‘The scaling up of breastfeeding to a near universal level could prevent 823 000 annual deaths in children younger than 5 years and 20 000 annual deaths from breast cancer’ (Victora et al, 2016: 475). It is sensible, given such potential benefits, that the World Health Organization (WHO) recommends that all infants should be breastfed exclusively for the first 6 months of their lives, with breastfeeding continuing up to 2 years and beyond (WHO/UNICEF, 2003). However, while the prevalence of breastfeeding at 12 months is highest in sub-Saharan Africa, south Asia and parts of Latin America, most high-income countries report a prevalence of less than 20%. Victora et al (2016: 477) noted ‘important differences—e.g. between the UK (< 1%) and the USA (27%), and between Norway (35%) and Sweden (16%)’. According to Brown (2015: 57), in the UK, ‘although 81% of mothers breastfeed at birth, by 6 weeks only 55% breastfeed at all.’ In Scotland, meanwhile, only 36% breastfeed exclusively for 6 weeks or more (Bradshaw et al, 2013).
Reasons cited by Brown (2015) for poor breastfeeding rates include the lack of support faced by breastfeeding women, public harassment, and negative attitudes. A recent example of the latter was provided by politician Sammy Wilson MP, who asserted that MPs who breastfed in the House of Commons would be engaging in ‘exhibitionism’ (BBC News, 2016). Lower breast-feeding rates in wealthier countries may be related to national laws on maternity leave, whereby some working mothers may only have 3 months of maternity leave following the birth of a child.
Brown (2015) cites the development of a formula-feeding culture as a further impediment to breastfeeding, but Obladen (2014a: 272) disagrees, adducing evidence to show that failure to breastfeed is not a recent phenomenon and concluding that ‘it is unlikely that it originated from the availability of commercial formula’. The 19th century's first proprietary infant formula was the Eagle brand's condensed and sweetened cows' milk, devised by Texan Gail Borden, which appeared in 1856 (Obladen, 2014b). Obladen (2014a: 272) observes the widespread ‘moralistic assumption’ that the 18th century saw bottle-feeding as being motivated by choice, rather than need: ‘In the reality of urban life, however, it was often the only way to save the infant's life.’
Breastfeeding alternatives
For women who decline breastfeeding—whatever their reasons—safe, viable alternatives must be available. While Battersby (2015) notes that, for many centuries, the wet-nurse was considered a safe alternative, she also presents evidence to show that by the late 18th century ass, goat, cow and sheep milk were in regular use. Goats' milk, however, was used less often in the UK compared to, for example, France, where Alphonse Le Roy in Aix initiated the direct suckling of foundlings by goats. Although cows' milk would become the traditional source of infant formula in the UK, Battersby (2015: 710) states: ‘Despite cows' milk being the dominant component of infant formulas, there has been a parental demand for goat milk infant formulas.’
In the 21st century, goats' milk has become a viable alternative to cows' milk as a source for infant formula (Box 1). In February 2012, the European Food Safety Authority (EFSA) Scientific Panel judged that goats' milk was an acceptable protein source for infant and follow-on formulas, subject to it complying with compositional criteria established in Directive 2006/141/EC (EFSA, 2012).
| November 2002 – A dossier was submitted to European Commission (EC) asking the EC to include goats' milk protein as a suitable protein source for infant formula and follow-on formula (European Food Safety Authority (EFSA), 2004) |
| February 2004 – The EFSA Scientific Panel concluded that the data submitted were insufficient to establish the suitability of goats' milk protein as a protein source for infant formula, and that unmodified goats' milk protein was not suitable to be used as a protein source in infant formula. This was because of methodological flaws, including small sample size, restriction to anthropometric parameters only, absence of a breastfed reference group, and non-adherence to the study protocol (EFSA, 2004) |
| December 2006 – Directive 2006/141/EC established compositional criteria for infant milk formula (European Commission, 2006) |
| February 2011 – A dossier was submitted, again asking the EC to include infant and follow-on formula manufactured from goats' milk (EFSA, 2012) |
| February 2012 – The EFSA Scientific Panel, after considering further evidence, including a double-blind randomised controlled trial (Zhou et al, 2011), concluded that protein from goats' milk could be suitable as a protein source for infant and follow-on formula, provided the final product complies with the compositional criteria laid down in Directive 2006/141/EC |
| March 2014 – In England, the Infant Formula and Follow-on Formula Regulations were amended (UK Government, 2013), permitting goats' milk as a source of protein in formula milks from March 2014 (Battersby, 2015) |
The results of a trial by Zhou et al (2011) helped influence the Scientific Panel of the EFSA to approve goats' milk infant formula. The researchers studied 200 formula-fed infants—either goats' milk formula or cows' milk formula—and 101 breastfed infants, from within 14 days of birth over a 12-month study period. They concluded: ‘The growth rate and nutritional status of infants fed goat milk formula are comparable to infants fed cow milk formula.’
