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The Right Sources of Amino Acids

Last updated: January-24,2023

Being replete with benefits for people from all age groups, amino acids are recommended as a part of the daily diet by most nutritionists and fitness experts. Our last article introduced you to an array of advantages of amino acids; this time we'd like to help people of all dietary preference understand how amino acids can be sourced.

What are the Sources of Amino Acids?

Essential amino acids cannot be produced by your body. These amino acids must be sourced from your diet. Some of the most common essential amino acids sources are:

Amino Acids for Vegans

When it comes to the vegan sources of essential amino acids, there are numerous options to choose from. Most plant-based sources contain multiple amino acids, but generally have a “limiting” amino acid—meaning that the source doesn't provide enough of that particular amino acid to be considered to be a “complete protein”. However, plant proteins can be combined to complement one another and supply the limiting amino acid in question. A rule of thumb is to combine a source of seeds, nuts or grains together with a legume in the same day to obtain sufficient amounts of all essential amino acids. Examples include rice and beans, or a peanut butter sandwich (peanuts are legumes).

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Spirulina, parsley, and fenugreek seeds contain a good amount of Lysine. Lysine can also be found in soybeans, tofu, isolated soy protein, avocados, almonds, cashews, chia seeds, and peas. These food can also help fulfill your intake of the three branched chain amino acids (BCAAs).

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Spirulina, a good source of Lysine, is rich in Threonine, Phenylalanine, and Tryptophan, too. Apart from the common ingredients, cacao, oats, and wheat provide you with Methionine while buckwheat provides you with a decent amount of Histidine.

Whole grains, lentils, peas, beans, legumes, pumpkin seeds, brazil nuts, quinoa, sunflower seeds contain good amounts of essential amino acids.

Sources of Amino Acids for Vegans

Amino Acids for Vegetarians

Apart from the plant-based sources, vegetarians can include dairy-based sources like cheese in their diet. Cottage cheese and whey protein are also rich in amino acids. Cheese contains Leucine, Lysine, Methionine, Threonine, Tryptophan, Histidine, and Valine. Other dairy products like yogurt can also help you fulfill your dietary intake.

Amino Acids for Non-vegetarians

Protein-rich food such as meat, more specifically red meat, pork, and poultry are the most common sources of amino acids. Eggs and fish like cod and sardines also provide high quantities of Amino acids. Meat-based sources are considered as complete sources of amino acids, as they contain all essential and non-essential amino acids.

Non-essential Amino Acids

When it comes to non-essential amino acids, most of it these are produced by the body. However, under certain specific conditions like when fighting an illness, or under stress, the body cannot produce enough Amino acids. To cover for such times, the sources of non-essential amino acids are like essential amino acids. Most of these are found in eggs, meats, fish, soybeans, lentils, chickpeas, nuts, etc.

Pros and Cons of Amino Acid Sources

Animal-based Sources


  • Animal-protein is widely available and there is always an abundance of common meat like poultry and eggs. Hence, finding the right ingredients is not generally a problem.
  • Animal-based proteins are complete sources which means that it becomes easier for your body to get all essential amino acids. Animal-based proteins also contain Vitamin A, B, and D as well as minerals like Zinc and Iron. When eating fish for proteins, remember it also contains a high dose of healthy fatty acids which are essential for our body.
  • Animal-based proteins are protein-dense as only a 3-ounce serving of meat can get you about 20 to 30 grams of proteins - ensuring that you reach your minimum intake of recommended amino acids.


  • It is difficult to trust the quality of meat as most meat available in the market comes from animals which are genetically modified or fed with high doses of antibiotics.
  • Red meats contain high levels of saturated fats, sodium, and cholesterol. High levels of these components can lead to hypertension, cardiac ailments, obesity, etc.
  • Production of meat also puts tremendous stress on the deteriorating environment as cows and other animals release high amounts of methane. There is also a subjective element of cruelty to animals and ethics.

Infographic - Pros and Cons of Animal-Based Sources of Amino Acids

Plant-based Sources


  • A plant-based diet is always healthier as it is rich in fiber and contains a very low amount of saturated fat, helping you maintain the ideal weight and a healthy heart.
  • Eating a diverse diet filled with proteins can help you get all the essential amino acids. They are simple to add and can even be snacked-on to increase your amino acid levels.
  • Plant-based sources of amino acids help you become less prone to food-borne illnesses, adding to your immunity.


