What is L-Phenylalanine?
L-Phenylalanine is an essential amino acid that cannot be produced by the body and must be obtained through diet or supplementation. L-Phenylalanine is a precursor to important neurotransmitters including dopamine, norepinephrine, and epinephrine, which are involved in mood, energy, and focus. L-Phenylalanine can also cross the blood brain barrier to increase levels of tyrosine, another amino acid involved in neurotransmitter production.

Health Benefits of L-Phenylalanine
L-Phenylalanine has a variety of potential health benefits including improved mood, increased focus and mental clarity, reduced anxiety and stress, and improved joint health.
Mood Enhancement
L-Phenylalanine has been shown to improve mood and reduce anxiety and stress. The amino acid works by increasing levels of dopamine, norepinephrine, and epinephrine, which are important neurotransmitters involved in mood regulation. L-Phenylalanine has also been shown to increase levels of tyrosine, another amino acid involved in neurotransmitter production.
Improved Focus and Mental Clarity
L-Phenylalanine has been shown to improve focus and mental clarity. The amino acid works by increasing levels of dopamine, norepinephrine, and epinephrine, which are important neurotransmitters involved in cognitive function. L-Phenylalanine has also been shown to increase levels of tyrosine, another amino acid involved in neurotransmitter production.
Reduced Anxiety and Stress
L-Phenylalanine has been shown to reduce anxiety and stress. The amino acid works by increasing levels of dopamine, norepinephrine, and epinephrine, which are important neurotransmitters involved in mood regulation. L-Phenylalanine has also been shown to increase levels of tyrosine, another amino acid involved in neurotransmitter production.
Improved Joint Health
L-Phenylalanine has been shown to improve joint health. The amino acid works by reducing inflammation and pain. L-Phenylalanine has also been shown to increase levels of collagen, a protein involved in joint health.
Side Effects of L-Phenylalanine
L-Phenylalanine is generally well tolerated and safe for most people. However, some people may experience side effects including headaches, anxiety, and stomach upset. L-Phenylalanine should be used with caution in people with phenylketonuria (PKU) or other disorders that affect amino acid metabolism. L-Phenylalanine should also be used with caution in people taking medications that affect dopamine levels.
Dosage and Supplements
L-Phenylalanine is available in a variety of forms including capsules, tablets, powder, and syrup. The recommended dosage of L-Phenylalanine depends on the reason for supplementation. For mood enhancement, the recommended dosage is 500-2000 mg per day. For improved focus and mental clarity, the recommended dosage is 250-500 mg per day. For reduced anxiety and stress, the recommended dosage is 500-2000 mg per day. For improved joint health, the recommended dosage is 500-1000 mg per day.
Mechanism of Action
L-Phenylalanine works by increasing levels of dopamine, norepinephrine, and epinephrine, which are important neurotransmitters involved in mood regulation. L-Phenylalanine has also been shown to increase levels of tyrosine, another amino acid involved in neurotransmitter production.
Pharmacokinetics
L-Phenylalanine is rapidly absorbed from the gastrointestinal tract and is distributed to all tissues. L-Phenylalanine is metabolized to tyrosine, which is then used to synthesize dopamine, norepinephrine, and epinephrine.
Half-Life
The half-life of L-Phenylalanine is 2-3 hours.
Interactions
L-Phenylalanine may interact with medications that affect dopamine levels. L-Phenylalanine should be used with caution in people taking antipsychotic medications, MAO inhibitors, or SSRIs.
Overdosages of L-Phenylalanine may cause headaches, anxiety, and stomach upset.
L-Phenylalanine should be used with caution in people with phenylketonuria (PKU) or other disorders that affect amino acid metabolism.
L-Phenylalanine should not be taken by pregnant or nursing women.
The safety of L-Phenylalanine in children has not been established.
Alternatives to L-Phenylalanine
There are a variety of alternative supplements that can be used for mood enhancement, including 5-HTP, SAMe, and omega-3 fatty acids. 5-HTP is a supplement that is similar to L-Phenylalanine in its ability to increase levels of dopamine and serotonin. SAMe is a supplement that is similar to L-Phenylalanine in its ability to increase levels of dopamine, norepinephrine, and epinephrine. Omega-3 fatty acids are similar to L-Phenylalanine in their ability to reduce inflammation and pain.