Protein vs. Amino Acids: What Are The Differences?

Protein and amino acids work together, but many people are confused about the differences between them, especially because you can buy protein powder and amino acid supplements separately.

Key Takeaways

  • Proteins are complex, long-chained molecules while amino acids are small, individual units, known as the “building blocks of protein”. Both are essential for muscle growth, recovery, and metabolism.
  • Proteins have diverse roles in the body whereas amino acids are the components enabling those roles.
  • Those consuming a variety of high-protein foods and protein supplements, whether from animal or plant-based sources, should be getting enough essential amino acids in their diet.
  • Ensuring athletes get an adequate amount of protein and branched-chain amino acids is crucial for muscle growth and repair, and preventing muscle breakdown during fat loss phases.

What Is Protein?

What Is Protein

Protein is made of a series of amino acids linked together. 

It is an essential nutrient in the diet because it makes up and supports the function of the muscles, bones, skin, hair, and hormones to name a few.

Protein is a major component of a wide range of foods, like meat, fish, eggs, dairy products, and legumes, but it needs to be broken down into smaller components to get absorbed and utilized by the body. 

What Are Amino Acids?

What are amino acids

Amino acids are the single units that makeup protein.

Think of them as the “broken down” form of protein that then gets absorbed and used by different parts of the body. 

There are 20 different amino acids, 11 of which are non-essential and can be made by the body. The remaining 9 are essential because they cannot be made by the body, and must be obtained through the diet. 

The 9 essential amino acids are:

  • Histidine
  • Isoleucine
  • Leucine
  • Valine
  • Lysine
  • Methionine
  • Phenylalanine
  • Threonine
  • Tryptophan

Different protein-rich foods contain different amino acids, so it’s important to include a variety of protein-rich sources to get enough of all the essential amino acids.

For this reason, it is recommended that you combine meat, egg, and legume sources of protein across different meals, rather than relying solely on one single source of protein. 

7 Differences Between Protein vs Amino Acids

7 differences between protein vs amino acids

Protein and amino acids work synergistically to maintain overall health.

The differences between them begin as soon as food is ingested. 

Take a protein-rich food source (e.g.chicken) as an example. It starts as a large protein molecule, and during ingestion and digestion in the stomach, it changes its structure and breaks down into amino acids.

Keeping this example in mind, here are some of the main differences between protein and amino acids:

1. Structure

Protein is a long chain of multiple amino acids linked together. Its long chain, shape, and folding capability make it a three-dimensional structure, which in turn determines the function a protein has in the body.

Amino acids are small, single units that are derived from protein. They are simple in structure because they are made up of an amino group, a carboxyl group, and a unique side chain (the characteristic that sets each of the 20 amino acids apart).

Amino acids structure

2. Function

Protein as a whole does many jobs. Hormones, for example, are proteins or are derived from proteins. Think insulin, which is needed for the absorption of energy in the body. 

Enzymes, which are made from proteins, are needed for metabolic reactions. Think digestion, in which the enzyme protease is needed to break down protein into amino acids. 

Protein also helps to build and repair tissues, form antibodies for the immune system, maintain fluid balance and regulate the body’s pH, and transport molecules to other parts of the body (e.g. GLUT, a protein transporter that moves energy in the blood to the cells).

Each amino acid is at the center of multiple key processes.

Take Valine, Leucine, and Isoleucine as examples.

These 3 essential branched-chain amino acids are particularly important in stimulating muscle growth and repair, which also affects performance (this is why they are sought after in sports nutrition).

3. Amount Required

The amount of protein needed per day varies depending on factors like age, activity level, nutrition, and exercise performance goals. 

Active adults generally require around 1 gram per pound of body weight (more if in a fat-loss phase), which corresponds to the approximation of 0.91g per pound of body weight advised by the ISSN.

For example, a woman weighing 120 lbs and strength training 3-4 times per week will need 120 grams of protein per day.

On the other hand, the amount of amino acids required per day will largely depend on the amount of protein consumed and the requirements of the individual. 

If the individual doesn’t consume a variety of protein sources or an adequate amount of protein in general, then a BCAA supplement is required.

4. Dietary Sources

Protein food sources that are rich in total protein are animal and plant-based foods.

Some examples include meat, fish, dairy products, eggs, legumes, nuts, seeds, and some grains like quinoa.

Essential amino acids are abundant in some protein food sources and less abundant in others.

Certain animal-based foods contain all 9 essential amino acids (e.g. beef, fish, eggs, and dairy), while others do not (e.g. beans and nuts).

Foods that contain all 9 essential amino acids are considered “complete proteins” whereas foods that do not are “incomplete proteins”.

5. Timing

Protein can be consumed across the whole day, ideally in portions of 20-40 grams to help manage hunger and optimize absorption. 

For those wanting to maximize muscle growth, it’s important to consume protein pre and post-exercise and before bedtime to minimize muscle wasting and aid in recovery.

Amino acids, if taken alone in the form of BCAAs, are best consumed around workouts, so before, during, or after exercise.

