What Are The Essential Amino Acids For Vegetarians & Vegans – Or Can You Get Complete Proteins From Plants?

Nutrition is a big part of veganism in many ways. One of the reasons why I think nutrition takes up such a big focus about vegetarianism and veganism is because the food we eat is a very intimate experience both personally and communally. We eat many of our meals together and we are taught about food and what is good for us from our family.

Sustenance i.e. food comes to mean love and care. Our mothers feed us from their bodies when we are just born and our parents continue to care for us and show affection and love for us with food. Food is a wonderful and social experience.

When you step away from the mainstream as vegetarians and vegans have done, people become concerned. Veganism is a form of protest against the cruelties of animal abuse. But in effect we are also pushing ourselves away from that communal table and the feast that socially bonds us.

Without saying it, we leave the seed planted in the minds of those who eat the way their parents ate and those before them. That seed is the question “am I eating the right foods?” Right of course can mean any number of things including healthy, compassionate etc.

And that question gets explored in the context of what vegans eat. Is a vegan diet healthy? And more specifically for our purposes. Are plant foods complete in protein requirements for humans?

Oftentimes this comes from a place of genuine concern. Other times those who are misguided are looking for validation for their continued journey along false paths.

In any event. We must deal with the question what are the essential amino acids needed for vegans and vegetarians? We must also deal with the question behind that one which is – can a vegan diet provide all necessary protein? Or, is plant protein a complete protein.

To answer this, we go back to the beginning of our understanding of the protein requirements of humans.

In 1914 Lafayette B. Mendel and Thomas B. Osborne studied the nutritional needs of protein in rats. This study showed that rats thrive on animal based foods like eggs, milk and meat and not so much of plant foods for their protein needs.

This is where we get the false notion that whey and eggs are the gold standard of protein. However, we are not rats and more recent research has shown that the amino acid and protein requirements of humans is very different to rats.

There are around 20 amino acids that we obtain from our food. Rats require 10 which they can’t make. These are called essential amino acids. Human adults require 8 to 10 essential amino acids depending on where you look. I’ll go with 9.

The essential amino acids are the building blocks of proteins that humans can’t synthesize themselves, as such, they must be provided by our food.

It used to be that plant foods were considered incomplete sources of protein which meant that a single source plant food like potatoes for example lacked enough of one or more amino acids for humans to thrive on. So essentially the idea was that vegans and vegetarians needed to eat a variety of plant foods in order to get their complete allotment of all essential amino acids.

This has been solidly debunked. Many, if not all starch based vegan foods contain complete protein amino acid profiles. That is to say, if you lived only on corn or potatoes or brown rice or wheat etc, you would not become protein deficient.

I’m not suggesting a mono-food diet. Variety is important not only for enjoyment but also for obtaining a full range of nutrients beyond protein like vitamins, minerals and antioxidants.

But you can get all the protein you need from individual starch based plant sources.

So what are the 9 essential amino acids required for human health? They are histidine (0.75), isoleucine (1.4), leucine (2.2), lysine (1.6), methionine (0.22), phenylalanine (0.56), threonine (1), tryptophan (0.5), and valine (1.6).

The numbers after the amino acid above are the minimum requirements required for that amino acid in grams per day.

Histidine it should be added is still in controversial status as far as whether it is an essential amino acid or not. According to the WHOpp 146, 147

If you look at Dr. McDougalls table for corn you see that it provides more than sufficient amounts of all 8 essential amino acids. When I add the amount of histidine that corn (2.6) provides based on 2500 calories we see that corn provides more than sufficient protein for all 9 essential amino acids.

You can do this yourself. You can take Table 23 from page 150 of the WHO’s document titled “Protein and Amino Acid Requirements in Human Nutrition” and you can then go to NutritionData.com and look up any food and determine the amino acid amounts in milligrams or grams provided by that food to determine if that food alone will provide all 9 essential amino acids in sufficient quantities for your needs based on your caloric requirements.

Let me go through an example with you. I love potatoes, in fact I think I could live on potatoes alone. Let’s see if I ate nothing but potatoes would I meet my protein requirements for each of the 9 essential amino acids.

Let’s say I weight 175 pounds and I’m at a healthy weight – a BMI of 23 – I’m 6′ tall. Therefore my calorie requirements per day at my weight are 2395 based on a “light activity” level using the Mifflin calorie calculator which I prefer as it seems to be more accurate.

Next I go to Nutrition Data and I choose Potato, baked, flesh and skin, without salt. You can choose with salt if you want as that won’t affect our protein measurements.

The default weight it gives me is for 1 potato large (299g) serving which provides 278 calories. To find how many servings of 1 large potato I need to meet my daily calories needs, I take my calorie needs (2395) and I divide by the amount of calories per 1 large serving of potato (278) and I get 8.6.

In other words, I need to eat 8.6 large potatoes to get my calorie needs of 2395 for the day.

Next I look at the protein values provided by 1 large potato according to Nutrition Data. Remember, the values that are provided are for the 1 large potato (299g) serving size, so I need to multiply the values by 8.6 to get the amount of each amino acid I will be supplied with having eaten my calorie requirements just in potatoes.

Before I do that math for you. I go first to the WHO report to determine my amino acid needs in mg for each of the 9 essential amino acids. The first column in Table 23 lists the requirements of each amino acid in mg/kg. So I need to first figure out what my weight is in kilograms. 175 pounds is 79.4 kilograms. So I take each of the 9 essential amino acid numbers which are in mg/kg and I multiply them 79.4 to get the amount of each amino acid in mg that I need on a daily basis.

Here are the numbers in milligrams: histidine (794), isoleucine (1588), leucine (3096.6), lysine (2382), methionine (794), phenylalanine (1985), threonine (1191), tryptophan (317.6), and valine (2064.4)

Now we figure out how much of each amino acid my 8.6 servings of 1 large potato provides. Here are at the answers. Numbers in milligrams: histidine (1384.6), isoleucine (2597.2), leucine (3861.4), lysine (3904.4), methionine (1006.2), phenylalanine (2855.2), threonine (2339.2), tryptophan (1006.2), and valine (3629.2)

As you can see if I ate only potatoes I would get more than enough of each of the 9 essential amino acids. And of course, the WHO guidelines include a safety margin too.

If you do this with all of the starch based vegan plant foods you will find that most provide more than enough of each of the 9 essential amino acids. There is no need for vegans to be concerned about adequate protein intake. There is NO reason for vegans to be concerned about making sure they get an adequate supply of all 9 essential amino acids. This goes for vegan bodybuilders too.


Eat a wide variety of whole plant foods making sure you get enough calories and you are golden.

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