Folic Acid in Pregnancy Possible Link to Food Allergies

New research has found a possible link between folic acid exposure in the womb and food allergies in early childhood.  The research was presented at the American Academy of Allergy Asthma and Immunology (AAAAAI)/World Allergy Organisation (WAO) Joint Congress in March 2018.

Researchers have found that babies who were exposed to high levels of folic acid in the womb had higher rates of food allergies.  However, more research is needed to find out whether this is due to pregnant women taking folic acid supplements or a genetic difference, or both.

Folic acid, or folate, is also known as Vitamin B9.  Folate is the natural form, as it is used in the body and found in foods such as:

  • leafy green vegetables (such as spinach, Brussels sprouts, broccoli, kale, cabbage and cauliflower),
  • citrus fruits (including orange juice),
  • whole grain foods,
  • lentils,
  • beans,
  • yeast extract,
  • poultry, pork and shellfish.
  • Liver is also high in folate, but is not safe to eat during pregnancy as it contains high levels of Vitamin A.

Folic acid is synthetic and is the type found in most supplements and fortified foods (e.g. some breakfast cereals).

Folate is really important for the normal development of a healthy baby, as it can reduce the chances of defects in the brain and spinal cord, such as spina bifida.    Most people get enough folate from their normal diet, but during pregnancy, it can be difficult to get a high enough level of folate from diet alone because you need so much more than usual.  In the UK, women are advised to take folic acid supplements while they are trying to conceive and for at least the first 12 weeks of pregnancy.

Most supplements contain folic acid.  The body has to convert this into a form of folate that it can use using an enzyme called MTHFR.  Folic acid that is not converted into folate is called ‘unmetabolised folic acid’.  This is what has been linked with a higher rate of food allergies.  Some people have a faulty MTHFR gene and are unable to convert folic acid into folate effectively and this could be a possible cause.

Some supplements are available that contain folate.  This will be listed in the ingredients of the supplement as “5-methyltetrahydrofolate” or “5-MTHF” on the label.  Taking this type of supplement avoids the buildup of unmetabolised folic acid, as it is already in the form that the body can use.

During pregnancy, it is really important to ensure you have a high enough intake of folate by eating plenty of foods rich in folate as well as taking a supplement.  If you are concerned about the risk of food allergies, for example if you have a family history of allergies, eczema and asthma, you may prefer to look for a supplement that contains a form of folate and avoid supplements containing folic acid.  If you are unsure, speak to your midwife or doctor for further advice.