It is worth noting that protein powders and many other combinations of foods also contain amino acids, so they are likely consumed throughout the day when protein is ingested.  

6. Digestion and Absorption

To put it simply, the absorption of amino acids cannot happen without the digestion of protein sources.

“The amino acid bioavailability of a protein source is best conceptualized as the amount and variety of amino acids that are digested and absorbed into the bloodstream after a protein is ingested”

International Society of Sports Nutrition

Protein digestion starts in the mouth and requires digestive enzymes to break it down into amino acids in the stomach, and from there, amino acids are absorbed into the bloodstream by the small intestine. 

From the bloodstream, amino acids travel to various tissue cells (e.g. muscles, hair, etc.) in the body to perform all the functions mentioned above. 

7. Supplements

Common protein supplements include whey, casein, and soy-based powders, with milk-derived (whey and casein) protein containing the highest quantity of essential and branched-chain amino acids. 

Egg white powder, and soy protein isolate also contain a decent amount of good-quality protein (according to the PDCAAS scoring system of protein quality, based on amino acid content and digestibility).

On the other hand, while it is well known that amino acids occur naturally in animal protein powder, they can also be obtained in the form of branched-chain amino acid powder. 

If they are to be consumed alone, the RDA suggests leucine alone should be higher than 45 mg per kilogram per day for active individuals. 

Taking this into consideration, along with the ideal 2:1:1 BCAA ratio (leucine: isoleucine: valine) present in animal protein, isoleucine, and valine should be half of that amount at around 22.5 mg per kilogram per day.

For example, if you weigh 150 lbs (60 kg), you would need at least 5.4 grams of BCAAs per day, to split between either pre-, intra, or post-exercise.

Here’s the breakdown for each amino acid:
  • 45 mg leucine x 60 kg = 2,700mg -> 2.7grams

  • 22.5 mg isoleucine x 60 kg = 1350mg -> 1.35 grams

  • 22.5 mg valine x 60 kg = 1350mg -> 1.35 grams

When taking a protein or amino acid supplement, look at the nutrient breakdown per scoop to know exactly how many BCCAs you are consuming.

The Role of Proteins and Amino Acids in Fitness and Bodybuilding

Protein and essential amino acids (particularly BCAAs) are one of the most researched topics when it comes to fitness and bodybuilding nutrition. 

While it is general knowledge that high protein diets with high concentrations of BCAAs are crucial for building muscle, preventing muscle breakdown (during fat loss phases), and aiding in recovery, delving deep into the science and addressing misconceptions is also worth discussing.  


Protein, especially for athletes, provides the necessary essential amino acids for the body to function and perform during exercise. 

For this reason, a protein intake of 1 gram per pound of bodyweight (more if dieting) is recommended for active individuals.

However, there is a common misconception that more protein corresponds to more muscle, which causes people to overconsume protein at the expense of other nutrients (carbs & fats).

Focusing solely on protein is not the best approach, as protein does not work alone. It needs to be combined with other nutrients (e.g. carbs and fats) and exercise (e.g. resistance training) to result in muscle growth.

Another misconception is that vegetarian and vegan diets don’t provide enough protein. 

When following these diets, it is possible to get enough protein by combining a variety of plant foods (think soy, legumes, and grains like quinoa) and incorporating more high-protein meals/snacks throughout the day.

In addition, there are many vegetarian and vegan protein powders on the market to support high protein needs.

Have a look at my vegetarian, high-protein meal plan here to give you some ideas

Amino Acids

Considering that muscles make up a large proportion of total body weight (around 40% for the general population, and more for athletes and bodybuilders), you can understand why BCAAs are important for athletes.

Certain plant-based foods do not contain enough BCAAs, so a common question that arises is whether plant-based diets provide enough essential amino acids. 

The answer is that while they are lower in essential amino acids and BCAAs (which is why they have a low PDCAAS score), as long as they are paired with different foods and protein is consumed in adequate amounts, they can provide enough amino acids to build muscle and recover.

This has also been confirmed by the ISSN, as well as in a recent study done in healthy young (untrained) men, which investigated the effects of a vegan and omnivore diet on changes in muscle mass and strength:

  • One group was on a plant-based diet supplementing with soy protein isolate, while the other group was on a mixed diet supplemented with whey protein
  • Subjects undertook a 12-week resistance training program.
  • Results showed no difference between the two groups in muscle strength and muscle growth.
  • The key takeaway here is that you can get enough essential amino acids regardless of the diet consumed if you plan accordingly.

Do You Need To Take Amino Acid Supplements If Already Consuming Enough Protein?

If you are already consuming enough protein from a variety of whole foods, you do not need to take amino acid supplements. 

As long as you are eating a varied diet and including different protein food sources from animal and/or plant foods, you are probably getting enough amino acids. 

If on top of your whole food diet, you are also taking whey or casein-based protein supplements (which contain the highest quantity of essential amino acids and BCAAs), then you likely will have more than enough amino acids in circulation. 

