Thanks in no small part to the efforts of the Milk Marketing Board from the 1950s onwards (do you remember “Full of natural goodness”, “Milk’s gotta lotta bottle”, or “Drinka pinta milka day”?) dairy produce enjoys an almost unassailable position in British dietary culture. Milk is seen as vital, an indispensable source of calcium and vitamin D, the foundation stone for healthy teeth and bones.
The health-care professions have been as taken in as anyone; not even evidence implicating dairy in the development of later-life problems such as heart disease has been able to undermine the belief that, for our children to get the best start, they need to be pumped full of cheese and yogurt, all washed down with a glass of nice-coldice- cold milk.
This cultural enthusiasm for dairy led the medical profession into a collective, decades-long blindness. Even today, parents who believe their child to be allergic to milk are likely to be dismissed as oddballs, clutching at improbable straws in an attempt to understand their offspring’s health problems. Dreadful eczema? That’s a skin disease. Intractable abdominal pain and digestive mayhem? There must be something wrong with the gut. Chronic cough and mucous? That’ll be the lungs.
Milk, after all, is what babies are made of. What could be wrong with such a natural, wholesome food? However, because of a growing body of research, there is a dawning appreciation that allergy to the proteins in cow’s milk is behind a range of childhood illnesses.
The journey towards this understanding has been made difficult by several confounding factors. First, there is more than one type of allergic reaction. Immediate hypersensitivity to milk, which is rarer, is easy to diagnose. Directly after exposure to cow’s milk protein, the affected individual displays a florid response, which includes swelling of the lips, face and eyes; a wheeze and breathing difficulty; and a rash called urticaria, which looks like widespread nettle stings.
Much more common in cow’s milk protein allergy (CMPA) is delayed hypersensitivity. This is tricky. There is no clear link in time between exposure and symptoms. These babies tend to have difficult-to-treat eczema, refractory respiratory problems and a range of digestive disorders such as reflux (where acid stomach contents come back into the gullet and mouth), diarrhoea or constipation, colicky pain and even bleeding into the bowel.
We still do not completely understand delayed hypersensitivity and it is likely to be more common than its currently estimated prevalence of around 5 per cent.
Even when delayed hypersensitivity is suspected, there are a number of factors that can frustrate the diagnosis. Unlike immediate hypersensitivity, there is no blood or skin-prick test that can be given. Confirmation can only come from strict exclusion diets, where one would expect symptoms to resolve over a period of between two and eight weeks.
Exclusion diets are hard to stick to. Doctors frequently advise parents to switch to soya-based products, but there is crossreactivity between cow’s milk and soya protein in around 60 per cent of cases. Failure to improve when on a soya-only diet is often mistakenly interpreted as ruling out CMPA.
Another common misconception is that breastfed babies can’t develop CMPA, yet the offending proteins in a dairy-consuming mother will cross into breast milk and provoke allergy in just the same way as with bottle-fed infants.
From an evolutionary perspective, consuming milk beyond babyhood is unnatural, yet all infants depend on milk in their first year or so. Breastfeeding mothers with allergic offspring can go dairyfree but bottle-fed babies are, figuratively speaking, up a gum tree.
Fortunately, there are now a number of formulas available to treat CMPA. In each, the protein components are hydrolysed – chemically “chopped up” into smaller units –which are less likely to provoke an allergic response. But these are very expensive and their growing use is a source of concern to those responsible for NHS prescribing budgets.
A better long-term solution is to encourage and support breastfeeding – currently fewer than a quarter of new mothers are still exclusively breastfeeding at six weeks.
This needs to be coupled with a thorough rethink of our relationship with dairy foods. Even experts in the field of CMPA remain spellbound by the belief that milk is essential for calcium and vitamin D, advising breastfeeding mothers to take artificial supplements if they are cutting out dairy.
But, in reality, milk is a relatively mediocre source of these nutrients. There are innumerable other foodstuffs that carry more calcium than milk – broccoli, figs, almonds, sesame seeds and leafy green vegetables, to name but a few.
As for vitamin D, getting ourselves and our children out into natural sunlight every day is nature’s time-honoured solution. Who knows, we might even inculcate a renewed enthusiasm for fresh air and exercise into the bargain.
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