Current methods for estimating dietary iron bioavailability do not work in China

Three current equations for estimating iron bioavailability were evaluated, and adjustments were proposed that would allow us to most effectively study iron bioavailability in China. Dietary intake data were obtained from 24-h dietary recalls taken over three consecutive days as part of the third Chinese National Nutrition Survey. Hemoglobin status was measured for 42,606 Chinese adults aged 18-60 y. The mean iron intake was 24.4 mg per capita per day, which was 177% of the Chinese RDA (209% of U.S. RDA). About 18% of the sample was classified as being anemic, indicating a large iron deficiency anemia and iron bioavailability problem in China. A number of methods proposed by World Health Organization and U.S. scholars were examined for adjusting iron bioavailability. Even the methods that consider several iron enhancers and inhibitors did not work adequately for the Chinese diet. The statistical assessment of the fit between iron bioavailability and hemoglobin status provided direction for adjusting the best of these predictive equations. We propose a new predictive approach for iron bioavailability which is more predictive of Chinese iron status. Consideration of additional dietary elements such as rice and bean consumption patterns are important. Our findings provide insight into additional factors which may influence iron bioavailability as well as possible improved methods for estimating the combined effect of multiple dietary factors on iron bioavailability, particularly in a vegetarian diet.     

Dietary and physiological factors that affect the absorption and bioavailability of iron

Iron deficiency, a global health problem, impairs reproductive performance, cognitive development, and work capacity. One proposed strategy to address this problem is the improvement of dietary iron bioavailability. Knowledge of the molecular mechanisms of iron absorption is growing rapidly, with identification of mucosal iron transport and regulatory proteins. Both body iron status and dietary characteristics substantially influence iron absorption, with minimal interaction between these two factors. Iron availability can be regarded mainly as a characteristic of the diet, but comparisons between human studies of iron availability for absorption require normalization for the iron status of the subjects. The dietary characteristics that enhance or inhibit iron absorption from foods have been sensitively and quantitatively determined in human studies employing iron isotopes. People with low iron status can substantially increase their iron absorption from diets with moderate to high availability. But while iron supplementation and fortification trials can effectively increase blood indices of iron status, improvements in dietary availability alone have had minimal influence on such indices within several weeks or months. Plentiful, varied diets are the ultimate resolution to iron deficiency. Without these, more modest food-based approaches to human iron deficiency likely will need to be augmented by dietary iron fortification.     

HFE genotype modifies the influence of heme iron intake on iron status

BACKGROUND: Public health policy to prevent iron deficiency through food fortification or other measures may be disadvantageous to people with hereditary hemochromatosis. METHODS: From a cohort of U.K. women, 2531 women were typed for C282Y and H63D mutations in the hemochromatosis gene. These women completed food frequency questionnaires and provided blood for iron status. RESULTS: C282Y homozygotes (n=31) had serum ferritin concentrations 2.4 times higher (95% confidence interval=1.9-3.1) than wild types (n=1774), but heterozygotes (n=726) were not different from wild types. H63D genotype had no effect on its own. The effect of heme iron intake (from meat, fish, and poultry) was 2.0 times greater (1.2-3.2) on C282Y homozygotes than other groups. Nonheme iron had little effect. CONCLUSIONS: There may be scope for dietary intervention in women homozygous for the C282Y mutation. C282Y heterozygotes and H63D homozygotes and heterozygotes have similar serum ferritin concentrations to wild type and need not reduce their meat intake other than as part of a normal healthy diet.     

Prevalence of leading types of dietary supplements used in the Third National Health and Nutrition Examination Survey, 1988--94

This report presents the prevalence of the leading types of dietary supplements taken during the third National Health and Nutrition Examination Survey (NHANES III), 1988-94. Approximately 40 percent of the U.S. population 2 months of age and older reported taking some type of dietary supplement in NHANES III, and the leading supplements taken were multivitamin/multiminerals (22 percent), multivitamins plus vitamin C (15 percent), vitamin C as a single vitamin (13 percent), other dietary supplements such as herbal and botanical supplements (7 percent), and vitamin E as a single vitamin (6 percent). To some extent, the leading types of supplements and order changed after stratifying the results by sex and age groups. Other major contributors were multivitamins with iron or fluoride taken by children, iron taken by adolescent and young adult females, and calcium taken by middle-aged and elderly females. There was also a high prevalence of use of potassium among middle-aged and elderly adults but this probably reflects its use as a medication rather than as a dietary supplement. Collecting information on dietary supplement use is an important part of monitoring the nutritional status of the U.S. population.     

