The pros and cons of replacing milk with powdered whey supplements.
Question: Friends gave us a powdered whey supplement, called Zeal, as a milk alternative for our two-year old son who has asthma. His asthma is minor, but I 
wonder whether this supplement could be of some value in making him less chesty/asthmatic. But if we use this supplement instead of milk, will he be missing out on anything?
Answer:
Asthma, allergy and atopic dermatitis rates have climbed in the past few decades, most notably in westernised countries. And this raises the question: what is it about westernised society that increases the risk of asthma, allergy and atopic dermatitis?
For starters, westernised countries contain more urban areas. However, rates of asthma and hay fever in urban and rural children are relatively similar. But, delve deeper and an intriguing disparity emerges.
Among children who live in rural areas, large differences occur in the rates of childhood asthma, hay fever and atopic sensitisation. In particular, children who grow up on farms have a significantly lower risk of these conditions than children who live in a rural area but not on a farm. It seems living on a farm provides protection against asthma, hay fever and various other allergies.
Having contact early in life with livestock (such as cattle, pigs and poultry) and livestock feed (such as hay, grain, straw and silage) and consuming unprocessed cow’s milk appear to be primarily responsible for this protection against asthma and allergies, according to a 2010 paper in Nature Reviews Immunology. However, the timing of exposure may be crucial, with exposure in utero and during the first years of life providing the strongest effect. Indeed, a 2008 New Zealand study, published in the European Respiratory Journal, found exposure to livestock and livestock fodder from conception to school age provided the strongest protection.
The impact of unprocessed cow’s milk on health is an interesting topic. It’s typically recommended that pregnant women and children avoid raw milk, given the higher risk of food-borne illness. However, dairy-farming families, including pregnant women and small children, frequently consume raw milk. And several studies have found that this unprocessed milk is associated with a reduced risk of asthma, hay fever, allergic sensitisation and atopic dermatitis.
The Gabriel study (a European study aimed at identifying genetic and environmental causes of asthma) found the consumption of raw milk, but not boiled milk, was associated with a reduced risk of asthma and hay fever, independent of other farm exposures. More specifically, the levels of whey proteins in the milk were inversely associated with asthma, but not with atopy, according to the findings in the Journal of Allergy and Clinical Immunology.
Milk contains two kinds of proteins: whey and casein. On one level, it makes sense that whey proteins in raw milk would have a protective effect: whey proteins in milk are less stable than casein proteins when heated. Which is what happens when milk is pasteurised – it’s held at between 72°C and 75°C for up to 30 seconds to reduce micro-organism levels.
However, considerably more research is needed before whey supplements can be recommended for children with asthma.
Nevertheless, the Zeal whey supplement is being marketed as a healthier alternative to cow’s milk for children. Worryingly, this supplement provides just 0.2g fat per 200ml (about 0.1%), which is much too low a level for a child under five.
The Ministry of Health recommends children under five have the equivalent of 500ml of milk daily as it is a relatively cheap source of energy, protein and other important micronutrients. But the Zeal supplement has just half the energy content of cow’s milk, is lower in protein, is considerably lower in vitamin B12 and has only about half the amount of calcium.
Short of moving your child to a farm, your best option is to continue using cow’s milk – unless your son has a diagnosed milk allergy – and await more research on the topic of cow’s milk, asthma and allergies.