Pregnancy and diet

Q. My first child is food intolerant and I am now pregnant again. Will what I eat during the pregnancy affect my baby's chances of having intolerances too? Is there anything I can do to minimise the problem?

A: When talking about diet in pregnancy, it is important to distinguish between allergies and intolerances, see factsheet on allergies and intolerances.


In families with a history of true allergy such as asthma, eczema and hayfever, avoidance of common allergens - especially nuts and peanuts, but also any known allergies in the family, eg dairy foods, egg, soy, wheat - is recommended in the last six to eight weeks of pregnancy and while breastfeeding. True allergies can be detected by skin prick tests.

Preventing allergy

There is evidence that taking lactobacillus GG (in Australia only available in Vaalia yoghurt) during late pregnancy and breastfeeding may help to prevent the development of childhood allergies. There is more information about this in the babies and children chapter in my book Fed Up.


For families with a history of food intolerance, it is thought that avoidance of salicylates and food additives during pregnancy will not prevent the development of food intolerance. Of course, the failsafe diet is recommended during breastfeeding if the baby is unsettled - with the supervision of a dietitian.

I recommend avoidance of ribonucleotides (flavour enhancers 635, 631, 627) - these additives are different from all others and reports suggest that they may in fact trigger food intolerance in unborn babies. I also recommend avoiding other additives, especially the bread preservative (propionates 280-283) and artificial food colourings. The safety of food additives on developing brains with regard to learning abilities have not been sufficiently tested and there are some rat studies which suggest negative effects.

Exposures which can worsen intolerances

Intolerances in susceptible children can be made much worse by exposure during pregnancy to a variety of toxic chemicals. It is a very good idea to avoid pesticides inside and outside the home, especially organophosphates such as chlorpyrifos and diazinon, but any pesticides are a risk. Avoid also solvents, strong household cleaners and volatile organic chemicals, eg in paints and glues, new homes, and new cars. Pregnancy and early childhood is not the time to have houses treated for pests or renovated. See also factsheet on Fumes and Perfumes.

When following the failsafe diet during pregnancy or breastfeeding, it is important to get a dietitian to check your nutrition, as requirements change.

Further reading:

Introduction to food intolerance

Factsheet on fumes and perfumes

Effects of exposure to pesticides and other toxic chemicals during pregnancy - 'Johnny can't read' -

Brusque AM and others. Chronic administration of propionic acid reduces ganglioside N-acetylneuraminic acid concentration in cerebellum of young rats. J. Neurol. Sci. 1998;158(2):121-4.

The information given is not intended as medical advice. Always consult with your doctor for underlying illness. Before beginning dietary investigation, consult a dietician with an interest in food intolerance. You can see our list of experienced and supportive dietitians 

© Sue Dengate update 30 June 2003