Pregnant women who eat a Mediterranean diet could protect their unborn child against asthma and other allergies later on, according to The Sun and other newspapers. A diet “high in vegetables and fish leads to fewer allergies once children are born”, the newspaper added. The Daily Mail said that “eating red meat more than three or four times a week appeared to increase the risks”.
The newspaper stories are based on a study in 468 Spanish women and their children which concluded that a Mediterranean diet in pregnancy reduced the risk of wheeze in children aged 6½. However, the study did not look at children who had a clinical diagnosis of asthma. Also, it relied on reports on diet from the mother six and a half years after the pregnancy; it is unlikely that this would have been remembered accurately. Asthma and allergies are common in children and have many causes, including family history. The study uses some weak methods and the newspapers have overstated the relationship between a mother’s diet during pregnancy and asthma-like symptoms in her children.
Another publication used data from this study which focuses on the child’s diet and risk of wheeze, and Behind the Headlines has previously identified its shortcomings – Behind the headlines: Eating, asthma and allergies. Much more research is needed before any causal link between what children or their mothers eat and the risk of allergy or asthma can be established.
Dr Leda Chatzi from the University of Crete and colleagues from other medical and academic institutes in Spain and Mexico carried out this research. The study was funded by Instituto de Salud Carlos III red de Grupos Infancia y Media Ambiente, the Fundacio ‘‘La Caixa’’, the Instituto de Salud Carlos III red de Centros de Investigacion en Epidemiologia y Salud Publica and an EU grant. The study was published in the peer-reviewed medical journal: Thorax .
The study was a small cohort study of 507 pregnant women, recruited between 1997 and 1998, and the children that were born, when they presented for antenatal care at general practices in Menorca, Spain. They were followed until their children were 6½-years-old. Four hundred and sixty-eight mother-child pairs that had complete data available at the end of the study were included in the analysis.
Each year, the parents were asked (through interview and questionnaire) about any medical events the child had experienced in the preceding 12 months. At the six and a half year follow up stage, the researchers determined whether the child had any asthma like symptoms (either currently or over the past 12 months or in preceding years) or allergies (using a skin prick test). Parents also filled in a food frequency questionnaire that would provide details of their child’s diet at 6½. A shorter food frequency questionnaire about the mother’s diet during her pregnancy was also completed. From these questionnaires, the researchers assigned scores to diet during pregnancy and the child’s diet that represented how carefully a Mediterranean diet was being followed (this was based on the intake of foodstuffs such as vegetables, legumes, fish, nuts, etc).
Details on education, socioeconomic class, marital status, maternal disease, child’s exposure to cigarettes, breastfeeding, use of supplements, child’s respiratory infections at one year old and other information were collected at a questionnaire during pregnancy and again at the end. Weight and height data were also collected from children at the six and a half year follow up. All of this information was used to adjust the analyses.
The researchers found that the child’s diet at 6½ years had little effect on the risk of persistent wheeze (one or more episodes of “whistling or wheezing from the chest” in the past year and in any preceding year), current atopic wheeze (wheeze associated with allergies) or current allergies alone (based on skin prick test).
The children of women who had a high adherence to a Mediterranean diet during pregnancy were less likely to have persistent wheeze, atopic wheeze or atopy at 6½ when compared with children of mothers who had low adherence scores. The results took into account gender, maternal and paternal asthma, maternal social class and education, body mass index and total energy intake at age 6½.
The researchers conclude that high adherence to a Mediterranean diet during pregnancy reduces the risk of wheeze and atopy in children at 6½.
This cohort study provides some evidence that a mother’s Mediterranean diet during pregnancy reduces the risk of allergies and asthma-like symptoms in their children. However, the following should be considered alongside these results:
Asthma and allergies are common in children and have multiple causes, including family history. Much further research is needed before any link between what children or their mothers eat and risk of allergy or asthma can be made.
Olive oil? Wonderful, not just for pregnant women and it tastes terrific too.