Simplified population data analysis using gamma distribution for nutritional requirements and its application to the estimation of iron requirements for women of child-bearing age.

BACKGROUND: Estimation of nutritional requirements is a difficult task, especially for nutrients whose requirements have skewed distribution like iron in menstruating women. OBJECTIVE: To mathematically develop a simplified population data analysis using gamma distribution for the estimation of nutritional requirements, not depending on extensive numerical calculation. METHODS: The required equations for the estimation of requirements were devised and solved. Existing data of iron intakes and iron losses in literature were fitted to cumulative distribution curves including gamma distribution. The proposed method was applied to the estimation of iron requirements in women using the National Health and Nutrition Survey data from 2003 to 2007 in Japan. RESULTS: The type 2 equation of nutritional state is first introduced: prevalence of inadequate nutritional state = Σ(individuals with intake/requirement <1)/(total number of individuals). The prevalence of inadequate nutritional status is determined by F-distribution with positive real number parameters, if the intake and the requirement have independent gamma distributions. The sum of basal and menstrual iron losses is well approximated by gamma distribution, if the basal and menstrual iron losses have independent gamma distributions. Using these relationships, an approximate estimate of iron requirements was determined. Iron intakes and losses were found to be well approximated by gamma distribution. The median of the coefficient of variation (CV) of basal iron loss was 34 %. A new correction method for intra-individual variation in gamma distribution under constant CV is presented also. The median of the estimated median iron requirement was 8.12 mg, 8.15 mg and 8.18 mg for women aged 18-29 years, respectively, as the exact numerical estimate, the approximate estimate using BETA.INV in Excel and the approximate estimate using F.INV in Excel. For women aged 30-49 years, it was 9.15 mg, 9.17 mg and 9.14 mg. The intake covering the needs of 97.7 % women was 14.55 mg, 14.44 mg and 14.49 mg for women aged 18-29 years, and 15.70 mg, 15.77 mg and 15.60 mg for women aged 30-49 years. CONCLUSION: The approximate estimates of iron requirements agreed well with the exact numerical estimate. The proposed method is useful for the estimation of iron requirements in menstruating women that usually requires extensive numerical calculations.

Serum lipid profiles of young Japanese women with iron deficiency without anemia.

PURPOSE: We aimed to evaluate the association between iron deficiency without anemia (IDNA) and serum lipid profiles in young women of around 20 years of age. METHODS: This study included non-anemic (hemoglobin ≥ 12 g/dL) female volunteers aged 18 to 22 years who were not taking mineral/vitamin supplements and living in the metropolitan area of Tokyo, Japan. These volunteers were classified into two groups based on their sFer (serum ferritin) levels: normal group (sFer ≥ 20 ng/mL, n = 36) and IDNA group (sFer < 20 ng/mL, n = 29). Venous blood samples were obtained from the antecubital veins of these volunteers after 10-12-h fasting to measure the hematological and biochemical parameters, including lipid levels and iron status. The results of each group were compared using Student's t-test or the Mann-Whitney U test (for inhomogeneous variance). RESULTS: The serum cholesterol levels varied depending on the iron status in the women. Serum high-density lipoprotein cholesterol (HDL-C) levels in the IDNA group were significantly higher (P = 0.006) than that in the normal group. However, the levels of total cholesterol (T-CHO), triglycerides (TG), and low-density lipoprotein cholesterol (LDL-C) were not significantly different between the groups. Serum LDL-C levels were positively and significantly correlated with sFer levels in the IDNA group (Kendall's rank correlation 0.264, P = 0.044), but not in the normal group. The sFer level was not correlated with serum HDL-C in both groups. The reason for the high serum HDL-C levels in young women with IDNA is not yet clear. Compared to the normal group, the frequency of eating bread containing bran was significantly higher (P = 0.031) and that for yogurt was significantly lower (P = 0.040) in the IDNA group. The proportion of the women who were susceptible to infection, which was measured using the Cornell Medical Index, was significantly higher in the IDNA group than in the normal group. Among those susceptible to infection, the serum HDL-C level of the volunteers in the IDNA group was significantly higher than that of the volunteers in the normal group (P = 0.024). CONCLUSIONS: Our findings suggest that lipid parameters may be associated with IDNA and susceptibility to infection. Further research is needed to elucidate the mechanisms underlying the changes in the serum cholesterol levels in individuals with IDNA and the clinical significance of these findings.