Longitudinal nutrient intake patterns of US adolescent women: the Penn State Young Women's Health Study.

PURPOSE: To use longitudinal nutrient intake data to determine whether dietary patterns remain consistent (or "track") as U.S. females progress from age 12 to 18 years. METHODS: Three-day diet records were collected at regular intervals over 6 years from participants in the Penn State Young Women's Health Study. Eighty-one subjects remained in the cohort during the study period. Tracking in body weight, in dietary intake of fat, sugar, iron, vitamin C, and in a total dietary score (TDS) was assessed using quartile-ranking analysis, year-to-year Pearson correlation analysis, and longitudinal linear analysis. RESULTS: Rank analysis revealed that subjects maintained their relative quartile positions for body weight throughout the study period, and year-to-year correlation coefficients for this variable were .93-.94. In contrast, rank and correlation analyses showed that the subjects did not track strongly with respect to any nutrient variable. Age 12 to 18 years correlation coefficients ranged from r = .04 for fat intake to r = .15 for the TDS. In longitudinal linear models, slopes differed in direction and significance across the original quartiles for nutrient intake, indicating varying dietary trends over time within the study population. CONCLUSIONS: Nutrient intake patterns do not track strongly throughout adolescence among U.S. females.     

State of iron repletion and cadmium tissue accumulation as a function of growth in young rats after oral cadmium exposure

To check the hypothesis that adequate dietary iron supplementation reduces cadmium retention and cadmium-induced anaemia during fast growth, three different dietary iron concentrations (6 mg/kg=iron-deficient; 55 mg/kg=marginal iron supply; 180 mg/kg=luxurious iron supply) were offered to growing rats. Four groups of rats at different age (44 days150±6 g, 49 days180±3 g, 57 days220±4 g, and 84 days295±9 g) received a diet with 55 mg Fe/kg which is a marginal iron-supply during growth. Six animals in each age group were exposed to 10 mg Cd/l as CdCl₂ in the drinking water for 1 week; six animals in each age group received no cadmium. In the youngest and oldest groups additional 6 animals were exposed to the same cadmium dose but received an iron-deficient (6 mg Fe/kg) and an iron-adequate diet (180 mg Fe/kg) together with corresponding controls. The state of iron repletion was monitored by the tissue iron content in liver, kidney, and duodenum as well as by the concentrations of haemoglobin, plasma iron and plasma transferrin. The youngest animals showed the highest percent weight increases. Cadmium administration influenced neither growth rates nor food and water intake. At a dietary iron content of 55 mg/kg, iron repletion was negatively correlated to growth while the cadmium content in liver and kidney showed a positive correlation. At fast growth, a dietary iron content of 6 mg/kg lead to iron-deficiency anaemia and high cadmium retention. At all dietary iron concentrations, cadmium retention as well as the cadmium-related reduction in haemoglobin concentration was significantly higher at fast growth. Adequate dietary iron supplementation reduced cadmium retention and cadmium-induced anaemia significantly. Thus, the delicate balance between iron supply and the increased iron demand during growth can be disturbed within one week by a daily cadmium intake as low as 0.7–1.3 mg Cd/kg body weight.Part of the data was presented in Bioavailability 93, Proceedings of Bioavailability 93, Vol. II, U. Schlemmer (ed.), Berichte der Bundesforschungsanstalt für Ernährung, Karlsruhe, 1994     

