Phytate contents in yeast and sourdough bread were lower than in reconstituted whole wheat flour (-52% and -71%, respectively). Total cecal pool of short-chain fatty acids, in particular the butyrate pool, was significantly increased by the ingestion of unrefined products. Calcium homeostasis was not modified by these nutritional conditions, whereas magnesium absorption was significantly greater in rats fed the control and sourdough diets than in those consuming whole wheat flour and yeast bread. Magnesium kidney excretion was slightly stimulated by sourdough bread. Compared with the control diet, iron balance was significantly reduced by reconstituted whole wheat flour diet. Yeast bread making counteracted the deleterious effects of whole wheat on iron absorption, whereas sourdough bread making enhanced iron absorption. Further, liver and plasma iron and transferrin saturation levels were lower in rats adapted to the flour diet than in other groups. Zinc absorption was strongly depressed in the presence of unprocessed reconstituted whole wheat flour in the diet, but yeast fermentation afforded a zinc assimilation comparable to the control diet, whereas the sourdough bread led to maximal zinc absorption. Copper absorption increased significantly when rats were fed the sourdough bread, whereas unprocessed whole flour depressed copper absorption (-41% versus control diet). CONCLUSION: Mineral bioavailability from reconstituted whole wheat flour can be improved by bread making. Although yeast fermentation minimizes the unfavorable effects of phytic acid, sourdough bread is a better source of available minerals, especially magnesium, iron, and zinc.     

Iron bioavailability and utilization in rats are lower from lime-treated corn flour than from wheat flour when they are fortified with different sources of iron

Although iron bioavailability from wheat flour fortified with iron has been widely studied, the bioavailability of lime-treated corn flour has not been evaluated sufficiently. We compared iron bioavailability and utilization of lime-treated corn flour and wheat flour supplemented with various iron sources. Bioavailability and utilization were determined in Sprague-Dawley rats using the iron balance and hemoglobin depletion-repletion methods. Rats were iron depleted by feeding them a low iron, casein diet for 10 d. During the repletion period, the rats were fed diets based on lime-treated corn flour or wheat flour, both supplemented with ferrous fumarate, ferrous sulfate, ferric citrate and reduced iron for 14 d. Hemoglobin was determined at the end of depletion and repletion periods. The phytate concentration was lower in wheat flour (114 mg/100g) than in lime-treated corn flour (501 mg/100g). Iron bioavailability and utilization by rats were higher from fortified and unfortified wheat flour than from the lime-treated corn flour counterparts. Iron utilization was greater in rats fed wheat flour supplemented with ferrous sulfate, followed by fumarate and citrate than in rats fed reduced iron. In lime-treated corn flour, iron utilization by rats fed unfortified flour and flour fortified with reduced iron did not differ, but utilization was higher in rats fed corn flour fortified with iron sulfate, fumarate and citrate than with reduced iron. We conclude that fortification of lime-treated corn flour with reduced iron has no effect on iron bioavailability or utilization, probably due to the high phytate content. Other iron compounds must be selected to fortify lime-treated corn flour when intended for public nutrition programs.     

Effect of wheat flour, Bengal gram flour and corn flour on lipid metabolism in rats

Male albino rats were fed on respective diets of wheat flour, Bengal gram flour and corn flour for 8 weeks at the 59% level. It was observed that the increase in weight after wheat flour and Bengal gram flour feeding was 6.8 and 12.0% respectively and that the decrease after corn flour feeding was 5.2% as compared to the control animals on sucrose diet. Serum cholesterol and liver cholesterol levels were significantly (p less than 0.01) decreased after wheat flour, Bengal gram flour and corn flour feeding.     

Lymphatic absorption of choline plasmalogen is much higher than that of ethanolamine plasmalogen in rats

Background  

Plasmalogen is a subclass of phospholipids widely distributed in animal tissues and ingested as food; however, the absorptive characteristics of different classes of plasmalogen have not been clarified.     

