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Community and International Nutrition

Milk Folate Secretion Is Not Impaired during Iron Deficiency in Humans¹

² Department of Nutritional Sciences, the Hospital for Sick Children and the University of Toronto, Toronto, Ontario, Canada; ³ Nutrition Department, Pennsylvania State University, University Park, PA 16802; ⁴ Instituto Nacional de Salud Publica, Cuernavaca, Mexico; and ⁵ Office of Dietary Supplements, National Institutes of Health, Bethesda, MD 20892–7517

^* To whom correspondence should be addressed. E-mail: deborah_l.o'connor{at}sickkids.ca.

	ABSTRACT

TOP ABSTRACT Introduction Subjects and Methods Results Discussion LITERATURE CITED

 
The purpose of this study was to examine whether maternal iron and/or folate status influences human milk folate secretion and is responsible for growth faltering of Otomi infants in Capulhuac, Mexico. Breast-feeding mothers (n = 71) were randomized at 22 ± 13 d (baseline) postpartum to receive a daily multivitamin supplement containing folic acid (400 µg) with and without iron (18 mg). Mothers provided blood and milk samples at baseline, and at 82 ± 15 and 138 ± 18 d postpartum. Iron supplementation significantly improved hematocrit and transferrin receptor concentrations but had no influence on maternal folate status or milk folate or iron concentrations. Forty-three percent of mothers (29/68) had low blood folate concentrations at baseline, whereas only 6% (4/66) had low blood folate concentrations at 138 d postpartum. Milk folate concentrations did not differ between Fe-deficient and Fe-sufficient women and provided adequate levels of dietary folate by 82 d postpartum. While milk iron concentrations were unrelated to maternal iron status, they decreased during lactation, and, by 138 d, they provided only 55% of the current recommendation. In conclusion, milk folate concentrations appear to be well preserved during maternal iron deficiency; hence, faltering growth among infants in Capulhuac, Mexico is unlikely the result of reduced milk folate concentration secondary to maternal Fe deficiency. However, milk Fe concentrations showed a temporal decline. Whether the disjuncture between recommended and actual Fe intakes among infants born with low Fe reserves and weaned to foods low in bioavailable Fe has functional consequences is worthy of further investigation.

	Introduction

TOP ABSTRACT Introduction Subjects and Methods Results Discussion LITERATURE CITED

In Capulhuac, Mexico, concern over growth faltering among Otomi Indian infants has led investigators to examine possible nutritional causes (10,11). Inadequate milk supply or inadequate nutrient composition of milk was proposed as a cause because growth faltering occurs before any report of gastrointestinal or respiratory infection and before the introduction of solids. Previous investigations regarding the nutritional intake of Otomi infants indicated that milk and macronutrient (carbohydrate, protein, and fat) intakes are greater or equal to those observed in more economically privileged human milk-fed infants (12). Therefore, the micronutrient content of human milk was postulated as the cause of faltering growth. The present randomized double-blinded placebo-controlled trial was designed to assess whether Fe and/or folate status of mothers and the accompanying composition of their milk might be responsible for growth faltering in this community. The intervention consisted of a daily maternal multivitamin (MV) supplement with folic acid (400 µg) with or without Fe (18 mg). We will report on maternal indices of Fe and/or folate status and milk folate and Fe composition. A description of the general growth characteristics of infants in this community is extensively described elsewhere (10,11).

Previously, we reported on baseline (mean of 22 ± 13 d postpartum) Fe and folate status of the 71 lactating women who participated in this intervention trial (13). Sixty-two percent of mothers (42/68) had nutritional anemia (hemoglobin <133 g/L), 36% (24/67) had Fe deficiency anemia, and 43% (29/68) had either a low plasma or erythrocyte folate concentration. Milk Fe concentration was unrelated to maternal Fe status and provided an amount of Fe to infants consistent with the recommended intake. Milk folate concentration, however, was low providing 70% of the recommended intake, a level that may not support the maintenance of adequate folate status in all breast-fed infants (13).