Effect of ascorbic acid intake on nonheme-iron absorption from a complete diet

BACKGROUND: Ascorbic acid has a pronounced enhancing effect on the absorption of dietary nonheme iron when assessed by feeding single meals to fasting subjects. This contrasts with the negligible effect on iron balance of long-term supplementation with vitamin C. OBJECTIVE: Our goal was to examine the effect of vitamin C on nonheme-iron absorption from a complete diet rather than from single meals. DESIGN: Iron absorption from a complete diet was measured during 3 separate dietary periods in 12 subjects by having the subjects ingest a labeled wheat roll with every meal for 5 d. The diet was freely chosen for the first dietary period and was then altered to maximally decrease or increase the dietary intake of vitamin C during the second and third periods. RESULTS: There was no significant difference in mean iron absorption among the 3 dietary periods despite a range of mean daily intakes of dietary vitamin C of 51-247 mg/d. When absorption values were adjusted for differences in iron status and the 3 absorption periods were pooled, multiple regression analysis indicated that iron absorption correlated negatively with dietary phosphate (P = 0.0005) and positively with ascorbic acid (P = 0.0069) and animal tissue (P = 0.0285). CONCLUSIONS: The facilitating effect of vitamin C on iron absorption from a complete diet is far less pronounced than that from single meals. These findings may explain why several prior studies did not show a significant effect on iron status of prolonged supplementation with vitamin C.     

Suboptimal iron status and associated dietary patterns and practices in premenopausal women living in Auckland, New Zealand

Purpose

To investigate associations between dietary patterns and suboptimal iron status in premenopausal women living in Auckland, New Zealand.

Methods

Premenopausal women (n = 375; 18–44 years) were included in this cross-sectional analysis. Suboptimal iron status was defined as serum ferritin <20 μg/L. Participants completed a 144-item iron food frequency questionnaire (FeFFQ) and a questionnaire on dietary practices to assess dietary intake over the past month. Factor analysis was used to determine dietary patterns from the FeFFQ. Logistic regression was used to determine associations between these dietary patterns and iron status.

Results

Seven dietary patterns were identified: refined carbohydrate and fat; Asian; healthy snacks; meat and vegetable; high tea and coffee; bread and crackers; and milk and yoghurt. Logistic regression suggested that following a “meat and vegetable” dietary pattern reduced the risk of suboptimal iron status by 41 % (95 % CI: 18, 58 %; P = 0.002) and following a “milk and yoghurt” pattern increased the risk of suboptimal iron status by 50 % (95 % CI: 15, 96 %; P = 0.003).

Conclusions

These results suggest that dietary patterns characterized by either a low intake of meat and vegetables or a high intake of milk and yoghurt are associated with an increased risk of suboptimal iron status. Dietary pattern analysis is a novel and potentially powerful tool for investigating the relationship between diet and iron status.     

Regulation of iron metabolism in Hamp −/− mice in response to iron-deficient diet

Background

Hepcidin, the liver-secreted iron regulatory peptide, maintains systemic iron homeostasis in response to several stimuli including dietary iron levels and body iron status. In addition, iron metabolism is controlled by several local regulatory mechanisms including IRP and Hif-2α activities independently of hepcidin. However, the roles of these mechanisms and their interaction particularly in hepcidin-deficient individuals are not yet fully understood. We, therefore, aimed to explore whether Hamp disruption affects iron homeostatic responses to dietary iron deficiency.

Methods

Hepcidin1 knockout (Hamp ^?/?) mice and heterozygous littermates were fed with control or iron-deficient diet for 2 weeks. The expression of iron-related genes and proteins were determined by quantitative PCR and Western blot, respectively.

Results

Two-week iron-deficient diet feeding in Hamp ^?/? mice did not alter serum iron but significantly reduced liver non-heme iron levels. This was also associated with increased ferroportin protein expression in the duodenum and spleen, whereas decreased expression was found in the liver. In addition, significant inductive effects of iron-deficient diet on Dcytb and DMT1 mRNA expression in the duodenum were noted with more pronounced effects in Hamp ^?/? mice compared with controls.

Conclusions

Hamp ^?/? mice exhibited a more dramatic increase in the expression of iron transport machinery, which may be responsible for the unaltered serum iron levels upon iron-deficient diet feeding in these mice. Despite the lack of hepcidin, Hamp ^?/? mice can maintain a degree of iron homeostasis in response to altered dietary iron through several hepcidin-independent mechanisms.     

