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Human milk in the second year and beyond

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Human Milk in the Second Year and Beyond
Virginia Thorley
Visual images of babies breastfeeding are overwhelmingly of young babies, such as newborns
and those under three or four months. To some extent the images are a reflection of the culture
in which we live, and they in turn serve to reinforce societal attitudes that breastfeeding by a
young infant is acceptable, but that it might embarrass the public to encounter an older, more
active infant at the breast. Outside of La Leche League and other breastfeeding-friendly settings,
the image of a child of a year or more breastfeeding regrettably has the potential to shock.
Avoiding embarrassment to an adult is given weight over the needs of the infant, and accepted
with little questioning about whose problem this expected embarrassment is. The challenge is
how to normalize the breastfeeding of older infants in the public perception. The World Health
Organization and UNICEF recommend continuing breastfeeding, after the introduction of
appropriate complementary foods, for two years or more.
1
,
2
They did not suggest that this be
done in the closet and this recommendation remains current and has never been superseded.
Part of the reluctance to show an older baby or toddler at breast is the common use of
images of breastfeeding which show a completely bare breast and upper body. While these
images have a positive role for promoting skin-to-skin contact, it is not something young
mothers may relate to as regards how they react in the reality of their own lives after they are out
and about. There is a need to include images where babies of all ages are being breastfed by
mothers in ordinary day clothes, something that mothers can see as doable for them, something
they can visualize themselves doing. In Western societies where the female breast has been
sexualised, an image of an older child at a bare breast may be misconstrued as obscene, or worse.
Images that are less confronting may be a way of educating the community without a backlash.
This is not the only reason why breastfeeding a baby of 6-24 months is not encouraged in
the community. Years ago there was an old wives’ tale told to breastfeeding mothers as their
babies reached the second half of the first year that their milk would ‘turn to water’ at a
particular age, usually the baby’s current age. This assertion was both illogical and unscientific.
Milk is still milk, even if it changes throughout lactation. Today, although the old wives’ tale in
its extreme form seems to have disappeared, mothers and health professionals still wonder if the
milk is nutritious enough for breastfeeding to be worthwhile in the second year. Yet, even today,
the information to answer this question is still limited.
It is true that there is a decline in some nutrients, but for some of them this has begun in
the early weeks or months. It is well known that this dynamic food changes as lactation
progresses, including the change from preterm colostrum and milk, the change from colostrum
through transitional milk to mature milk, and changes during weaning at whatever age. This
happens without being subject to human error, as it happens naturally. Surely we can trust the
breasts to continue to produce suitable milk for the particular stage of lactation?
Studies of the nutrients in human milk in the second year are few and most are old, with
limited numbers, outdated collection methods, or conducted in resource-poor environments
where mothers and children are commonly malnourished.
3
Nevertheless, Onyango and
colleagues reported that breast milk contributed a typical 328 kcal/day or 32% of energy intake
to toddler diets in a resource-poor area of western Kenya.
4
This is an important contribution in a
poor area. Complementary foods were of inadequate quality and even if breastfeeding continued,
the children’s growth was suboptimal. However, it was significantly worse in children whose
breastfeeding was replaced by an increased intake of complementary foods.
Kathleen Dewey has provided useful information about the significant nutrition provided
by a mother’s milk, even when her child is eating other foods in addition to breastfeeding. This is
particularly the case for protein, fat and most vitamins into the toddler period.
5
Minerals such as
iron, zinc and calcium need to be provided through complementary foods (formerly known as
‘solids’), though the bioavailability of zinc in human milk is high. Dewey calculated that 448 ml
of breast milk per day provides the child of 12-23 months with significant nutrition. She
presented the percentages as those required from complementary foods. The following list is a
recalculation of this information as the percentage provided by human milk in this model.
Keeping in mind that some of these values are approximations because the recommended
nutrient intakes are uncertain, the percentages of the recommended daily intake of some of the
important components are:
- Energy: 313 kcal/d (29%)
- Protein: 4.7 g/d (43%)
- Vitamin A: 300 μg RE/d (75%)
- Folate: 38 μg/d (76%)
- Vitamin C: 18 mg/d (60%).5
These percentages are for a child receiving a substantial amount of human milk. Obviously, for a
child receiving less of her mother’s milk, the percentages will be less, but still important.
It is difficult to measure and compare concentrations of some ingredients in what is a
dynamic fluid. Fats, an important component in human milk for the toddler, are a case in point
as they change during a feed, diurnally (during a 24-hour period) and between individuals.
6
.
Recent research by Mandel et al has shown that the milk of mothers who were breastfeeding
beyond a year had significantly increased fat and energy content compared with mothers feeding
infants between 2 to 6 months of age.
7
It appears that lactose and total carbohydrates remain
stable throughout lactation. However there appears to be a decline in concentration of a number
of components of human milk such as sIgA and oligosaccharides, though for some of these the
decline occurs early, rather than later. Changes in mineral and vitamin concentrations have been
attributed to changes in the mammary gland during the weaning process.