	Subjects and Methods

TOP ABSTRACT Introduction Subjects and Methods Results Discussion LITERATURE CITED

 
    Subjects. The study was conducted in San Mateo Capulhuac, Mexico, a rural farming community inhabited by indigenous Indians (2800 m above sea level). As described in detail elsewhere, Otomi women subsist on a diet low in Fe bioavailability (12,13). Intake of animal sources of protein is limited, and the calculated dietary intake of phytic acid is high because of the consumption of corn (65% of energy intake) and other phytate-containing vegetables. While dark green leafy vegetables and legumes are often consumed, they are boiled for a prolonged time, thus reducing their folate content.

Following childbirth, Otomi women were approached in the local medical clinic for participation in the study. Inclusion criteria included: 1) 17 to 37 y of age, 2) free of chronic diseases, 3) free of pregnancy complications, 4) currently taking no medication, 5) not consuming alcoholic beverages, 6) gave birth to a full-term infant of appropriate length and weight, 7) planned to exclusively breast-feed, and 8) willing to comply with the experimental protocol. Informed consent was obtained from each subject. Approval for the use of subjects in this investigation was obtained from Institutional Review Boards at the Instituto Mexicano del Seguro Social (IMSS), Mexico City and The Pennsylvania State University, State College, PA.

    Intervention. During the first clinic visit after childbirth (22 ± 13 d postpartum), participants were randomized to receive 1 of 2 treatments: 1) a multivitamin supplement containing 400 µg folic acid and 18 mg of elemental Fe, or 2) a multivitamin supplement containing 400 µg folic acid without Fe. Other vitamins in the preparations (Stresstabs, Lederle Consumer Health) included: -tocopherol (30 mg), vitamin C (500 mg), thiamin (10 mg), riboflavin (10 mg), niacinamide (100 mg), vitamin B-6 (5 mg), vitamin B-12 (12 µg), biotin (45 µg), and pantothenic acid (20 mg). These supplements were chosen because they contained 400 µg of folic acid and were available with and without Fe. Women were randomized using shuffled cards marked with coded numbers by clinic physicians. Supplements were provided daily for 6 mo. Clinic physicians monitored the distribution of the supplements. Study subjects, clinic physicians, field workers, and researchers responsible for collecting or measuring any outcome variables were unaware of the treatment group that each woman was assigned or the difference in supplement composition.

    Measurements. During well-baby clinic visits, anthropometric measurements of mothers were made using standardized procedures at 1, 2–3, and 5 mo postpartum (14). Weights were determined using electronic scales with a precision of ± 50 g (Tanita W8; Tanita). Heights (± 1 mm) were determined using a clinical stadiometer (Holtain).

Maternal dietary intakes of energy, protein, fat, carbohydrate, Fe, folate, and vitamin B-12 were estimated using 3-day records. Community workers, trained by a nutritionist, recorded in-home dietary intakes for 2 consecutive days for each participant. Dietary intake was assessed for 1 weekend day by an interactive 24-h dietary recall method, using standard serving-size information previously collected in the home. Nutrient intakes were then tabulated using Mexican food composition tables (15).

Blood samples were taken from women, following an overnight fast, and were collected into tubes containing EDTA or trace-element–free tubes without an anticoagulant (Vacutainer, Becton-Dickinson). A portion (100 µL) of whole blood was diluted in 10 v of 0.1 mol/L potassium phosphate buffer containing 0.05 mol sodium ascorbate. Milk was collected by complete expression of 1 breast at least 2 h after the previous feeding using an electric breast pump (Egnel). For folate analyses, 0.05 mol/L sodium ascorbate was dissolved into milk and plasma samples. Milk and blood samples were then frozen at –70° C. For Fe analyses, milk, serum, and plasma samples were immediately frozen at –20° C.

    Biochemical and milk analyses. A complete blood count analysis (hemoglobin, hematocrit, and MCV) was performed using fresh blood samples and an electronic particle counter analyzer (ACT8 Coulter Counter, Beckman Coulter). Accuracy of hemoglobin determinations was ± 2 g/L, with an interassay CV of 3%. Immunoprecipitation was used to determine C-reactive protein with an interassay CV of 4.9% at a level of 2 mg/L (SANOFI, Pasteur Diagnostic). Erythrocyte and plasma folates were determined by microbiological assay using cryoprotected Lactobacillus rhamnosus (ATCC 7469, American Type Tissue Culture Collection) as the test organism (16). The interassay CV was 5.4% for plasma folate and 12.3% for erythrocyte folate.