  • Plant-based sources of proteins also contain a high level of carbohydrates which you may not want if you are trying to lose or maintain weight. The protein-per-calorie levels of plant-based proteins are much lower than animal-based proteins.
  • Plant-based sources contain low levels of Zinc, Vitamin B, and Iron. Hence, they may require supplementation.
  • Soy, a plant-based source of proteins, contains phytoestrogens (i.e. plant estrogens) which may bind to estrogen receptors in the body. For people with, or at high-risk for, estrogen-responsive cancers, this may have potentially negative effects. For others, there is no risk.

Infographic - Pros and Cons of Plant-Based Sources of Amino Acids

How is Amino Acid Utilized in the Body?

Most of the Amino acids are broken down in your liver, while specific amino acids are degraded in your Liver or Muscles. The nitrogen atom in the amino group is separated from the parent chain. Some of the nitrogen is used for bodily processes and biosynthesis while the excess is incorporated into forming urea by your liver. This is released in your bloodstream and then excreted by the Kidney.

How Do You Measure Protein Quality

In the past, methods for measuring protein quality included Protein Efficiency Ratio (PER), Biological Value (BV) and Net Protein Utilization (NPU). For the most part, these methods are now considered outdated and inferior to the current method for evaluating protein quality, Protein Digestibility Corrected Amino Acid Score (PDCAAS). PDCAAS is based on both the amino acid requirements of humans and their ability to digest it. The highest possible PDCAAS for a protein is 1.

The PDCAAS rating was adopted by the US Food and Drug Administration (FDA) and the Food and Agricultural Organization of the United Nations/World Health Organization (FAO/WHO) in 1993 as "the preferred 'best'" method to determine protein quality. A new protein quality measure (digestible indispensable amino acid score; DIAAS) may ultimately replace PDCAAS, but that has not yet happened. Therefore, for the time being PDCAAS is the method of choice for evaluating protein quality.

Following is a table with the PDCAAS for the proteins discussed in this article 1-5:

PDCAAS Protein
1.00 Casein [iii]
1.00 Egg White [v]
1.00 Soy Protein [v]
1.00 Whey Protein [v]
0.93 Pea Protein [iv]
0.91 - 0.99 Fish Protein [i]
0.84 - 0.97 Hemp Protein [ii]
0.51 Algael Protein [v]

Conclusion - Now You Know How Amino Acids Can Be Sourced

Amino acids perform crucial functions like regulating your bodily functions, improving your growth, boosting your immune system, and ensuring better mental health. Essential amino acids cannot be produced by the body and are hence sourced from our diet.

Depending on our dietary preferences, we can either opt for a plant-based or an animal-based diet which can equip us with the desired levels of amino acids essential for our body. During certain specific conditions like illnesses, stress, or performing strenuous physical activity can increase our requirement of Amino acids. Amino acid supplements can help in such cases where your diet is insufficient for providing you with an adequate amount of Amino acids.

Every source of Amino acid comes with an associated set of Pros and Cons, and thus must be carefully evaluated before sticking to a choice or forming an opinion. Taking the right amino acids in the right quantity can help you achieve the desired levels of body growth.

For more information on amino acids, including how to create your own line of high-quality dietary supplements, speak to the experts at NutraScience Labs! Call us at 855-492-7388 or request a free contract manufacturing price quote!

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[i]Boutrif E, Food Quality and Consumer Protection Group, Food Policy and Nutrition Division, FAO, Rome. Recent Developments in Protein Quality Evaluation. Food, Nutrition and Agriculture. 1991;2/3. http://www.fao.org/docrep/U5900t/u5900t07.htm.

[ii]Report of an FAO Expert Consultation. Dietary protein quality evaluation in human nutrition. FAO Food and Nutrition Paper 92. Food and Agriculture Organization of the United Nations. Rome, 2013:3.

[iii]Hoffman JR, Falvo MJ. Protein—Which is Best? Journal of Sports Science and Medicine. 2004;3:118-130.

[iv]Laetitia GUERIN-DEREMAUX Evaluation of the nutritional quality of NUTRALYS® Nutritional Study Abstract N°12 – V2 – January 2010.

[v]Product Information Bulletin: Solazyme Whole Algal Protein. Document Number: C-Q-00173-L01 Revision: 1. Effective Date: 13-11-08.

October 23rd, 2019

About the Author:

Gene Bruno

Gene Bruno, MS, MHS, RH(AHG) - Mr. Bruno possesses over 43 years of dietary supplement industry experience. With a Master's degree in nutrition and a second Master's degree in herbal medicine, he has a proven track record of formulating innovative, evidence-based dietary supplements. Mr. Bruno currently serves as both the Senior Director of Product Innovation at Twinlab Corporation and Professor of Nutraceutical Science at Huntington University of Health Sciences.