Breast milk and energy intake in exclusively, predominantly, and partially breast-fed infants

OBJECTIVE: To investigate the extent to which breast milk is replaced by intake of other liquids or foods, and to estimate energy intake of infants defined as exclusively (EBF), predominantly (PBF) and partially breast-fed (PartBF). DESIGN: Cross-sectional. SETTING: Community-based study in urban Pelotas, Southern Brazil. SUBJECTS: A total of 70 infants aged 4 months recruited at birth. MAIN OUTCOME MEASURES: Breast milk intake measured using a "dose-to-the-mother" deuterium-oxide turnover method; feeding pattern and macronutrient intake assessed using a frequency questionnaire. RESULTS: Adjusted mean breast milk intakes were not different between EBF and PBF (EBF, 806 g/day vs PBF, 778 g/day, P=0.59). The difference between EBF and PartBF was significant (PartBF, 603 g/day, P=0.004). Mean intakes of water from supplements were 10 g/day (EBF), 134 g/day (PBF) and 395 g/day (PartBF). Compared to EBF these differences were significant (EBF vs PBF, P=0.005; EBF vs PartBF, P<0.001).The energy intake of infants receiving cow or formula milk (BF+CM/FM) in addition to breast milk tended to be 20% higher than the energy intake of EBF infants (EBF, 347 kJ/kg/day vs BF+CM/FM, 418 kJ/kg/day, P=0.11). CONCLUSIONS: There was no evidence that breast milk was replaced by water, tea or juice in PBF compared to EBF infants. The energy intake in BF+CM/FM infants tended to be 20% above the latest recommendations (1996) for breast-fed and 9% above those for formula-fed infants. If high intakes are maintained, this may result in obesity later in life. SPONSORSHIP: International Atomic Energy Agency through RC 10981/R1.     

Macro- and trace-mineral intakes of exclusively breast-fed infants

Intakes of calcium, phosphorus, magnesium, zinc, sodium, potassium, iron, and copper of 45 exclusively breast-fed infants were determined during the first 4 mo of life. Direct 24-h measurements of milk intake and mineral contents of human milk were used to estimate mineral intakes. Daily intakes of Ca, P, Zn, K, Na, Fe, and Cu decreased significantly over the study period while the intake of Mg increased. With the exception of Mg, mineral intakes on a weight basis displayed significant quadratic trends over the 4 mo. In spite of seemingly low-mineral intakes, growth progressed satisfactorily.     

Antioxidant content of the milk of Nigerian women and the sera of their exclusively breast-fed infants

The content of many nutrients in breast milk are dependent on the nutritional status of the lactating woman. This is particularly true for fat and water-soluble vitamins, some of which have antioxidant properties. We have previously reported that the total antioxidant content of the milk of women residing in different regions of the developing world varies significantly. In this report we describe the relationship between the antioxidant status of lactating women and their exclusively breast-fed infants from different ethnic groups in Nigeria and the antioxidant content of breast milk. The total antioxidant content of milk from 47 Nigerian women (32 Fulani, 8 Ibo, 3 Yoruba and 4 other ethnic groups) was determined using the Randox^® assay. Maternal and infant serum total antioxidant activity were also measured using the same assay. The milk of the Fulani women contained significantly lower antioxidant capacity than the milk from the other ethnic groups (1.1 mmol/L vs. 3.1 mmol/L, p = <0.001). The antioxidant content in the serum of the Fulani women and their exclusively breast-fed infants was also significantly lower that the other non-Fulani subjects. For the combined subjects there was a significant correlation between the maternal antioxidant status and the antioxidant content of breast milk (p < 0.001, r = 0.62) and between the infant antioxidant status and milk (p < 0.001, r = 0.77). The maternal and infant serum antioxidant levels were also significantly correlated (p < 0.001, r = 0.74). These data suggest that the antioxidant status of exclusively breast-fed infants is dependent on the antioxidant status of their mothers.     

