CLINICAL USES FOR L-TYROSINE
Several clinical studies have linked L-tyrosine with relief from symptoms of physical or environmental stress, such as intense cold or heat. In a study of military cadets, published in “Brain Research Bulletin” in 1999, those who supplemented with 2 grams of L-tyrosine for five days showed better memory and cognitive performance in a stressful physical training program than those who did not. Studies of L-tyrosine and depression have been less conclusive. A review published in “Alternative Medicine Review” in 2000 looked at numerous older studies and found L-tyrosine only possibly helpful for milder forms of depression.
FOOD SOURCES AND DOSAGE
L-tyrosine is found in an array of healthy foods, including poultry, soy, avocados, bananas, almonds, pumpkin seeds, cottage cheese and yogurt. For supplementing with L-tyrosine, Hyla Cass, author of “Natural Highs,” suggests 500 to 1,000 milligrams daily on an empty stomach in the morning. She warns that it can cause anxiety and insomnia in some people, and that those with a history of mental illness should never take
As with all amino acids, protein foods are the best sources, and tyrosine is no exception. You can get tyrosine from a wide variety of protein-rich foods. Chicken and turkey are good meat choices. Tyrosine-rich dairy foods include milk, cheese, yogurt and cottage cheese. Other tyrosine-containing foods are peanuts, almonds, avocados, bananas, lima beans, pumpkin seeds and sesame seeds. Tyrosine deficiency is rare, according to the University of Maryland Medical Center. However, tyrosine plays a role in thyroid function, so tyrosine deficiency is linked to underactive thyroid.
ROLE OF TYROSINE IN THE BODY
Without tyrosine, your body wouldn’t be able to handle stress or make important hormones. The nonessential amino acid is an essential part of many of the neurotransmitters — brain chemicals — your body needs to combat stress, including epinephrine, norepinephrine and dopamine. Tyrosine is also needed for the proper functioning of your adrenal, thyroid and pituitary glands. These glands are needed to make hormones such as thyroid hormone, which helps regulate the metabolic activities of your organs, and the hormone that maintains fluid and salt balance known as aldosterone. And as a necessary component of melanin, tyrosine also plays a role in determining the pigment of your hair and skin.
FOODS HIGH IN TYROSINE
Tyrosine is found in a wide variety of foods — from meats to cheese — making it easy to ensure you’re getting what you need. The amount of tyrosine you need each day is linked to the essential amino acid precursor phenylalanine — for adults, that is 14 milligrams per kilogram per day. If you weigh 180 pounds — with weight in pounds divided by 2.2 to determine kilograms of body weight — you need 1.145 milligrams of phenylalanine/tyrosine a day, about half coming from each amino acid.
Some of the best sources of tyrosine include Parmesan cheese with 559 milligrams per ounce, roasted soybeans with 1,392 milligrams per cup and roast beef with 1,178 milligrams per 3-ounce serving. Pork chops, salmon, turkey and chicken are also rich in tyrosine, with 900 to 1,000 milligrams per 3-ounce cooked portion.
OTHER FOOD SOURCES OF TYROSINE
Even if you don’t eat foods rich in tyrosine, you’re sure to get what you need eating a varied diet. One egg has 250 milligrams and a cup of cooked white beans 450 milligrams of tyrosine. Eating 1/4 cup of peanuts can help you get 351 milligrams, and 1 ounce of pumpkin seeds yields 306 milligrams. Both diced Swiss and provolone cheese have about 500 milligrams of tyrosine per 1/4-cup serving. Grain sources of the amino acid include oats with 447 milligrams per 1/2 cup and wild rice with 139 milligrams per 1/2 cup.
IS EXTRA TYROSINE BENEFICIAL?
Most people can make enough tyrosine from phenylalanine so they don’t need to worry about the amount they get from food. However, people with
phenylketonuria, an inherited disorder, can’t process phenylalanine and must avoid it to prevent brain damage. While those with PKU can’t handle phenylalanine, they still need tyrosine and are given a protein supplement that contains it. If you have PKU, you should talk to your doctor about whether you need to include foods rich in tyrosine before making any changes to your diet to prevent exposure to phenylalanine.
If you’re under stress, your body may not be able to make enough tyrosine, according to the University of Maryland Medical Center, and may benefit from getting it from other sources. That said, there is little evidence to support the need for extra tyrosine in the diet to help combat stress, according to a 2007 report published in Journal of Psychiatry and Neuroscience.
WHAT ABOUT SUPPLEMENTS?
You may consider adding tyrosine supplements if you’re under stress and feel your diet is inadequate to meet your needs. You shouldn’t add any dietary supplement to your regimen until you talk to your doctor, however. Additionally, you need to be cautious about using tyrosine in supplement form if you take thyroid medications, monoamine oxidase inhibitors or levodopa, due to potential interactions. Supplementation may also trigger headaches, especially in people who suffer from migraines, or cause an upset stomach. Tyrosine supplements should be avoided by people with hyperthyroidism or Grave’s disease because of its potential effects on thyroid hormone levels