Hi Alison,
This is an interesting question - I am regularly met with questions regarding the digestability, safety and nutritional adequacy of animal milks such as UHT when these are proposed for non-breastfed infants as part of an emergency response.
With regards to your question about which age group should not receive animal milk (U6M or 1 year), this varies per setting (e.g. the recommendation is 1 year in the UK, the OG-IFE 2017 Section 5.15 suggests 6 months). Note that the 2021 UNICEF Programming Guidance on Procurement and Use of BMS in Humanitarian Settings states the following:
"Infants and young children older than 6 months of age who do not receive breastmilk can use RUIF if available and affordable. However, whole fat milk that has undergone ultra-heat treatment (UHT) can also be used for this age group and will be cheaper. Alternative milks, including pasteurized full-cream milk from a cow, goat, sheep, camel or buffalo; ultra-high temperature liquid milk; fermented liquid milk; or yogurt could also be used. These alternatives are all safer than PIF."
My understanding is that this is a "compromise" for resource-limited emergency settings. Unfortunately no reference is provided but I assume the statement on safety is referring to PIF risks around hygiene, bacterial growth etc. but not necessarily nutritional adequacy (e.g. UHT vs. Stage 1 Formula) - it would be interesting to learn more from colleagues at UNICEF regarding this.
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Page 10 of this First Steps Nutrition Guidance on Animal milks in the diets of children aged 1-4 years answers the question "Are there any nutritional risks associated with animal milk consumption?" stating - amongst other risks - that animal milk is a poor source of iron and it is for this reason that UK dietary guidelines advise against the introduction of cows’ milk into the diets of children before the age of 12 months.
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With regards to cheaper powdered milks such as follow-on formula, here is the FSN Guidance on Drinks for young children marketed as ‘growing-up’ and ‘toddler milk’ . High free sugar content is a key concern. Some interesting quotes:
‘Growing-up and toddler milks are marketed as an alternative to whole cows’ milk for toddlers and children over 1 year. There’s no evidence to suggest that these products provide extra nutritional benefits for young children’ (NHS, 2021).
‘No unique role of young-child formulae with respect to the provision of critical nutrients in the diet of infants and young children living in Europe can be identified, so that they cannot be considered as a necessity to satisfy the nutritional requirements of young children when compared with other foods that may be included in the normal diet of young children.’ (European Food Safety Authority - EFSA, 2013)
Risks are covered on page 5.
Hope that helps a little - Isabelle