Longitudinal study on the dietary selenium intake of exclusively breast-fed infants and their mothers in Finland

The dietary selenium intakes of a group of 13 lactating women living in the Helsinki metropolitan area and those of their 10 exclusively breast-fed infants were studied twice during the course of lactation. The first survey period of the women ranged from 6 to 8 weeks post-partum and the second from 17 to 22 weeks post-partum. The selenium intakes of the infants were determined at 1 and 3 months post-partum. In addition, the concentrations of selenium in the breast milk of four of the mothers were determined 6 months post-partum. Milk samples were collected by a method eliminating errors due to diurnal variations and variations during a single feeding. The validity of the analytical method employed was confirmed by means of an interlaboratory collaboration. The level of selenium concentration in the breast milk fell significantly (P less than 0.0005) from 10.7 +/- 1.6 micrograms/l at 1 month of lactation to 5.8 +/- 1.2 micrograms/l at 3 months of lactation, but remained at that level for up to 6 months of lactation (5.6 +/- 0.4 micrograms/l). The total dietary selenium intake of the infants fell significantly (P less than 0.0005) from 8.0 +/- 1.8 micrograms/d to 4.7 +/- 1.1 micrograms/d at 1 and 3 months post-partum, respectively. The mean maternal dietary selenium intake was 36 +/- 13 micrograms/d during the first survey period and 30 +/- 12 micrograms/d during the second survey period.(ABSTRACT TRUNCATED AT 250 WORDS)     

Evaluation of test-weighing for the assessment of milk volume intake of formula-fed infants and its application to breast-fed infants

Test-weighing (TW) was evaluated in formula-fed (FF) infants by comparison with direct measurement (DM) of formula intake during a 24 h period at 1, 2, 4 and 6 mo of age. Formula intakes estimated by TW ranged from 87 to 93% of those determined by DM over the 6-mo period. During the study period the number of feedings per day decreased but were not significantly different for FF and BF infants. Volume of intake per feeding by FF infants increased significantly during the 6-mo period whereas milk intakes of BF infants were not different at the four ages studied. These data indicated that when the number of daily feedings decreased with age, FF infants increased their volume of intake per feeding whereas BF infants did not adjust their intakes. Mean volume of milk intake at 4 and 6 mo, estimated by TW, was significantly greater in FF infants compared to breast-fed (BF) infants matched for age and size. Data from this study indicated clearly that when milk intakes of BF infants are compared to those of FF infants, both groups of infants should be test-weighed.     

Boron concentrations in milk from mothers of exclusively breast-fed healthy full-term infants are stable during the first four months of lactation

Because boron is a bioactive element that satisfies several of the criteria for essentiality in humans, the aim of the present work was to determine the profile of boron metabolism in human milk during the first 4 mo of lactation. The concentration of boron and other minerals was determined in archived milk collected (1980-84) 1 time/mo for 4 mo from lactating mothers of full-term, exclusively breast-fed infants living in Houston, TX. A linear model (treating month as a continuous variable) indicated that B concentrations were stable (P = 0.14) between mo 1 [3.88 +/- 0.6 mumol (42 +/- 6.5 microg)/L milk] and 4 [3.24 +/- 0.6 micromol (35 +/- 6.5 microg)/L milk, mean +/- SEM]. Mg concentrations increased slightly over time (1.18 +/- 0.09 to 1.36 +/- 0.09 mmol/L, P < 0.0001), whereas Ca concentrations decreased slightly (7.01 +/- 0.29 to 6.68 +/- 0.29 mmol/L milk, P < 0.02) and Zn decreased substantially (0.04 +/- 0.004 to 0.02 +/- 0.004 mmol/L milk, P < 0.0001). Similarities in findings reported here and earlier (from samples collected in St. John's, Newfoundland) provide further evidence that boron may be metabolically regulated. Future investigations of boron regulatory mechanisms should focus on metabolism of bone as the major storage site of B and kidney excretion, the major excretory route for B.     

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.     

Selenium status of exclusively breast-fed infants as influenced by maternal organic or inorganic selenium supplementation

A longitudinal dietary Se supplementation study on lactating mothers was performed to determine the possibilities of improving the Se status of exclusively breast-fed infants. A total of 200 mothers randomized into three groups received either no Se supplements, 100 micrograms of selenite, or 100 micrograms of yeast-Se daily. Maternal and infant serum Se concentrations showed a linear correlation during exclusive breast-feeding. Yeast-Se in the dose administered was safe and more effective than selenite in increasing the Se concentrations of maternal serum and milk, and infant serum. The mean estimated daily Se intakes of the infants were 7.7 +/- 2.2, 8.9 +/- 2.2, and 11.5 +/- 4 micrograms, in the control, selenite, and yeast-Se groups respectively. Though the infant Se intakes of the unsupplemented and selenite-supplemented mothers were below the lower limit of the safe and adequate range as set by the US National Research Council, their serum Se concentrations increased steadily over the 6-mo study period. As maternal serum Se also increased by over 50% during the same period the results suggest that a maternal daily intake of 50-75 micrograms is adequate during lactation.     