Investigating the Essentiality and Requirements of Iron from the Ancient to the Present.

This review discusses the development of studies that evaluated the essentiality and requirements of iron from the ancient to the present. The therapeutic effects of iron compounds were recognized by the ancient Greeks and Romans. The earliest recognition of the essentiality of iron was stated by Paracelsus, a distinguished physician alchemist, in the sixteenth century. Iron was included in the earliest nutritional standard prepared for the Royal Army by E. A. Parkes, the first professor of hygiene. The League of Nations Health Organisation determined average iron requirements based on literature review. In the first US Recommended Dietary Allowances (RDA), the RDA of iron was determined from the results of iron balance studies. In the current Dietary Reference Intakes, iron requirements were determined based on the factorial method with the aid of Monte Carlo simulation for combining basal and menstrual iron losses. Population data analysis is a recently developed alternative that does not use the pre-estimated iron absorption rate and requires the prevalence of inadequacy instead. Population data analysis uses the convolution integral for combining basal and menstrual iron losses to ensure the required accuracy. This review also provides new estimates of hair and nail iron losses.

Iron deficiency without anaemia is a potential cause of fatigue: meta-analyses of randomised controlled trials and cross-sectional studies.

Fe deficiency is a prevalent nutritional disease, and fatigue is a common complaint in the general and patient population. The association between Fe deficiency without anaemia (IDNA) and fatigue is unclear. Here, we performed a meta-analysis to evaluate the therapeutic effect of Fe on fatigue in patients with IDNA and the association between IDNA and fatigue in the population. Articles from the PubMed database up to 19 January 2016 were systematically searched. A total of six relevant randomised controlled trials (RCT) and six relevant cross-sectional studies were identified. All outcomes were converted into effect sizes. In the meta-analysis of the six RCT, we identified a significant therapeutic effect of Fe in fatigue patients with IDNA (pooled effect size 0·33; 95 % CI 0·17, 0·48; I 2=0·0 %; P<0·0001). A sensitivity analysis found that the overall results (i.e. significant association) were robust. In the meta-analysis of the six cross-sectional studies, the association between IDNA and fatigue was not significant (pooled effect size 0·10; 95 % CI -0·11, 0·31; I 2=57·4 %; P=0·362). A sensitivity analysis found that the overall results (i.e. no significant association) were not robust; removal of one study made the outcomes significant. These meta-analyses suggest that improving Fe status may decrease fatigue. Further research is necessary to identify diagnostic criteria for selecting fatigue patients who might benefit from Fe therapy and to assess the prevalence of IDNA with fatigue in the general population.

Estimation of iron requirements for women by numerical analysis of population-based data from the National Health and Nutrition Surveys of Japan 2003-2007.

Iron requirements were estimated from the results of the National Health and Nutrition Surveys of Japan 2003-2007 using the numerical analysis of requirements based on an integral equation. The numerical analysis used population-based data on iron nutriture, the prevalence of inadequate iron status, and the distribution of iron intakes. The cutoff value for inadequate iron status was defined as a serum ferritin concentration <30ng/mL. Iron intakes and menstrual blood losses followed a log-normal distribution and published values were corrected accordingly to calculate usual values. For women aged 18-29 years old, the median of the estimated median iron requirement (corresponding to the estimated average requirement by using the terminology of the dietary reference intakes) was 7.59mg (range, 6.86-8.11). The median of the estimated usual iron intake covering the needs of women with 80mL per cycle of menstrual blood loss was 11.27mg (range, 10.16-12.00), and the median of the usual iron intake covering the needs of 97.7% of women was 13.93mg (range, 12.55-14.81). For women aged 30-49 years old, the corresponding figures were 8.13mg (range, 7.96-8.69), 11.95mg (range, 11.72-12.77), and 14.71mg (range, 14.44-15.72).

Effect of dietary nickel deprivation on vision, olfaction, and taste in rats.

