Amino Acids, Not Just Building Blocks of Proteins

How much protein should I eat? Does it make a difference how and when I eat protein? Are animal or plant sources of protein better for me? These are all questions we will be exploring as we progress through this Health Matters series on protein nutrition.

There are many different opinions about protein nutrition and no shortage of people proclaiming their beliefs. My intent through this series of articles has been to first build a foundation of concepts before we explore these questions.

Previous articles have discussed concepts such as the tremendous number roles that proteins have in our bodies, that amino acids are the building blocks we use to build all of these proteins and that we eat protein to supply us with the amino acids we can’t make for ourselves. The next concept to think about is that many amino acids are not just building blocks for making the proteins – the

have other roles essential to life. This is a really important thing to keep in mind as many of the amino acids that we can’t make for ourselves have roles essential for being alive. Not all food sources of protein are rich in these amino acids.

One of the ways that certain amino acids are used by the body is as raw material for making something else we must have. The neurotransmitter serotonin is a good example. Our nerve cells interact with each other through fascinating set ways that include one nerve cell sending out chemical messages to the next nerve (or brain) cell. One of these key neurotransmitters is serotonin.

Serotonin is made and broken back down in our body over and over and over again every day all the time. Substances being continuously synthesized and being broken down is a very common theme in physiology.

We do not directly eat serotonin. You can’t take a serotonin pill (but you can take an SSRI – I will talk about that in a later article).

We make serotonin by taking the essential amino acid tryptophan and through 2 enzyme based chemical reactions add on to it then break off a part. So, does that mean if you want to “boost your serotonin levels” you should eat a lot of foods rich in tryptophan? That is a question we can explore in more detail later but as a general rule it can be said that biology is usually more complicated. For example, it is notable that we use tryptophan to produce another substance called kynurenic acid which has multiple effects.

We make another neurotransmitter, dopamine, from an amino acid. We use the essential amino acid phenylalanine that gets converted into tyrosine to make dopamine. Dopamine in turn can be used in chemical reactions to make other neurotransmitters: epinephrine and norepinephrine.

Another role that amino acids can serve is as factors that signal or promote physiologic processes. The essential amino acid leucine is a good example. Leucine is an essential amino acid that acts as a signal to stimulate skeletal muscle protein synthesis. There appears to be somewhat of a threshold leucine level that fully turns on muscle protein synthesis and this may have a practical impact on meal planning.

In a later article I will in more depth discuss the topic of the effects leucine and muscle protein synthesis. I will go into the science just a bit more and talk a lot more about the practical aspects such as which foods are good sources of leucine. For those interested in a deeper dive into the science of leucine today I would suggest checking out the works of protein researcher Don Layman, PhD – here is a lecture he gave at Rutgers University on leucine. 

This health matters series on protein will continue with introducing concepts such as what is a limiting amino acid, food characteristics that impact amino absorption, and protein turnover. Practical matters that will be addressed will include the effect of protein on kidney health, what are good sources of protein and how much protein you should eat.

I encourage you to check out my other 2 articles I posted this weekend: “Exercise Planning and Programing: Inspiration, Motivation, Discipline, Habit, and Passion”, and “9 Adaptations: Long Duration Endurance”.

Thanks for reading. Please share.

Russ