Complementary feeding with cow's milk alters sleeping metabolic rate in breast-fed infants

Although it is widely accepted that energy expenditure in infants is a function of feeding pattern, the mechanism behind this is not well understood. The objectives of this observational study were as follows: 1) to compare minimal observable energy expenditure (MOEE) between 2 subgroups of breast-fed infants, a BM group in which breast milk was the only source of milk and a BCM group given cow's milk in addition to breast milk; and 2) to identify potential mediators of a feeding pattern effect. For this purpose, infants were classified by feeding group on the basis of a mother's recall. Respiration calorimetry was used to measure MOEE in 62 infants (n = 35 BM, n = 27 BCM) aged 8.7 mo in Pelotas, southern Brazil. Breast-milk intake was measured using deuterium oxide, complementary food intake by 1-d food weighing, total energy expenditure and total body water using doubly labeled water; anthropometric indices were calculated. MOEE was 1672 +/- 175 kJ/d in BM compared with 1858 +/- 210 kJ/d in BCM infants (P < 0.001). Mass-specific MOEE was 201 +/- 24.6 and 216 +/- 31.9 kJ/(kg . d) in BM and BCM infants, respectively (P = 0.041). MOEE (kJ/d) was mediated by protein intake and fat-free mass (R(2) = 41.4%). We conclude that complementary feeding with cow's milk alters the sleeping metabolic rate in breast-fed infants. These findings deserve attention in relation to "metabolic programming" and the development of obesity later in life.     

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.     

Effects of different levels of vitamin C intake on the vitamin C concentration in human milk and the vitamin C intakes of breast-fed infants

The influence of maternal intake of vitamin C on the vitamin C concentration in human milk and on the vitamin C intakes of breast-fed infants has not been demonstrated conclusively. This study examined these influences of diet and supplementation in 25 lactating women administered 90 mg of ascorbic acid for 1 day followed by 250, 500 or 1000 mg/day for 2 days or unsupplemented for 1 day followed by either 0 or 90 mg ascorbic acid supplement for 2 days. Vitamin C content in milk and urine was determined by the 2,4-dinitrophenylhydrazine method. Vitamin C intakes of infants were calculated from milk volume, as determined by the test-weighing method and from vitamin C levels in milk samples obtained at each feeding. Total maternal intakes of vitamin C, which exceeded 1000 mg/day or 10-fold the RDA for lactation (100 mg/day), did not significantly influence the vitamin C content in milk or the vitamin C intakes of infants. However, maternal vitamin C intake was positively correlated (r = 0.7) with maternal urinary excretion. These differences in milk and urine response to vitamin C intake suggest a regulatory mechanism for vitamin C levels in milk.     

2H2O turnover method as a means to detect bias in estimations of intake of nonbreast milk liquids in breast-fed infants

OBJECTIVE: Firstly, to compare food, and macronutrient intake as obtained from a single 24-h recall and a frequency questionnaire (FQ) covering a 14-day period in breast-fed infants aged 4 months of age. Secondly, nonbreast milk water intake (NB-WI, ml/day) was used as an estimation of energy and macronutrient intake, and NB-WI as calculated from FQ (NB-WIFQ) was compared with NB-WI as measured using the dose-to-the-mother 2H2O turnover method (NB-WIDO) covering the same 14-day period. DESIGN: Cross-sectional. SETTING: Community-based study in urban Pelotas, Southern Brazil. SUBJECTS: In all, 67 breast-fed infants aged 4 months of age recruited at birth. MAIN OUTCOME MEASURES: (1) Bias in estimations of food and macronutrient intake of the 24-h recall relative to FQ; (2) Bias in NB-WIFQ relative to NB-WIDO. RESULTS: In infants with an energy intakeFQ from complementary foods above the 50th percentile (1.03 kcal/day), estimations of water, tea, juice, and milk intake were not different between 24-h recall and FQ (n=34). Nor were estimations of energy and macronutrient intake (protein, fat, and carbohydrates) different between the two methods, and bias was nonsignificant. NB-WIDO was divided into quintiles and compared with NB-WI(FQ). The first two quintiles included negative values for NB-WIDO as a result of random errors of the 2H2O turnover method. Subsequently, bias of NB-WIFQ relative to NB-WIDO was positive in the 1st (P=0.001) and 2nd quintile (P=0.638), respectively. Bias was negative for the three highest quintiles, and within this group, underestimation by FQ was significant for the 3rd and 4th quintile (-57.4%, P=0.019; -43.7%, P=0.019). CONCLUSIONS: Firstly, at the age of 4 months FQ covering a 14-day period provides similar results on food and macronutrient intake as compared to a single 24-h recall for estimations of complementary liquid foods. Secondly, NB-WIFQ appeared to be a good proxy for macronutrient and energy intake in breast-fed infants receiving other liquids. In infants with NB-WIDO>0, the method provides a useful tool for the detection of bias from FQ, and results indicate an underestimation from FQ relative to the 2H2O turnover method. This exercise could be applied wherever the 2H2O turnover method is used in combination with conventional food consumption techniques for measuring intake of nonbreast milk liquids of breast-fed infants in whom solid foods have not yet been introduced. It would help interpreting estimations of macronutrient intake, and could be relevant to studies of dietary intake of infants and its relationship with growth and health.     