8
Even so, human milk
continues to provide significant nutrition and infection protection for the toddler.
Oligosaccharides are the third most prevalent component in human milk. They decline
by the end of the first year, with the proportions of different oligosaccharides also changing.3
Considering the sheer quantities of this important prebiotic early in lactation, what remains in the
second year is still substantial and far superior to anything offered by alternative feeding
methods. The oligosaccharides in products marketed as ‘toddler milks’ are much less diverse and
they are not the ones found in human milk. Replacing breastfeeding with a ‘toddler milk’
inevitably reduces the child’s intake of this important prebiotic.
The information presented here is reassuring for mothers and their advisers who are
concerned about ‘picky eaters’. Mercifully for the breastfed child, meals at the breast provide a
good deal of quality nourishment, supplemented by meals of complementary foods.
Research has shown that breast milk is still an important part of toddler diets. However
there is a great need for new, well-designed studies of the milk composition of well-nourished
mothers during their infant’s second year, in countries such as New Zealand and Australia. As
the weaning process skews changes in milk composition - for instance, an increase in protein
after an earlier decline3,
9
- such a study should compare milk content between mothers whose
babies are weaning and mothers continuing to produce significant amounts of milk.
References
1
World Health Organization. Global strategy for infant and young child feeding. (Geneva: WHO, 2003). Available
at; http://www.who.int/child_adolescent_health/documents/9241562218/en/index.html Accessed on 7
September 2014.
2
World Health Organization. The optimal duration of exclusive breastfeeding. Report of an Expert Consultation.
Geneva: WHO, 2001. Available at
http://www.who.int/child_adolescent_health/documents/nhd_01_09/en/index.html Accessed 7 September 2014.
3
Perrin MT, Fogelman A, Allen JC. The nutritive and immunoprotective quality of human milk beyond 1 year
postpartum: are lactation-duration-based exclusions justified? Journal of Human Lactation 2013; 29(2); 341-349.
4
Onyango AW, Receveur O, Esrey SA. The concentration of breast milk to toddler diets in western Kenya. Bulletin
of the World Health Organization 2002; 80(4): 292-299.
5
Dewey K. Nutrition, growth, and complementary feeding of the breastfed infant. Pediatric Clinics of North
America 2001; 48(1): 87-104. [Access the full article for details.]
6
Lawrence RA, Lawrence RM. Breastfeeding: A guide for the medical profession. (Maryland Heights, MI:
Elsevier/Mosby, 7th edn., 2011): 100-101, 110 -114.
7
Mandel D, Lubetzky R, Dollberg S, et al. Fat and energy contents of expressed human milk in prolonged lactation.
Pediatrics 2005; 116: e432-e435.
8
Karra MV, Udipi SA, Kirksey A, Roepke JL. Changes in specific nutrients in breast milk during extended lactation.
American Journal of Clinical Nutrition 1986; 43(4); 495-503.
Biography
© Virginia Thorley, OAM, PhD, IBCLC, FILCA, 2015
Virginia Thorley is one of the pioneers of the breastfeeding movement in Australia. Her interest
began when, living in a remote area, she sought personal breastfeeding help from La Leche
League by letter. She has subsequently filled a number of roles for the Australian
Breastfeeding Association. Dr Thorley has published widely in refereed journals, as well as
books for mothers (now out of print). She was in the first cohort to certify IBCLC in 1985, and is
a Medical Historian with two research higher degrees. In 2008 she was inducted as a Fellow of
International Lactation Consultant Association (FILCA).
ResearchGate has not been able to resolve any citations for this publication.
Article
Full-text available
An increasing trend towards breast-feeding infants beyond 6 mo of age has been observed in this country. The present study was designed to examine the effect of extended lactation on the concentrations of vitamins B6 and C, free and total folacin, calcium, zinc, and magnesium. Forty mothers were studied from 7 months of lactation until they stopped breast-feeding. Subjects were requested to collect milk samples monthly at a morning feeding between 7 AM and 10 AM. Between 7 and 25 mo of lactation, levels of zinc, calcium, vitamin B6, and vitamin C tended to decrease, whereas levels of free and total folacin remained unchanged. Magnesium levels decreased only after 18 mo of lactation. The decrease in concentrations of zinc and calcium paralleled the decrease in feeding frequency. Changes observed in this study on the composition of human milk may reflect physiological changes in the mammary gland during weaning.
