How safe is cow’s milk in the raw and homogenised state? When can cow’s milk be given to infants and how can we protect children against developing allergies to cow’s milk?
These are just some of the questions that have come up in the media lately and are in need of some clarification.
A market has grown recently in New Zealand for raw milk. This is best defined as a milk product, from a cow, goat sheep or other animals udder, which has not been heat-treated to kill bacteria.
Raw milk has missed the pathogen elimination step, which prevents bacteria passing from an infected udder into milk, or contamination from the farm environment e.g. faecal contaminants on the teats of cow’s crossing into the milk.
The pro’s and con’s of raw milk production
Those who promote raw milk sales believe:
- That the protein in raw milk is healthier as it has not been denatured by heating
- The full fat in the milk is retained at a level around 4.5-6% compared to 3.3% in pasteurised milk.
- Some believe that this higher fat level in the diet can aid weight reduction
- Raw milk contains higher levels of vitamins D, K, B and C.
- Raw milk has not been homogenised. A process in milk production which breaks down the fat particles so that the cream remains in the milk suspension rather than separating out. Homogenisation also increases the shelf life of milk.
However there is some concern that once broken down into smaller particles the fat combines with an enzyme Xanthine Oxidase (XO) allowing it to pass easily into the blood stream thereby increasing the risk of atherosclerosis and heart disease. In raw milk the XO is free-floating and harmlessly digested.
Currently in New Zealand whole cream milks such as Anchor (silver top) and ® (farmhouse) milks are not homogenised. When milk is manufactured it is the cream is separated out (leaving cream and skimmed milk) then standardised (cream put back according to the type of milk being made) then homogenised and finally pasteurised.
While research is continuing into the action of XO it is important to note that low-fat milks such as Trim® and Calci-Trim® milks have had much of their fat removed before they are homogenized and these are the milks that are recommended as part of a healthier diet for all New Zealanders over 5years of age.
The MOH in New Zealand recommend that care should be taken when drinking raw milk as it may contain harmful bacteria such as Salmonella, E coli 0157, campylobacter and Listeria Monocytogens.
The ministry recommend that groups at risk of illness such as children, the elderly, pregnant women or those with weakened immune systems should avoid raw milk.
Raw milk production is illegal in many countries including Australia and Canada. In the UK raw milk must carry warning labels.
A total of 55 cases of hospitalization have been linked with raw milk consumption in NZ nationwide over the past 2 years.
Safety advice if using raw milk
- Buy this milk from trusted farmers
- This trust being dependent on their adhering to safe practices for the milking, manufacturing, storage, transporting and exporting of raw milk products as outlined by the government and ministry for primary industries.
- Refrigerate raw milk at 4 deg C or less.
- Discard raw milk that has spent more than 2 hours at room temperature.
- All those people mentioned in the “at risk category” should heed the warning and avoid it.
When can infants drink cow’s milk?
When the milk producer ‘Fonterra’ expressed concern in August this year that whey protein concentrate, identified as being supplied to Nutricia® (for infant formula production), might have been contaminated with the harmful bacteria Clostridium botulinum, many mothers of formula fed babies began looking for substitutes.
While this concern was later revoked talk back radio fielded many calls from people at the time who recommended old-fashioned remedies such as giving babies scalded cow’s milk.
A better alternative would have been to recommend that parents should look for an alternative brand of infant formula.
Cow’s milk is not recommended to children under 12months because:
- Cow’s milk is a poor source of Vitamin E and essential fatty acids
- Cow’s milk is low in iron and can lead to iron deficiency if used excessively..
- As it contains high levels of protein, sodium and potassium this can put unnecessary strain on the infant’s immature kidneys.
By comparison breast milk changes to suit the infants needs as it grows:
- Initially colostrum contains more protein, vitamin A and sodium chloride and a lower content of lactose, fat and potassium than normal milk. Colostrum lasts for around 2 weeks and is packed full of immune factors which continue to protect infants from infections for as long as they are breast-fed.
- At the transition phase the breast milk still contains protein along with slowly rising levels of lactose and fat.
- Mature breast milk contains slightly less protein but more fat and lactose than transitional milk. It is also a good source of calcium and iron, polyunsaturated fat for retinal and brain development and taurine to aid fat absorption.
For those unable to breast feed, infant formula now contains many of these nutrients. However it does not contain the human anti-bodies and lymphocytes that help to safe guard infants from life threatening diseases such as chest, ear and urinary infections and meningitis. Breast milk also minimises the risk of diarrhoea and protects the infant from allergic reactions such as eczema.
The MOH recommend the following milks for children:
- Under 2yrs breast milk or formula. Standard (silver top) milk can be introduced after 12mths
- 2yrs on gradually change to fat reduced milks e.g Light blue or Mega milk® then transition onto low-fat milks such as Trim® or Calci-trim® as these milks contain more protein and calcium and less fat than whole milk and are suitable for the whole family.
Can cow’s milk allergy be prevented?
It was once believed that if mothers avoided an allergen during pregnancy and whilst breast-feeding (eg cow’s milk, egg, soy etc) it would help prevent their off spring from developing food allergy.
This is now considered incorrect and that later introduction of allergens found in cow’s milk, peanut, egg etc is associated with an increase rate of allergy to that food.
While general feeding guidelines recommend solids are introduced to children at 6mths, allergy prevention advice is that solids can be introduced from 4mths onwards, with no case for avoiding commonly allergenic foods.
If you have a strong family history of food allergy then discuss this with your GP or Paediatrician.
Testing for one type of food allergy( using skin prick or ssIgE) will often discover another. In one study around 40% of infants presenting with cow’s milk allergy had egg allergy.
Also for some allergens (e.g. egg and milk) total avoidance is not always necessary. Up to 75% of egg or cows milk allergenic children may tolerate this as an ingredient in well cooked foods (e.g. a baked product).
Some confusion does exist regarding food labelling. Particularly when the label may say that there a potential trace of an allergen. At present Dietitian’s are working with the MOH and manufacturers to help to align the food guidelines with what is in the product. .
Infants with cow’s milk allergy need an alternative for weaning or supplementation of breast-feeding. Goat’s milk is not a good substitute as there is extensive cross reactivity. Special authority funding is available for extensively hydrolysed formula (eHF) and amino acid formula (AAF) for infants meeting PHARMAC criteria, but need to be regularly re-evalulated as AAF is an expensive alternative. Many infants with cow’s milk allergy can tolerate soy.
Luckily most (80%) of children allergic to cow’s milk are able to tolerate it by the age of 5 years.
Milk is a valuable source of calcium, zinc and B group vitamins required throughout life. While some people do dislike the flavour of it and others may have allergies or intolerances to milk there are always alternative types of milks that can be tried.
Encouraging children to drink milk and water is a healthier alternative to consuming fruit juice and carbonated drinks.
For more information read Lea’s articles on:
If you would like to discuss any of these issues or have a nutritional assessment to determine your own calcium requirements then contact us today
Ministry of primary industries Information on Raw milk and also Infant formula recall www.mpi.govt.nz
Sinclair J, Brothers S, Jackson P, Stanley T, Ang M, Brown P, Craig A, Daniell A, Doocey C, Hoare S, Lester S,McIlroy P, Ostring G, Purvis D, Sanders J, Smiley R, Sutherland M, Townend T, Wilde J, Williams G. IgE mediated food allergy- diagnosis and management in New Zealand children. The NZ Med Journal 16 Aug 2013, Vol 126No 1380; ISSN 1175 8716