Breastfeeding: Benefits and Implications. Part Two
BREASTFEEDING
Recent guidelines from the Department of Health recommend exclusive breastfeeding for the first six months (26 weeks) of an infant’s life with the late introduction of solids being cited as protective against the development of asthma, eczema and atopy.1 However, it has been suggested that national and international recommendations for the age of introducing solid foods (weaning) are founded on insufficient evidence.2 In part two of her update, JUNE THOMPSON looks at the conflicting literature regarding whether exclusive breastfeeding for six months conveys significant benefits for babies and if current recommendations that a delayed introduction of solids is protective against the development of asthma and allergy are supported by the evidence
Community practitioner2005; 78, 6:218-219
Since the World Health Organization revised the infant feeding recommendation for exclusive breastfeeding from 4-6 months to 6 months in 2001,3 the debate over the optimal duration of exclusive breastfeeding has been long and heated.
More recently, the Department of Health’s current feeding guidelines recommending that breastfed babies not start solids before six months’ have been described as ‘a messy muddle’.4
It has also been suggested that breastfeeding promotion has focused on encouraging mothers to breastfeed for a prescribed duration of time, usually according to government targets rather than the mother’s own wishes.5
Furthermore, despite this recommendation, most parents, including paediatricians, appear to continue to introduce solids by 3-4 months.2,6-8 Does ignoring this recommendation compromise the health of babies?
Breast milk is best
Health visitors are expected to give parents advice that is supported by research based evidence, and there is increasing evidence that events early in life such as growth rate and type of milk feeding may have long-term consequences for health.2 For example, it has been shown in a number of animal models as well as in humans, that growth promotion during infancy may predispose the individual to an increased risk of high blood pressure, obesity, non- insulin dependent diabetes, and ischaemic heart disease later in life.2
Most of this data relating to infant feeding have examined the effect of the type of milk used,2 and there is extensive scientific evidence to support the consensus that breastfeeding is the best way to feed an infant.1
However, the data that exclusive breastfeeding for 6 months conveys significant benefit over breastfeeding for just 4 months are limited9 and the effect of introducing solid foods on the health of the baby has been relatively neglected.2
Scientific evidence about the timing of solid food introduction is scarce with research having mainly focused on the duration of breastfeeding10 and it has been suggested that national and international recommendations for the age of introducing solid foods (weaning) are founded on insufficient evidence.2
Definitions
The introduction to solid feeding and the gradual replacement of milk by solid food as the main source of nutrition is the process known as weaning.
Complementary feeding is the provision of any nutrient containing foods or liquids other than breast milk and includes both solid food and infant formula. In the UK the terms ‘weaning’ and ‘complementary feeding’ are sometimes used synonymously to mean infant solid feeding.7
Exclusive breastfeeding is defined as an infant’s consumption of human milk with no supplementation of any type (no water, no juice, no non-human milk and no foods) except for vitamins, minerals and medications.11
What are the risks associated with starting solids early?
In the UK there is a consensus among scientists and policy makers that weaning should not occur before 4 months of age, but there is debate about the universal application of a policy to delay weaning until 6 months of age.7 The debate encompasses concerns about growth and nutritional adequacy of exclusive breast milk feeding for all infants until 6 months of age versus the risks, especially of infection, associated with earlier weaning.7
The introduction of complementary foods to the diet (weaning) is a critical nutritional stage in an infant’s life.8 The decision when to wean must balance the risk that weaning too early will stress the immature gut, kidneys, and immune system as well as decreasing exposure to the protective effects of breast milk, while weaning too late may result in under-nutrition and feeding problems.8
According to the Department of Health, introducing solids before sufficient development of the neuro-muscular co-ordination (to allow the infant to eat solid foods) or before the gut and kidneys have matured (to cope with a more diverse diet), can increase the risk of infections and development of allergies such as eczema and asthma.1
Data from two Honduran trials found that exclusive breastfeeding for six months does not slow a baby’s growth, but reduces gastrointestinal infections, delays the return of fertility, and helps the mother lose weight.12
However, a review of data2 from over 1600 infants from five prospective randomised trials of weaning before and after 12 weeks of age found little evidence of any influences on health either way up to the age of 18 months independent of type of milk feeding, gender, and potential socio-economic confounding factors.
The outcomes in question included higher rates of atopy and gastroenteritis, chest infections and sleep patterns. Early weaned babies were larger at 12 weeks, but any differences in growth disappeared by 18 months.2 It has also been argued that, in the UK, the WHO recommendations for weaning take no account of the likely differing nutrient requirements of the exclusively breastfed versus the formula or mixed formula and breastfed infant.7
On present knowledge it could be argued that breastfed infants should receive foods such as meat or iron-fortified foods earlier in the weaning process than formula fed infants, in whom cereals would suffice as the initial solid food.7
Does breastfeeding prevent allergic disease?
