L-tyrosine- where to find it, what it does, and should you supplement?
Between client inquiries and my research, the amino acid l-tyrosine has popped up quite a bit. Stress, focus, and performance are a few of the touted benefits of taking it. However, as with most supplements, the nitty-gritty doesn’t always turn out for everyone. So let’s look at what it is and does and the evidence behind l-tyrosine.
Given that tyrosine and l-tyrosine are pretty much the same thing, I’m going to drop the ‘l’ and use tyrosine for the remainder of this article unless referring to the supplement.
Hi! I’m l-tyrosine.
Tyrosine
There are 20 amino acids in total, and tyrosine is one of them. Amino acids are the building blocks to proteins, and proteins do A LOT in the body. Hence why we need to consume so much in the diet!
Where do we get it from?
If you’re eating balance diet, it’s not difficult to consume adequate amounts of tyrosine. According to myfooddata.com, below are the top 10 sources:
Beef
Pork chops
Salmon
Chicken breast
Firm tofu
Milk
Low-fat ricotta cheese
White beans
Pumpkin seeds
Wild rice
What does tyrosine do in the body?
Great, so we know what it is and where we eat it, but what does this little amino acid do in the body? Well, it does quite a bit.
Dopamine, norepinephrine and epinephrine
Tyrosine plays a role in forming dopamine. Dopamine is a neurotransmitter that has major involvement in…
“…regulating motor neurons, spatial memory function, motivation, arousal, reward and pleasure, as well as in lactation, sexual behavior, and nausea.”
So, a lot. Andrew Huberman has done extensive work on what dopamine is and does, highlighting its major role in reinforcing behaviours. Podcast here.
Norepinephrine (AKA noradrenaline) and epinephrine are part of the fight-or-flight system. They are both involved in regulating blood pressure by triggering vasoconstriction (increasing blood pressure) and increasing this by raising blood output from the heart. Also, it increases circulating levels of glucose and free fatty acids- all to provide enough blood and energy during a stressful event.
What gives with the two names if they have the same functions? According to drugs.com…
Although norepinephrine and epinephrine are structurally related, they have differing effects. Noradrenaline has a more specific action working mainly on alpha receptors to increase and maintain blood pressure whereas epinephrine has more wide-ranging effects. Norepinephrine is continuously released into circulation at low levels while epinephrine is only released during times of stress.
Below are photos of tyrosine in action, including its pathway into those neurotransmitters, where they form, and where they function. Feel free to skip the biochem stuff if it’s not your thing.
Figure 1.
A molecular perspective. Tyrosine is the precursor for these 3 neurotransmitters.
Figure 2.
figure 3.
Figure 4.
Next, going from tyrosine to these neurotransmitters occurs in the adrenal glands (figure 2,3), which sit atop the kidneys, as well as in nerve synapses (figure 4).
TYR- tyrosine
DA- Dopamine
NE- Norepinephrine
EPI- Epinephrine
Supplementing
I recently dug into a review about nutrition for the warfighter which can be found here. One of the recommended supplements was l-tyrosine due to the…
“Benefits of supplementing L-tyrosine may include improved speed and accuracy of information processing and vigilance [in the warfighter].”
While there is evidence to support the supplement, these effects may not present for everyone.
I say this for three reasons. Improved wakefulness in situations of sleep deprivation and resilience to acute stress has the most relative data second to enhancing resilience to acute stresses, given that mechanistically, stressful situations deplete nor/epinephrine levels.
But even in those trials, there appears to be co-founding that doesn't equal out to the same level of outcome data we have to a supplement like creatine. (If you can't tell, I'm a big creatine guy.)
Second, is the involvement of dietary protein. As mentioned above, you are likely consuming enough tyrosine while eating a balanced diet. Does extra tyrosine make a significant difference for someone eating enough protein to support whole-body protein synthesis and muscle protein synthesis?
Third, tyrosine's benefits depend on the available dopamine and nor/epinephrine levels. Under stressful situations, these neurotransmitters can become depleted, but I offer the following thoughts:
How would the average person know their baseline neurotransmitter level?
If stress depletes these neurotransmitters, by how much, and is it enough to warrant a supplement?
Do these neurotransmitters become depleted differently depending on the person’s tolerance to stress or perceived stress?
With that said, l-tyrosine is pretty cheap, so if you have the expendable income it may be worth a shot. It is relatively safe to consume, with examine.com concluding…
L-tyrosine is Generally Recognized as Safe (GRAS) in the USA. When L-tyrosine is used orally and short term at a dose of ≤150 mg/kg or ≤12 g per day for up to three months is generally safe.
That’s a lot of tyrosine. For me, a 200lb guy, that’s about 13.5 grams, with most supplements containing 500mg (ish) tablets.
Conclusion
To supplement, or not to supplement. That is the question. With l-tyrosine, I’m at the junction of potentially beneficial and more evidence is definitely needed. If you have expendable income, it may be worth a shot. It is relatively safe to consume and may help with resilience to acute stress and improved wakefulness in situations of sleep deprivation.
References
Dopamine: Functions, Signaling, and Association with Neurological Diseases | SpringerLink
Norepinephrine | Definition, Function, Effects, & Facts | Britannica
CV Pharmacology | Norepinephrine, Epinephrine and Acetylcholine - Synthesis, Release and Metabolism
L-Tyrosine — Health benefits, dosage, safety, side-effects, and more | Supplements - Examine