Improving iron absorption from a Peruvian school breakfast meal by adding ascorbic acid or Na2EDTA

BACKGROUND: Iron-fortified school breakfasts have been introduced in Peru to combat childhood iron deficiency. OBJECTIVE: We evaluated whether iron absorption from a school breakfast meal was improved by increasing the ascorbic acid content or by adding an alternative enhancer of iron absorption, Na2EDTA. DESIGN: In a crossover design, iron absorption from test meals was evaluated by erythrocyte incorporation of 58Fe and 57Fe. The test meals (wheat bread and a drink containing cereal, milk, and soy) contained 14 mg added Fe (as ferrous sulfate) including 2.0-2.6 mg 58Fe or 4.0-7.0 mg 57Fe. RESULTS: Geometric mean iron absorption increased significantly from 5.1% to 8.2% after the molar ratio of ascorbic acid to fortification iron was increased from 0.6:1 to 1.6:1 (P < 0.01; n = 9). Geometric mean iron absorption increased significantly from 2.9% to 3.8%, from 2.2% to 3.5%, and from 2.4% to 3.7% after addition of Na2EDTA at molar ratios relative to fortification iron of 0.3:1, 0.7:1, and 1:1, respectively, compared with test meals containing no added enhancers (P < 0.01; n = 10 for all). Iron absorption after addition of ascorbic acid (molar ratio 0.6:1) was not significantly different from that after addition of Na2EDTA (molar ratio 0.7:1). CONCLUSIONS: Ascorbic acid and Na2EDTA did not differ significantly in their enhancing effects on iron absorption at molar ratios of 0.6:1 to 0.7:1 relative to fortification iron. Additional ascorbic acid (molar ratio 1.6:1) increased iron absorption significantly. Increasing the molar ratio of Na2EDTA to fortification iron from 0.3:1 to 1:1 had no effect on iron absorption.     

Increasing the cooking temperature of meat does not affect nonheme iron absorption from a phytate-rich meal in women

The effect of increasing cooking temperatures of meat on nonheme iron absorption from a composite meal was investigated. Cysteine-containing peptides may have a role in the iron absorption enhancing effect of muscle proteins. Heat treatment can change the content of sulfhydryl groups produced from cysteine and thereby affect iron absorption. Twenty-one women (25 +/- 3 y) were served a basic meal without meat and two other meals consisting of the basic meal plus 75 g of pork meat cooked at 70, 95 or 120 degrees C. The meals were extrinsically labeled with (55)Fe or (59)Fe. Iron absorption was determined from measurements of whole-body (59)Fe retention and the activity of (55)Fe and (59)Fe in blood samples. Nonheme iron absorptions were 0.9 (0.5-4.0)% (P = 0.06), 0.7 (0.4-3.9)% (P = 0.1) and 2.0 (1.3-3.1)% (P < 0.001) greater when meat cooked at 70, 95 or 120 degrees C, respectively, was added to the basic meal. Increasing the cooking temperature of meat did not impair nonheme iron absorption compared with cooking at 70 degrees C. Because the cysteine content of meat decreased with increasing cooking temperature, this argues against a specific contribution of sulfhydryl groups from cysteine residues in the promotion of nonheme iron absorption by meat proteins.     

Aqueous ethanol extraction of dietary soy protein isolate improves 59Fe absorption by the rat from a casein-based test meal

A commercial soy protein isolate (SPI) was further processed in an attempt to understand how a diet based on SPI can cause decreased iron retention by the rat from a separately administered casein-based test meal. Groups of eight rats were fed either a casein-based diet or a diet based on SPI. The acid-precipitated SPI was incorporated into diets as such, after neutralization, after 60% (v/v) ethanol extraction and neutralization, or after 60% ethanol exposure and neutralization. All dietary SPI was heat-treated by exposure to steam at 108 degrees C for 30 min. Rats were fed their respective diets, each containing 25 mg Fe/kg, for 13 d, and then all rats were fed a 59Fe-radiolabeled 2.5-g casein test meal containing 64 micrograms of iron. Ingested radioactivity was determined following the meal, and retained radioactivity over the subsequent 10-d period. Absorption was not distinguishable for groups fed the casein-based (78.3 +/- 3.6%) and the ethanol-extracted, SPI-based diet (80.2 +/- 5.4%). Absorption was lower (P less than 0.01) for groups fed each of the other SPI-based diets: SPI as such (68.3 +/- 8.9%), neutralized SPI (69.8 +/- 5.0%) and ethanol-exposed SPI (67.6 +/- 4.8%). An ethanol-extractable component of SPI may be responsible for decreased iron absorption by animals fed SPI prior to a radiolabeled test meal.     

