Longitudinal manganese and copper balances in young infants and preterm infants fed on breast-milk and adapted cow's milk formulas

1. Mn and Cu intake and retention in twenty full-term infants and six preterm infants were studied on the basis of 72 h balances. The age of the infants was 2-16 weeks and the gestational age of the preterm infants (triplets) 34 and 36 weeks. Three nutrition schemes were pursued: breast-fed, formula-fed with unsupplemented adapted formula and formula-fed with trace element supplementation. 2. The mean Mn concentration of all breast-milk samples (n 2339) was 6.2 micrograms/l. The two formulas had similar Mn concentrations (77 and 99 micrograms/l) but had different Fe, Cu (121 and 619 micrograms/l), Zn and I contents. The mean Cu concentration in mother's milk was 833 micrograms/l. 3. The following mean daily Mn intakes and retentions (micrograms/kg) respectively were measured: breast-fed full-term 1.06 (SD 0.43) and 0.43 (SD 0.65), formula-fed full-term 14.2 (SD 3.1) and 2.8 (SD 4.8), formula-fed preterm 15.0 (SD 2.2) and 0.06 (SD 5.87). The results for Cu were 114.5 (SD 22.3) and 88.0 (SD 46.5) micrograms/kg in breast-fed, 19.8 (SD 4.2) and 4.6 (-11.5-9.6) in the unsupplemented formula-fed and 106.4 (SD 18.9) and 55.5 (SD 20.3) in the supplemented formula full-term infant group. No significant influence of the trace element contents of the formulas on the relative retention of Mn or Cu was found. 4. Young preterm infants, and to some degree young full-term infants, often had negative Mn balances caused by a high faecal excretion. The formulas with a Mn concentration below 100 micrograms/l gave a sufficient supply of Mn. Preterm infants fed on the unsupplemented formula had a marginal Cu supply and their first balances were negative (-3.8 (SD 1.8) micrograms/kg). 5. In accordance with the estimated safe and adequate daily dietary intakes (recommended dietary allowances), formula-fed infants receive much more Mn than breast-fed infants and their absolute retention is higher. 6. Cu from breast-milk had a significantly better biological availability than that from cow's milk formula. If retentions similar to those in breast-fed infants are intended, we conclude, therefore, that cow's milk formula should be fortified with Cu up to a level of at least 600 micrograms/l.     

Long-chain polyunsaturated fatty acids in breast milk and early weight gain in breast-fed infants

The long-chain PUFA (LCPUFA) content of an infant's diet might affect early weight gain. In early trials on supplementation of formula feeding n-3 LCPUFA affected weight gain adversely. n-6 LCPUFA are thought to promote adipose tissue development and might be associated with higher weight gain. We studied the association between the natural n-3 and n-6 LCPUFA content of breast milk of Dutch women and weight and BMI gain of their breast-fed infants in the first year of life. The children in this study were enrolled in the Prevention and Incidence of Asthma and Mite Allergy (PIAMA) birth cohort study and were born in 1996-1997 in The Netherlands. Parents reported their child's weight and length in a questionnaire. Of a subgroup of the total population breast-milk samples were collected (n 244). The fatty acid composition of breast milk was determined by GLC and expressed as weight percentages. Linear regression was used for data analysis. Mean gain in weight, length and BMI per week from birth to 1 year of age was 119.5 (SD 16.1) g, 0.48 (SD 0.05) cm and 0.06 (SD 0.03) kg/m2, respectively. The associations between n-6 and n-3 LCPUFA in breast milk, and infant weight, length and BMI gain were weak and inconsistent. The n-3 and n-6 LCPUFA content in breast milk did not affect weight or BMI gain in the first year of life in breast-fed term infants.     

Smoking during pregnancy and lactation and its effects on breast-milk volume

The influence of cigarette smoking on daily breast-milk volume was measured by the dose-to-mother deuterium-dilution method in 10 smoking and 10 nonsmoking mothers. After administration of deuterium to the mother, breast milk and infant saliva were sampled over 14 d and analyzed by mass spectrometry. Nonsmoking mothers had a significantly greater breast-milk volume than did smokers [961 +/- 120 vs 693 +/- 110 g/d, mean +/- SD; t = 5.21, P less than 0.0001). Growth rates of the infants were also measured. Weight increase of infants of non-smoking mothers was 550 +/- 130 g whereas of infants of smoking mothers it was only 340 +/- 170 g (t = 3.11, P less than 0.01). These results indicate that cigarette smoking has a negative influence on breast-milk volume whereas the lower infant-growth rates of the smoking mothers suggest also that their breast-milk output was insufficient to support the energy requirements of their infants.     

