Protein – The Basics

What is protein?

Protein is one of the three main macronutrients your body needs for proper function. It is vital to your body’s tissue and organ structure, function, and regulation and overall cell health. It is a large, complex molecule made up of a string of hundreds to thousands of smaller units called amino acids.The actual sequence in which the amino acids combine is what gives each protein its specific function. While there are over 100 amino acids, there are only 20 biologically active amino acids in humans:

Guide To The Twenty Common Amino Acids

Essential vs. Non-essential

Of these 20 amino acids, 11 are non-essential and nine are essential. Non-essential amino acids (solid circle in chart above) can be produced inside your body through diet and metabolism of other amino acids and substances. Essential amino acids (broken circle in chart above) can only be provided through your diet — you must eat them! Sometimes arginine is considered an essential amino acid because it is essential for young people, but in the general adult population, it usually non-essential.


Complete vs. Incomplete

Complete Protein

A complete protein is a protein that contains all the essential amino acids. Complete proteins are called “high quality proteins” because they have everything you need and are easily utilized by your body. All animal-based sources of protein are complete:Complete Proteins

  • Meat (from pigs, cows, poultry, or wild game)
  • Fish
  • Milk
  • Eggs

There are also plant-based sources of complete proteins:

  • Quinoa
  • Buckwheat
  • Hemp seed
  • Chia seed
  • Amaranth
  • Soy


Incomplete Protein

An incomplete protein is a protein that is low on or missing one or more essential amino acid. There are only plant-based sources of incomplete proteins:

  • Vegetables (e.g., corn or peas)
  • Whole grains (e.g., wheat)
  • Legumes (e.g., beans, chickpeas, or lentils)
  • Nuts (e.g., peanuts, walnuts, or cashews)
  • Seeds (e.g., pumpkin, sesame, or sunflower)
  • Rice
  • Oats

Complementary Protein Pairings

Though not all proteins are complete, it is possible to pair up two incomplete proteins to create a complementary protein pairing. Meaning, when you eat those two proteins in the same meal (or over the same day), you give your body all nine essential amino acids, thus providing the same effect as consuming a whole protein source. For example, beans are low in methionine, while corn is low in tryptophan and lysine.

Corn and Beans

Together, you get all nine essential amino acids! Of course the alternative would be to eat lots and lots of beans until you got enough methionine, but that’s not my recommendation.

Here are some other good pairing examples:

  • Rice + Legumes (e.g., rice and beans)
  • Legumes + Whole Grains (e.g., hummus on whole wheat pita chips)
  • Whole Grains + Nuts (e.g., peanut butter on whole wheat toast)
  • Nuts or Seeds + Legumes (e.g., roasted pumpkin seeds in lentils)


That’s it! Those are the protein basics. Hopefully you now feel like a protein expert… Time for a snack!!




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