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Breast Feeding and 'Food Allergy'

Dr David L. J. Freed, MB, MD, MIBiol Allergist; Professional Advisor to LLLGB

I am frequently asked whether good nutrition during pregnancy and lactation helps to prevent allergies, both in the mother and in the child in later years. Food allergy and food intolerance are getting more common, and it is probable that the poor eating habits of teenagers is partly responsible for that.

Starting at the earliest moment, straight after birth, the best nutrition of all is that provided by mother's milk.This wonderful food also provides immunological protection for the baby and activates mother/baby love. The composition of mother's milk changes according to the weather and other factors, so as ideally to suit baby's changing needs. The breast is a complex biochemical and immunological factory, constantly sampling mother's bloodstream and passing onto the baby tiny doses of food molecules that mother herself has been eating. To these food molecules the breast adds a healthy dose of antibodies against those food molecules, thus preparing the baby gently for the day when he will start on those foods himself.

Problems can arise, though, when the baby himself is allergic to one of these foodstuffs. This is more likely if one or both parents are themselves allergic, but can also strike "out of the blue", in a baby with perfectly healthy parents. The result is a baby who is "allergic to his own mother's milk!" - at least some of the time. He's not really allergic to mother's milk, only to the traces of that particular food that mother has ingested. If the baby starts shrieking a few hours or a day after the mother ate prawns, for example, you don't have to be a genius to make the connection. Of course, babies shriek for all sorts of other reasons too, and it may be impossible to be sure. If the baby is allergic to a food the mother takes every day, he may well shriek every day (and night), probably because his tummy hurts all the time. Severely allergic babies may have chronic diarrhoea and fail to grow properly.

Sadly, the commonest foodstuff to cause allergies is cow's milk and its various products, and this of course is one of those foodstuffs that most mothers have every day, in one form or another.So if a baby cries all the time when being breast fed, the mother would be well advised to try the experiment of omitting milk herself for a few days. If baby quietens down, mother will have to continue avoiding milk, and will need to find other sources of calcium, vitamins and protein until after weaning. If milk avoidance doesn't help, it may be some other food antigen, such as fish, citrus, coffee or soya, and it will be a good idea for mother to try the effect of avoiding those also. If that also fails to improve matters, guesswork has failed, and the last resort will be a GP referral to the Regional Immunology Laboratory, where it may be possible to get her milk sampled for food antigens. Certainly it is NOT a good idea to abandon breastfeeding without at least trying!

Whether breast-feeding protects the baby against developing allergies in later life is still controversial (breast-feeding is a particularly emotive subject!) but in general the positive evidence is mounting and getting stronger, and can now be accepted as the truth, especially when one or both parents are also allergic. The best is exclusive breast-feeding, with baby having nothing at all apart from that, not even a drink of water. (Don't worry about baby becoming dehydrated. On very hot days, babies regulate their intake, if allowed to, and the milk becomes more watery - they are at no risk).

But if baby has had some other feed apart from mother's milk, don't despair; any breast milk is better than none. The entire anti-allergic effect of breastfeeding is likely to be lost if the mother smokes. (Even the father smoking will encourage allergies to some extent).

The commonest foods to cause allergic reactions are (in approximate order of frequency)
(1) milk and its products,
(2) wheat,
(3) food preservatives, colouring's, or other additives,
(4) fish,
(5) soya,
(6) citrus,
(7) coffee.

Artificial sweeteners are also somewhat worrisome; theoretically it would not be surprising if they caused allergic reactions, but in practice reports of clinical reactions are still rare. After those common food allergens, the list goes on to a huge variety of other foods, all of which can cause allergy sometimes but not so frequently. Some mothers, if they have themselves had allergies, are advised to avoid the commonest allergens during pregnancy and lactation, whether or not they have reactions to them. They are also advised not to wean their babies onto milk, wheat etc but onto "safe" foods like lamb or potato. I think this advice is both too lenient and too restrictive. On the one hand, there is no such thing as a "safe food" in allergy; who is to say that this particular baby might not be allergic to lamb and potato? On the other hand, by avoiding milk and wheat until long after weaning, we may be denying the baby their goodness while also losing the safety factor given by early breast-feeding.

Weaning, in my view, should begin at whatever age the baby starts to reach out for the foods on mother's plate, and the baby should be offered exactly those foods that she was herself consuming while lactating (obviously they will have to be liquidised or otherwise made suitable). There is no point in using tins and jars of manufactured "baby-food" - why should they suit baby any better than anything else? Provided mother has been eating bread (for example) frequently during lactation, with no obvious problems, baby should be given bread as well, preferable wholemeal, so as to get accustomed to it and derive its full value while still protected by his mother's milk. It might even protect against later allergies. If in spite of that allergic reactions still develop, they will soon become obvious and only then will it be necessary to avoid that food.

Somewhat related is the subject of pets. Having a furry pet in the child's family can often help prevent allergies developing in later life - but once allergies have developed it's too late, and the cat will have to go.

Be on the watch, during the toddler years, for the development of food addictions. This seems a strange, even paradoxical concept, but it happens. Certain foods contain peptides (partially digested proteins) which exert an effect rather like a small dose of morphine - hence the name exorphins. This effect cannot work in a child with a healthy strong digestion, only in one whose digestive system leaves proteins partly undigested, but there is no easy way of telling this in advance. If you see a child gradually becoming more faddy and picky about his food, watch to see what it is he really likes, and will eat a lot of. There's almost always something. Once again, the commonest food addictants are milk, wheat, and caffeine. The classic picture is of a child who will eat nothing but breakfast cereal with milk, plus bread/toast/biscuits, chocolate and cola drinks. Offer him meat and green vegetables and he'll suddenly lose all appetite, even though he strongly maintains he's hungry. This is food addiction. It is not a true allergy, but is likely to lead to one in years to come (besides being nutritionally unbalanced). It can be nipped in the bud, if spotted early, by keeping the diet varied, so that no food item becomes a daily habit.

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