Iron absorption from a breakfast cereal: effects of EDTA compounds and ascorbic acid

Sodium iron ethylenediaminetetracetic acid (NaFeEDTA) has been recommended for food fortification programmes to improve iron status but its performance in commercial products has not been evaluated. The effect of EDTA on iron absorption from fortified cornflakes, given as part of a typical Western breakfast, was determined in a double-blind randomised study with 20 non-anaemic female volunteers, using experimentally prepared iron compounds, enriched with 58Fe, and faecal monitoring. Five meals were compared: hydrogen reduced iron, hydrogen reduced iron plus Na2EDTA (molar ratio EDTA:Fe 1:2), hydrogen reduced iron plus NaFe(III)EDTA at two different molar ratios (EDTA:total Fe 1:3 and 1:2), and hydrogen reduced iron plus 15 mg ascorbic acid (ascorbic acid:Fe 1.3:1). The iron and EDTA compounds were accurately weighed into gelatine capsules and taken with unfortified cornflakes, semi-skimmed milk and tea on two consecutive days; the iron dose per meal was 3.75 mg. Iron absorption from all five test meals was measured in each volunteer with a minimum wash-out period of 2 weeks between tests. Geometric mean iron absorption (%) from the 5 tests was 14.1, 17.6, 20.6, 24.4 and 17.5 respectively (equivalent to 0.5-0.9 mg absorbed iron). There was a significantly higher iron absorption from the mixture of reduced iron and NaFe(III)EDTA (EDTA:Fe 1:2) than from reduced iron alone (p = 0.014). It is not known whether the higher absorption was from reduced iron or NaFeEDTA or both. Absorption was not increased significantly with NaFe(III)EDTA (EDTA:Fe 1:3), Na2EDTA (EDTA:Fe 1:2) or ascorbic acid (15 mg).     

Oxalic acid does not influence nonhaem iron absorption in humans: a comparison of kale and spinach meals

OBJECTIVE: To evaluate the influence of oxalic acid (OA) on nonhaem iron absorption in humans. DESIGN: Two randomized crossover stable iron isotope absorption studies. SETTING: Zurich, Switzerland. SUBJECTS: Sixteen apparently healthy women (18-45 years, <60 kg body weight), recruited by poster advertizing from the staff and student populations of the ETH, University and University Hospital of Zurich, Switzerland. Thirteen subjects completed both studies. METHODS: Iron absorption was measured based on erythrocyte incorporation of (57)Fe or (58)Fe 14 days after the administration of labelled meals. In study I, test meals consisted of two wheat bread rolls (100 g) and either 150 g spinach with a native OA content of 1.27 g (reference meal) or 150 g kale with a native OA content of 0.01 g. In study II, 150 g kale given with a potassium oxalate drink to obtain a total OA content of 1.27 g was compared to the spinach meal. RESULTS: After normalization for the spinach reference meal absorption, geometric mean iron absorption from wheat bread rolls with kale (10.7%) did not differ significantly from wheat rolls with kale plus 1.26 g OA added as potassium oxalate (11.5%, P=0.86). Spinach was significantly higher in calcium and polyphenols than kale and absorption from the spinach meal was 24% lower compared to the kale meal without added OA, but the difference did not reach statistical significance (P>0.16). CONCLUSION: Potassium oxalate did not influence iron absorption in humans from a kale meal and our findings strongly suggest that OA in fruits and vegetables is of minor relevance in iron nutrition.     

The efficacy of a local ascorbic acid-rich food in improving iron absorption from Mexican diets: a field study using stable isotopes

BACKGROUND: One potentially sustainable approach to improving iron status at the community level is to encourage the consumption of local ascorbic acid-rich foods, in conjunction with meals high in nonheme iron. OBJECTIVE: The study, conducted in rural Mexico, measured stable isotopes of iron to evaluate the effect on iron absorption of the addition of 25 mg ascorbic acid as agua de limón (limeade) to 2 typical meals per day for 2 wk. DESIGN: Fifteen nonpregnant, nonlactating, iron-deficient (ferritin < 12 microg/L) women (x +/- SD age: 28.3 +/- 7.7 y) fasted overnight and were brought to a community clinic. After an initial blood sample, subjects consumed 0.25 mg (57)Fe with both breakfast and lunch for 14 d. On day 29, another blood sample was taken, and a reference dose of 2.7 mg (58)Fe with 25 mg ascorbic acid was given. For the following 15 d, participants consumed 0.25 mg (57)Fe added to both breakfast and lunch with 25 mg ascorbic acid added to each meal as limeade. A final blood sample was taken on day 59. RESULTS: Iron absorption was calculated from recovery of isotopes in blood obtained 14 d after administration of each isotope. When 25 mg ascorbic acid as limeade was added to test meals twice a day for 2 wk, iron absorption increased significantly (P < 0.001) in every subject: the mean absorption rose from 6.6 +/- 3.0% to 22.9 +/- 12.6%. CONCLUSIONS: The consumption of 25 mg ascorbic acid as limeade twice daily with meals substantially improved iron absorption and may improve the iron status of nonpregnant, nonlactating, iron-deficient women.     