Growth and milk intake of exclusively breast-fed Myanmar infants

Twenty-nine exclusively breast-fed infants from moderate and low socio-economic groups were followed-up from birth to 6 months of age. Breast milk intake and body weight of the infants were measured at monthly intervals and morbidity recorded. It is interesting to note that although the mean birth weight of 2.76 kg was only 85 per cent of the NCHS reference standard, catch-up growth occurred whereby the exclusively breast-fed infants attained 94 per cent and 101 per cent of the reference standard at 1 and 2 months of age respectively. At 3 months of age, the mean weight of the infants was 99 per cent of the reference standard and then the growth curve began to falter between 4 and 5 months of age, from 97 per cent at 4 months to 93 per cent of the reference standard at 5 months, the mean weight increment (kg/month) between 4 and 5 months being (less than -1 SD) of the reference value. On the other hand, milk intake of these infants increased from 453 g/d at 1 month to 621 g/d at 4 months reaching a value of 655 g/d at 5 months. It was also observed that the morbidity pattern did not seem to differ, especially at 3-4 months and 4-5 months. The faltering of growth between 4 and 5 months of age was probably due to the fact that the increase in breast milk intake was not sufficient to meet the increase in nutritional requirements needed for the growth of these infants after the age of 4 months.     

Energy supplementation in the last trimester of pregnancy in East Java, Indonesia: effect on breast-milk output

Breast-milk output was measured in women who during the last trimester of pregnancy consumed a high- or low-energy supplement (53 and 55 women, respectively). Infant and mother pairs were enrolled at 2 or 6 wk postpartum. Test weighings were done four times at 8-wk intervals. Mean breast-milk output ranged from 682 to 744 g/d in the age period of 2 wk to 7 mo. There was no difference in milk output between the two experimental groups. In all cohorts, breast-feeding frequency influenced milk output positively. Only at age 18-22 wk did the mothers' prepregnancy or 4-wk postpartum body mass index play an additional role. The results confirm that breast-milk output of mildly undernourished women is comparable with that of well-nourished women. Short-term energy supplementation during pregnancy did not increase breast-milk output, probably because the sample studied was not at nutritional risk.     

Duration of exclusive breast-feeding: introduction of complementary feeding may be necessary before 6 months of age

The WHO recommends exclusive breast-feeding for the first 6 months of life. At present, <2 % of mothers who breast-feed in the UK do so exclusively for 6 months. We propose the testable hypothesis that this is because many mothers do not provide sufficient breast milk to feed a 6-month-old baby adequately. We review recent evidence on energy requirements during infancy, and energy transfer from mother to baby, and consider the adequacy of exclusive breast-feeding to age 6 months for mothers and babies in the developed world. Evidence from our recent systematic review suggests that mean metabolisable energy intake in exclusively breast-fed infants at 6 months is 2.2-2.4 MJ/d (525-574 kcal/d), and mean energy requirement approximately 2.6-2.7 MJ/d (632-649 kcal/d), leading to a gap between the energy provided by milk and energy needs by 6 months for many babies. Our hypothesis is consistent with other evidence, and with evolutionary considerations, and we briefly review this other evidence. The hypothesis would be testable in a longitudinal study of infant energy balance using stable-isotope techniques, which are both practical and valid.     

Selenium and breast-feeding

The objective of the present review is to discuss Se nutrition during breast-feeding, encompassing environmental and maternal constitutional factors affecting breast-milk-Se metabolism and secretion. A literature search of Medline and Webofscience was used to retrieve and select papers dealing with Se and breast milk. Although Se in natural foods occurs only in organic form, breast milk responds to organic and inorganic Se in supplements. Inorganic Se (selenite, selenate), which is largely used in maternal supplements, is not detectable in breast milk. The mammary-gland regulating mechanism controls the synthesis and secretion of seleno-compounds throughout lactation, with a high total Se level in colostrum that decreases as lactation progresses. Se appears in breast milk as a component of specific seleno-proteins and seleno-amino-acids in milk proteins that are well tolerated by breast-fed infants even in high amounts. Se in breast milk occurs as glutathione peroxidase (4-32 % total Se) > selenocystamine > selenocystine > selenomethionine. The wide range of breast-milk Se concentrations depends on Se consumed in natural foods, which reflects the Se content of the soils where they are grown. Se prophylaxis, either through soil Se fertilization or maternal supplements, is effective in raising breast-milk Se concentration. In spite of wide variation, the median Se concentration from studies worldwide are 26, 18, 15, and 17 microg/l in colostrum (0-5 d), transitional milk (6-21 d), mature milk (1-3 months) and late lactation (>5 months) respectively. Se recommendations for infants are presently not achieved in 30 % of the reported breast-milk Se concentrations; nevertheless Se status is greater in breast-fed than in formula-fed infants.     

