How much breast milk do babies need?

Long-term adequacy of exclusive breast-feeding: how scientific research has led to revised opinions

The present paper reviews the research of the authors and their colleagues over the past 20 years to provide improved nutritional and anthropometric guidelines for the assessment of lactational adequacy and for when the weaning process might be initiated. The nutritional guidelines are based on revised dietary energy requirements. The basic assumption is that since breast milk is a well-balanced food, if energy needs are satisfied so will those for essential nutrients. Energy requirements for young babies have been derived from the application of the doubly-labelled-water technique. This approach indicated that 460 kJ (110 kcal)/kg per d at 1 month and 397 and 355 kJ (95 and 85 kcal)/kg per d at 3 and 6 months respectively would be satisfactory for a nutrient content of high bioavailability. Translated into a breast-milk intake of 850 ml/d the latter would cover the dietary energy needs of the average child growing along the 50th centile until at least 4 months, but the typical child from many developing countries following the 25th centile until 6 months. The importance of revised growth reference values for infancy, equally crucial for assessing lactational adequacy, is also reviewed. In contrast with the shapes of earlier reference patterns, growth trajectories are different when babies are fed in accordance with modern paediatric advice. Mothers and health professionals using the older growth charts to assess the progress of a baby can be misled into assuming that the weaning process needs to be introduced sooner than necessary. Examples of this situation within the context of a developing country are provided.

Daily dietary intake of copper, zinc, and selenium of exclusively breast-fed infants of middle-class women in Burundi, Africa

Copper (Cu), zinc (Zn), and selenium (Se) in human milk of middle-class Burundian women during the first 10 mo of lactation have been determined. Wet acid digestion, using nitric and perchloric acids, and atomic absorption spectrometric analysis have been used. Daily intakes have been calculated and proven to decrease from 0.39 +/- 0.05 (colostrum) to 0.16 +/- 0.02 (mature milk), 2.3 +/- 0.3 (colostrum), to 1.2 +/- 0.2 mg (mature milk) and 10.9 +/- 1.5 (colostrum) to 5.3 +/- 0.8 micrograms (mature milk) for Cu, Zn, and Se, respectively. Since values for this African country are nonexistent, intake levels are compared with literature data and found to be somewhat higher than those observed in other poorly nourished countries. The recommended safe and adequate daily intake for infants of 0-6 mo of age, as proposed by the National Research Council of the USA, is only met for Burundian infants < 1 mo of age. The function of copper (Cu) and zinc (Zn) as essential trace elements has been known for quite a number of years (1). Also, selenium (Se) is a trace element essential for the activity of glutathione peroxidase (2) and type I iodothyronine 5-deiodinase (3). For all three elements, an adequate intake is necessary for satisfactory infant growth and development (4). In view of the almost total lack of relevant data on Burundi (Africa), we have determined Cu, Zn, and Se in human milk of middle-class Burundian women during the first 10 mo of lactation (5). The aim of this study is to assess infants' elemental intake for this country and compare this with literature data on trace elemental intake of exclusively breast-fed infants.

Water supplementation in exclusively breastfed infants during summer in the tropics

This study was designed to determine the need for water supplementation to maintain water homoeostasis in exclusively breastfed infants during summer in a tropical country. A prestudy questionnaire revealed that 97% of 34 nurses and 63% of 70 doctors advocated such supplementation. 45 healthy, male, exclusively breastfed babies, aged 1-4 months, were recruited from a well-baby clinic. 9 who had never received supplemental water plus a random selection of 14 others were allocated to group I (breastmilk only); the remaining 22 infants were allocated to group II (breastmilk plus supplemental fluid according to the mother's usual practice). The babies were studied at the hospital for 8 h; breastmilk intake was measured by weighing the infant before and after each feed, water intake by calibrated bottles, and urine output by accurate collection and measurement. The maximum room temperatures were 34-41 degrees C and relative humidities 9-60% (below 50% in all but 3 infants). In group II the mean water intake was 11% (95% confidence interval 7-16%) of the total fluid intake. Both breastmilk intake (274 vs 210 ml) and total fluid intake (274 vs 233 ml) were higher in group I than in group II (p = 0.003, p = 0.073, respectively), after adjustment for age, weight, length, room temperature, and humidity. However, there were no significant differences between the groups in urine output, urine or serum osmolality, weight change, or rectal temperature whether or not the factors adjusted for included total fluid intake. Thus, exclusively breastfed infants do not need supplemental water to maintain water homoeostasis; a reduced breastmilk intake is a potential disadvantage of this practice.

Decrease in serum IgE associated with limited restriction in energy intake to treat toddler's diarrhea

Toddler's diarrhea may be an allergic disease and its recurrences can be avoided with education to "internal spontaneity" in feeding, i.e., by education to a limited and reproducible decrease in eating incentives at the onset of meals. Serum IgE was thus investigated in 16 experimental children in a random comparison with 16 controls, all aged 1 to 4 years, before and after seven months' dietary treatment. Compliance was measured with a seven-day written diary, while serum IgE was measured by PRIST, before and after dietary treatment. A 21% decrease in energy intake (p less than 0.05) and about five times increase in fruit and nonstarchy vegetable intake amount was seen in treated children. A decrease in serum IgE level of 13.9 +/- 43.5 U/ml was found in the "internal spontaneity" group, as opposed to an increase of 33.2 +/- 50.5 U/ml in the control one (p less than 0.01). The differences between examinations were significantly correlated to the increase in NSV acceptance in all children plotted together (r = .51, p less than 0.005). The overall NSV effect on the changes of the 2 muscle areas, 2 symptoms, and 2 percent growth, 15 nutritional, 5 immune and 3 hepatic indices was significant with MANOVA (p less than 0.01). The education to "internal spontaneity" may be a useful tool for prevention of overeating, diarrhea recurrences and IgE increase in the second/third year of life.

