Amino Acids – The Uncomplicated Guide

Whether that one gym-obsessed friend of yours can’t stop gushing about them, or you’re familiar with the term “complete protein” but do not know what’s actually behind it, chances are that you’ve heard of amino acids before. While amino acids play a significant role in keeping us vital and healthy, a plethora of myths about them still exist. This article will answer all of your immediate questions about amino acids and help you navigate through the murky waters of (false) nutrition claims.

What are Amino Acids?

Amino acids are the building blocks proteins are made out of. When you eat protein, your body automatically breaks it down into amino acids. The human body then uses these compounds made up of oxygen, nitrogen, carbon, and hydrogen to help facilitate, along with many other bodily processes, hormone production and the synthesis of neurotransmitters.

Humans need about twenty amino acids to be healthy, most of which our bodies can produce themselves. Nine of them, the so-called “essential amino acids” (EAAs), we need to consume through food on a daily basis. The essential amino acids are:

  • histidine
  • isoleucine
  • leucine (more about that later)
  • lysine
  • methionine
  • phenylalanine
  • threonine
  • tryptophan and
  • valine

What are Complete Proteins?

Foods that contain all nine essential amino acids are referred to as “complete proteins”. Dairy, meat, fish, poultry, and eggs are all complete sources of protein. But as most animal proteins, they come with negative effects on the environment and unwanted compounds such as cholesterol, saturated fats, or antibiotics.

Here at EcoWorlder, I encourage you to look at food as a complete “package”, not just as a certain macro- (or micro-) nutrient. In this sense, plant-based sources of complete proteins are the more sustainable and nutrient-dense alternative, as they come loaded with fibers, vitamins, minerals, and phytonutrients. Plant-based sources of EAAs include:

  • hemp
  • soy
  • quinoa
  • chia seeds
  • buckwheat
  • and many more!

Plant-based protein sources differ from animal-based ones in that many do not have a complete amino acid profile, unlike the examples listed above. However, this does not imply that their non-vegan counterparts are better. Protein sources such as red or processed meat, for example, have been linked to an increased risk of heart disease, while vegetarians and vegans are generally at a lower risk of chronic diseases and cancer (1).

But no need to stress about only consuming complete sources of protein. You don’t have to have a complete amino acid profile in every meal! As a vegan, you can easily get enough EAAs in as long as you generally eat a variety of different protein source. In fact, “research has shown that you simply need to eat from a variety a protein sources over a period of about 2-3 days to ensure adequate intake of all the essential amino acids” (2).

Besides “complete proteins” there are also “complementary proteins”. These are combinations of foods which amino acid profiles complement each other to form complete proteins. Food combinations that together have a complete amino acid profile are combinations of legumes and whole grains, grains and nuts, or legumes and nuts. A perfect example is a meal of rice and beans or whole wheat toast with peanut butter. Here’s an overview created by RanchoLaPuerta of which plant proteins complement each other:

Image: RanchoLaPuerta

Plant-based EAAs and Fitness

Fitness aficionados often criticize plant-based nutrition because many plant foods have relatively little amounts of leucine, an essential amino acid that plays a key role in muscle protein synthesis ( and thus muscle building).

Leucine’s Chemical Structure

But studies show that when the same amount of overall protein was consumed, “both plant and animal-based proteins have reached the amount of leucine needed to optimize muscle protein synthesis, resulting in no differences between the sources” (3). We can conclude that someone who lives plant-based will not be at any disadvantage when it comes to potential muscle growth.

Of course, if you want to be on the extra safe side, you can always consume leucine-rich plant foods (yes, they exist!) such as any soy products, seitan, oats, peanuts, and legumes. Alternatively, the fitness industry is saturated with various EAA supplements (not to be confused with BCAAs) that claim to optimize muscle protein synthesis and boost athletic performance.

The graph by VegFAQs gives a clear oversight of plant foods that have high amounts of leucine (in grams).

Image: @VegFAQs

Key Takeaways

  • amino acids are the building blocks of protein
  • there are nine essential amino acids that need to be consumed through food intake
  • a “complete protein” source has all nine essential amino acids
  • eating enough essential amino acids on a plant based diet is not an issue




(3) Norton LE, Wilson GJ, Rupassar I, Garlick PJ, Layman DK: Leucine contents of isonitrogenous protein sources predict post prandial skeletal muscle protein synthesis in rats fed a complete meal. FASEB. 2009, 22: 227.224

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