Serum Fe and total Fe binding capacity were determined by the colorimetric method of Fielding (1980), modified for determination in microliter sample volumes (17). Accuracy and reproducibility were verified using fetal bovine serum with a certified value [32 ± 2 µmol/L (176 ± 10 µg/dL) Lot 7000C, Atlanta Biologicals]. Analysis in our laboratory yielded a serum Fe concentration of 30 ± 0.7 µmol/L.

Milk folate samples were processed with a tri-enzyme extraction procedure before the microbiological assay as described in detail by Lim et al. (18). The accuracy and reproducibility of these assays were assessed using infant formula with a certified value (1.29 ± 0.28 mg folic acid/kg) (Standard reference material 1846, National Institute of Standards and Technology). Analysis in our laboratory yielded a folate concentration of 1.33 ± 0.05 mg folate/kg. Plasma ferritin was determined by radio-immunoassay (Diagnostic Products) and verified by a human recombinant ferritin standard (19 ± 1.5 µg/L). Results from our laboratory yielded 20 ± 1.1 µg/L with an interassay CV of 3.6%. Enzyme immunoassay was used to determine the concentration of serum transferrin receptor (RAMCO Laboratories) using both high and low quality control serum samples. The interassay CV was 4.6% at a concentration of 13.5µg/L.

For milk Fe measurement, quartz vials containing thawed milk were dried to a constant weight. Samples were ashed for 12 h in a muffle furnace at 500° C before being cooled in a dessicator. Ash was then dissolved in a 2 mol/L HNO₃ solution containing 2% thioglycolic acid for Fe reduction. An aliquot of 50 µg was placed in a 96-well plate and 100 µL of chromogen (as for serum Fe analysis) was added. Standard reference material 1846 infant formula (certified value of 11.4 ± 0.7 mmol/kg) was used to assess the accuracy and precision of the milk Fe assay. Analysis in our laboratory yielded a Fe concentration of 10.7 ± 0.5 mmol/kg.

    Statistical analysis. Data are presented as means ± SD or medians for continuous variables and as proportions for categorical data. Univariate analyses were conducted using t tests for continuous variables and chi-square tests for categorical variables. Multivariate analyses were performed using mixed linear models for repeated measures analysis, i.e., ANOVA for continuous response variables (PROC MIXED) and logistic regression for binary response variables (PROC GENMOD). Where possible, outcome variables that were not normally distributed were transformed. Multivariate analyses were adjusted for treatment group, days postpartum (because attendance at clinic visits varied by mothers), and baseline differences between treatment groups (plasma folate concentrations). All models tested for the interaction between treatment group and days postpartum, and all analyses were repeated excluding females with an elevated C-reactive protein concentration (>11 mg/L) at any of the time points (n = 11). A 2-sided P-value of 0.05 indicated statistical significance. Statistical analyses were conducted using SAS (version 9.1; SAS Institute).

	Results

TOP ABSTRACT Introduction Subjects and Methods Results Discussion LITERATURE CITED

 
    Subjects. Of 71 Otomi participants, 68 women provided sufficient data at all 3 time points for an intention-to-treat analysis of primary outcomes (34 women in each treatment group) (Fig. 1). Women visited the medical clinic at 22 ± 13, 82 ± 15, and 138 ± 18 d postpartum. As described in detail elsewhere (13), the mean BMI, weight, and height of women at the first postnatal clinic visit was 24.5 ± 3.0 (range: 19.4–34.9), 53 ± 8.0 kg (range: 38–77 kg), and 1.5 ± 0.1 m (range: 1.3–1.7 m), respectively. All but 9 subjects were stunted (height <152.7 cm); however, none were wasted (BMI <17.8 kg/m²) (19). The mean parity was 3, and 17 (24%) of the women were primiparous. Nearly 90% of women had <3 y of education.

View larger version (18K): [in this window] [in a new window]   Figure 1  Flowchart of study subject enrollment and inclusion.