Daily chromium intake by infants in Belgium

The chromium content of human breast milk, infant formulae, cow's milk and beikost was measured by graphite furnace atomic absorption spectrometry following different digestion steps. No significant variation in chromium concentration during lactation was found. The mean concentration was 0.18 ng/ml. The daily chromium intake for Belgian infants of 3 months of age using different types of food was estimated. Exclusively breast fed infants consumed 0.1 microgram/day, while for infants fed cow's milk the intake was five times higher. The exclusive use of commercial infant formulas resulted in an intake of 2 up to 10 micrograms chromium a day.

Diminution in energy expenditure during lactation

Energy expenditure at rest and in response to a meal and to an infusion of noradrenaline was measured in 12 lactating women and compared with that in seven bottle feeding women and seven non-pregnant, non-lactating controls. The energy response of the lactating women was remeasured after lactation stopped. During lactation the resting metabolic rate was unaltered but there was a reduced response to infusion of noradrenaline and to a meal, which increased to normal control values after lactation stopped. Such reductions in expenditure were not found in women who had been bottle feeding and were tested at a similar six to eight weeks post partum. These findings suggest that metabolic efficiency is enhanced in lactating women, who may not need to increase energy intake to the extent suggested by current recommended dietary allowances.

Dietary selenium intake in Belgium for different population groups at risk for deficiency

An estimation of the dietary selenium intake in different population groups in Belgium has been carried out. 24 h duplicate meals and food consumption statistics combined with concentration levels in different foods, as determined by hydride generation atomic absorption spectrometry, are used. Dietary intake of selenium is low to very low, especially for vegetarians (12.7 +/- 9.1 micrograms) and patients on long-term total parenteral nutrition (1.2 +/- 0.8 microgram). The different intakes are discussed and compared with intakes published for other countries, while the importance of bioavailability of the selenium in food in the risk of deficiency is stressed.

Weaning practices in the United Kingdom and variations in anthropometric development

The influence of different weaning practices on the dietary energy intake and growth of Cambridge infants has been investigated. Bottle fed children were in general given solid foods sooner, 10.6 weeks for boys and 13.9 weeks with girls: among breast-fed babies the average age was 14.9 weeks in the case of boys and 17.4 weeks for girls. All four groups of children exhibited different growth patterns from those of the NCHS and Tanner reference curves. Over the first three months both boys and girls exhibited a faster velocity of growth in weight, length and weight-for-length. After this time, however, growth velocity was slower than that of the reference children particularly among breast-fed boys who were not given solids until after 16 weeks. For most of infancy triceps and subscapular skinfold thicknesses remained around the 10th centile of the corresponding Tanner reference children, although again the babies weaned later had the lower values. Bottle-fed infants had growth patterns similar to those of the earlier weaned breast-fed babies for all parameters. It is concluded that babies grow differently now that infant feeding patterns have changed.

The weanling's dilemma: are we making progress?

In many developing countries the weanling child (the breastfed child who is regularly receiving additional food) still suffers a high level of morbidity and mortality from diarrhoeal disease. The initiation of weaning is a critical event. No clear strategy exists for substantially enhancing the breast milk output of demand feeding mothers in underprivileged communities. Remarkably little progress has been made in our ability to advise mothers, either on a collective or an individual basis, as to when they should supplement the diet of their breastfed offspring, one continuing problem being the failure to adopt appropriate growth standards for infants. Furthermore there has been little attempt to improve traditional weaning foods in terms of consistency, shelf life and bioavailability of nutrients. Increasing insights into the normal growth pattern of breastfed infants and knowledge of localised appropriate traditional food technology remain grossly underexploited.

Daily intake of selenium by bottle-fed infants in Belgium

The selenium content of commercial infant formulae, processed milk and beikost was measured by hydride generation atomic absorption spectrometry after previous wet acid digestion. The median daily intake by infants (1-6 months) fed milk, soya or cereal-based infant formulae was 3.0-7.8 micrograms/day; lower than the mean daily intake by Belgian breast-fed infants (6.1-8.6 micrograms/day) and cow's milk bottle-fed infants (7.6-10.8 micrograms/day).

Feeding, growth, and biochemical studies in very low birthweight infants

Fifty infants of gestational age 28 to 32 weeks and birthweight less than 1501 g were reviewed on the expected date of delivery and at conceptional ages of 4, 8, and 12 months. All infants were at home by the expected delivery date, were fed on demand, and weighed regularly. On the expected delivery date and at 4 months, the amounts of formula milk and weaning food accepted were recorded; energy and protein intakes were calculated; and serum sodium, potassium, urea, protein, and osmolality were measured. The birthweight of these infants ranged between the 3rd and 75th centiles (on average about the 20th) but at the expected delivery date was, on average, below the 3rd centile. Infants who had been weaned in the first 4 months after the expected delivery date (n = 26) had similar energy and protein intakes and similar biochemical indices to those weaned later (n = 24). They achieved catch up growth (below 3rd to 10-25th centile) by 1 year, irrespective of the time of weaning and without any differences in metabolic 'stress'.

Longitudinal study of the selenium content in human breast milk in Belgium

The selenium content of expressed human milk obtained at different stages of lactation from 32 lactating mothers was measured by hydride generation atomic absorption spectrometry after previous wet acid digestion. The highest selenium level was found in colostrum (14.8 ng/g; wet weight), subsequently the content declined and plateaued off after one month (9.4 ng/g; wet weight). The daily selenium intake for Belgian infants of 3 months of age was found to be 7.1 micrograms (girls) and 8.1 micrograms (boys), which is lower than the values obtained in most other countries and lower than the recommended safe and adequate daily intake of 10 to 40 micrograms/day for the same age group.