Infant intake of fatty acids from human milk over the first year of lactation

Despite the importance of human milk fatty acids for infant growth and development, there are few reports describing infant intakes of individual fatty acids. We have measured volume, fat content and fatty acid composition of milk from each breast at each feed over a 24 h period to determine the mean daily amounts of each fatty acid delivered to the infant from breast milk at 1, 2, 4, 6, 9 and 12 months of lactation in five women. Daily (24 h) milk production was 336.60 (SEM 26.21) and 414.49 (SEM 28.39) ml and milk fat content was 36.06 (SEM 1.37) and 34.97 (SEM 1.50) g/l for left and right breasts respectively over the course of the first year of lactation. Fatty acid composition varied over the course of the day (mean CV 14.3 (SD 7.7) %), but did not follow a circadian rhythm. The proportions (g/100 g total fatty acids) of fatty acids differed significantly between mothers (P<0.05) and over the first year of lactation (P<0.05). However, amounts (g) of most fatty acids delivered to the infant over 24 h did not differ during the first year of lactation and only the amounts of 18:3n-3, 22:5n-3 and 22:6n-3 delivered differed between mothers (P<0.05). Mean amounts of 18:2n-6, 18:3n-3, 20:4n-6 and 22:6n-3 delivered to the infant per 24 h over the first year of lactation were 2.380 (SD 0.980), 0.194 (SD 0.074), 0.093 (SD 0.031) and 0.049 (SD 0.021) g respectively. These results suggest that variation in proportions of fatty acids may not translate to variation in the amount delivered and that milk production and fat content need to be considered.     

Human-milk intake measured by administration of deuterium oxide to the mother: a comparison with the test-weighing technique

A comparison was made between the dose-to-the-mother deuterium-dilution method and the conventional test-weighing technique for determining human-milk intake in five exclusively breast-fed infants and in four breast-fed infants who received supplemental foods. After administration of 2H to the mothers human milk and infant urine were sampled over 14 d and analyzed for 2H:1H ratios by gas-isotope-ratio mass spectrometry. Infant total body water was determined by 18O dilution. The test-weighing procedure was conducted for 5 d consecutively. The intake of human milk (mean +/- SD) estimated by 2H dilution was 648 +/- 63 g/d and estimated by test-weighing was 636 +/- 84 g/d. The mean difference between the two methods was not significantly different from 0. The 2H-dilution and test-weighing techniques provide similar estimates of human-milk intake.     

Breast-milk vitamin A as an indicator of the vitamin A status of women and infants.

This article reviews the evidence for using breast-milk vitamin A as an indicator of vitamin A status and provides technical information for researchers who want to use this indicator to assess the vitamin A status of women and breast-fed children. Breast-milk vitamin A is a unique indicator for assessing the vitamin A status of lactating women and their breast-fed infants, and has recently been recommended by WHO for use in monitoring global elimination of vitamin A deficiency. Assessing breast-milk vitamin A is less invasive than alternative approaches for assessing a mother''s vitamin A status and not at all invasive for her infant. Collection of milk samples in the field is generally feasible and acceptable. Breast-milk vitamin A appears to be an especially good indicator for measuring the impact of vitamin A interventions on women and infants, and for this purpose, it is more responsive than other indicators.     

Association of infant feeding practices in the general population with infant growth and stool characteristics

This was a prospective cohort study of 976 infants from birth to 12 months of age. Infants were fed breast milk, goat infant formula, cow infant formula, or a combination of formula and breast milk during the first 4 months of age. Data on type of milk feeding and infant growth (weight and height) were collected at birth and at 4, 8, and 12 months during routine clinical assessment. The number and consistency of bowel motions per day were recorded based on observational data supplied by the mothers. Infants fed breast milk or goat or cow infant formula during the first 4 months displayed similar growth outcomes. More of the infants fed cow infant formula had fewer and more well-formed bowel motions compared with breast-fed infants. The stool characteristics of infants fed goat formula resembled those of infants fed breast milk.     

