Updated: Nov 4
I've had a fascination with amino acids lately. In my undergraduate studies, we learned that amino acids are the "building blocks of protein". With an exercise science major, the focus was on building muscle tissue. That was mildly interesting to me at the time and I stored that knowledge in a corner of my brain somewhere. Recently, amino acids have resurfaced to the forefront of my focus with having more interesting roles than I previously learned. So now, I'm all in! Before I dive into that, I'd like to explain what amino acids are.
Amino acids are molecules that when combined, create protein. They are categorized as essential or nonessential. Nonessential amino acids are made within our bodies. Essential amino acids are delivered to our bodies via the food we consume. There are nine essential amino acids. If you are a meat eater, you are getting all of your essential amino acids, although eating meat has its own risks such as ingesting hormones, developing cardiovascular disease, and increasing inflammation in your body. On an environmental level, commercial animal farming has a major negative impact on climate change but that's for another blog post. If you followed a plant based diet or eat meat sparingly, it is important to vary the vegetables that you eat because one type of vegetable alone does not have all of the essential amino acids. The combination of multiple vegetables may have the complete package; a famous combination being beans and rice. There are a few non-meat foods that actually do have all the essential amino acids including hemp seeds, chia seeds, quinoa, soy, dairy, spirulina, eggs, and buckwheat. For my vegetarian and vegan friends, the idea that there is an inadequacy of amino acids from a plant based diet has not been supported in the research, as long as the types of vegetables consumed are variable (9). A heed of warning: increased dairy protein intake of over 30 grams per day has been associated with increased risk of prostate cancer in men (8). Think yogurt, dairy, cheese, eggs, and whey protein. I wonder what impact it has on women? Dairy is often inflammatory for our system and tends to be one of the first foods to try cutting out in an elimination diet experiment.
And now for the most exciting part! Here are some of the functions of amino acids:
Tissue building. Injured? Rehabbing after surgery? Recovering from child birth? Get those essential amino acids! They help us build new tissue in our body. Protein containing the essential amino acid called leucine has been studied for the prevention and treatment of sarcopenia, the decline in muscle mass as we age.
The essential amino acid tryptophan is part of the chemical pathway that creates serotonin. Serotonin is a hormone that is mostly produced in our gut with the help of tryptophan, an essential amino acid. People that are diagnosed with depression are often prescribed medication that is known as Selective Serotonin Reuptake Inhibitors (SSRI's), which means it aims to increase the amount of serotonin in our system. Why? Because serotonin levels tend to be low for these folks. In this fascinating discussion on the Huberman Lab podcast, Dr. Lisa Feldman Barrett, PhD mentions that if you're feeling down, eat some protein! Now you know why. There have been studies looking at a low tryptophan level being associated with anxiety and depression and a higher level being associated with improved mood. Serotonin is also important for body temperature regulation, sexual drive, stress response, memory, and nocioception (how a stimulus registers as pain to our body and brain). Check out this NPR article about low serotonin levels in people with long COVID.
This same pathway goes a step further to create melatonin. Melatonin! Sleep! Melatonin is a hormone that signals to our body that it's time to sleep. We know that taking a melatonin supplement is one of the many suggestions for getting better sleep. What if we instead recommend to ingest foods with the essential amino acid tryptophan?
Tryptophan is also part of the chemical pathway known has the kynurenine pathway. This pathway influences our body's immune response, how we deal with inflammation, neurotransmission (how efficiently our nerves communicate with each other), and cell energy.
Does this mean we should take amino acid supplements? I'm not sure. In a recent study (6), researchers suggest there may be harmful side effects from taking amino acid supplements and that more research is needed to explore this topic. Ultimately, and what is usually the best answer, the optimal way to get all the essential amino acids is to have a variable diet with whole foods that are preferably organic. If you use protein powder, look at the ingredient list for what is used as the source of protein and research to see if that source has all 9 essential amino acids. For example, my protein power uses pea protein but it also has hemp seeds and spirulina in the ingredients.
There is still debate on how much protein is enough for a healthy diet. Excessive protein intake is taxing for the liver and kidneys. Experts have discussed that in the western diet, there is an overconsumption of protein amongst the meat eating population. In the research, the recommendation of protein intake per day wavers from .83 grams of protein per kilogram (kg) of body weight for a sedentary adult to as high as 2 grams per kg of body weight for an active adult (10). For simplicity's sake, let's look at 1 gram of protein: for a 150-pound person, it is recommended that they get 68 grams of protein per day. It makes theoretical sense that if you are recovering from an injury, child birth, or surgery, you would want to aim for the higher recommendation.
All in all, it is the same take-home message that we've heard plenty of times before; make your plate as colorful as possible by eating a variety of vegetables, legumes, nuts, seeds, and grains. If you have a suspicion that you might not be getting enough protein, keep track of the total grams you consume for a few days. Using your body weight in kilograms, calculate what the recommended amount is for you (I suggest using 1 gram of protein per 1 kg of body weight to makes things simple). Remember that this is just a recommendation! Your body may need a little more or a little less to thrive. Are you getting enough? Maybe getting too much? Are there other symptoms you are experiencing, such as poor sleep or a foul mood, that may just need some tweaking of your diet?