Article
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To understand the relative contributions of breast milk and the weaning diet to overall nutrient intake, with a view to designing and implementing appropriate programmes to improve complementary feeding in developing countries. Complementary food intake was measured in a sample of 250 toddlers (mean baseline age: 13.9 +/- 2.4 months) using 24-h dietary recall interviews administered once every 3 weeks over a 6-month period. Breast-milk intake over a 24-h period was measured using the test-weighing method in a subsample of 50 children. Regression effects of age and sex on observed milk intakes were estimated and imputed to the whole sample to estimate mean intake over the observation period. Total energy and nutrient intakes were evaluated for adequacy with reference to published estimates of toddler requirements. Total energy intake (1029 kcal/day) was adequate, with breast milk supplying an average of 328 kcal/day (32%), but vitamin A, riboflavin, calcium, iron and zinc intakes were below current estimates of required intakes. Observed limitations in nutrient intake were consistent with the finding that almost half of the toddlers were stunted. The prevalence of wasting was 6% at baseline and 4% at final assessment. Although food consumption increased when breastfeeding stopped, it could not fully compensate for the fat and vitamin A previously supplied by breast milk. The nutritional role of mother's milk in the second year is inversely related to the adequacy of the complementary diet. In this study, breast milk was an irreplaceable source of fat and vitamin A. When the weaning diet is inadequate for key nutrients because of low intake or poor bioavailability, breast milk assumes greater nutritional significance in the second year of life but does not guarantee adequate nutrient intakes.
Article
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To estimate fat and energy contents of human milk during prolonged lactation. Thirty-four mothers, of term, healthy, growing children, who had been lactating for >1 year (12-39 months) were recruited. Control subjects were 27 mothers, of term infants, who had been lactating for 2 to 6 months. Fat contents of the milk samples were estimated as creamatocrit (CMT) levels. Energy contents of the milk were measured with a bomb calorimeter. The groups did not differ in terms of maternal height and diet, infant birth weight, gestational age, or breastfeeding frequency. They differed significantly in terms of maternal age, maternal weight, and BMI. The mean CMT levels were 7.36 +/- 2.65% in the short-duration group and 10.65 +/- 5.07% in the long-lactation group. The mean energy contents were 3103.7 +/- 863.2 kJ/L in the short-duration group and 3683.2 +/- 1032.2 kJ/L in the long-duration group. The mean CMT levels and mean energy contents were correlated significantly with the duration of lactation (R2 = 0.22 and R2 = 0.23, respectively). In multivariate regression analysis, CMT levels (or energy contents) were not influenced by maternal age, diet, BMI, or number of daily feedings but remained significantly influenced by the duration of lactation. Human milk expressed by mothers who have been lactating for >1 year has significantly increased fat and energy contents, compared with milk expressed by women who have been lactating for shorter periods. During prolonged lactation, the fat energy contribution of breast milk to the infant diet might be significant.
Chapter
In March, 2001 The World Health Organization (WHO) convened an Expert Consultation to recommend to WHO an optimal duration of exclusive breastfeeding. WHO formulated the specific questions to be addressed, selected the membership for the meeting, prepared background documents, and provided the venue for the meeting. After the meeting WHO formally accepted the recommendations and began to implement them. The Consultation recommended that WHO change its recommendation on exclusive breastfeeding from four-to-six months to a recommendation to promote exclusive breastfeeding for six months. This recommendation was contingent upon WHO also accepting and implementing other recommendations to deal with possible detrimental side effects, and to support mothers who did not exclusively breastfeed for six months. The amount of scientific evidence available was more than is often available for policy decisions in health, but much less than desirable to address issues of generalizability across and within populations. The evidence for the contingent recommendations was also less than desirable and raises a number of important research questions that now need to be addressed.
Article
Human milk is the ideal food for infants because of its unique nutritional characteristics. [30] and [35] For example, in terms of protein content, human milk has a high ratio of whey to casein, a relatively high proportion of nonprotein nitrogen, and high concentrations of certain specific proteins.14 These components serve nutritional and nonnutritional functions.30 Also, human milk is rich in some fatty acids essential for brain development and contains several nonlactose carbohydrates that have a role in resistance to infection. Furthermore, human milk changes in composition as infants mature.After a certain age, however, human milk alone no longer can supply all of an infant's nutritional requirements, and complementary foods are needed to ensure adequate nutrition and growth. It is commonly assumed that an increased need for energy and protein is the primary factor dictating complementary feeding, but some of the micronutrients are likely to become limiting sooner than the macronutrients. If a mother nurses on demand and is well nourished, her milk supply probably can keep pace with her infant's energy needs for considerably longer than 6 months. By contrast, the amount of iron provided by human milk may become insufficient even before 6 months if an infant has suboptimal iron reserves at birth.This article reviews the contribution of human milk to nutritional needs during the first 2 years of life, growth patterns of breastfed infants, and recommendations regarding the age of introduction and optimal nutrient density of complementary foods. The focus is on healthy, term infants; other articles in this issue cover feeding of preterm infants.37 For detailed discussion of specific nutritional needs of breastfed infants, the reader is referred to articles on iron,25 polyunsaturated fatty acids29 and vitamins.24
The nutritive and immunoprotective quality of human milk beyond 1 year postpartum: are lactation-duration-based exclusions justified
  • M T Perrin
  • A Fogelman
  • J C Allen
Perrin MT, Fogelman A, Allen JC. The nutritive and immunoprotective quality of human milk beyond 1 year postpartum: are lactation-duration-based exclusions justified? Journal of Human Lactation 2013; 29(2); 341-349.