The Dietary Difference Between Complete and Incomplete Proteins

Everything that we eat has a nutritional value, and when we look at the proteins that we eat, we should make sure they help us reach our dietary needs. But what are complete and incomplete proteins, and should you care?

Most of us simply recognize that protein is protein, but there are several nuances within the types of proteins we consume. And they DO make a difference. 

But before we dive into the difference between complete and incomplete proteins, let's make sure you know what protein is, why you need it, and what it is made of. 

What is protein and why do we need it?

From reaching your fitness goals, to using protein to help you maintain a healthy weight, different types of protein can help your overall health. But all protein, no matter the source, is made up of a combination of different amino acids. 

Your body only needs about 20 different amino acids to make all the types of protein found in the human body. Amino acids are broken into three distinct groups

1. Essential amino acids are the nine amino acids that your body cannot naturally produce. You can only get essential amino acids from the food you eat, which is why they are deemed essential.

2. Non-essential amino acids are the eleven other amino acids your body uses to create protein in the body, but your body can make these amino acids on its own.

These should still be included in your diet, even though you can produce them. Typically, your body only produces non-essential amino acids when low or insufficient amounts have been consumed.

3. Conditionally essential amino acids are non-essential amino acids that become essential because of a change in your body. These changes most often occur during pregnancy, adolescence, or some kind of trauma.

Once your body is able to regulate normally again, conditional essential amino acids become non-essential again. 

All foods we eat contain a different combination of amino acids. The combination of those amino acids is what makes a protein source either a complete or incomplete protein. 

We need both essential and nonessential amino acids for optimal health, and therefore we also need both complete and incomplete proteins. 

But before we discuss the difference complete and incomplete proteins make for your body, let’s talk about all the amino acids that make up those complete and incomplete proteins. 

The 9 essential amino acids

You need all nine essential amino acids in order to make a complete protein. The list below is in no particular order, and one essential amino acid is not more important than the other - you need a balanced amount of all of them. 

  1. Histidine: essential for several functions including your immune response, nervous system regulation, digestion, and sexual function

  2. Isoleucine: essential for immune function and energy production

  3. Leucine: essential for rebuilding muscle, vital protein synthesis, and wound healing

  4. Lysine: essential for collagen production, protein synthesis, and the absorption of certain minerals like calcium

  5. Methionine: essential for regulating metabolism and to aid in the absorption of zinc, selenium, and other minerals

  6. Phenylalanine: essential for the production of other amino acids and neurotransmitters

  7. Threonine: essential for metabolism and immune system function as well as helping to strengthen your connective tissues

  8. Tryptophan: essential for appetite regulation, as well as regulating your mood.

  9. Valine: essential for energy production, muscle growth, and muscle regeneration.

The 11 non-essential amino acids

The eleven non-essential amino acids are the remaining amino acids that your body needs within the list of twenty amino acids. These amino acids you can produce within the body, but should still be consumed to help supplement your body’s natural production. 

The eleven non-essential amino acids do not influence whether a food is a complete or incomplete protein.

Do not let the term “non-essential” fool you. Your body can still use all eleven non-essential amino acids for specific functions and will benefit from having a little extra to distribute. 

Many non-essential amino acids are a precursor to essential amino acids, meaning that when consuming non-essential amino acids, your body can convert them into essential amino acids. 

  1. Alanine: converts glucose to energy in the body

  2. Arginine: removes ammonia from your body, supports immune system function, and helps with wound healing, cell division, and hormone production

  3. Asparagine: helps with the development of brian cells and overall brain function

  4. Aspartic acid: precursor to four essential amino acids

  5. Cysteine: supports healthy liver function and antioxidant function

  6. Glutamic acid: converted to glutamate, a neurotransmitter important for memory and learning

  7. Glutamine: removes ammonia from the body, helps you to maintain a healthy pH level, and supports protein synthesis

  8. Glycine: may improve sleep and maintaining a healthy sleep cycle by regulating the central nervous system

  9. Proline: primary amino acid found in collagen protein

  10. Serine: supports your neurotransmitter function and helps to regulate metabolism

  11. Tyrosine: precursor to epinephrine, norepinephrine, and dopamine 

The difference between complete and incomplete proteins 

Now that we know that all proteins are composed of amino acids, we can distinguish between complete and incomplete proteins. 

All proteins are made up of amino acids. Even incomplete proteins are composed of amino acids - they are simply lacking one or more of the essential amino acids. 

A complete protein is a food protein containing all nine essential amino acids. 

An incomplete protein is a food protein that does not contain all nine essential amino acids, or does not contain a high enough level of all nine essential amino acids to be useful to your body. 