Early studies on dietary nickel deprivation found decreased reproduction rate in pigs and decreased insemination and conception rates in goats. Studies from our laboratory demonstrated that nickel deprivation impaired male reproductive function of rats. A physiological amount of nickel modulates the function of cyclic nucleotide-gated cation channels (CNG channels) in vitro. Thus, because CNG channels have important roles in spermatozoa function, it was speculated that the impairment of reproduction by nickel deprivation was through an effect on CNG channels. Because CNG channels are found in retinal photoreceptor, olfactory receptor, and taste receptor cells, we hypothesized that nickel deprivation would also alter light/dark preference, odor preference to female rat urine, and taste preference/aversion in rats. In the light/dark Y-maze, nickel deprivation significantly decreased time spent in the dark arm by rats. The number of sniffs to estrous female urine was significantly increased only in nickel-supplemented rats. The number of licks at the saccharin bottle was significantly decreased by dietary nickel deprivation. These findings suggest that nickel has a biological role in the special senses: vision, olfaction and taste.

Iron deficiency without anemia is associated with anger and fatigue in young Japanese women.

Iron deficiency without anemia (IDNA), the most prevalent nutritional deficiency worldwide, affects young women of reproductive age. This study aimed to elucidate the relationship between IDNA and mental and somatic symptoms including anger and fatigue using the Japanese version of the Cornell Medical Index Health Questionnaire (CMI-J). Data regarding demographic characteristics, anthropometry, hematological, and biochemical indices of the iron status, frequencies of selected food intakes assessed by self-administered food frequency questionnaires (FFQs), frequencies of nonspecific symptoms, and grades of neurotic tendencies assessed by CMI-J were collected from 76 young women aged 18-22 years living in the metropolitan area of Tokyo, Japan. The subjects were classified as having IDNA (hemoglobin (Hb)≥12 g/dL and serum ferritin<20 ng/mL; n=29), having iron deficiency anemia (IDA) (Hb<12 g/dL and serum ferritin<20 ng/mL; n=10), or having a normal iron status (Hb≥12 g/dL and serum ferritin≥20 ng/mL; n=36). One subject was excluded from the analyses because of Hb<12 g/dL and serum ferritin≥20 ng/mL. Fisher's protected least significant difference and the Dwass-Steel-Chritchlow-Fligner multiple comparison tests were used to compare the data of the three groups. P values<0.05 were considered significant. Sections M-R (mental complaints) were significantly higher in the IDNA subjects than in the normal subjects. No significant difference in CMI scores was found between the normal and IDA subjects. Sections I (fatigability), Q (anger), and R (tension) were significantly higher in the IDNA subjects than in the normal subjects, regardless of no significant differences between the normal and IDA subjects in those sections. Young women with IDNA demonstrated a significantly higher proportion of neurotic tendencies (grades II-IV). The intake frequency score of canned or bottled green tea fortified with vitamin C was significantly higher in the IDNA subjects than the IDA subjects. The findings suggest that IDNA may be a risk factor for anger, fatigue, and tension in women of childbearing age.

Toxicity of so-called edible hijiki seaweed (Sargassum fusiforme) containing inorganic arsenic.

The UK Food Standards Agency and its counterparts in other countries have warned consumers not to eat hijiki (Sargassum fusiforme; synonym Hizikia fusiformis), a Sargasso seaweed, because it contains large amounts of inorganic arsenic. We investigated dietary exposure of hijiki in weaning male F344/N rats fed an AIN-93G diet supplemented with 3% (w/w) hijiki powder for 7 weeks, compared with those fed only an AIN-93G diet. Body weight, body temperature, blood and tissue arsenic concentrations, plasma biochemistry and hematological parameters were measured. We found that feeding rats a 3% hijiki diet led to a marked accumulation of arsenic in blood and tissues, and evoked a high body temperature and abnormal blood biochemistry including elevated plasma alkaline phosphatase activity and inorganic phosphorus, consistent with arsenic poisoning. These findings should prompt further investigations to identify the health hazards related to consumption of hijiki and related Sargassum species in humans.

Comparison of a modified hemoglobin regeneration efficiency method with a slope-ratio assay in measuring relative bioavailability of cocoa powder iron using rats.