Iron stores and haemoglobin iron deficits in menstruating women. Calculations based on variations in iron requirements and bioavailability of dietary iron

BACKGROUND: Iron stores and haemoglobin iron deficits in menstruating women can be calculated from body iron losses and absorption of dietary iron using recently developed methods. OBJECTIVE: To examine iron balance (iron status) expressed as body iron stores or haemoglobin iron deficits in menstruating women from amounts of iron lost (iron requirements) and amounts of dietary iron absorbed. Calculations are made both of stationary states and of the rate of changes in iron stores (iron status) when any of the two main factors determining iron balance are changed. DESIGN: The study is based on (1) previous and new equations describing relationships between iron absorption, iron requirements (losses), iron stores and/or haemoglobin deficits and (2) published data on iron requirements and their variation in menstruating adult women. RESULTS: Both iron stores and haemoglobin iron deficits are strongly related to iron requirements and absorption of dietary iron and follow the same equations during states of iron repletion and iron deficiency. When, for example, increasing or decreasing the bioavailability of the dietary iron, about 90% of the change in iron stores will occur within 1 y. CONCLUSIONS: There are strong relationships between iron requirements, bioavailability of dietary iron and amounts of stored iron. The observations that a reduction in iron stores and a calculated decrease of haemoglobin iron had the same increasing effect on iron absorption suggest that the control of iron absorption is mediated from a common cell, that may register both size of iron stores and hemoglobin iron deficit, eg the hepatocyte. European Journal of Clinical Nutrition (2000) 54, 650-657.     

Iron intake affects lipid peroxidation and glutathione peroxidase activity of distal colonic mucosa

The purpose of this study was to examine the effect of low, adequate, and high dietary iron (Fe) levels on lipid peroxidation, glutathione S-transferase (GST) and glutathione peroxidase (GSH-Px) activities, and glutathione (GSH) concentrations in colon and liver. Male Sprague Dawley rats were fed iron deficient (DFe; 14 mg Fe/kg diet; N=8), adequate iron (AFe; 39 mg Fe/kg diet, N=8), or high iron (HFe; 454 mg Fe/kg diet; N=8) diets for 3 weeks. Liver Fe concentrations were 26, 84, and 243 ug/g wet weight, respectively, for rats fed DFe, AFe, and HFe diets (p<0.0001). Lipid peroxidation was increased 70% in distal colonic mucosa of rats fed HFe diets compared to that of rats fed AFe and DFe diets (p<0.01), but lipid peroxidation was unaffected by diet in proximal colon or liver. While distal colonic mucosal GSH-Px activity was lower in DFe rats (0.062 U/mg protein), than in AFe rats (0.091 U/mg protein), and HFe rats (0.089 U/mg protein) (p<0.05), iron intake had no effect on GSH-Px activity in proximal colon or liver. The distal colon had higher GSH-Px activity than proximal colon (p<0.0001). GST activity in colon and liver, and hepatic GSH concentrations were not altered by dietary iron intakes. This study suggests that distal and proximal colonic mucosa may respond differently to changes in Fe status.     

Is "processed" a four-letter word? The role of processed foods in achieving dietary guidelines and nutrient recommendations

This paper, based on the symposium "Is 'Processed' a Four-Letter Word? The Role of Processed Foods in Achieving Dietary Guidelines and Nutrient Recommendations in the U.S." describes ongoing efforts and challenges at the nutrition-food science interface and public health; addresses misinformation about processed foods by showing that processed fruits and vegetables made important dietary contributions (e.g., fiber, folate, potassium, vitamins A and C) to nutrient intake among NHANES 2003-2006 participants, that major sources of vitamins (except vitamin K) were provided by enrichment and fortification and that enrichment and fortification helped decrease the percentage of the population below the Estimated Average Requirement for vitamin A, thiamin, folate, and iron; describes how negative consumer perceptions and consumer confusion about processed foods led to the development of science-based information on food processing and technology that aligns with health objectives; and examines challenges and opportunities faced by food scientists who must balance consumer preferences, federal regulations, and issues surrounding food safety, cost, unintended consequences, and sustainability when developing healthful foods that align with dietary guidelines.     