    Dietary assessment. Energy and nutrient intakes from food did not vary between treatment groups (Table 1). Energy intake was the only measure that changed over time; showing an increase with the number of days postpartum (P = 0.01). The mean BMI of women did not change over time. The unadjusted mean BMI of women at the first, second, and third clinic visits were 24.5 ± 3.0, 24.4 ± 3.1, and 24.2 ± 3.1, respectively.

    Biochemical indices of Fe and folate status. Among biochemical and milk measures, there was an interaction between treatment group and days postpartum for hematocrit (P = 0.01) and transferrin receptor (P = 0.02) concentrations (Table 2). Unadjusted mean hematocrit values (1) in the MV + folic acid + Fe group were 0.39 ± 0.05, 0.42 ± 0.04, and 0.44 ± 0.03 at the first, second, and third clinic visits, respectively. In the MV + folic acid group, unadjusted mean hematocrit values (1) were 0.41 ± 0.04, 0.41 ± 0.04 and 0.43 ± 0.04, respectively (Table 2). Unadjusted mean transferrin receptor concentrations (mg/L) for the 3 postnatal clinic visits were 8.6 ± 5.4, 7.8 ± 3.2, and 7.3 ± 2.4, respectively for the MV + folic acid + Fe group and 8.6 ± 7.8, 10.1 ± 5.5 and 10.2 ± 6.3, respectively for the MV + folic acid group.

    Fe and folate status. The proportion of women with Fe and/or folate deficiency did not vary significantly by treatment group or by days postpartum when determined by multivariate analysis adjusting for baseline plasma folate concentrations. There was, however, a reduction in the indices of Fe and folate deficiency by days postpartum in both treatment groups (Fig. 2). Of the 18% (12/67) of women with Fe deficiency and low blood folate at baseline, there were only 2/65 (3%) and 1/64 (2%) remaining at the second and third clinic visits, respectively. Findings were similar when women with an elevated C-reactive protein concentration at any time during follow-up (n = 11) were excluded from analyses.

View larger version (11K): [in this window] [in a new window]   Figure 2  Prevalence of iron deficiency anemia (panel A) and folate deficiency (panel B) in lactating Otomi women receiving either a multivitamin (MV) containing folic acid and iron or a MV containing folic acid without iron. Numbers above the bars represent the number of women classified as deficient (numerator) over the total number of subjects in the treatment group (denominator). Women were classified as iron-deficient anemic if they were positive for 2 indexes of iron deficiency (i.e., plasma ferritin 12µg/L, transferrin saturation 16%, MCV 80 fL with hemoglobin 133 g/L). Subjects were classified as folate deficient if they had plasma folate concentrations 10 nmol/L or an erythrocyte folate concentration 360 nmol/L. Statistical analyses were performed using repeated measures for mixed modeling and adjusted for treatment group, baseline plasma folate concentration, and length of follow-up. Treatment groups did not differ in the proportion of mothers that were deficient using mixed model analysis, adjusting for days postpartum, and baseline plasma folate concentration.

	Discussion

TOP ABSTRACT Introduction Subjects and Methods Results Discussion LITERATURE CITED

The data presented here for lactating women contrasts markedly from that of animal studies in which milk from Fe-deficient rats and pigs contained up to 50% less folate than milk from Fe-sufficient animals (6–9). In animal models, the magnitude of reduction in milk folate concentration was sufficient to impair the folate status and growth in nursing offspring. There are a number of possible explanations as to why earlier observations in rats were not reproduced in humans. First, the relative metabolic cost of lactation in relation to whole body metabolism in animal models, particularly rodent models, exceeds that of the humans; hence, there is a greater likelihood of seeing nutrient interactions in animal models (20,22,27). Second, influential environmental factors, including dietary factors, can be rigorously controlled in animal studies. Uncontrolled environmental factors in human studies conducted in the field, and the resultant variability introduced, frequently makes it difficult to detect differences previously observed under controlled laboratory conditions. For example, in our previously reported animal studies, maternal diets contained adequate and identical quantities of all nutrients, excluding Fe. In the present study, women consumed variable amounts and frequently less than the recommended amounts of energy and protein, both of which could impact on maternal folate metabolism.