Breast milk and lipid intake distributions for assessing cumulative exposure and risk

Breast milk consumption is the primary route of infant exposure to certain lipophilic toxicants that have accumulated over decades in maternal adipose tissue, as well as to less persistent toxicants from maternal exposure during lactation. Such infant exposures occur at a time of rapid growth and development when susceptibility to certain toxicants can be greatest. Breast milk and lipid intake rates are presented for the 0-6 and 0-12 month age periods for infants fed according to the American Academy of Pediatrics' current recommendations (exclusive breast-feeding for 0-6 months and continued breast-feeding to 12 months). Intake rates are normalized to infant bodyweight to account for the covariance of consumption and bodyweight. Frequency distributions describe the population variability in intake. For age 0-12 months, daily average milk intake is 100.7 +/- 22.7 g/kg day (mean +/- SD), with a 95th percentile of 153.5 g/kg day. Breast milk intake distributions are also developed for infants exclusively breast-fed (no significant calories from non-breast milk sources) over their first year, and for the entire (nursing and non-nursing) infant population. For short-term exposures, intake can be derived from the regression equation presented here. Lipid intake estimated assuming a 4% lipid content (current risk assessment practice) is compared and found comparable to that derived from measured lipid content. The national trend of increased breast-feeding found in surveys further supports including the breast milk pathway in risk assessment.     

Sources of variance in milk and caloric intakes in breast-fed infants: implications for lactation study design and interpretation

Between-individual variation (BIV) and day-to-day variation (DDV) of total caloric and human milk intakes were examined in 17 infants. Nine were studied at months 5 and 6; 8 at months 6 and 7. All 17 were exclusively breast-fed for 5 full mo after which solid foods were added to the diet. Each infant was studied for five consecutive 24-h periods during which serial measurements were made of milk intake (test weighing) and solid food intake (pre- and postfeeding jar weighing). Total daily caloric intakes (kcal/day) were (mean +/- SD) 492 +/- 57, 547 +/- 70, and 567 +/- 98 at months 5, 6, and 7, respectively. Estimates of caloric intakes (kcal/kg/day) adjusted for body weight were 65.9 +/- 6.7, 72.6 +/- 11.2, and 70.9 +/- 13.0 at months 5, 6, and 7, respectively. Milk intakes (g/day) were 735 +/- 85, 640 +/- 106, and 562 +/- 214 at months 5, 6, and 7, respectively. BIV of milk intake increased after the introduction of solid foods. DDV (expressed as coefficient of variation) of caloric intake was nearly constant at each monthly observation and BIV increased from 8.8 at month 5 to 14.6 at month 7. The numbers of 24-h periods and subjects required for estimates of known precision of caloric and milk intakes of older breast-fed infants can be determined from these estimates of variance.     

Studies in human lactation: milk volumes in lactating women during the onset of lactation and full lactation

After validation of test-weighing procedures milk volumes produced by 13 multiparous Caucasian women were followed longitudinally through the first year of lactation. All practiced exclusive breast-feeding for at least 5 mo. Milk transfer to the infant was low on days 1 and 2 and increased rapidly to 498 +/- 129 g/d (means +/- SD) on day 5 and then more slowly to 753 +/- 89 g/d during months 3-5. There was a characteristic milk volume for each mother-infant pair that was significantly related neither to milk yield on days 4-6 nor to birth weight. It was, however, strongly related to infant weight at 1 mo, suggesting that infant and/or maternal factors coming into play during the first month of life are strong determinants of subsequent milk transfer to the infant.     

Early infant feeding practices in Jinan City,Shandong Province,China

To investigate early infant feeding practices in Jinan, China, a cross-sectional study was carried out in April-May 2000. Data were collected through structured interviews among nearly all the mother-infant pairs (247) in four communities in the city with infants under seven months of age. All but one was born in a hospital and rooming-in (infant sleeping in same room as mother) was widely practiced. Breastfeeding was practiced universally, but first contact with the new-born was delayed one or more hours for 51% of subjects. Colostrum was given to 94% of the infants, yet during the first three days, all but 34% were given water, artificial baby milk, glucose or other prelacteal feeds. Among infants under 4 months of age, 35% were currently exclusively breastfeeding, but at two months only 40% were, and only half that many had received nothing but breast-milk since birth. Exclusive breastfeeding has probably increased in China, but further promotion is still needed in this area.     

Session 4: Mineral metabolism and body composition iron status of breast-fed infants

Fe deficiency is a common nutritional disorder during infancy, particularly in low-income countries. The Fe status of a breast-fed infant is strongly influenced by the body Fe content at birth, which is determined by factors that operate before birth (maternal Fe status before and during pregnancy; infant gestational age and birth weight) and at the time of delivery (the timing of umbilical cord clamping). Delaying the clamping of the umbilical cord for 2 min can increase body Fe content by approximately 33% (75 mg), and results in greater Fe stores at 6 months of age. After birth, male gender and a rapid rate of weight gain are associated with lower Fe status. During the first half of infancy dietary Fe requirements depend on Fe stores at birth. For an exclusively-breast-fed full-term normal-birth-weight infant with delayed umbilical cord clamping, whose mother had adequate Fe status during pregnancy, the Fe provided from stores and breast milk is sufficient for >/=6 months, but before this time higher-risk infants may become Fe deficient. Fe supplementation can be beneficial for high-risk infants, but can have adverse effects on growth and morbidity of Fe-replete infants. After 6 months most breast-fed infants will require complementary foods that are rich in Fe.     

