Tyrosine, or L-tyrosine, is a non-essential amino acid crucial for building proteins and producing vital neurotransmitters and other substances. The body synthesizes it from phenylalanine, another amino acid. This article explores the potential benefits of L-tyrosine, including its role in weight loss, cognitive function, and thyroid health, alongside dosage recommendations and potential side effects.
What is Tyrosine?
Tyrosine, also known as L-tyrosine, is one of the 20 amino acids that are used to build proteins in the body. Classified as a "non-essential amino acid," it is synthesized from phenylalanine. Tyrosine serves as a precursor to several important neurotransmitters and substances, including epinephrine, norepinephrine, and dopamine. These chemicals play a role in regulating mood, energy, and thyroid function.
Tyrosine is found in various protein-rich foods, including meat, eggs, dairy products, nuts, beans, oats, and wheat. In order for tyrosine to be converted into neurotransmitters, the body also needs adequate amounts of nutrients like vitamin B6, folate, and copper. It is also available in protein powder and capsule form, and is sometimes found in workout supplements.
How Tyrosine Works
Tyrosine helps the brain produce stimulating and "feel good" neurotransmitters. Supplementing with tyrosine is thought to increase levels of dopamine, adrenaline, and norepinephrine. By increasing these neurotransmitters, it may help improve memory and performance in stressful situations.
Tyrosine influences levels of dopamine, which regulates the reward and pleasure centers, and adrenaline, which is responsible for the "fight-or-flight response" when under stress. Dopamine, epinephrine, and norepinephrine (catecholamines), are responsible for motivation, energy, interest, sexual functioning, pleasure/reward, drive, attention, and concentration. They are associated with positive stress states such as being in love, exercising, listening to music, and sex.
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Unlike the amino acid tryptophan, levels of tyrosine increase when someone eats foods high in protein or takes supplements. Levels of the amino acids tryptophan and tyrosine fluctuate depending on whether someone eats carbohydrate- or protein-rich meals. That means for most people it’s a good idea to include both types of these macronutrients their diets.
Potential Benefits of L-Tyrosine
Cognitive Function and Mental Performance
One of the most well-known benefits of L-tyrosine is its potential to enhance cognitive function, particularly under stressful conditions. Stress can negatively affect reasoning, memory, attention, and knowledge by decreasing neurotransmitters. Research suggests that tyrosine supplementation may help maintain mental capacity when taken before a stressful activity. It may help decrease mental fatigue and help with cognitive functions, including memory.
Studies have demonstrated that tyrosine can improve working memory during mentally demanding tasks and enhance cognitive flexibility, which is the ability to switch between tasks or thoughts. Supplementing with tyrosine has also been shown to benefit those who are sleep deprived. A single dose of it helped people who lost a night’s sleep stay alert for three hours longer than they otherwise would.
However, it's important to note that no research suggests that supplementing with tyrosine in the absence of a stressor can improve mental performance. In other words, it won’t increase brainpower.
Thyroid Function
Tyrosine plays a crucial role in thyroid health. The body uses tyrosine to make thyroxine, a thyroid hormone. It is a building block for the thyroid hormones, so supplementing with it might raise their levels too high. People who are taking thyroid medications or have an overactive thyroid should be cautious when supplementing with tyrosine.
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Potential Role in Weight Loss
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. Catecholamines, like the neurotransmitters produced by tyrosine, are necessary for the activation of thermogenesis and are integral for a healthy metabolism.
However, when used in combination with other natural fat-burning substances, such as cayenne, green tea and caffeine, there’s some evidence that it may help with fat loss in overweight adults, although only slightly.
Phenylketonuria (PKU)
L-tyrosine is commonly used in protein supplements for an inherited disorder called phenylketonuria (PKU). People with PKU are not able to process the amino acid phenylalanine, which the body uses to make tyrosine. To prevent tyrosine levels from becoming too low, people with PKU are advised to consume medical foods that contain tyrosine and very little phenylalanine.
Other Potential Uses
Ongoing research suggests that tyrosine may be useful for managing symptoms of heroin withdrawal and alcohol withdrawal, along with decreasing alcohol consumption when used along with the drug naltrexone.
Dosage and Administration
In the diet, tyrosine is found in dairy, meats, fish, eggs, nuts, beans, oats, and wheat. 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.
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In supplement form, tyrosine has most often been used by adults in doses of 100-300 mg/kg by mouth daily. In most studies, adults have safely taken about 100 to 150 milligrams per 2.2 pounds (or 1 kg) of body weight, which is equivalent to about 7 grams per day for an average-sized adult.
Effects of tyrosine supplements may be felt in as little as 30 to 60 minutes, depending on the dose taken and whether food has recently been consumed. Splitting doses can also be useful if you’re looking to elongate alertness and prevent fatigue. It should be taken on an empty stomach without food, since eating other amino acids can interfere with its absorption.
Side Effects and Precautions
Tyrosine is commonly consumed in foods. Tyrosine is possibly safe when taken as a medicine, short-term. It seems to be safe when taken in doses up to 150 mg/kg daily for up to 3 months. Some people experience side effects such as nausea, headache, fatigue, and heartburn.
It is important to be aware of potential interactions with certain medications:
- Levodopa (L-dopa): Tyrosine might decrease how much levodopa the body absorbs, potentially reducing the drug's effectiveness. Doses of these two drugs should be separated by several hours to avoid this.
- Thyroid Hormone: Taking tyrosine with thyroid hormone pills might cause there to be too much thyroid hormone. This could increase the effects and side effects of thyroid hormones.
Special precautions should be taken in the following cases:
- Pregnancy and breast-feeding: There isn't enough reliable information to know if tyrosine is safe to use when pregnant or breast-feeding.
- Thyroid disorders: Taking extra tyrosine might increase thyroxine levels too much, potentially worsening hyperthyroidism and Grave's disease.