Iron status of middle-aged women in five counties of rural China

OBJECTIVE: To determine the relationships of dietary iron sources, other dietary factors, and lifestyle to iron status among premenopausal and recently postmenopausal Chinese women with widely varying regional dietary patterns. DESIGN: Cross-sectional. Subjects were interviewed, blood samples were drawn, and dietary intakes were measured by a 3-day dietary survey for subjects in the five survey counties. SETTING: Rural China. SUBJECTS: About 80 randomly selected subjects per county among women aged 32 66 y. MAIN OUTCOME MEASURES: Blood hemoglobin, plasma ferritin, and plasma iron. RESULTS: Total iron intake was relatively high (15-29 mg/d) compared to developed counties. Heme iron intake was negligible in two of the study counties. Overall levels of iron deficiency anemia were relatively low in these generally iron-stressed women. There was no clear statistical relationship between iron intake and physiological iron status. Although several measures of dietary intake (heme iron, dietary calcium, animal protein) were correlated with several measures of iron status before adjusting for survey county, only dietary animal protein was significantly positively correlated with plasma ferritin after adjusting for the possibly confounding factor of the survey county (r= 0.15, P = 0.009). Intakes of potential inhibitors of iron absorption, such as tea, even in very high amounts, were not correlated to iron status. Plasma ferritin was positively correlated with plasma retinol (P = 0.024) and cholesterol (P = 0.007). Systemic inflammatory response, as indicated by high plasma C-reactive protein levels, was shown to be raised in a group of subjects with apparently contradictory high levels of ferritin and low levels of hemoglobin (P = 0.03). CONCLUSIONS: Iron nutriture in these areas of rural China seemed more related to physiological factors such as inflammatory response, menses, plasma vitamin A and cholesterol, than to dietary factors.     

Toddler diets in the U.K.: deficiencies and imbalances. 1. Risk of micronutrient deficiencies

The toddler diet in the U.K. changed considerably during the 25 years between the last two national dietary surveys, and these and other reports suggest that the nutritional intake of many toddlers does not comply with national recommendations. This is a concern for parents and health care workers because both deficiencies and excesses in nutrition are associated with increased risk of diseases, such as iron deficiency anaemia, rickets, dental caries and diseases related to obesity. Paradoxically, a decrease in energy intake has been accompanied by a rise in obesity, while a parallel fall in vitamin and mineral intake has been seen in tandem with an increase in diseases associated with nutritional deficiency. Establishing good dietary habi in early childhood is therefore important for short-term health. Dietary patterns at this time may be crucial to later behaviour and, if carried through to adulthood, may affect long-term health. In particular, deficiencies of micronutrients such as iron, zinc and vitamin D are a cause for con cern. Childhood diseases such as rickets, which affects bone development and was thought to have been eradicated, have re-emerged in recent years and the prevalence of iron deficiency anaemia has increased, particularly among migrant populations among migrant populations. Part 1 of this review considers the relationship between current toddler diet and micronutrient deficiencies, focusing on the impact of deficiency on both short- and longterm health. In Part 2 (to be published in Journal of Family Health Care 2007; 17[6]), the authors will consider effects on health of nutritional imbalance resulting from overconsumption of energy and nutrients.     

Prediction of dietary iron absorption: an algorithm for calculating absorption and bioavailability of dietary iron

BACKGROUND: Dietary iron absorption from a meal is determined by iron status, heme- and nonheme-iron contents, and amounts of various dietary factors that influence iron absorption. Limited information is available about the net effect of these factors. OBJECTIVE: The objective was to develop an algorithm for predicting the effects of factors known to influence heme- and nonheme-iron absorption from meals and diets. DESIGN: The basis for the algorithm was the absorption of iron from a wheat roll (22.1 +/- 0.18%) containing no known inhibitors or enhancers of iron absorption and adjusted to a reference dose absorption of 40%. This basal absorption was multiplied by the expected effect of different amounts of dietary factors known to influence iron absorption: phytate, polyphenols, ascorbic acid, meat, fish and seafood, calcium, egg, soy protein, and alcohol. For each factor, an equation describing the dose-effect relation was developed. Special considerations were made for interactions between individual factors. RESULTS: Good agreement was seen when measurements of iron absorption from 24 complete meals were compared with results from use of the algorithm (r(2) = 0.987) and when mean iron absorption in 31 subjects served a varied whole diet labeled with heme- and nonheme-iron tracers over a period of 5 d was compared with the mean total iron absorption calculated by using the algorithm (P = 0.958). CONCLUSIONS: This algorithm has several applications. It can be used to predict iron absorption from various diets, to estimate the effects expected by dietary modification, and to translate physiologic into dietary iron requirements from different types of diets.     

