Proteins can be categorized as incomplete or complete proteins. Complete proteins contain all nine essential amino acids, compounds that are building blocks for the macronutrient.
Examples of complete proteins are options such as dairy, eggs, and quinoa, but most complete proteins are animal-based. Here's more about these types of proteins and how much protein to get in your diet.
Complete proteins contain all nine essential amino acids—organic compounds that help build neurotransmitters and hormones. The nine essential amino acids include:
- Histidine
- Isoleucine
- Leucine
- Lysine
- Methionine
- Phenylalanine
- Threonine
- Tryptophan
- Valine
These amino acids aren't made within the body and have to come from food. Complete proteins usually come from animal sources. However, some plant-based sources, like soy, quinoa, and pistachios, can be considered complete proteins.
Complete Protein Examples
The majority of complete proteins are from animal-based foods. However, some sources are plant-based.
Dairy
Dairy products are a great complete protein source. In particular, cow milk protein has the highest amount of branched-chain amino acids compared to other foods.
Eggs
Eggs also top the list of complete protein sources. They come with other nutrients, like selenium, choline, and vitamins A and D, which are protective against chronic diseases.
Fish
Essential amino acids are abundant in fish. Fish muscle accounts for 15 to 25% of the protein content in fish but also has the highest content of essential amino acids. When you eat a fish filet, you are eating the muscle mass from a fish's sides and consuming these nutrients.
Meat
You're not limited to a certain type of meat such as beef, chicken, or turkey for complete proteins. Animal products like duck, lamb, pork, rabbit, and veal meats are all other options you could choose from.
Quinoa
Quinoa, one of many beneficial whole grains, is considered one of the plant-based complete protein sources. It is naturally gluten-free and contains fiber and other nutritious plant-based compounds.
Soy
Soybeans have an amino acid composition comparable to that of animal proteins. When analyzed, researchers noted that some soy products like soy drink and tofu have only eight amino acids (missing tryptophan). However, soy is still considered a complete protein.
Animal-based foods are complete proteins. Most plant foods are incomplete—meaning certain amino acids are missing from the protein puzzle.
However, the terms "complete protein" and "incomplete protein" are misleading. If a person consumes enough calories from a healthful, varied diet—even from plant-based foods only—they should get an adequate supply of essential amino acids within 24 hours.
Protein Needs
How much protein a person needs depends on factors such as their age and sex. The following general amounts are recommended for adults:
- 19-30 years old: 5 to 7 ounce-equivalents (oz-equiv)
- 31-59 years old: 5 to 7 oz-equiv
- 60+ years old: 5 to 6.5 oz-equiv
It's also important to get just the right amount of protein you need. Over time, too much protein intake can lead to high blood pressure, while too little protein consumption can result in muscle loss.
Combining Proteins
You can combine incomplete proteins to get any necessary nutrients and amino acids. Combining those proteins means pairing them to mimic the amino acid levels you would get from animal proteins.
For example, you can eat so-called "complementary proteins" together. Rice and beans are good examples of complementary proteins. The amino acids missing from beans are found in rice and vice versa. You don't have to eat these proteins at the same time as long as they are eaten throughout the day.
Here are some examples of snacks and mini-meals that incorporate proteins:
- Add veggies, like shredded zucchini or finely chopped kale and fresh fruit to oats, and garnish generously with nuts, seeds, or both.
- Layer cooked, chilled quinoa and hummus and scoop it up with raw veggies.
- Whip up energy balls made from nut butter or sunflower seed butter, mixed with rolled oats or toasted quinoa and dried fruit, rolled in chia seeds.
- Add black beans and cooked, chilled wild rice to garden salads.
- Toss buckwheat soba noodles with veggies, black-eyed peas, and a sauce made with almond butter seasoned with ginger, garlic, and chili pepper.
- Garnish lentil and veggie soup with chopped walnuts or pecans.
- Whip chickpea flour into fruit and veggie smoothies along with sprouted pumpkin seeds.
- Drizzle oven-roasted veggies with tahini or serve with pesto made from olive oil, herbs, and nuts.
Complete protein food sources are ones that have all essential amino acids, while incomplete proteins don't. Complete proteins are animal-based, though quinoa and soy are recognized as plant-based sources. The amount of protein you need in your diet depends on factors like your age or sex. However, talk with a healthcare provider or registered dietitian for guidance to ensure you get enough protein.