Many protein foods that are incomplete proteins actually contain all nine amino acids, but not enough of all of them to be considered complete. That’s why the nuance between complete and incomplete proteins is smaller than you might think.

Most plant foods are considered to be incomplete proteins because they lack one or more of the amino acids your body requires to build new cells. 

Complete proteins are commonly associated with animal proteins, but they can also be found in plant foods like soy products, hemp, chia seeds, buckwheat, and nutritional yeast. 

So between complete and incomplete proteins, what should you be eating more of? Let’s make sure you are getting all the complete and incomplete proteins you need out of your diet. 

Can I get all the amino acids I need from the food I eat?

You may be able to get enough amino acids from consuming both complete and incomplete proteins. Incomplete protein foods can become complete proteins when combined with other foods to give a high enough concentration of all nine amino acids. 

This may only be a concern for those that follow a vegetarian or vegan diet, because if you eat animal proteins regularly, you are already likely getting a high level of all nine essential amino acids

A lot of people like to overcomplicate the idea of making an incomplete protein complete, and there is no need to memorize the amino acid combinations in all plant foods to do this. 

Many dietary experts suggest that simply eating a balanced diet with plenty of grains, legumes, protein-rich vegetables, seeds, and nuts and you will reach the necessary essential amino acid goals. 

One common example of plant-based foods that are deemed incomplete proteins (but become complete proteins when combined) is rice and beans (or lentils). 

Taking grains and legumes, and combining them, in most cases makes them a complete protein combination because together they contain a high enough level of all nine essential amino acids. 

More attention may be put on making incomplete proteins complete if you are someone looking to increase muscle mass. However, if you are working on losing or maintaining a healthy weight, less of a focus needs to be on complete proteins.

Identifying your overall protein needs can help you identify food combinations and protein sources that work best for you. 


Examples of complete protein foods

Examples of incomplete protein foods

  • Eggs
  • Fish
  • Poultry
  • Beef
  • Pork
  • Soy (tofu, miso, tempeh, edamame)
  • Quinoa 
  • Spirulina 
  • Chia seeds
  • Hemp 
  • Buckwheat
  • Amaranth 
  • Legumes
  • Nuts
  • Seeds
  • Grains
  • Vegetables

 

Not all nuts, grains, and legumes are incomplete proteins, as you will see on the list of complete protein foods above. Keep in mind that you can make incomplete protein foods complete proteins. 

Some examples of incomplete protein food combinations that make a complete protein include: 

  • Whole grains with legumes: rice and beans or hummus and pita bread

  • Whole grains with nuts/seeds: nut butter on whole wheat toast or a grain bowl topped with sliced almonds

  • Legumes with nuts/seeds: a salad with chickpeas and pumpkin seeds

The moral of the story is that yes, you can get all of the essential amino acids you need through the food you eat, even if you don’t eat animal products of any kind. 

The most important thing is to focus on a well-rounded and balanced diet that includes a wide variety of legumes, grains, nuts, seeds, and vegetables throughout the day. As long as your diet is well balanced, the number of complete and incomplete protein foods you eat shouldn’t matter. 

That being said, not everyone is eating a well balanced diet, and in those cases, how many complete and incomplete proteins you consume can make a difference. 

What if I’m not getting enough protein?

Knowing your personal needs when it comes to protein is the first step in identifying whether or not you are getting enough complete and incomplete protein. Some of us may struggle to meet protein needs that fit our goals, especially as we age or activity levels change our health goals. 

Something that may help reach protein requirements in any diet is adding a protein supplement of some kind to your daily routine. This can come in the form of a protein powder or a liquid protein supplement. 

There are several types of protein supplements to choose from, but how do you know if it is a complete protein or not? 

Should you be taking a protein supplement that contains both essential and nonessential amino acids?

While a focus should be put on your essential amino acids, keep in mind that taking non-essential amino acids simply helps your body to distribute amino acids more efficiently to areas of need. 

For instance, if you have arthritis, your body may need more non-essential amino acids like proline to help your body produce more collagen protein. 

Collagen is not naturally a complete protein, but you can find supplements, like ProT Gold, that fortify the collagen peptide protein with the missing amino acids to make it a complete protein.

This way, you are getting the best of both worlds. You’re supplementing your diet with essential amino acids to ensure that you are giving your body the nutrients it needs, and you are also receiving some non-essential amino acids to help boost and support natural body functions. 

The protein supplement you choose will depend on your health needs, but finding a collagen peptide protein, like ProT Gold, will solve the issue of trying to distinguish between complete and incomplete proteins.