Effect of nutrition education and diet modification in iron depleted preschool children in nurseries in Tehran: a pilot study

In view of the high prevalence of iron deficiency in preschool children and its consequences, this study was carried out to examine the effect of nutrition education and dietary modification on 438 two- to six-year-old nursery school children in Tehran in 1999. Sixty-two children who were judged anemic, iron-depleted, or having low iron stores were randomly allocated to "control," "dietary modification" (consuming one additional citrus fruit after lunch), and "nutrition education" (teaching the mothers proper eating patterns based on the food pyramid) groups. Food habits were surveyed, including 24-hour dietary recall and food frequency, as well as timing of consumption of special items; this survey was carried out for each child before and after intervention. After three months, blood samples were taken from the subjects. The prevalence of anemia, iron depletion, and low iron stores was 11.4, 62.8, and 15.1% respectively, with no significant differences observed in hemoglobin and percent transferrin saturation (%TS) between the groups. Mean+/-SD serum ferritin concentrations in "control," "diet modification," and "nutrition education" groups were 8.9+/-3.1, 9.5+/-3.7, and 6.9+/-2.3 microg/dL. The same figures at the end of intervention were 6.9+/-3.5, 11.2+/-5, and 10.7+/-5.9 microg/dL, respectively. Analysis of variance showed ferritin concentrations to be significantly different, in that there was a reduction in the control and elevation in the nutrition education groups. There was no significant difference in %TS before and after the intervention. During three months of intervention, changes in frequency of fruit and fruit juice intake after the meals in nutrition education and diet modification groups were significantly correlated to serum ferritin alteration. Frequency of fruit juice intake (rich in vitamin C) after meals (at least five times a week) can significantly increase serum ferritin within three months. Therefore, educating mothers of iron-deficient children while increasing the iron stores in children can prevent the recurrence of iron deficiency and result in general child well-being.     

Peer Reviewed: Dietary Intake of Minerals and the Risk of Ischemic Stroke in Guangdong Province,China, 2007-2008

Introduction

Previous studies have investigated the association between mineral intake and the risk of ischemic stroke, but results are inconsistent. We conducted a case-control study to ascertain the associations between intake of dietary potassium, calcium, magnesium, sodium, and iron and the ischemic stroke risk in the southern Chinese population.

Methods

Information on lifestyle and typical food consumption was obtained from 374 hospital inpatients with ischemic stroke and 464 hospital-based control patients. Added sodium from salt or soy sauce could not be reliably quantified, but participants were asked to characterize their diet as low in salt, normal, or high in salt. Logistic regression analyses were performed to assess possible associations between the effects of mineral intake and ischemic stroke risk.

Results

The mean weekly intakes of potassium, calcium, magnesium, and iron were lower among case patients than among control patients. Sodium was an exception. Lower stroke risk was associated with higher weekly dietary calcium or magnesium levels (adjusted odds ratio, 0.32) for the highest versus lowest category of intake, and significant dose-response relationships were seen. No significant associations were found for potassium, iron, or sodium. However, patients who consumed a salty diet were more than twice as likely as those whose diet was light in salt to experience an ischemic stroke.

Conclusion

The findings suggest that lowering sodium intake while maintaining high levels of dietary calcium and magnesium may help prevent ischemic stroke in southern Chinese adults.     