Iron absorption from wheat flour: effects of lemonade and chamomile infusion

ObjectiveWe measured iron bioavailability of meals based on wheat flour consumed by a vulnerable population in Latin America.MethodsBioavailability of iron (ferrous sulfate) from fortified noodles, noodle soup, noodle soup eaten with lemonade sweetened with panela (unrefined whole cane sugar), bread alone, and bread consumed with a chamomile infusion sweetened with panela was studied using the double isotopic method in 13 women.ResultsIron bioavailabilities from bread, noodles, and noodle soup were not significantly different (7.4%, 6.3%, and 6.0%, respectively). Iron absorption from noodle soup was significantly higher when given with lemonade (11.0%) compared with absorption of the same meal without lemonade (P < 0.02) or with the absorption of noodles (P < 0.04). Iron absorption of bread given alone or with chamomile infusion sweetened with panela (8%) was not significantly different.ConclusionIron bioavailability of meals based on wheat flour, fortified with ferrous sulfate, is improved when given with lemonade. The consumption of this beverage may be an alternative to further increase the effectiveness of wheat flour fortification in preventing iron deficiency in low-income Latin American populations.     

Lutein bioavailability is higher from lutein-enriched eggs than from supplements and spinach in men

Lutein may be protective against diseases such as age-related macular degeneration (ARMD). At present, data regarding bioavailability of lutein from various sources are insufficient. Healthy men (n = 10) participated in an intervention study with a crossover design. After a 2-wk washout period during which they consumed a low-carotenoid diet, the men were administered 1 of 4 lutein doses (lutein supplement, lutein ester supplement, spinach, and lutein-enriched egg) for 9 d. All lutein doses provided 6 mg lutein except for the lutein ester dose, which provided 5.5 mg lutein equivalents. Serum samples were collected from fasting subjects on d -14, 1 (baseline), 2, 3, and 10 and analyzed for changes in lutein concentration. Triacylglycerol-rich lipoproteins (TRL) were separated from postprandial blood samples (0-24 h) after the first lutein dose and analyzed for lutein concentration. Subjects completed all 4 treatments of the study in random order. Results from repeated-measures 1-way ANOVA showed that the baseline and dose-adjusted lutein response in serum was significantly higher after egg consumption than after lutein, lutein ester, and spinach consumption on d 10. There was no significant difference in TRL response. In conclusion, the lutein bioavailability from egg is higher than that from other sources such as lutein, lutein ester supplements, and spinach. The lutein bioavailability from lutein, lutein ester supplements, and spinach did not differ. This finding may have implications for dietary recommendations that may decrease the risk of certain diseases, e.g., ARMD.     

Iron absorption and bioavailability in rats of micronized dispersible ferric pyrophosphate

Unlike commercial ferric pyrophosphate, micronized dispersible ferric pyrophosphate (MDFP: Sun-Active Fe) does not precipitate and is completely dispersible in liquid form. MDFP shows a sharp particle size distribution at a nanometer level, which is several times smaller than that of commercial ferric pyrophosphate. The bioavailability of MDFP was compared to ferric pyrophosphate, sodium ferrous citrate, and ferrous sulfate by three bioavailability tests in rats; namely the serum iron concentration curve, the hemoglobin regeneration efficiency, and Association of Official Analytical Chemists' hemoglobin repletion test. The high area under curve value, a lag in peak time, and continued high serum iron concentration by MDFP over the other iron compounds indicates a sustained release of iron in the serum iron concentration curve method. MDFP showed the highest hemoglobin regeneration efficiency among all the iron compounds tested. The relative biological value of MDFP per unit of ferrous sulfate in each bioavailability test showed a high value as compared to other iron compounds. The above results suggest that MDFP is an ideal compound with high bioavailability for iron fortification in various liquid applications.     

Low bioavailability of carbonyl iron in man: studies on iron fortification of wheat flour

The bioavailability in man of commercially available elemental iron powders is unknown despite their extensive use for fortification of flour. Carbonyl iron, which is widely used in Europe, is considered as one of the best reduced iron powders based on studies both in vitro and in animals. In this study, a 55Fe labeled carbonyl iron was prepared by neutron irradiation and used to fortify wheat flour. The native iron of the wheat was extrinsically labeled by 59FeCl3. Doubly labeled wheat rolls were served with different meals. The ratio of absorbed 55Fe/59Fe is a direct measure of the fraction of carbonyl iron that joins the nonheme iron pool and is made potentially available for absorption. This relative bioavailability of carbonyl iron was unexpectedly low and varied from 20 to 5% when the iron fortified wheat rolls were served with different meals. The baking process did not change the relative bioavailability nor the addition of ascorbic acid. The low and variable bioavailability of carbonyl iron in man, makes it necessary to reconsider the rationale of using elemental iron powders for the fortification of foods for human consumption.     