Regardless of maternal Fe status, or whether they received a Fe-containing supplement, milk folate concentrations increased with time (P < 0.0001). Whether this increase reflects improved maternal folate status as a result of consuming a folic acid-containing MV or the physiological increase previously reported for well-nourished women (28), cannot be assessed with our study design. Judging from the improvement in blood folate values, it appears certain that 400µg/d of supplemental folic acid is sufficient for treating and preventing maternal folate deficiency during lactation.

At the 22 ± 13 d clinic visit, the median milk folate concentration was 53% of the 192 nmol/L reported for well-nourished women and used to calculate the adequate intake level of folate for infants, aged 0–6 mo, in the Dietary Reference Intakes (18,22,29,30). Assuming a mean milk intake of 0.85 L/d for Otomi infants, aged 0–5 mo, the median folate intake of infants in this community would be 45 µg/d or 70% of the adequate intake level (13). In contrast, by 82 ± 15 d and 138 ± 18 d of age, the median folate intake of infants would be 105 and 98% of the adequate intake level, reflecting the increase in milk folate concentration with the duration of breast-feeding. So, whereas early in lactation, some infants may be ingesting only a marginal folate intake for maintenance of tissue folate concentrations, as lactation progressed, milk folate concentrations were likely sufficient to meet the dietary folate requirements of most infants.

The high prevalence of maternal Fe deficiency postpartum in the present study, despite dietary Fe intakes that exceeded the RDA (9 mg/d), likely reflect the low bioavailability of Fe in the diets consumed and the net maternal Fe deficit accrued during pregnancy (RDA = 27 mg/d) (21). While supplementation with a low dose, Fe-containing MV (18 mg/d), during early lactation, was more effective than a MV without Fe in improving hematocrit and tranferrin receptor concentrations, Fe supplementation did not improve other indices of Fe status (e.g., hemoglobin and plasma ferritin). At 82 and 138 days postpartum, 32% (21/65) and 23% (15/66) of lactating women, respectively, remained Fe-deficient. Furthermore, supplementation with 18 mg/d of Fe did not result in a significant reduction in the proportion of women who were classified as Fe-deficient at each postpartum clinic visit. Together, these data suggest the following: dietary intakes of Fe alone, in Capulhuac, Mexico, are insufficient for reversing maternal Fe deficiency during early lactation; 18 mg of supplemental Fe is more effective than diet alone in resolving maternal Fe deficiency postpartum; and a higher dose of Fe may be warranted if the objective is to expeditiously resolve maternal Fe deficiency.

The elevated Fe requirement and high incidence of Fe deficiency anemia during pregnancy, particularly in the third trimester, is well-characterized (13,21,31–37). The consequences of poor maternal Fe status postpartum is increasingly being recognized as a nonbenign condition, and is shown to be related to maternal fatigue, depression, and ability to care and nurture offspring (38–42).

Consistent with previous literature, milk Fe composition was unaffected by maternal Fe intake or status in the present study (43,44), and milk Fe concentrations significantly declined as lactation progressed. Based on the median milk Fe concentration reported herein, we estimate that human milk would provide 0.37 mg/d of highly available Fe to an infant consuming 0.85 L of human milk/d at 22 d postpartum. However, by 138 d postpartum, this same volume of milk would provide only 0.15 mg/d of Fe to infants in this community, which is 55% of the adequate intake level (21). Contrary to the previously held belief that infants are parasites with respect to sequestering Fe from their mother in utero, the current thinking is that mild to moderate maternal Fe deficiency can contribute to lower Fe reserves at birth (42,45–50). If this is indeed the case, Otomi infants born to Fe-deficient mothers may be disproportionately vulnerable to low milk Fe concentrations. Indeed, Meinzen-Deer et al. (51) recently reported that infants from Mexico City that were exclusively breast-fed for >6 mo were at increased risk of anemia if their mother had a history of anemia.