Allergic diseases represent a major burden of health problems in industrialised countries.13 Asthma is one of the most common diseases in childhood, causing substantial morbidity and considerable costs to the health care system10 and it has been an article of faith among paediatricians and allergists that breastfeeding is beneficial for the prevention of allergic disease.14
Indeed, current feeding guidelines1 recommend delayed feeding of solids for the prevention of asthma and atopy, and follow the view that allergen avoidance leads to a reduction of asthma and allergy. This is thought to be mediated by sensitisation against food and subsequent inhalant allergens which have been found to be associated with asthma and allergy. The sensitisations are believed to result from early life exposure to these allergens.10
Recently, however, several publications have challenged the view that breastfeeding is protective against allergic disease, particularly with respect to the long-term outcomes for asthma,14 with some studies showing no protective effect, or even an increased risk.15
In one recent study, after following more than 600 children up to the age of 5.5 years, researchers found no evidence for a protective effect of late introduction of solids for the development of preschool wheezing, transient wheezing, atopy or eczema.10
The same study found too a statistically significant increased risk of eczema in relation to late introduction of egg,10 whereas the American Academy of Pediatrics recommends solids be delayed to 6 months of age, and the introduction of certain foods, including egg, be delayed until after a child’s first birthday.9
Another study also found no evidence that weaning before or after 12 weeks influenced the likelihood of the infant developing atopy.2 However, in a cohort of preterm infants, exposure to more than four foods before 4 months of age was associated with an increased risk of eczema at the age of 12 months post-term.16
Conclusion
There is no doubt that breast milk remains the gold standard for feeding babies. Mothers should be encouraged to breastfeed for six months and thereafter as long as the mother and infant wish. However, as has been stated, the data that exclusive breastfeeding for 6 months conveys significant benefit over breastfeeding for just 4 months are limited,9 the introduction of solids is still a confusing issue and how we interpret the data for parents is complicated.6
Although current feeding guidelines recommend delayed feeding of solids for the prevention of asthma and atopy, research concerning exclusive breastfeeding and prevention of allergies is conflicting and does not allow an authoritative statement to be made regarding the relation between the introduction of solids and the development of allergy.10 Above all, mothers and babies are individuals and should be treated as such.
The interests of infant health may be better served by encouraging more mothers to breastfeed, if only for a few weeks, and by discouraging solid feeding before 4 months than by recommending exclusive breastfeeding for six months.7
There is no doubt of the many benefits of breastfeeding, but benefits such as a high IQ, less gastrointestinal and other infections, were already known well before the 6 month edict.4
Health professionals should consider realigning themselves toa ‘woman centred’ rather than ‘breastfeeding centred’ role. A woman centred advocate who supports a mother’s own decisions and helps her to feel positive about herself and her role as a mother would be more effective than a breastfeeding centred advocate.5
There is no doubt that breast milk remains the gold standard for feeding babies. Mothers should be encouraged to breastfeed for six months and thereafter as long as the mother and infant wish
References
1 Department of Health. Infant Feeding Recommendation. London: May 2003.
2 Morgan J et ai. Does weaning influence growth and health up to 18 months? Archives of Disease in Childhood 2004; 89: 728-733.
3 World Health Organization. The optimal duration of exclusive breastfeeding: Report of an expert consultation. Geneva: WHO, 2001.
4 Moorhead J. To wean, or not to wean. The Guardian, Parents G2, 10.11.04.
5 McInnes R. Mothers dealt with incompatible expectations during breast feeding and weaning. Commentary. Evidence-Based Nursing 2003; 6: 92.
6 Bauchner H. Atoms. Introduction of solids – still a confusing issue. Archives of Disease in Childhood 2004; 89:295.
7 Foote KD, Marriott LD. Weaning of infants. Archives of Disease in Childhood 2003; 88: 488-492.
8 Wright CM et al. Why are babies weaned early? Data from a prospective population based cohort study. Archives of Disease in Childhood 2004; 89: 813-816.
9 Bauchner H. Atoms. The complexity of early weaning. Archives of Disease in Childhood 2004; 89: 799.
10 Zutavern A, von Mutius E, Harris J et al. The introduction of solids in relation to asthma and eczema. Archives of Disease in Childhood 2004; 89: 303-308.
11 American Academy of Pediatrics. Breastfeeding and the use of human milk. Pediatrics 2005; 115, 2: 496-506.
12 Kramer MS, Kakuma R. The optimal duration of exclusive breastfeeding. A systematic review (Cochrane Review). The Cochrane Library, Issue 3. Oxford: Update Software, 2002.
13 Host A, Halken S. Primary prevention of food allergy in infants who are at risk. Current Opinion in Allergy & Clinical Immunology 2005; 5,3: 255-259.
14 Kemp A, Kakakios A. Asthma prevention: Breast is best? Journal of Paediatnc Child Health 2004; 40, 7: 337-339.
15 Kull I et al. Breast-feeding reduces the risk of asthma during the first 4 years of life. Journal of Allergy and Clinical Immunology 2004; 114, 4: 755-760.
16 Morgan JB et al. Eczema and early solid feeding in preterm infants. Archives of Disease in Childhood 2004; 89: 309-314.
June Thompson
Part time health visitor and freelance journalist
Copyright TG Scott & Son Ltd. Jun 2005