New Zealand-based Grant et al (2005), in a double-blind randomised controlled trial, allocated 72 newborns to either goats' or cows' milk formula for 168 days, resulting in a similar conclusion, that the growth of infants fed goats' milk formula was not different to that of infants fed cows' milk formula.
Infant formula: cows' milk or goats' milk?
Because of the sensitive target group, all infant formula must comply with stringent compositional regulations laid down in Directive 2006/141/EC (European Commission, 2006). This regulation has been revised and will be replaced by EU regulation 2016/127 (European Commission, 2016). Changes include the mandatory addition of the unsaturated fatty acid docosahexaenoic acid (DHA). Other ingredients permitted—but not mandatory—to be added to infant formulas include specific fatty acids and dietary fibres. Although all infant formulas share a similar compositional base, using either goats' milk or cows' milk results in formulas with different characteristics.
Digestibility of goats' milk
Goats' milk is highly nutritious and a good source of several macro- and micronutrients. The special characteristics concerning the composition of goats' milk mean that its nutritional utilisation is higher compared to cows' milk (Ceballos et al, 2009).
Milk has two types of protein—casein and whey—which differ in composition between goats' milk and cows' milk. Caseins are ‘slowly’ digested and result in more saturation, whereas the ‘fast’ whey proteins are more easily digestible (Ceballos et al, 2009; Inglingstad et al, 2010). The concentration of αS1-casein is significantly lower in goats' milk (Park, 2006). This casein largely determines the structure of the coagulate in the human stomach, enhancing goats' milk digestibility owing to the fact that ‘goat milk produces a more fragile rennet curd than bovine milk’ (Park, 2007: 76). There is evidence that the poor cheese-making ability of goats' milk compared to cows' milk is a result of its lower casein content ‘and differences in casein micelle composition, size and hydration between the two species' (Park, 2007: 76).
Mean casein micelle size varies between goats' milk and cows' milk (Inglingstad et al, 2010). The larger size of goat casein micelles may explain their increased susceptibility to hydrolysis by gastric enzymes (Inglingstad et al, 2010).
Whey protein, constituting the soluble phase of milk, is a liquid derived from milk during cheese production, which separates casein from whey. Whey proteins are of high quality, containing raised concentrations of essential amino acids. Goat whey is hydrolysed quicker than bovine whey (Pintado and Malcata, 2000). Moreover, goats' milk proteins are digested quicker than cows' milk proteins by human gastric and duodenal enzymes (Almaas et al, 2006).
The Scientific Panel of the EFSA (2012) judged that a whole goats' milk formula with a casein: whey ratio of 80: 20 did not produce different growth and nutritional outcomes from those provided by a standard whey-based cows' milk formula with a whey: casein ratio of 60: 40. Goats' milk formulas—as is the case for cows' milk formulas—can be adjusted to enhance their protein composition to a whey: casein ratio of 60: 40, utilising the natural digestibility and raised essential amino acid composition of goat whey protein. Box 2 lists some of the key differences between infant formulas based on goats' milk and cows' milk.
| Goats' milk infant formula: |
|---|
| Has lower concentrations of αS1-casein protein than cows' milk formula, with the advantage of forming a softer coagulate in the stomach |
| Naturally contains higher concentrations of nucleotides, and—unlike cows' milk formula—does not require supplementation |
| Contains more easily digested proteins than those in cows' milk protein, related to goat whey protein in particular |
Goats' milk within the allergy framework
Contrary to the assumption by some consumers that goats' milk may be a solution to cows' milk allergy, the EFSA concluded that there were insufficient data to support the belief that the incidence of allergic reactions is lower when feeding goats' milk infant formula compared with cows' milk infant formula, and, according to Crawley and Westland (2014: 20), ‘this has not changed’. The protein in goats' milk is similar in such a way that babies who suffer from medically confirmed cows' milk protein allergy can also react to goats' milk protein. Crawley and Westland (2014: 20) added:
‘The Department of Health recommends that infants with proven cows' milk protein intolerance can be prescribed an extensively hydrolysed infant formula. Goats' milk based infant milk is also unsuitable for babies who are lactose-intolerant as it contains similar levels of lactose to cows' milk based infant formulas.’
