Breast Milk? A Letter from Dr G
Breast milk is the perfect answer to well-balanced nutrition for infants. The biological and nutritional composition of breast milk is constantly changing to satisfy the physiological needs of an infant.
For just a few days after delivery, mothers secrete colostrum as the first type of breast milk. Poor in lactose, the low volume of colostrum is a rich source of protein and minerals such as sodium, chloride and magnesium. In addition, colostrum is rich in immune cells and immunomodulating factors such as IgA and lactoferrin. This composition confers immune-protection and promotes infant growth.
In between the third day and a week, the new-born will receive a higher volume of milk called transitional milk. This is lower in protein but higher in lactose and lipids. The transitional milk evolves gradually into a more mature one and into fully matured milk by four to six weeks postpartum. Similar in composition, the mature milk is subject to fine changes during all period of lactation to meet the child’s requirements.
Breast milk contains over four hundred different proteins, mostly whey, mucin proteins and fewer caseins. Similar in energy but different in some micronutrients, formula and cow’s milk have a higher concentration of proteins compared to human milk. Casein is highly concentrated in cow’s milk, therefore it is more difficult to digest.
For perfect nutritional support, as well as antimicrobial and immunomodulatory activities, an optimum protein profile is required. Besides a variety of cells, like macrophages, T cells, stem cells and lymphocytes, human milk contains oligosaccharides that play a role in immunomodulatory activities. In fact, these types of carbohydrates act as prebiotics to support the growth of the beneficial bacteria within the infant gastrointestinal tract, providing protection against gastrointestinal infection.
Human milk contains numerous growth factors such as epidermal growth factor, for the maturation of the intestinal mucosa, growth-regulating hormones, neuronal and vascular endothelial growth factors. Therefore, breastfeeding is essential to regulate metabolism and body composition as well as assist the physiological development of the gastrointestinal tract, endocrine, vascular and nervous system (1).
Secretion and excretion of breast milk are induced by baby suckling, a reflex determined by a correct latching. This will increase the bonding experience between the mother and child. The correct latching, as well as correct hygiene, is an important factor in avoiding sore and cracked nipples which might cause an interruption of breastfeeding. Hygiene and sanitation issues in the developing world can be avoided by breastfeeding, as human milk is not sterile but hygienic. Therefore, breastfeeding might reduce the incidence of infectious diseases in developing countries and hence reduce the risk of infant and child mortality.
With a negative correlation to the risk of obesity in later life. Breastfeeding has a protective effect on sudden infant death syndrome. Breastfeeding has also been associated with better cognitive development and increased performance in intelligence tests in childhood and adolescence (2,3).
The benefits of breastfeeding also include the mother, with reduced anaemia and weight loss due to the increase in energy expenditure. Breastfeeding shows a maternal protective effect over the breast, cervical and ovarian cancer (4,5) and amenorrhea prolactin-induced can be seen as a benefit towards a contraceptive method.
Infants with galactosemia should not receive breast milk. Neither should infants receive breast milk where the mother has HIV or Hepatitis B. Caution with breastfeeding is required in the case of maternal medications or when a mother is receiving radioactive diagnostic agents. Special nipples are required in the case of severe cleft palate or micrognathia in infants. For temporary conditions that are limiting breastfeeding, it is important to use a breast pump to maintain the stimulation of milk production.
More energy and plenty of nutrients are required during lactation.
The total energy expenditure increment recommended for a mother during the first six months of lactation changed from 454-574kcal/day by COMA (1991), to 330kcal/day by SACN (2011). These differences might be based on a calculation assumption, and hence difficult to agree with, or due to gaps in our knowledge.
A similar scenario of assumption for the recommendation of extra 11g protein/day is perhaps estimated without considering the overload of proteins in the UK diet (8). Supplementation of vitamins C and B is the right choice in developing countries, commonly affected by these types of deficiencies. In the UK, data shows no need for vitamin A but a need for vitamin D supplementation, perhaps higher than 10 microg/day recommended, in order to reflect the whole population including vegan or non-pescatarian mothers, where the level of vitamin D is already low. However, we need more knowledge and clear stratified data across the UK in order to tailor an optimal nutritional recommendation during lactation.
Mass media, friends, cultural, personal, environmental and social factors may influence the decision to breastfeed.
Husbands’ advice has been reported as an important influencing factor for infant feeding intention (6). Multiple pieces of evidence show how employment, social attitudes, public facilities for breastfeeding and the content of advice given to mothers by health workers affect breastfeeding intentions.
Even when the decision to breastfeed has been taken, mothers may be discouraged by factors such as personal perceptions, public facilities, employment and employer support, husband involvement, social attitudes and social support. Prenatal education and early knowledgeable support from family or health care providers may positively influence the feeding outcomes (6). Exclusive breastfeeding in Scotland has seen no improvement between 2006 and 2016. A drop-off in exclusive breastfeeding from birth to six weeks has been recorded in 2005 and 2010 (7). Clearly something needs to be done to improve this trend.
Investing resources and highly qualified personnel might be the first step. Influencing mass media and public opinion, informing the risks of not breastfeeding through a national capillary public health campaign, with mandatory pre-natal educational courses and “face to face” support for young families might also help to address the problem. Targeting a sociodemographic pool of mothers in deprived areas, with low income, young age and low educational level is also necessary.
By Dr Gregorio Torchia
1 Human Milk Composition: Nutrients and Bioactive Factors
Olivia Ballard, JD,Ardythe L. Morrow,Pediatr Clin North Am. 2013 February ; 60(1): 49–74. doi:10.1016/j.pcl.2012.10.002.
2 Long term effects of breastfeeding, A systematic review
Bernardo L. Horta, MD, PhD, Cesar G. Victora, MD, PhD World Health Organization. ISBN 978 92 4 150530 7
3 Breastfeeding and dummy use have a protective effect on sudden infant death syndrome.
Alm B, Wennergren G, Möllborg P, Lagercrantz H. Acta Paediatr. 2016 Jan;105(1):31-8. doi:10.1111/apa.13124. Epub 2015 Sep 2.
4 Breastfeeding Mode and Risk of Breast Cancer: A Dose-Response Meta-Analysis.
Unar-Munguía M, Torres-Mejía G, Colchero MA, González de Cosío T. J Hum Lact. 2017 May;33(2):422-434. doi:10.1177/0890334416683676. Epub 2017 Feb 14.
5 Breastfeeding factors and risk of epithelial ovarian cancer.
Modugno F, Goughnour SL, Wallack D, Edwards RP, Odunsi K, Kelley JL, Moysich K, Ness RB, Brooks MM. Gynecol Oncol. 2019 Jan 25. pii: S0090-8258(19)30060-5. doi: 10.1016/j.ygyno.2019.01.017.
6 Factors influencing decision to breastfeed.
Sarah K.F. Kong BAppSci RN RM MPH Diana T.F. Lee MSc PhD RN RM First published: 29 April 2004 https://doi.org/10.1111/j.1365-2648.2004.03003.
7 Infant Feeding Survey 2010
Fiona McAndrew, Jane Thompson, Lydia Fellows, Alice Large, Mark Speed and Mary J. Renfrew SACN
Dietary Reference Values for Energy (2011)
Department of Health, Dietary Reference Values for Food Energy and Nutrients for the United Kingdom (1991)National Diet and Nutrition Survey: results from years 5 and 6 combined of the Rolling Programme 2012/2013 – 2013/2014 (2016)