High levels of vitamin D in pregnant mothers can raise their baby's risk of developing food allergies after birth, a new study has claimed.
Researchers from the Helmholtz Centre for Environmental Research (UFZ) and the Martin Luther University in Halle-Wittenberg in Germany found that pregnant women should avoid taking vitamin D supplements.
The long term study included 622 mothers and their 629 children. 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 results indicated that 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.
Scientists also got evidence for the mechanism that could link vitamin D and food allergies. Dr Gunda Herberth 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.
It was found that 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.
"Based on our information, an excess of vitamin D can increase the risk of children developing a food allergy in the first two years of their life," researchers said in a statement.
The study was published in the journal Allergy.
