Compositional and functional characteristics of goat milk and relevance as a base for infant formula

This summary is adapted from ‘Compositional and functional characteristics of goat milk and relevance as a base for infant formula’ by Prosser 2021 Global consumption of goat milk is increasing¹. In the past, raw goat milk was occasionally used to feed infants, however this is strongly discouraged now due to the risk of deficiencies and infections². The first commercial goat milk formula was produced in the 1980s and since then there have been multiple studies related to its nutritional status. The European Food Safety Authority concluded that goat milk was a suitable source of protein for use in infant formula in 2012. The review summarised here aimed to highlight the differences between goat and cow milk and further the infant formula from which they are derived. Cow and goat milk have comparable concentrations of total protein, amino acids, casein, whey, lactose, total fat, and calcium. Goat milk has higher levels of non-protein nitrogen than cow milk and human milk, and therefore needs differing levels of nucleotide monophosphates added for infant formula production. In terms of carbohydrates, lactose is 10% lower in goat milk compared to cow milk, and both goat and cow milk have much lower levels than human milk. Goat and cow milk fat globule membrane have been seen to be similar to both each other and to human breast milk, but the minor proteins are different across all three. As in cow milk, levels of vitamin C, vitamin B12, folate and vitamin D are not sufficient in goat milk and formula must be fortified to provide adequate levels. The casein proteins from goat milk may be digested more easily than those of cow milk due to a slightly different structural form³. There have been multiple studies reporting that goat milk reduced symptoms of abdominal pain, bloating and diarrhoea. The mechanism through which this occurs is yet to be elucidated but some animal studies have shown that goat milk may protect against heat stress and intestinal inflammation. Goat milk also has a differential effect on the intestinal microbiome compared to cow milk. Increased uptake of various minerals such as calcium, iron and magnesium has also been found to be associated with goat milk over cow milk in animal models with impaired capacity. There are some indications that goat milk may have a greater satiating effect than cow milk, but this is yet to be shown in infants. Both goat and cow milk contain potentially allergic proteins, but 3 studies have shown allergy to be less frequent in response to goat milk^4,5,6. However, there have also been reports of goat milk allergy in children with no evidence of allergy to cow milk. A large proportion of children with allergy to cow milk proteins also reacted to goat milk, but required a much greater volume⁷. This does mean that infant formula based on goat milk should not be used to treat infants with cow milk allergy. In the production of infant formula, both goat and milk proteins must be diluted, lactose, vegetable oils, and specific vitamins and minerals must be added. Whey protein is usually added to cow milk formula, but it has been found that whole goat milk is sufficient without this addition. Formulas may also contain a mixture of added vegetable oils with goat milk fat or vegetable oils only. There has yet to be a direct comparison between these approaches, but it is thought that goat milk fat may contribute to better absorption of minerals. There have been four clinical trials comparing goat milk and cow milk based infant formulas. In all the studies, growth in infants fed goat milk or cow milk formula did not differ and was comparable to breast-fed infants. In one study that assessed these outcomes, there were no differences in adverse health events and health-related outcomes. Infants received adequate supply of folate and iron with the goat milk formula. The microbiome was compared in one study, which found infants fed goat milk had a more similar composition to breast-fed infants than infants fed cow milk. There were no differences in allergy-related outcomes across the studies. Despite this, these studies were likely too small to detect such a difference due to the relatively low incidence of these symptoms, and therefore larger studies will be needed to further investigate this finding. These results summarise that goat milk-based formula is a safe option. In conclusion, there is still a lot to be learned about goat milk formula use in infants. It cannot yet be concluded if goat milk formula is a better option than cow milk formula, but there is evidence that they are broadly similar in what is known so far. Future large clinical trials may further reveal potential benefits.

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References

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