Radiolabeled iron in soybeans: intrinsic labeling and bioavailability of iron to rats from defatted flour

Soybeans can be efficiently labeled with radiolabeled iron by supplying the iron via a nutrient culture medium as an iron salt or as a chelate. By using dual labeled iron and EDTA, it was determined that none of the chelator was transported to the shoots with the iron. Therefore, the use of chelated iron as the iron source in the nutrient medium should not affect assessments of bioavailability of iron from plants. Bioavailability (determined from whole-body retention curves of 59Fe in rats) of iron from defatted soy flour was relatively high and addition of vitamin C did not significantly enhance absorption of iron from defatted soy flour.     

Effect of dietary fiber on mineral absorption in growing rats

The effect of "indigestible" polysaccharides fed at the 10% level in a semi-synthetic diet on absorption of Ca, Fe, Zn, Cu, Cr and Co, on weight gain and on fecal dry matter excretion was studied over a period of 8 days in five groups of 12 weanling male rats each and compared to a control group. Carrageenan (C) and agar-agar (AA) reduced absorption of all minerals tested, Na-alginate (NA-A) decreased Fe-, Cr- and Co-absorption, carob bean gum (CBG) and gum guar (GG) interfered with the absorption of Zn, Cr, Cu and Co. In a second study the long-term effect of GG and AA-ingestion at the 10% dietary level on mineral absorption was investigated during three 4-day balance periods of a 21-week feeding trial in 24 young rats. Mineral content of rat carcasses, assayed at the termination of the experimental period, did not reveal any significant differences between controls and animals fed AA or GG, suggesting that the rat is able to compensate for the increased fecal losses, presumably by reduced urinary losses. Ingestion of AA, C or Na-A resulted in a marked increase of fecal dry matter, indicating that hardly any of these substances were degraded, whereas a considerable portion of GG and CBG was metabolized, presumably due to the action of intestinal bacteria.     

Effects of dietary lipid composition and inulin-type fructans on mineral bioavailability in growing rats

ObjectiveThis study reports the effects of feeding with a combination of inulin-type fructans (ITF) and fish oil (FO) on mineral absorption and bioavailability as part of a semipurified diet offered to rats.MethodsMale Wistar rats (n = 24) were fed a 15% lipid diet (soybean oil [SO] or a 1:0.3 fish:soybean oil mixture [FSO]) and diets containing the same sources of lipids supplemented with 10% ITF (Raftilose Synergy 1) ad libitum for 15 d. Feces and urine were collected for mineral analyses during the last 5 d of the test period. Fatty acid composition was determined in liver and cecal mucosa homogenates. Liver and bone mineral analyses were performed by atomic absorption spectrophotometry. Bone biomechanical analyses were evaluated by a 3-point bending test.ResultsCompared with the controls, ITF-fed rats had enlarged ceca and a significant decrease in cecal content pH (P < 0.001). The apparent mineral absorption was improved in these rats, and this effect was enhanced by dietary combination with FO for all minerals except for magnesium. Addition of ITF to the diet resulted in higher bone mineral content (calcium and zinc) and bone strength, but increased bone mineral content was only statistically significant in FO-fed animals. A decrease in liver iron stores (P = 0.015) was observed in rats fed FO, considering that ITF consumption returned to levels comparable to the SO control group.ConclusionThese findings confirm the positive influence of ITF on mineral bioavailability, which was potentiated by addition of FO to the diet.     

1,25 dihydroxycholecalciferol-mediated calcium absorption and gene expression are higher in female than in male mice

Recent advances in bone and calcium (Ca) metabolism have relied upon genetically modified mice. However, although human studies have identified gender as an important modulator of Ca metabolism, its effect on Ca metabolism has not been examined in mice. Here we examined basal and vitamin D-regulated Ca absorption (in situ ligated loops) and mRNA levels for the apical membrane calcium channel, TRPV6, and the calcium binding protein, calbindin D(9k) (CaBP) mRNA levels (real-time PCR) in duodenum of female and male mice. At 2 mo of age, females fed a 5 g Ca/kg diet had higher Ca absorption (62.3 +/- 4.8 vs. 47 +/- 3.6%) and TRPV6 mRNA levels than males even though plasma 1,25 dihydroxyvitamin D [1,25(OH)(2) D] was not different. In mice fed high (20 g/kg), normal (5 g/kg), or low (0.2 g/kg) Ca diets for 7 d to alter plasma 1,25(OH)(2) D (91 +/- 12, 322 +/- 25, and 587 +/- 43 pmol/L, respectively), the relation between Ca absorption (slope = 0.116 vs. 0.084, P = 0.021) or duodenum TRPV6 mRNA (slope = 0.042 vs. 0.025, P = 0.034) and circulating 1,25(OH)(2) D was steeper in females. After a single 1,25(OH)(2) D injection (200 ng/100 g body weight), peak induction of TRPV6 mRNA was 2-fold greater (at 6 h) and CaBP mRNA was 20% higher in females (at 16 h). Duodenal vitamin D receptor mRNA levels did not differ between genders. Our data indicate that female mice are more sensitive to changes in serum 1,25(OH)(2) D levels than males and that this must be considered when using mice to study calcium and bone biology.     