In conclusion, results from the present study indicate that milk folate concentrations are well preserved during maternal Fe deficiency and that the growth faltering among Otomi infants is not likely due to reduced milk folate concentration as a result of the high prevalence of maternal Fe deficiency in Capulhuac, Mexico. Given the increase in milk folate concentration with the duration of lactation, most infants should meet their dietary requirement for this nutrient by the twelfth week of life. In contrast, milk Fe concentrations decreased during follow-up, whereby, at 138 d postpartum, infants were consuming, on average, 55% of the recommended adequate intake level for Fe. Whether the disjuncture between recommended and actual Fe intakes in this community, where infants may be born with low Fe reserves and are weaned to foods low in bioavailable Fe, has a functional consequence is worthy of further investigation.

	ACKNOWLEDGMENTS

 
We thank Christina Goia of the Clinical Research Support Unit at the Hospital for Sick Children for statistical support and advice.

	FOOTNOTES

 
¹ Financial support was provided by the Consejo Nacional de Ciencia y Tecnologia of Mexico, the Natural Sciences and Research Council of Canada, and The Pennsylvania State University.

Manuscript received 7 March 2006. Initial review completed 1 May 2006. Revision accepted 30 June 2006.

	LITERATURE CITED

TOP ABSTRACT Introduction Subjects and Methods Results Discussion LITERATURE CITED

 

1. World Health Organization. ACC/SCN fourth report on the world nutrition situation. Geneva: WHO, 2000.

2. Herbig AK, Stover PJ. Regulation of folate metabolism by iron. In: Massaro EJ, Rogers JM, editors. Folate and human development. New Jersey: Humana Press; 2002. P. 241–62.

3. O'Connor DL. Interaction of iron and folate during reproduction. Prog Food Nutr Sci. 1991;15:231–54.[Medline]

4. Chanarin I, Rothman D, Berry V. Iron deficiency and its relation to folic acid status in pregnancy: results of a clinical trial. BMJ. 1965;5433:480–5.

5. Chanarin I, Rothman D. Further observations on the relation between iron and folate status in pregnancy. BMJ. 1971;2:81–4.[Medline]

6. O'Connor DL, Picciano MF, Sherman AR. Milk folate secretion and folate status of suckling pups during iron deficiency. Nutr Res. 1989;9:301–18.

7. O'Connor DL, Picciano MF, Sherman AR, Burgert SL. Depressed folate incorporation into milk secondary to iron deficiency in the rat. J Nutr. 1987;117:1715–20.[Abstract/Free Full Text]

8. O'Connor DL, Picciano MF, Tamura T, Shane B. Impaired milk folate secretion is not corrected by supplemental folate during iron deficiency in rats. J Nutr. 1990;120:499–506.[Abstract/Free Full Text]

9. O'Connor DL, Picciano MF, Roos MA, Easter RA. Iron and folate utilization in reproducing swine and their progeny. J Nutr. 1989;119:1984–91.[Abstract/Free Full Text]

10. Hernandez-Beltran M, Butte N, Villalpando S, Flores-Huerta S, Smith EO. Early growth faltering of rural Mesoamerindian breast-fed infants. Ann Hum Biol. 1996;23:223–35.[Medline]

11. Butte NF, Villalpando S, Wong WW, Flores-Huerta S, Hernandez-Beltran MJ, Smith EO, Garza C. Human milk intake and growth faltering of rural Mesoamerindian infants. Am J Clin Nutr. 1992;55:1109–16.[Abstract/Free Full Text]

12. Villalpando S, Butte NF, Wong WW, Flores-Huerta S, Hernandez-Beltran MJ, Smith EO, Garza C. Lactation performance of rural Mesoamerindians. Eur J Clin Nutr. 1992;46:337–48.[Medline]

13. Villalpando S, Latulippe ME, Rosas G, Irurita J, Picciano MF, O'Connor DL. Milk folate but not milk iron concentrations may be inadequate for some infants in a rural farming community in San Mateo, Capulhuac, Mexico. Am J Clin Nutr. 2003;78:782–9.[Abstract/Free Full Text]

14. Gibson RS. Principles of nutritional assessment. 2nd edition. New York: Oxford University Press; 2005.

15. Hernandez M, Bourges H. Valor nutritivo de los alimentos Mexicanos. Tables de uso pratico. (Nutritional values of foods. Tables for practical use.) Mexico City: National Institute of Nutrition, 1977.