Dietary iron promotes azoxymethane-induced colon tumors in mice

There is accumulating evidence that high levels of dietary iron may play a role in colon carcinogenesis. We used a mouse model to investigate the impact of elevated dietary iron on incidence of aberrant crypt foci (ACF; a preneoplastic lesion) on tumor formation and on induction of oxidative stress. A/J mice were injected intraperitoneally, once a week for 6 weeks, with the colonotropic carcinogen, azoxymethane (AOM) or saline (vehicle controls). Following AOM or saline treatments, mice were placed on diets of high (3,000 ppm) and low (30 ppm) iron. Mice in each treatment group were sacrificed at 6 and 10 weeks following the final injection with AOM or saline. Colons were removed for subsequent histopathological analysis, which revealed average increases of 4.6 +- 1.3 vs. 10.4 +- 2.5 total tumors at 6 weeks and 30.75 +- 2.7 vs. 41.5 +- 4.4 total tumors at 10 weeks per AOM-treated mouse on low- and high-iron diets, respectively. There were no significant differences in incidence of ACF attributable to iron, although there was a trend toward greater crypt multiplicity per focus in mice on high-iron diets. Notably, no tumors were observed in mice receiving vehicle control injections in place of carcinogen, regardless of the level of dietary iron. These data suggest that iron exerts its effect at the stage of tumor promotion, but is not sufficient to initiate tumor formation. To learn more about mechanisms by which iron promotes tumor growth, colons were assayed for several biomarkers of oxidative stress [BOS; total F2-isoprostanes (F2-IsoPs), 15-F2t-isoprostanes (8-IsoPGF2s), Isofurans (IsoFs), and 8-hydroxyguanosines (8-OH[d]Gs)], as well as iron absorption, programmed cell death, and cellular proliferation. Elevated PCNA and TUNEL staining of the colon epithelium revealed hyperproliferative and apoptotic responses to iron, while no significant differences between iron groups were observed in each of the BOS that were assayed. Our results suggest that, following carcinogen exposure, elevated dietary iron promotes the growth of tumors with altered cellular homeostasis through a mechanism that is independent of oxidative stress.     

Calcium supplementation and iron status of females

Iron balance is regulated in part by the level of iron absorption, which is influenced by iron stores and the level of erythropoietic activity. In short-term absorption studies, dietary calcium and supplemental doses of calcium chloride or calcium carbonate inhibited iron absorption from concomitantly consumed meals. In contrast, several long-term intervention studies of the effect of calcium supplementation on iron status in populations at potentially high risk for compromised iron status failed to show reductions in various indicators of iron status including serum ferritin levels. The evidence suggests that long-term consumption of calcium supplements does not affect overall iron status. An adaptive response, possibly involving an upregulation in the efficiency of iron absorption, has been suggested as a possible explanation for the disparity between the results from short- and long-term studies.     

The implication of the mineral ratios of Cucumis myriocarpus Naud. and Pergularia daemia (Forsk.) Chiov. in human diets

Vegetables are considered to be the most affordable and sustainable sources of several micronutrients that are essential for physical and mental development, immune system functioning, and various metabolic processes in humans. However, their effectiveness as dietary sources of minerals is influenced by mineral-mineral interactions that may either enhance or reduce the absorption of certain micronutrients in the body. The awareness of such interactions, therefore, is useful when selecting vegetables that could help meet specific dietary criteria for improving micronutrient status. The purpose of this study was to investigate the suitability of Cucumis myriocarpus and Pergularia daemia as sources of mineral nutrients based on their mineral ratios for calcium, iron, potassium, and phosphorus. The Ca/Fe, Ca/K, Ca/Mg, and Ca/Zn ratios were 4.9, 0.9, 2.1, and 9.4, respectively, in C. myriocarpus. For P. daemia the same ratios were 1.7, 0.3, 1.6, and 9.7, respectively. A negative interaction was predicted between calcium and potassium, while the other calcium ratios were considered to be appropriate. The Fe/Zn ratio was adequate for C. myriocarpus (1.9) but excessive for P. daemia (5.6), while the K/Na ratio was good in both vegetables at 39.5 and 12.8, respectively. The P/Ca ratio was 0.2 in C. myriocarpus and 0.3 in P. daemia. Both wild vegetables could be promoted as natural sources for the minerals analyzed, but some adjustment of the P/Ca and Ca/K ratios would be required. Furthermore, the selection of P. daemia for either iron or zinc supplementation is not recommended because of the high Fe/Zn ratio.