Bioavailability for rats of thiamin in whole wheat and thiamin-restored white bread

The relative biological value of thiamin in leavened bread (whole wheat and thiamin-restored white) and thiamin mononitrate was examined by using thiamin-deficient rats as the test model. Erythrocyte transketolase (ETK) activities and liver thiamin content responded positively to graded but suboptimal levels of dietary thiamin in these rats. Biological values were calculated (slope ratio assay) by using these response parameters, which may depict the body's thiamin status, at least in the deficient rats. Compared to thiamin in thiamin mononitrate (100%), the biological value of thiamin in breads measured 88% (white bread) and 91% (whole wheat bread) based on ETK activity and 68% (white bread) and 75% (whole wheat bread) based on liver thiamin response. Thus, diets high in fermented cereal foods (thiamin enriched or not) may require a generous allowance of thiamin to compensate for reduced biological value.     

Alkylresorcinols in wheat and rye flour and bread

The alkylresorcinol (AR) content and relative homologue composition were determined in Norwegian flours and bread. The following average values for total AR content (μg/g dm) were found: wholegrain wheat flour available only to bakers (490) and to both consumers and bakers (710), refined wheat flour (36), wheat bran (3625), wholegrain spelt wheat flour (650), refined spelt wheat flour (80), wholegrain rye flour (972), refined rye flour (90) and rye bran (2753). The C17:0/C21:0 ratio was 0.1 for wheat and 0.8–0.9 for rye, confirming that it can be used to distinguish between wheat and rye. The AR content of Norwegian refined wheat flour was higher than that of Swedish, due to a consistently higher milling extraction rate in Norway. The content of AR varied from 27 to 2766 μg/g dm in hard bread and 21 to 548 μg/g dm in soft bread. The highest contents were found in bread with a high proportion of wholegrain flour and/or bran, in agreement with earlier studies. There was a good correlation (r = 0.91) and a high compliance between calculated and analysed AR levels in soft bread, confirming that AR can be used as a biomarker for wholegrain wheat and/or rye content in a cereal product.     

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

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

Calcium absorption is significantly higher in adolescents during pregnancy than in the early postpartum period

BACKGROUND: Early childbearing may limit skeletal consolidation and increase calcium demands in adolescents. OBJECTIVE: The purpose of this study was to characterize calcium absorption in pregnant and lactating adolescents. DESIGN: Fractional calcium absorption was evaluated in 23 adolescents (mean +/- SD age: 16.5 +/- 1.4 y) during the third trimester of pregnancy (34.7 +/- 1.0 wk gestation) and again in 15 of these adolescents 31 +/- 8 d after delivery. Eight adolescents were breastfeeding their infants during the follow-up study. Fractional calcium absorption was determined by using oral ((46)Ca or (44)Ca) and intravenous ((42)Ca) stable calcium isotopes. Total-body and lumbar spine bone mineral density were measured in adolescents during the postpartum period by using dual-energy X-ray absorptiometry. RESULTS: Fractional calcium absorption was significantly greater during pregnancy than at 3-4 wk postpartum [0.526 +/- 0.152 (n = 23) compared with 0.297 +/- 0.108 (n = 15); P < 0.0001]. Lumbar spine z scores measured 19-44 d after delivery (n = 15) were significantly associated with calcium intake during pregnancy (y = -3.53 + 0.107x; R(2) = 0.355, P < 0.02) and were inversely related to fractional calcium absorption during pregnancy (y = 3.489 - 6.66x; R(2) = 0.52, P = 0.002). A total of 33% (5/15) of adolescents had lumbar spine z scores that met the definition of osteopenia (n = 3) or osteoporosis (n = 2) in the early postpartum period. CONCLUSIONS: Calcium absorption in adolescents was significantly higher during the third trimester of pregnancy than in the early postpartum period, and higher calcium intakes during pregnancy appeared to be protective against loss of trabecular bone at the lumbar spine.