L-Tyrosine And Pregnancy

Many expectant mothers question the safety and effectiveness of dietary supplements during pregnancy. L-tyrosine, a nonessential amino acid, contributes to the body's production of melanin and improves the function of the thyroid, pituitary and adrenal glands. Although the body produces L-tyrosine on its own, the amino acid also is found in dairy products, bananas, soy products and avocados, and is available as a dietary supplement. Consult your obstetrician or midwife before using L-tyrosine or other dietary supplements during pregnancy.

Proposed Benefits

According to the University of Maryland Medical Center, L-tyrosine found in protein supplements might help treat people who suffer from phenylketonuria, or PKU, a serious health condition that affects the metabolization of phenylalanine. Because phenylalanine produces tyrosine, people with PKU might develop a tyrosine deficiency. Although L-tyrosine often is taken as a depression medication, there is little research that supports the efficacy of the supplement in treating the condition. Consult your physician before taking L-tyrosine supplements to treat PKU or depression during pregnancy.

Effect on Fetal Development

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L-tyrosine deficiency in expectant mothers who suffer from maternal PKU might cause birth defects, including low birth weight and congenital heart disease. Although earlier research indicated that L-tyrosine might have a positive effect on maternal PKU, a 2009 study published in "Molecular Genetics and Metabolism" reports that L-tyrosine supplementation increases tyrosine levels above the recommended amount and is not a valid treatment option. Talk to your physician about treatment options if you suffer from PKU and are pregnant or trying to conceive.

Side Effects

Mild side effects might occur as a result of taking L-tyrosine supplements. Reported side effects include nausea, fatigue, headaches and heartburn. Because these also are common ailments during pregnancy, the supplement might exacerbate these symptoms. Side effects are more common in concentrated or high dosages of the dietary supplement. Consuming foods that contain L-tyrosine poses no known side effects.


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Avoid using L-tyrosine supplements if you are taking certain medications, including thyroid hormones or monoamine oxidase inhibitors, or MAOIs. Because tyrosine aids in the production of thyroid hormone, it might cause excessive levels when used in conjunction with synthetic thyroid hormones. Taken with L-tyrosine supplements, MAOIs might lead to hypertensive crisis, or severe elevation of blood pressure, which can cause a stroke or heart attack. Pregnant and nursing mothers should avoid taking L-tyrosine due to a lack of current research on the safety and efficacy of the supplement.