16. Tamura T. Microbiological assay of folate. In: Picciano MF, Gregory J, Stokstad REL, editors. Folic acid metabolism in health and disease. New York: Wiley-Liss and Sons; 1990. P. 121–37.

17. Fielding J. Serum and iron binding capacity. In: Cook J, editor. Iron. New York: Churchill Livingstone; 1980.

18. Lim H, Mackey A, Tamura T, Wong S, Picciano MF. Measurable folates in human milk are increased by treatment with alpha-amylase and protease in addition to folate conjugase. Food Chem. 1998;63:401–7.

19. Kuczmarski RJ, Ogden CL, Grummer-Strawn LM, Flegal KM, Guo SS, Wei R, Mei Z, Curtin LR, Roche AF, Johnson CL. CDC growth charts: United States. Adv Data. 2000;(Jun 8) 314:1–27.[Medline]

20. National Research Council, Food and Nutrition Board. Dietary reference intakes for energy, carbohydrate, fiber, fat, fatty acids, cholesterol, protein, and amino acids (macronutrients). Washington, DC: National Academy Press; 2005.

21. National Research Council, Food and Nutrition Board. Dietary reference intakes for vitamin A, vitamin K, arsenic, boron, chromium, copper, iodine, iron, manganese, molybdenum, nickel, silicon, vanadium and zinc. Washington, DC: National Academy Press, 2005.

22. National Research Council, Food and Nutrition Board.Dietary reference intakes for thiamin, riboflavin, niacin, vitamim B6, folate, vitamin B12, pantothenic acid, biotin, and choline. Washington, DC: National Academy Press; 2005.

23. Cook JD, Skikne BS. Iron deficiency: definition and diagnosis. J Intern Med. 1989;226:349–55.[Medline]

24. Latulippe ME, Rosas MG, Villalpando S, Picciano MF. Utility of TfR and TfR-ferritin index for assessment of iron deficiency is not complicated by folate deficiency in lactating women. FASEB J. 2000;14:A508.

25. Brouwer DA, Welten HT, Reijngoud DJ, van Doormaal JJ, Muskiet FA. Plasma folic acid cutoff value, derived from its relationship with homocysteine. Clin Chem. 1998;44:1545–50.[Abstract/Free Full Text]

26. O'Connor DL, Latulippe ME, Campos C, Merlos C, Villalpando S, Picciano MF. Folate deficiency does not alter the usefulness of the serum transferrin receptor concentration as an index for the detection of iron deficiency in Mexican women during early lactation. J Nutr. 2005;135:144–9.[Abstract/Free Full Text]

27. National Research Council. Nutrient requirements of laboratory animals. 4th revised edition. Washington, DC: National Academy Press; 1995.

28. O'Connor DL, Green T, Picciano MF. Maternal folate status and lactation. J Mammary Gland Biol Neoplasia. 1997;2:279–89.[Medline]

29. Brown CM, Smith AM, Picciano MF. Forms of human milk folacin and variation patterns. J Pediatr Gastroenterol Nutr. 1986;5:278–82.[Medline]

30. O'Connor DL, Tamura T, Picciano MF. Pteroylpolyglutamates in human milk. Am J Clin Nutr. 1991;53:930–4.[Abstract/Free Full Text]

31. Beard JL, Dawson H, Pinero DJ. Iron metabolism: a comprehensive review. Nutr Rev. 1996;54:295–317.[Medline]

32. Akesson A, Bjellerup P, Berglund M, Bremme K, Vahter M. Soluble transferrin receptor: longitudinal assessment from pregnancy to postlactation. Obstet Gynecol. 2002;99:260–6.[Abstract/Free Full Text]

33. Picciano MF. Pregnancy and lactation: physiological adjustments, nutritional requirements and the role of dietary supplements. J Nutr. 2003;133:1997S–2002S.[Abstract/Free Full Text]

34. Ettyang GA, van Marken Lichtenbelt WD, Oloo A, Saris WH. Serum retinol, iron status and body composition of lactating women in Nandi, Kenya. Ann Nutr Metab. 2003;47:276–83.[Medline]