The slope-ratio assay is being used as a gold standard for determining iron bioavailability in foods. We compared the modified hemoglobin (Hb) regeneration efficiency (HRE) method (Yokoi K, Konomi A, & Otagi M (2009) Br J Nutr 102: 215-220) with the slope-ratio assay for measurement of iron bioavailability. The relative bioavailability of iron in cocoa powder was measured by both methods using ferric citrate as a control (i.e., 1.00). In the slope-ratio assay, thirty-two 4-week-old male F/344 N rats were depleted in iron stores for 28 days, and then eight groups of four rats each were repleted for 25 days using graded levels of dietary ferric citrate or the cocoa powder. The slope for the cocoa powder 1.720 g Hb/L/(mg Fe/kg) was 0.99 that of ferric citrate 1.727 g Hb/L/(mg Fe/kg). On the other hand, the HRE value of the cocoa powder was 0.96 that of ferric citrate, based on the previous report. The relative iron bioavailabilities measured by both methods agreed, indicating that the modified HRE method is compatible with the slope-ratio assay in measuring the bioavailability of iron in foods.

A possible role of plasma aldosterone in hypotension secondary to iron-deficiency anaemia combined with zinc deficiency in rats.

Patients with Fe-deficiency anaemia are often afflicted by hypotension. However, the mechanism of secondary hypotension in Fe-deficiency anaemia is unknown. To investigate the pathogenesis of secondary hypotension in Fe-deficiency anaemia, we examined the effects of Fe deprivation on plasma aldosterone concentration and blood pressure in rats. A total of forty 4-week-old male Sprague-Dawley rats were assigned into four treatment groups of ten each for the 4-week study: Fe-deficient group (FD), Zn-deficient group (ZD), Fe/Zn-deficient group (FZD) and control group (CON). At days 26 and 27, blood pressure was measured by the tail-cuff method. Plasma aldosterone concentration was determined by ELISA. The data were analysed by Tukey's multiple comparison test. Rats in the FZD had significantly lower mean blood pressure (P < 0·01) and diastolic blood pressures (P < 0·05) and plasma aldosterone concentration (P < 0·01) compared to the CON. These results suggest that blood pressure is decreased in Fe-deficiency anaemia combined with Zn deficiency partly due to decreased circulating aldosterone concentrations in addition to decreased haematocrit.

Iron bioavailability of cocoa powder as determined by the Hb regeneration efficiency method.

Fe deficiency is a public-health problem worldwide, and effective measures for preventing Fe deficiency are needed. The aim of the present study was to determine the bioavailability of Fe in cocoa using the Hb regeneration efficiency (HRE) method. Thirty-five F344/N male weanling rats were fed a low-Fe diet for 4 weeks to deplete body Fe stores. Then, four groups of seven animals each were repleted for 20 d using a modified AIN-93G diet fortified with ferrous sulphate, ferric citrate or two brands of cocoa powder to provide a total dietary Fe concentration of 20 mg/kg. As a negative control, seven rats were maintained on the low-Fe diet. The HRE were 0.733, 0.350, 0.357 and 0.336 for ferrous sulphate, ferric citrate and the two brands of cocoa powder, respectively. The relative biological values (RBV), defined as the ratio of the sample HRE to that of ferrous sulphate, were 0.478, 0.488 and 0.459 for ferric citrate and the two brands of cocoa powder, respectively. The Fe bioavailability of cocoa was significantly less than that of ferrous sulphate and was similar to that of ferric citrate. The difference in Fe bioavailability between the two brands of cocoa powder was negligible. When the negative control was used to correct the data, estimates of the RBV derived from Hb gain were similar to those derived from the HRE. These results suggest that cocoa is a significant source of moderately bioavailable Fe.

Dermal absorption of inorganic germanium in rats.

So-called germanium 'health' products including dietary supplements, cosmetics, accessories, and warm bath service containing germanium compounds and metalloid are popular in Japan. Subchronic and chronic oral exposure of germanium dioxide (GeO(2)), popular chemical form of inorganic germanium causes severe germanium toxicosis including death and kidney dysfunction in humans and experimental animals. Intestinal absorption of neutralized GeO(2) or germanate is almost complete in humans and animals. However, it is not known whether germanium is cutaneously absorbed. We tested dermal absorption of neutralized GeO(2) or germanate using male F344/N rats. Three groups of rats were treated with a 3-h topical application of hydrophilic ointment containing graded level of neutralized GeO(2) (pH 7.4): 0, 0.21 and 0.42 mg GeO(2)/g. Germanium concentration in blood and tissues sampled from rats after topical application of inorganic germanium was measured by inductively coupled plasma-mass spectrometry. Animals topically applied 0.42 mg GeO(2)/g ointment had significantly higher germanium concentrations in plasma, liver, and kidney than those of rats that received no topical germanium. The results indicate that skin is permeable to inorganic germanium ion or germanate and recurrent exposure of germanium compounds may pose a potential health hazard.

