Washington: High vitamin D levels in expectant mothers appear to raise the risk of children developing a food allergy after birth, a new study has found.
The survey carried out by the Helmholtz Centre for Environmental Research and the Martin Luther University in Halle-Wittenberg in Germany has concluded that pregnant women should avoid taking vitamin D supplements.
Dr. Kristin Weibe`s team from Leipzig used samples from the LiNA cohort that the Helmholtz Centre for Environmental Research (UFZ) had established together with the St. Georg municipal clinic between 2006 and 2008 headed by Dr. Irina Lehmann.
The level of vitamin D was tested in the blood of the pregnant mothers and also in the cord blood of the children born. In addition to this, questionnaires were used to assess the occurrence of food allergies during the first two years of the children`s lives.
The result was clear: in cases where expectant mothers were found to have a low vitamin D level in the blood, the occurrence of food allergies among their two-year old children was rarer than in cases where expectant mothers had a high vitamin D blood level.
In reverse, this means that a high vitamin D level in pregnant women is associated with a higher risk of their children to develop a food allergy during infancy.
Furthermore, those children were found to have a high level of the specific immunoglobulin E to food allergens such as egg white, milk protein, wheat flour, peanuts or soya beans.
The UFZ scientists also got evidence for the mechanism that could link vitamin D and food allergies.
Dr. Gunda Herberth - also from the Department of Environmental Immunology at the UFZ - took a closer look at the immune response of the affected children and analysed regulatory T-cells in cord blood in particular. The cells are capable of preventing the immune system from overreacting to allergens, with the result that they protect against allergies.
The UFZ researchers know from earlier analyses that the allergy risk increases in cases where too few regulatory T-cells are present in cord blood. The interesting result of the current research project: the higher the level of vitamin D found in the blood of mothers and children, the fewer regulatory T-cells could be detected. The correlation could mean that vitamin D suppresses the development of regulatory T-cells and thus increases the risk of allergy.
Apart from diet, Dr. Kristin Weibe explained that the level of vitamin D is mainly affected by conditions such as season, exposure to the sun and the amount of time spent outdoors - these factors were also taken into account in the current risk analyses of vitamin D and food allergy.
Even though the occurrence of food allergies is undoubtedly affected by many other factors than just the vitamin D level, it is still important to take this aspect into consideration.
The study was published in the February issue of the medical journal Allergy.