0～6月龄纯母乳喂养儿每日母乳摄入量评估

母乳能为婴儿提供出生后最初6个月所需的能量和绝大多数营养素。健康、纯母乳喂养儿的平均每日母乳摄入量是制定婴儿营养素适宜摄入量的重要依据。称重法和氘标水法是估计婴儿母乳摄入量的主要方法。本文检索了近30年母亲健康的0～6月龄健康、纯母乳喂养儿的平均母乳(成熟乳)摄入量,估算为日均776.6±141.5 g,即749.6ml/d;取整数为780 g/d或750 ml/d。因此,在估计我国0～6月龄婴儿营养素适宜摄入量时,推荐采用婴儿母乳摄入量780 g/d(或750 ml/d)。[营养学报,2013,35(2):134-136,141]     

Growth pattern of exclusively breast-fed infants during the first six months of life in Ile-Ife,Osun State,Nigeria

Several studies to determine the growth pattern of exclusively breast fed infants have provided varying conclusions as to the sufficiency of breast milk alone to support adequate growth for the first six months of life. Disagreement exists concerning the optimal timing of introduction of complementary foods to exclusively breast fed infants. This prospective study thus examined the adequacy of breast milk alone to support normal growth during the first six months of life in our environment. The overall objective was to propose a scientifically sound national recommendation on the appropriate timing for the introduction of complementary feeding in Nigeria. Three hundred and fifty-two mother/infant pairs were serially recruited into the study; all babies were aged 14 days or less and weighed 2.5 kg and above. Three hundred and forty-five (98%) were successfully followed up till the infants were six months old. By six months, 264 (76.5%) were exclusively breast-fed, while 81 (23.5%) had commenced complementary feeding. Growth curves of exclusively breast-fed infants showed increasing weight from birth to six months. Although the 50th percentile birth weight for both boys and girls were the same (3.2 kg), boys gained weight faster than the girls from the age of one month to six months and were heavier at six months. Additionally, the 50th percentile curves of these infants (both genders) for the first six months were above the 50th percentile curve of the World Health Organisation and National Centre for Health Statistics (WHO/NCHS) reference currently used on our national "road to health" (growth monitoring) cards. It was concluded that exclusive breast-feeding supported adequate growth during the first six months of life for most of the children studied and that our national recommendation that infants be introduced to complementary feeding at six months is appropriate.     

Trans fatty acids in human milk in Canada declined with the introduction of trans fat food labeling

Trans fatty acids in human milk have raised concerns because of possible adverse effects on infant growth and development. Analyses of human milk in the late 1990s in Canada showed high amounts of trans fatty acids from partially hydrogenated oils. Canada introduced labeling of trans fatty acids on retail foods in 2003. We analyzed trans and cis unsaturated and saturated fatty acids in human milk collected from 87 women in 2004-2006 and compared the levels to those in milk collected from 103 women in 1998 and analyzed using similar methods. The total trans fatty acids (mean +/- SEM, g/100 g fatty acids) in human milk in Canada decreased significantly, from 7.1 +/- 0.32 in 1998 to 6.2 +/- 0.48, 5.3 +/- 0.49, and 4.6 +/- 0.32 over 3 consecutive 5-mo periods from November 2004 to January 2006. The milk total trans fatty acids were significantly and inversely related to 16:0, 18:2(n-6), 18:3(n-3), 20:4(n-6), 22:4(n-6), and 22:5(n-6) and positively related to 18:0 and conjugated linolenic acids (P < 0.05, n = 190). The estimated exposures of exclusively breast-fed infants to trans fatty acids decreased from a mean and 95th percentile intake of 2.0 and 4.4 g x infant(-1) x d(-1) in 1998 to 1.33 and 2.41 g x infant(-1) x d(-1), respectively, in late 2005. The estimated intake of the mothers was 4.0 (range 0.51-12.3) and 2.2 (0.56-7.65) g x person(-1) x d(-1) in 1998 and late 2005, respectively. Our studies show trans fatty acids have decreased in human milk in Canada, which suggests a concomitant decrease in trans fatty acid intake among lactating women and breast-fed infants.