Sodium iron EDTA [NaFe(III)EDTA] as a food fortificant: erythrocyte incorporation of iron and apparent absorption of zinc, copper, calcium, and magnesium from a complementary food based on wheat and soy in healthy infants

BACKGROUND: Phytic acid is a strong inhibitor of iron absorption from fortified foods. In adults, this inhibitory effect can be overcome by adding ascorbic acid with the iron fortificant or by using a "protected" iron compound such as NaFeEDTA. In addition, the use of NaFeEDTA as an iron fortificant has been reported to increase zinc absorption in adult women. No information is available on iron bioavailability from NaFeEDTA or the influence of NaFeEDTA on minerals and trace elements in infants. OBJECTIVE: We aimed to compare iron bioavailability from a complementary food based on wheat and soy fortified with either NaFeEDTA or ferrous sulfate plus ascorbic acid. The apparent absorption of zinc, copper, calcium, and magnesium was evaluated in parallel. DESIGN: Stable-isotope techniques were used in a crossover design to evaluate erythrocyte incorporation of iron 14 d after administration of labeled test meals and the apparent absorption of zinc, copper, calcium, and magnesium on the basis of fecal monitoring in 11 infants. RESULTS: Geometric mean erythrocyte incorporation of iron was 3.7% (NaFeEDTA) and 4.9% (ferrous sulfate plus ascorbic acid) (P = 0.08). No significant differences in the apparent absorption of zinc, copper, calcium, or magnesium were observed between test meals (n = 10). CONCLUSIONS: Iron bioavailability from a high-phytate, cereal-based complementary food fortified with either NaFeEDTA or ferrous sulfate plus ascorbic acid was not significantly different. NaFeEDTA did not influence the apparent absorption of zinc, copper, calcium, or magnesium. NaFeEDTA does not provide any nutritional benefit compared with the combination of a highly bioavailable iron compound and ascorbic acid.     

Assessing household wealth in health studies in developing countries: a comparison of participatory wealth ranking and survey techniques from rural South Africa

Background  

Accurate tools for assessing household wealth are essential for many health studies in developing countries. Household survey and participatory wealth ranking (PWR) are two approaches to generate data for this purpose.     

Assessing household wealth in health studies in developing countries: a comparison of participatory wealth ranking and survey techniques from rural South Africa

Background

Environmental pollution as a cause of congenital anomalies is sometimes suspected because of clustering of anomalies in areas of higher exposure. This highlights questions around spatial heterogeneity (clustering) in congenital anomaly rates. If spatial variation is endemic, then any one specific cluster is less remarkable, though the presence of uncontrolled geographically clustered risk factors is suggested. If rates are relatively homogeneous across space other than around specific hazards, then evidence for these hazards causing the clusters is strengthened. We sought to estimate the extent of spatial heterogeneity in congenital anomaly rates in the United Kingdom.

Methods

The study population covered about one million births from five registers in Britain from 1991–1999. We estimated heterogeneity across four geographical levels: register area, hospital catchment, electoral ward, and enumeration district, using a negative binomial regression model. We also sought clusters using a circular scan statistic.

Results

Congenital anomaly rates clearly varied across register areas and hospital catchments (p < 0.001), but not below this level (p > 0.2). Adjusting for socioeconomic deprivation and maternal age made little difference to the extent of geographical variation for most congenital anomaly subtypes. The two most significant circular clusters (of four ano-rectal atresias and six congenital heart diseases) contained two or more siblings.

Conclusion

The variation in rates between registers and hospital catchment area may have resulted in part from differences in case ascertainment, and this should be taken into account in geographical epidemiological studies of environmental exposures. The absence of evidence for variation below this level should be interpreted cautiously in view of the low power of general heterogeneity tests. Nevertheless, the data suggest that strong localised clusters in congenital anomalies are uncommon, so clusters around specific putative environmental hazards are remarkable when observed. Negative binomial models applied at successive hierarchical levels provide an approach of intermediate complexity to characterising geographical heterogeneity.     