Association between zinc pool sizes and iron stores in premenopausal women without anaemia.

The simultaneous occurrence of Zn and Fe deficiencies in man has been known since the discovery of human Zn deficiency. However, it is not established that low Fe stores per se or Fe-deficiency anaemia infer low Zn status. Therefore our objective was to identify relationships between Zn and Fe status in premenopausal women without anaemia. We also examined the contribution of food frequencies and blood loss to Zn and Fe status. The subjects were thirty-three apparently healthy premenopausal women without anaemia, who were not taking dietary supplements containing Zn or Fe or oral contraceptives. Main outcomes were Zn kinetic parameters based on the three-compartment mammillary model and serum ferritin (SF) concentration; contributing factors were the frequency of consumption of specific foods and menorrhagia. Lower SF was significantly associated with smaller sizes of Zn pools. The breakpoint in the relationship between SF and the lesser peripheral Zn pool was found to be 21.0 microg SF/l. SF also correlated positively with frequency of beef consumption and negatively with bleeding through menstrual pads (BTMP). Similar to SF, the Zn pool sizes correlated positively with frequency of beef consumption, and negatively with BTMP. In summary, Zn pool sizes and Fe stores were highly correlated in premenopausal women. SF concentrations < 20 microg/l suggest an increased likelihood of low Zn status.

Effects of zinc and/or iron deficiency on rectal temperature in rats.

O'Dell et al. reported that rectal temperature was decreased by zinc deficiency in rats. However, it is not known whether a combined deficiency of zinc and iron affects rectal temperature. Forty 4-wk-old male Sprague-Dawley rats were assigned into four dietary treatment groups of 10 rats each for the 4-wk study: zinc-deficient group (4.5 mg Zn and 35 mg Fe/kg diet; -Zn), iron-deficient group (30 mg Zn/kg diet, no supplemental iron; -Fe), zinc/iron-deficient group (4.5 mg Zn/kg diet, no supplemental iron; -Zn-Fe), and control group (AIN-93G; Cont). At d 24-27, the rectal temperature was determined. The rectal temperature of the -Zn group was significantly lower than the Cont group. The rectal temperature of the -Zn-Fe group was similar to that of the Cont group, although thyroid-stimulating hormone and total thyroxin concentrations were the lowest in the -Zn-Fe group among all groups. The pattern of the plasma nitrate/nitrite concentrations across groups was similar to rectal temperature. Although observation of the rectal temperature is not conclusive, the balance between zinc and iron intake seems to determine the body temperature set point. These results suggest that the thermogenic effect of thyroid hormones is not thought to influence the paradoxical maintenance of rectal temperature in combined deficiency of zinc and iron.

Zinc deficiency decreases plasma erythropoietin concentration in rats.

In 1985, Paterson and Bettger found hypoplastic hematopoiesis in severely zinc-deficient rats. Therefore, we investigated plasma erythropoietin concentration in zinc-deficient rats. Forty 4-wk-old male Sprague- Dawley rats were assigned into 4 dietary treatment groups of 10 for the 4-wk study: zinc-deficient group (4.5 mg zinc and 35 mg iron/kg; -Zn), iron-deficient group (30 mg zinc/kg, no supplemental iron; -Fe), zinc/ iron-deficient group (4.5 mg zinc/kg, no supplemental iron; -Zn-Fe), and control group (AIN-93G; Cont). Water intake determined at d 19 was similar among all treatment groups. At d 27-28, bioimpedance was measured. The intracellular water/extracellular water ratio was significantly increased in the -Zn group (p < 0.05). Compared to the Cont, group, the plasma erythropoietin concentration was increased by iron deficiency and decreased by zinc deficiency (p < 0.01). Hematocrit was significantly decreased in both the -Fe and -Zn-Fe groups and was significantly increased in the -Zn group (p < 0.01). Transferrin saturation in the -Fe and -Zn-Fe groups was significantly lower than the Cont group (p < 0.01), and that of the -Zn group was highest among all groups. The low plasma erythropoietin concentration might account for depressed hematopoiesis associated with zinc deficiency.