Energy requirements of breast-fed infants

Current recommendations for energy intake are reviewed in light of emerging data on energy intakes of breast-fed infants and on total daily energy expenditure of infants. For determination of energy requirements, the historical approach based on observed intakes of healthy infants is compared with a newly proposed approach based on energy expenditure and deposition. A data set of exclusively breast-fed infants is used to illustrate the circuity of either approach. Energy intake, expenditure, and stores must be evaluated in an assessment of dietary adequacy. Ultimately, energy requirements of infants should reflect growth rate, body composition, and level of physical activity conducive to optimal health and neurobehavioral development.     

Bacteriostasis of Escherichia coli by milk. I. Colonization of breast-fed infants by milk resistant organisms.

Human milk has a bacteriostatic effect on Escherichia coli in vitro. The milks of 40 mothers were tested for this effect against E. coli isolated from their stools, from those of their own babies, and from those of babies not breast-fed. The milks had a direct bacteriostatic effect, not dependent on complement, on some but not all the strains of E. coli. Breast-fed babies receiving supplementary bottle feeds were colonized with milk-resistant strains, whereas bottle-fed babies and, surprisingly, babies completely breast-fed were colonized equally with milk-sensitive and milk-resistant strains, as were the mothers. These results suggest that the bacteriostatic effect of human milk, demonstrable in vitro does sometimes operate in vivo. The antibacterial activity of human milk is not infleunced by the O, H, or K antigens of E. coli and is effective against other Gram-negative organisms, e.g. Salmonella, Klebsiella, Proteus.     

Nutritional rickets in breast-fed infants

A ten-year literature review was prompted by the fortuitous discovery of nutritional rickets in a "well child." Sixty-three cases were identified, suggesting that this disease is not so rare as thought. Rickets should be considered in the differential diagnosis of nonspecific musculoskeletal complaints and poor growth. Vitamin D supplementation in breast-fed children should be prescribed more often.     

Human milk intake and growth faltering of rural Mesoamerindian infants.

To determine whether growth faltering during early infancy was attributable to inadequate intake of human milk, the nutrient intakes and growth of 30 Otomi infants from Capulhuac, Mexico, were studied at 4 or 6 mo of age. Growth was monitored monthly from 1 through 6 mo of age. The 2H dose-to-the-mother method was used to measure human milk intake. Energy, protein, lactose, and fat concentrations in milk were analyzed by standard techniques. Mean (+/- SD) human milk intakes were 885 +/- 145 and 869 +/- 150 g/d at 4 and 6 mo, respectively. Protein and lactose concentrations in milk were normal but fat and consequently energy concentrations were abnormally low. Energy intakes averaged 81 +/- 14 kcal.kg-1.d-1 at 4 mo and 72 +/- 14 kcal.kg-1.d-1 at 6 mo. Growth faltering by 6 mo was evidenced by the significant decline in growth velocities and National Center for Health Statistics Z scores. Weight gain at 6 mo was 8.1 +/- 3.5 g/d and length gain was 1.0 +/- 0.34 cm/mo. Weight-for-age and length-for-age Z scores were -0.81 +/- 0.94 and -1.51 +/- 0.83, respectively. Growth velocities were not significantly correlated with nutrient intakes. Growth faltering among the Otomi infants despite energy intakes comparable to those of breast-fed infants in more protected environments may have resulted from an increase in the need for nutrients or from a growth-limiting nutrient, other than energy, in their diet.