Measuring the shortage of medical practitioners in rural and urban areas in developing countries: a simple framework and simulation exercises with data from India

This paper suggests a simple framework to estimate the shortage of medical practitioners in rural and urban areas in developing countries. Shortages are defined with respect to four main considerations. The overall numbers and also the different categories of practitioners in the rural and urban areas, the relatively greater difficulties of access in the rural areas (which reduce the number of accessible practitioners) and the greater health hazards in those areas (which lead to greater need for medical treatment).The quantitative effect of these factors is examined by undertaking simulation exercises with data for the Ujjain district in Madhya Pradesh state, India and also data for that state. The simulations turned up the following results. The un-weighted total number of practitioners, per head of population, is relatively greater in the rural areas; this is because of the relatively large numbers of the unqualified doctors in those areas. On the other hand, a 'quality adjusted' total, with lower weights for the unqualified doctors, found little overall difference between the rural and urban areas. Third, allowance for rural-urban differences in the difficulties of access showed that the number of accessible practitioners is much lower in the rural areas. Fourth, rural-urban differences in the incidence of health hazards and estimates of the need for medical treatment also showed a marked shortage of practitioners in the rural areas.The main implication of the results is that developmental efforts in the rural areas, including improvements in transport facilities and reduction of health hazards, would help to greatly reduce the shortage of practitioners in those areas. Training programmes to improve the quality of practitioners in the rural areas are also required.     

Human milk as a source of ascorbic acid: no enhancing effect on iron bioavailability from a traditional complementary food consumed by Bangladeshi infants and young children

BACKGROUND: Iron bioavailability from traditional complementary foods based on cereals and legumes can be expected to be low unless ascorbic acid-rich foods are incorporated into the diet. OBJECTIVE: We evaluated human milk as a source of ascorbic acid for enhancing iron bioavailability from khichuri, a complementary food based on rice and lentils. DESIGN: Erythrocyte incorporation of stable iron isotopes 14 d after administration was used as a proxy for iron bioavailability. Children aged 8-18 mo (n = 31) were breastfed (32-90 mg ascorbic acid/kg human milk) immediately after intake of 4 servings of khichuri labeled with (57)Fe (test meal B) and were offered water after intake of 4 servings of khichuri labeled with (58)Fe (test meal A). Test meals were fed twice daily during 4 d in the order of AABBAABB or BBAABBAA. RESULTS: The mean intakes of human milk and ascorbic acid were 274 g (range: 60-444 g) and 14 mg (range: 4-28 mg, respectively). The mean molar ratio of ascorbic acid to iron was 2.3 (range: 0.7-4.6). The geometric mean iron bioavailability from khichuri fed with or without human milk was 6.2% and 6.5%, respectively (P = 0.76, paired Student's t test). CONCLUSIONS: Although human milk contributed significant quantities of ascorbic acid, no significant difference in iron bioavailability was found between khichuri consumed with water and that consumed with human milk. These results indicate either that the molar ratio of ascorbic acid to iron was not sufficiently high to overcome the inhibitory effect of phytic acid in khichuri (30 mg/serving) or that components of human milk modified the influence of ascorbic acid on iron bioavailability.     

Plasma very low density lipoproteins from male rats fed casein or soybean protein diets: a comparison of fatty acid composition and influence on prostanoid production

In studies with male rats fed for 4 wk semipurified diets containing olive oil and casein or soybean protein, protein-dependent effects were observed in the fatty acid composition of the VLDL lipids, especially with regard to the pattern of polyunsaturated fatty acids. Compared with VLDL from rats fed soybean protein diet (S-VLDL), VLDL from casein-fed rats (C-VLDL) contained a greater level of oleic acid, and a reduced level of linoleic acid and arachidonic acid, in the phosphatidylcholine fraction. The proportion of 5,8,11-eicosatrienoic acid, 20:3 (n-9), varied among the different lipid classes. The highest concentration of this fatty acid (13% by weight of total fatty acids) was observed in the phosphatidylinositol fraction of C-VLDL. The level of linoleic acid was approximately halved in the triacylglycerol and cholesteryl ester fractions of C-VLDL compared with S-VLDL. When mouse peritoneal macrophages were incubated with different concentrations of S-VLDL, a saturable accumulation of 6-keto-prostaglandin F1 alpha (6-keto-PGF1 alpha) and thromboxane B2 (TXB2) was observed in the cell medium. In contrast, very low levels of 6-keto-PGF1 alpha and TXB2 were observed in the cell medium of macrophages incubated with C-VLDL at different lipoprotein concentrations, suggesting that the composition of VLDL may play an important role in relation to cellular prostanoid metabolism.