What is it?
L-tyrosine is a nonessential amino acid (protein building block) that the body synthesizes from phenylalanine, another amino acid. Tyrosine is important to the structure of almost all proteins in the body. It is also the precursor of several neurotransmitters, including L-dopa, dopamine, norepinephrine, and epinephrine.
Where is it found?
Dairy products, meats, fish, wheat, oats, and most other protein-containing foods contain tyrosine.
What do the advocates say?*
Since it is a precursor to substances like epinephrine, norepinephrine, and dopamine, L-tyrosine may be a good supplement choice for those trying to lose weight because, theoretically, it may help speed metabolism. However, it should only be considered for people who also suffer from symptoms such as fatigue and depression.
There are no studies specifically showing that L-tyrosine helps to promote weight loss.
L-tyrosine is best taken without food. Because it can be stimulating, especially when used in large amounts, it should not be taken in the evening. As is the case when supplementing with any individual amino acid, it’s possible to upset the balance by taking just one.
How much is usually taken by dieters?
Most people should not supplement with L-tyrosine. Some human research with people suffering from a variety of conditions used 100 mg per 2.2 pounds of body weight, equivalent to about 7 grams per day for an average-sized person. The appropriate amount to use in people with PKU is not known, therefore, the monitoring of blood levels by a physician is recommended.
Are there any side effects or interactions?
L-tyrosine has not been reported to cause any serious side effects. However, it is not known whether long-term use of L-tyrosine, particularly in large amounts (such as more than 1,000 mg per day) is safe. For that reason, long-term use of L-tyrosine should be monitored by a doctor.
Vitamin B6, folic acid, and copper are necessary for conversion of L-tyrosine into neurotransmitters.
Are there any drug interactions?
Certain medicines may interact with L-tyrosine. Refer to drug interactions for a list of those medicines.
*Dieters and weight-management advocates may claim benefits for L-tyrosine based on their personal or professional experience. These are individual opinions and testimonials that may or may not be supported by controlled clinical studies or published scientific articles on L-tyrosine. For more complete and detailed information, including references and safety information, see L-Tyrosine as a nutritional supplement.
Copyright 2007, Healthnotes, Inc., 1505 S.E. Gideon St., Suite 200, Portland, Oregon 97202, www.Healthnotes.com.
2006-09-07
