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Complete Vs. Incomplete Protein Sources
Nate Morrow Contributor
Healthy Eating Tips
Complete Vs. Incomplete Protein Sources
October 3, 2012 UpdatedSeptember 25, 2017
Delving into the world of fitness and nutrition, itís easy to be overwhelmed by talk of nutrients. The one you inevitably end up hearing about Ė a lotó is protein.
But what is it? Youíve probably heard or read about it as a big part of building muscle, but there are some other important and often-overlooked aspects of the different protein sources that you may not know.
Letís start with the basicsÖ
What Is Protein?
One of the three macronutrients your body needs to function properly (along with fats and carbohydrates), proteins are primarily important for tissue growth and repair, but also necessary for digestion, metabolism, and the production of antibodies to fight infection. Comprising 10% of your brain and 20% of your heart, liver, and skeletal muscles, protein is obviously key to maintaining a strong, healthy body. What you may not realize, however, is how important it is for a healthy mind.
When you digest protein, itís broken down into its component amino acids, which are then reassembled into 50,000 different forms your body can use for things like hormones, enzymes, and neurotransmitters. Not only do these amino acids form the building blocks of your brainís neural network and have significant impact on your mood and brain function, but are especially important in infantsí developing brains.1 Specifically, the protein neurexin, is responsible for directing new nerve cells to their correct locations in the brain where they form their initial connections.
Complete vs Incomplete Protein Sources
Your body needs 22 different types of amino acids to function properly. Adults can synthesize 13 of those within the body (known as non-essential amino acids), but the other 9 must be obtained from food (known as essential amino acids). Itís these essential amino acids that derive the classification of protein as either complete or incomplete.2
Complete Protein Sources
Complete proteins are those that contain all essential amino acids in sufficient quantity Ė these are typically animal-based proteins, but a few plant sources are also considered complete. A few examples are (* indicates plant-based):
Dairy products (milk, yogurt, whey)
Hemp and chia seed*
Incomplete Protein Sources
Incomplete proteins are those that donít contain all 9 essential amino acids, or donít have sufficient quantities of them to meet the bodyís needs, and must be supplemented with other proteins. These include:
Nuts & seeds
Just because they are incomplete doesnít make them inferior, though, they just need to be combined to provide the right balance of essential aminos. Proteins that, in combination, make a complete amino acid profile are known as complementary proteins. Here are a few tasty examples:
Rice and beans
Spinach salad with almonds
Hummus and whole-grain pitas
Whole-grain noodles with peanut sauce
Complementary proteins donít necessarily need to be eaten together, but since your body doesnít store amino acids for later use in protein combining, they should be eaten throughout a dayís meals.3
Plant vs. Animal Protein Sources
A bit of a controversy is brewing over whether animal or plant-based proteins 4 are better for you. Some nutritionists argue that humans are better suited to digesting animal proteins since they are closer to our own biological makeup and contain all the amino acids we need to survive. On the other side, many contend that plant-based proteins are healthier and animal-based proteins are not necessary if you have proper variety in your diet.5
While animal proteins have somewhat better absorption and availability to the body (See: The Protein Digestibility Corrected Amino Acid Score), what Iíve found is that most of the arguments for either side have less to do with the proteins themselves,6 and more to do with the foods in which they are found (i.e., meats being higher in fat and cholesterol vs. grains being high in carbohydrates) and the morality of eating animals. For most people, the body handles both types of protein equally well.
One potential problem with animal protein is that it tends to be higher in sulfur-containing amino acids, which causes increased acidity and could lead to calcium depletion as the body tries to balance out its pH level. This is typically not an issue when consumed in moderation with a well-balanced diet, however.
The only major knock on plant protein is its incompleteness, but that is, again, easily overcome with a well-balanced diet.
How Much Of Protein Sources Should You Eat?
The current Recommended Daily Allowance of protein for adults is 0.36 grams per pound of body weight. This translates to 64 grams of protein for a 180lb man. Research shows that protein intakes as high as 0.8 Ė 1.0 gram/lb can help those individuals looking to build muscle, or retain muscle while losing fat during a resistance training program. We will cover protein requirements and absorption in more depth in other articles.
A higher protein diet is often recommended during a fat loss program because of proteinís high thermic effect (up to 30% of calories from protein are burned off during digestion) and its ability to satisfy hunger.
For your reference:
1 cup of milk has 8 grams of protein
An 8-ounce container of yogurt has about 11 grams of protein
A 3-ounce piece of meat has about 21 grams of protein
1 cup of dry beans has about 16 grams of protein
So How Exactly Should You Eat Your Protein Sources?
As with so many things, the key to protein is balance. It is a vital and often-misunderstood part of our diets, but we need to remember that the quality and type of protein can be as important as how much we consume.
Making sure you have a good combination of high-quality proteins in your diet is a good step towards a healthy body and mind.