Anecdotal evidence indicates that infants who display sensitivity to cows' milk products, but who do not suffer from a medically confirmed cows' milk protein allergy, could possibly benefit from a goats' milk-based infant formula. Further research is needed in this field.
Fat composition in infant formula
The fatty acid composition of infant formulas is defined by law, and based on the fatty acid composition of human milk. These fatty acids are regularly obtained from vegetable fat blends in combination with the fatty acids that are naturally present in milk powder ingredients. Infant formulas can also be enriched with additional fatty acids, for their suggested health benefits, provided that their safety for use is proven.
Goat milk fats
Fat occurs in milk as fat globules, and those in goats' milk are smaller and with a greater surface area than those in cows' milk (Attaie and Richter, 2000). Lipases—enzymes that break down fat in the gut—are supposedly able to attack the lipids in these small fat globules more rapidly (Park et al, 2007). Lipases also attack the ester linkages of shorter-chain fatty acids more readily. Goats' milk naturally contains a significantly higher concentration of short- and medium-chain fatty acids compared to cows' milk (Ceballos et al, 2009), meaning that goats' milk fatty acids are more easily digested. The majority of the fatty acid composition in goats' milk infant formula—as for cows' milk formula—comes from added vegetable fat blend. Nevertheless, the benefits of goats' milk fatty acids may be applicable, depending on the goats' milk powder ingredients used.
Vegetable fats further defined
Uhl et al (2015) highlight the importance of the fatty acid composition of different tissue lipids, which are important in early postnatal development, noting that long-chain polyunsaturated fatty acids (LCPUFAs) occur in relatively high concentrations in neuronal tissue and the retina. They cite evidence showing that the inclusion of LCPUFAs in formula enhances infants' visual acuity, maturation and cognitive function. And according to Agostoni (2008: S41): ‘The 2 most abundant [LCPUFAs] in the brain are docosa hexaenoic acid (DHA) and arachidonic acid (ARA), where they have a functional and structural role in infant development.’
According to Szabó et al (2010), human milk lipids—unlike standard vegetable oils—have relatively high concentrations of beta-palmitate (palmitic acid at the sn-2 position of the glycerol backbone).
The fatty acid composition of infant formula must comply with the compositional requirements defined by law in Directive 2006/141/EC (European Commission, 2006). Infant formulas can also be enriched with vegetable oil rich in beta-palmitate. To obtain a high beta-palmitate concentration, and thus a structure similar to that of human milk, enzymatically treated palm oil—which differs considerably from regular palm oil—is a required ingredient. For these types of oil, the palmitic acid at the sn-2 position is often combined with oleic acids at the sn-1 and sn-3 position of the glycerol backbone. Studies indicate that a high beta-palmitate fat blend in infant formula improves fat and mineral absorption, and can positively affect stool consistency (Kennedy et al, 1999; Bar-Yoseph et al, 2013).
Goats' milk and faecal microbiota
In an analysis of stool samples taken from 90 Australian infants at 2 months of age, Tannock et al (2013) compared the faecal microbiotas between 30 infants fed goats' milk formula, 30 infants fed cows' milk formula, and 30 breastfed infants as the gold standard. The authors hypothesised that there might be differences in microbiota compositions of infants fed goats' milk formula rather than cows' milk formula, and the results showed that the total microbiotas and Lachnospiraceae anaerobic bacterial populations ‘were more similar in breast milk/goat milk comparisons than in breast milk/cow milk comparisons' (Tannock et al, 2013: 3045).
Further differences between regular goats' milk, cows' milk and human milk
Considering the mode of milk secretion, Battersby (2015) highlights two types of mammalian milk production: in the merocrine process cell components are not released into the milk droplets, whereas in the apocrine process—central to human milk production—the milk contains cellular components.
In addition, Le Parc et al (2014: 1560) explain that human milk, compared to ruminant milk, is relatively rich in the glycoprotein lactoferrin, but add: ‘Goat milk lactoferrin may better mimic the functional properties of human milk lactoferrin and therefore be an improvement over bovine milk lactoferrin in formula supplementation.’
