What does it mean if something is not a complete protein? Does that mean that you don’t get protein from it or just not enough?
An excellent question. Protein is one of the major macronutrients, along with carbohydrates and fat, that make up the food we eat. They make up a good percentage of our body structure and perform many vital functions. Simply stated, without proteins there would be no life.
Proteins are molecules made up of smaller molecules called amino acids. There are 22 different types of amino acids which can combine in thousands of possible combinations to make different proteins. Of these amino acids, 8 are considered essential. This means that the body is unable to create them out of raw materials and that they therefore need to be taken from food. So when a protein is said to be “incomplete”, this means that it does not contain all 8 of the essential amino acids. Without all of the essential amino acids your body will be unable to perform many of the vital processes necessary for its proper functioning and deficiency symptoms will start to appear.
Most vegetarian proteins are not complete, whereas animal proteins are. So if your meal has meat, eggs or dairy products you needn’t be overly concerned about protein completeness. If the main component of protein is coming from vegetable sources, however, it’s a good idea to practice protein combining to ensure that you’re getting a healthy balance.
Protein combining means making up for what is lacking in one vegetarian protein source by eating something which complements it. If one of your protein sources is low in methionine, for example, you could combine it with another source with plenty of methionine but low in, say, lysine. The two sources will complement each other in what they lack alone. It is also possible to combine vegetarian protein sources with animal protein sources to maximize the vegetarian protein. The amino acids missing in the vegetarian source will be complemented by the animal source.
Now this may sound like an overly-complicated process, but it’s actually quite simple. This is because the tendency is for groups of foods to have similar amino acid profiles. So you needn’t carry around a list of which food contains which amino acid you only need a couple of rules of thumb. In other words, you don’t need to know that rice is lacking lysine or isoleucine, you just need to know that grains should be combined with legumes to make a complete protein.
Here’s a quick list of rules for combining proteins:
Grains + Legumes (like beans and rice, corn and beans, bean burrito)
Seed or Nuts + Legumes (like in hummus, tempeh with sesame)
Grains + Dairy or Eggs (like bread and butter, rice and eggs, creamed corn)
Vegetables + Dairy or Eggs (like sliced eggs in salads, vegetable omelettes, eggplant parmesan)
Things become even less complicated when you consider that all 8 essential amino acids don’t necessarily need to be eaten at the same meal. If you have a grain for breakfast and a legume for lunch the overall balance for the day will be a complete protein.
If you look at the examples in the above list you’ll see that a lot of traditional foods seem to have taken protein combining into consideration. Over thousands of years of eating, our ancestors likely figured out over time that they were healthier if eating vegetarian protein sources in certain combinations. This is likely why beans and rice, succotash (corn and beans) or oatmeal with milk have become staples in different traditional cultures.
So this is what is meant by “complete” or “incomplete” protein. Very important to know, but also very easy to take into consideration.
About Author: Doug DiPasquale, Holistic Nutritionist and trained chef, living in Toronto.