Numerical methods for estimating iron requirements from population data.

The estimation of iron requirements is crucial for nutrition and food policy. The traditional methods for estimating iron requirements are balance methods based on iron intakes and excretions and factorial methods based on estimated iron absorption rates and estimated iron losses from body compartments. As an alternative, numerical methods for estimating iron requirements from population data of iron status were developed. The iron status data reported by Satoh (1991) were used in the sixth edition of Recommended Dietary Allowances for Japanese. The menstrual iron losses in Japanese premenopausal women were estimated from the literature to calculate total iron losses as the sum of basal iron losses and menstrual iron losses. The use of this alternative method is illustrated by analyzing the same population data comprising the prevalence of iron deficiency and the distribution of iron intake. The estimated average requirements were affected by the form of distribution function, the relative standard deviation of requirements, and the correlation coefficient between iron intakes and requirements. We conclude that numerical methods can be very useful for estimating iron requirements and to elucidate dietary recommendations of iron. These methods may contribute to determining requirements of other nutrients as well as iron.

Association between plasma zinc concentration and zinc kinetic parameters in premenopausal women.

The objective of this study was to measure relationships between plasma zinc (Zn) concentrations and Zn kinetic parameters and to measure relationships of Zn status with taste acuity, food frequency, and hair Zn in humans. The subjects were 33 premenopausal women not taking oral contraceptives and dietary supplements containing iron and Zn. Main outcomes were plasma Zn concentrations, Zn kinetic parameters based on the three-compartment mammillary model using 67Zn as a tracer, electrical taste detection thresholds, and food frequencies. Lower plasma Zn was significantly (P < 0.01) associated with smaller sizes of the central and the lesser peripheral Zn pools, faster disappearance of tracer from plasma, and higher transfer rate constants from the lesser peripheral pool to the central pool and from the central pool to the greater peripheral pool. The break points in the plasma Zn-Zn kinetics relationship were found between 9.94 and 11.5 micromol/l plasma Zn. Smaller size of the lesser peripheral pool was associated with lower frequency of beef consumption and higher frequency of bran breakfast cereal consumption. Hypozincemic women with plasma Zn <10.7 micromol/l or 700 ng/ml had decreased thresholds of electrical stimulation for gustatory nerves. Our results based on Zn kinetics support the conventional cutoff value of plasma Zn (10.7 micromol/l or 700 ng/ml) between normal and low Zn status.

Nickel deficiency diminishes sperm quantity and movement in rats.

Early studies on nickel essentiality with rats and goats indicated that nickel deprivation impaired reproductive performance. Nickel also has been found to influence cyclic nucleotide gated channels (CNG); these types of channels are important in sperm physiology. Thus, two experiments were conducted to test the hypothesis that nickel deficiency affects sperm physiology in a manner consistent with nickel having an essential function related to CNG channel functions. The experiments were factorially arranged with four treatment groups of eight weanling rats in each. In experiment 1, the treatments were supplemental dietary nickel of 0 and 1 mg/kg and N(omega)-nitro-L-arginine methyl ester (L-NAME, a nitric oxide synthase inhibitor) added to the drinking water (50 mg/100 mL) the last 3 wk of an 8-wk experiment. In experiment 2, the treatments were supplemental dietary nickel at 0 and 1 mg/kg and supplemental dietary sodium chloride (NaCl) at 0 and 80 g/kg. The NaCl and L-NAME variables were included to act as stressors affecting CNG channel activity. The basal diet contained per kilogram about 27 microg of nickel and 1 g of sodium. After 8 wk in experiment 1 and 16 wk in experiment 2, urine while fasting and testes and epididymis in both experiments, and seminal vesicles and prostates in experiment 2 were harvested for analysis. Nickel deprivation significantly decreased spermatozoa motility and density in the epididymides, epididymal transit time of spermatozoa, and testes sperm production rate. Nickel deficiency also significantly decreased the weights of the seminal vesicles and prostate glands. Excessive NaCl had no effect on sperm physiology; however, it decreased prostate gland weights. The findings support the hypothesis that nickel has an essential function that possibly could affect reproductive performance in higher animals, perhaps through affecting a CNG channel function.