If you know that your protein and BCAA intake from whole foods is low, then this can easily be remedied by consuming a protein powder supplement containing BCAAs.

Frequently Asked Questions

What Are the Best Sources of Complete Proteins?

The best sources of complete protein, containing all 9 essential amino acids, are animal-based sources, including beef, fish, dairy, and eggs.

However, plant-based sources (combined properly) such as soy, legumes, nuts, and seeds can still provide all of the essential amino acids.

Can Vegetarians and Vegans Get All the Essential Amino Acids From Plant-based Foods?

Yes, vegetarians and vegans can obtain all essential amino acids from plant-based foods by combining a diverse range of protein sources such as beans, chickpeas, lentils, soy, certain grains, nuts, and seeds.

With proper planning, a well-balanced plant-based diet can provide all the essential amino acids you need.

How Can I Calculate My Daily Protein Needs?

To calculate your daily protein needs as an active person, multiply your weight in pounds by 1 (1 is the approximation of 0.91 grams per pound of bodyweight which is the ISSN protein guidelines for athletes).

This gives you the approximate grams of protein you should aim for daily.

What Are the Potential Effects of Consuming Too Much Protein or Too Many Amino Acids?

Excessive protein and amino acids, if not utilized, can get stored as fat or excreted. It might also bring about imbalances or low intakes of other nutrients (e.g. carbs and fiber), which might cause gut-related issues.

Lastly, for those with pre-existing kidney disease, excess protein can stress the kidneys.


Shimomura, Y., & Kitaura, Y. (2018). Physiological and pathological roles of branched-chain amino acids in the regulation of protein and energy metabolism and neurological functions. Pharmacological Research, 133, 215-217.

Hevia-Larraín, V., Gualano, B., Longobardi, I. et al. High-Protein Plant-Based Diet Versus a Protein-Matched Omnivorous Diet to Support Resistance Training Adaptations: A Comparison Between Habitual Vegans and Omnivores. Sports Med 51, 1317–1330 (2021).

Sanvictores T, Farci F. Biochemistry, Primary Protein Structure. [Updated 2022 Oct 31]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2023 Jan-. Available from:

Mishra, N. K., Chang, J., & Zhao, P. X. (2014). Prediction of membrane transport proteins and their substrate specificities using primary sequence information. PloS one, 9(6), e100278.

Waldron M, Whelan K, Jeffries O, Burt D, Howe L, Patterson SD. The effects of acute branched-chain amino acid supplementation on recovery from a single bout of hypertrophy exercise in resistance-trained athletes. Appl Physiol Nutr Metab. 2017 Jun;42(6):630-636. doi: 10.1139/apnm-2016-0569. Epub 2017 Jan 27. PMID: 28177706.

Jäger, R., Kerksick, C. M., Campbell, B. I., Cribb, P. J., Wells, S. D., Skwiat, T. M., Purpura, M., Ziegenfuss, T. N., Ferrando, A. A., Arent, S. M., Smith-Ryan, A. E., Stout, J. R., Arciero, P. J., Ormsbee, M. J., Taylor, L. W., Wilborn, C. D., Kalman, D. S., Kreider, R. B., Willoughby, D. S., Hoffman, J. R., … Antonio, J. (2017). International Society of Sports Nutrition Position Stand: protein and exercise. Journal of the International Society of Sports Nutrition, 14, 20.

Campbell, B., Kreider, R. B., Ziegenfuss, T., La Bounty, P., Roberts, M., Burke, D., Landis, J., Lopez, H., & Antonio, J. (2007). International Society of Sports Nutrition position stand: protein and exercise. Journal of the International Society of Sports Nutrition, 4, 8.

Schaafsma G. The protein digestibility-corrected amino acid score. J Nutr. 2000 Jul;130(7):1865S-7S. doi: 10.1093/jn/130.7.1865S. PMID: 10867064.

Mero A. Leucine supplementation and intensive training. Sports Med. 1999 Jun;27(6):347-58. doi: 10.2165/00007256-199927060-00001. PMID: 10418071.

Frontera WR, Ochala J. Skeletal muscle: a brief review of structure and function. Calcif Tissue Int. 2015 Mar;96(3):183-95. doi: 10.1007/s00223-014-9915-y. Epub 2014 Oct 8. PMID: 25294644.

Hoffman, J. R., & Falvo, M. J. (2004). Protein – Which is Best?. Journal of sports science & medicine, 3(3), 118–130.

About The Author

Giulia Rossetto

Giulia Rossetto is a qualified Dietitian and Nutritionist. She holds a Masters in Human Nutrition (University of Sheffield, UK) and more recently graduated as a Dietitian (University of Malta). Giulia aims to translate evidence-based science to the public through teaching and writing content. She has worked 4+ years in clinical settings and has also published articles in academic journals. She is into running, swimming and weight lifting, and enjoys spending time in the mountains (she has a soft spot for hiking and skiing in the Italian Dolomites).

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