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A new way to measure diet during pregnancy best predicts childhood allergy

Published: July 21, 2022

More and more children are developing allergic diseases such as food allergies, asthma/wheeze, atopic dermatitis and allergic rhinitis. Some scientists think that what a mother eats in pregnancy may influence the chances that her baby will grow up and develop an allergic disease later in life. There are many methods scientists use to measure diet, including dietary indices and measures of diet diversity. A dietary index gives a score to the quality of food a person eats and how much of each food. Measurements of diet diversity look at the total number of foods a person eats and may count only healthy or unhealthy foods. There are many indices and many measures of diet diversity. However, it is unclear which index or measurement should be used to determine if maternal diet during pregnancy is linked to an allergic disease in her child.

In a recent issue of The Journal of Allergy and Clinical Immunology: In Practice, Venter et al. assessed the effect of maternal diet during pregnancy on asthma, wheeze, atopic dermatitis or dry, itchy skin, food allergy, allergic rhinitis or seasonal allergies, and a combined outcome of any allergy, not including wheeze. The goal was to determine the best way to view maternal diet and any resulting allergic diseases in the child. The data came from the Healthy Start study. The study recruited pregnant women and collected information about their children from birth to four years old.

The authors compared 5 different ways to measure diet, including 1) the Healthy Eating Index, 2) a measure of total diet diversity, 3) a measure of healthy diet diversity, 4) a measure of unhealthy diet diversity, and 5) the maternal diet index. The maternal diet index is a new way to measure mothers’ diet in pregnancy and was designed to look at foods which seem to be linked to allergy in offspring. The maternal diet index includes foods linked with prevention of allergy, like yogurt and vegetables, and foods linked with risk of allergy, like red meat, rice and grains, fried potatoes, cold cereals and 100% fruit juice. Understanding which foods are most protective against offspring allergy can help scientists make recommendations to parents.

The study included 1218 pairs of mothers and children. All mothers provided detailed descriptions of their diet in pregnancy by recording what they ate for at least 2 full days and by describing their general eating habits. Medical records for the children gave information about diagnoses with allergic disease. Models were used to compare whether the different measures of diet for mothers in pregnancy were most predictive of allergy in the children. The investigators compared diets and looked at other factors like the child’s gender, race, ethnicity, duration of breastfeeding, and when solid foods were introduced. They also looked at whether the mother herself had asthma, other pregnancies, smoked while pregnant, and how many calories the mother ate on average when she was pregnant.

The maternal diet index, the Healthy Eating Index, and the healthy diet diversity index all predicted whether the child was diagnosed with at least one disease, including atopic dermatitis, food allergy, allergic rhinitis or asthma. The best prediction came from the new maternal diet index. Total diet diversity and unhealthy diet diversity did not predict child diseases very well. When the authors looked at the allergic diseases separately, the new maternal diet index was also the best way to predict whether the child got the specific allergy outcome.
Measuring both healthy and unhealthy foods in pregnancy helps give the most information about the risk of most allergies in children. It seems that eating more yogurt and vegetables, and reducing intake of low-fiber, sugary and fatty foods may help parents change the risk of allergy in their child. The researchers hope to conduct a clinical trial to see if what they observed can be tested carefully.  

The Journal of Allergy and Clinical Immunology: In Practice is an official journal of the AAAAI, focusing on practical information for the practicing clinician.

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