35. Haidar J, Muroki NM, Omwega AM, Ayana G. Malnutrition and iron deficiency in lactating women in urban slum communities from Addis Ababa, Ethiopia. East Afr Med J. 2003;80:191–4.[Medline]

36. Dijkhuizen MA, Wieringa FT, West CE, Muherdiyantiningsih, Muhilal. Concurrent micronutrient deficiencies in lactating mothers and their infants in Indonesia. Am J Clin Nutr. 2001;73:786–91.[Abstract/Free Full Text]

37. Takimoto H, Yoshiike N, Katagiri A, Ishida H, Abe S. Nutritional status of pregnant and lactating women in Japan: a comparison with non-pregnant/non-lactating controls in the National Nutrition Survey. J Obstet Gynaecol Res. 2003;29:96–103.[Medline]

38. Corwin EJ, Murray-Kolb L, Beard JL. Low hemoglobin level is a risk factor for postpartum depression. J Nutr. 2003;133:4139–42.[Abstract/Free Full Text]

39. Ross SD, Fahrbach K, Frame D, Scheye R, Connelly JE, Glaspy J. The effect of anemia treatment on selected health related quality life domains: a systematic review. Clin Ther. 2003;25:1786–805.[Medline]

40. Flechtner H, Bottomley A. Fatigue and quality of life: lessons from the real world. Oncologist. 2003;8: Suppl 1:5–9.[Abstract/Free Full Text]

41. Beard JL, Hendricks MK, Perez EM, Murray-Kolb LE, Berg A, Vernon-Feagans L, Irlam J, Isaacs W, Sive A, Tomlinson M. Maternal iron deficiency anemia affects postpartum emotions and cognition. J Nutr. 2005;135:267–72.[Abstract/Free Full Text]

42. Perez EM, Hendricks MK, Beard JL, Murray-Kolb LE, Berg A, Tomlinson M, Irlam J, Isaacs W, Njengele T, et al. Mother-infant interactions and infant development are altered by maternal iron deficiency anemia. J Nutr. 2005;135:850–5.[Abstract/Free Full Text]

43. Gaspar MJ, Oretga RM, Moreiras O. Relationship between iron status in pregnant women and their newborn babies. Investigation in a Spanish population. Acta Obstet Gynecol Scand. 1993;72:534–7.[Medline]

44. Vuori E, Makinen SM, Kara R, Kuitunen P. The effects of the dietary intakes of copper, iron manganese, and zinc on the trace element content of human milk. Am J Clin Nutr. 1980;33:227–31.[Abstract/Free Full Text]

45. Allen LH. Multiple micronutrients in pregnancy and lactation: an overview. Am J Clin Nutr. 2005;81: suppl:1206S–12S.[Abstract/Free Full Text]

46. Bhargava M, Iyer PU, Kumar R, Ramji S, Kapani V, Barghava SK. Relationship of maternal serum ferritin with foetal serum ferritin, birth weight and gestation. J Trop Pediatr. 1991;37:149–52.[Medline]

47. Choi JW, Kim CS, Pai SH. Erythropoietic activity and soluble transferrin receptor level in neonates and maternal blood. Acta Paediatr. 2000;89:675–9.[Medline]

48. Singla PN, Gupta VJ, Agarwal KN. Storage iron in human foetal organs. Acta Paediatr Scand. 1985;74:701–6.[Medline]

49. Singla PN, Tyagi M, Hankar R, Dash D, Kumar A. Fetal iron status in maternal anaemia. Acta Paediatr. 1996;85:1327–30.[Medline]

50. Gaspar MJ, Ortega RM, Moreiras O. Relationship between iron status in pregnant women and their new-born infants. Acta Obstet Gynecol Scand. 1993;72:534–7.[Medline]

51. Meinzen-Derr JK, Guerrero ML, Altaye M, Ortega-Gallegos H, Ruiz-Palacios GM, Morrow AL. Risk of infant anemia is associated with exclusive breast-feeding and maternal anemia in a Mexican cohort. J Nutr. 2006;136:452–8.[Abstract/Free Full Text]

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