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The Side Effects of Folic Acid Intolerance

author image Joe King, M.S.
Joe King began writing fitness and nutrition articles in 2001 for the "Journal of Hyperplasia Research" and Champion Nutrition. As a personal trainer, he has been helping clients reach their fitness goals for more than a decade. King holds a Bachelor of Science in kinesiology from California State University, Hayward, and a Master of Science in exercise physiology from California State University, East Bay.
The Side Effects of Folic Acid Intolerance
Grains and wheat are fortified with extra folic acid. Photo Credit Ingram Publishing/Ingram Publishing/Getty Images

Folic acid, or vitamin B-9, is one of the water-soluble B-complex vitamins that is essential for numerous body functions, including DNA replication and repair as well as cell division and growth. Although folic acid is considered an essential part of your diet and is found in many foods such as flour, grains, rice and pasta, some individuals have an intolerance, or allergy, to folic acid. If you have a folic acid allergy, you are advised to stay away from foods containing high amounts of folic acid and folate in order to help minimize the symptoms of an allergy.

Causes of Folic Acid Intolerance

Allergic reactions to folic acid are caused by the inability of your immune system to decipher what folic acid really is when it is introduced to your body. Instead of allowing your immune system to digest and absorb folic acid, your immune system will fight against it, identifying folic acid as a harmful threat to your body instead of a helpful vitamin. Your immune system will react to folic acid by producing antibodies and histamine that may cause symptoms similar to the common allergy. Even if only minor symptoms occur, you may be at greater risk for a more serious allergic reaction to folic acid.

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Drug Interactions and Folic Acid Allergy

Even if you are not normally intolerant to any vitamins, a folic acid allergy may occur when it is ingested in combination with certain drugs and medications. Folic acid may decrease the effectiveness of some cancer drugs, because these drugs are meant to inhibit cellular reproduction while folic acid promotes it. Folic acid may also affect the effectiveness of drugs to treat neurological disorders such as schizophrenia and psychosis due to a disruption in the release of neurotransmitters in your brain. If you are on certain cancer and anti-psychotic medications, you may also increase the risk of developing an allergy to folic acid.

Symptoms of an Allergic Reaction

An allergic reaction to folic acid typically affects your skin, lungs, sinuses and intestinal tract. You may develop skin rashes or hives, as well as irritation and redness of your skin as a result of an allergic reaction to folic acid. Respiratory effects include coughing, wheezing, difficulty breathing and a tightness in your chest. Your sinuses may feel excess pressure and nasal congestion, and your digestive system may experience nausea, bloating, gas and diarrhea as a result of folic acid intolerance. Consult your physician if you experience any of these symptoms to determine whether folic acid is causing them or if another substance is involved.

Folic Acid Intolerance Considerations

Since folic acid intolerance manifests itself as a generic allergic reaction in most cases, it may be easily mistaken for a host of other common allergies. Some foods that naturally contain folic acid may also contain other nutrients that can be highly allergic, therefore your symptoms may not necessarily be the result of folic acid intolerance, but rather an allergy to a different nutrient contained within the food. Proteins found in shellfish, meat, grains and certain vegetables may be the root cause of your allergy, and not folic acid. Consult your physician for an allergy test to determine which nutrient is actually causing your allergic reaction.

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  • "Nutrition for Health, Fitness, and Sport"; Melvin H. Williams; 2002
  • "The New Encyclopedia of Vitamins, Minerals, Supplements, and Herbs"; Nicola Reavley; 1999
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