Which foods are complete proteins?

October 23, 2025 •

3 min read

Proteins are composed of amino acids, and of the 20 amino acids the body needs, nine are classified as “essential” and must be obtained from your diet. Knowing which foods are complete proteins is crucial for ensuring you consume all nine essential amino acids necessary for optimal health, muscle growth, and repair.

Quick Summary

This article details the top animal-based and plant-based complete protein sources, which contain all nine essential amino acids. It also explains how to combine incomplete plant proteins effectively to create a complete amino acid profile throughout the day.

Key Points

Complete Proteins Defined: These foods contain all nine essential amino acids that your body cannot produce on its own.
Animal Sources are Complete: Most animal products, including meat, poultry, fish, eggs, and dairy, are complete protein sources.
Key Plant-Based Options: Soy (tofu, tempeh, edamame), quinoa, buckwheat, and hemp seeds are notable plant foods that provide complete protein.
Combine Incomplete Proteins: Plant-based incomplete proteins, like grains and legumes, can be combined (e.g., rice and beans) to create a complete amino acid profile.
Daily Intake Matters Most: It is not necessary to combine complementary proteins in the same meal; consuming a variety throughout the day is sufficient.
Benefits of Complete Proteins: Adequate intake supports muscle growth, tissue repair, satiety, and a healthy metabolism.

What Defines a Complete Protein?

A complete protein is any food source that provides all nine of the essential amino acids your body cannot produce on its own. These nine essential amino acids are histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, and valine. The body needs these amino acids as building blocks for a vast array of critical functions, from repairing tissues to synthesizing enzymes and hormones. Conversely, an incomplete protein lacks one or more of these essential amino acids. While most animal products are naturally complete proteins, many plant-based foods are incomplete but can be combined to achieve a full amino acid profile.

Animal-Based Complete Protein Sources

Animal products are the most straightforward sources of complete protein, as they naturally contain all nine essential amino acids in consistent quantities. These include various meats, poultry, fish, seafood, eggs, milk, yogurt, and cheese.

Plant-Based Complete Protein Sources

For vegetarians and vegans, or those simply seeking more plant-based options, several foods offer a complete amino acid profile.

Notable Plant Sources

Soy Products: Tofu, tempeh, edamame, and soy milk are among the few plant-based sources providing all nine essential amino acids.
Quinoa: This pseudocereal is a naturally complete protein, also offering fiber, iron, and magnesium.
Buckwheat: Another gluten-free pseudocereal recognized as a complete protein and a good fiber source.
Hemp Seeds: Provide complete protein and healthy fats.
Chia Seeds: Contain all essential amino acids, although lysine levels might be lower compared to other sources.

Combining Incomplete Proteins

The body maintains an amino acid pool, allowing it to combine amino acids from different foods consumed throughout the day to create complete proteins. Effective combinations include:

Legumes with Grains: Such as rice and beans.
Legumes with Nuts/Seeds: Like hummus with whole-grain pita.
Grains with Dairy/Soy: For instance, oatmeal with soy milk.

Complete vs. Incomplete Protein: A Comparison Table


Feature	Complete Proteins	Incomplete Proteins
Essential Amino Acids	Contain all nine essential amino acids in sufficient quantities.	Lack or have insufficient amounts of one or more essential amino acids.
Primary Sources	Animal products (meat, eggs, dairy), soy, quinoa, buckwheat.	Most plant-based foods, including nuts, seeds, legumes, and grains.
Complementary Pairing	Not necessary to combine with other proteins for a complete amino acid profile.	Can be paired with other incomplete proteins to form a complete profile.
Nutritional Profile	Often rich in other nutrients like iron, zinc, and B vitamins.	Often rich in fiber, vitamins, minerals, and antioxidants.

Making Smart Dietary Choices

Achieving a full spectrum of essential amino acids is straightforward through dietary variety. For those consuming animal products, complete proteins are readily available. For vegetarians and vegans, incorporating a range of plant-based options like soy, quinoa, and complementary combinations of legumes, grains, nuts, and seeds throughout the day ensures adequate intake. Consulting a registered dietitian can provide personalized guidance. For further reading on the function of amino acids, the National Institutes of Health (NIH) provides resources: https://www.ncbi.nlm.nih.gov/books/NBK557845/.

Conclusion

Understanding which foods are complete proteins is key to a balanced diet. Animal-based products, soy, and quinoa are excellent sources. Those on plant-based diets can easily meet their needs by consuming a variety of protein sources and complementary combinations over the day, providing the essential building blocks for optimal health.

Frequently Asked Questions

The nine essential amino acids are histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, and valine. They are considered essential because the human body cannot produce them, and they must be obtained through food.

No, it's a common myth that vegetarians and vegans need to combine incomplete proteins at every meal. The body can store and draw from a pool of amino acids throughout the day to meet its needs, so a variety of protein sources over 24 hours is sufficient.

Effective complementary protein pairings include rice and beans, peanut butter on whole-grain bread, hummus with whole-grain pita, and lentil soup with whole-grain crackers.

Yes, quinoa is one of the few plant-based foods that is considered a complete protein, containing all nine essential amino acids. It is also gluten-free and rich in fiber and minerals.

Most nuts and seeds are incomplete proteins, meaning they lack one or more essential amino acids. However, hemp seeds and chia seeds are considered complete proteins, though chia's lysine levels can be lower.

If you have a soy allergy, you can still get complete proteins from other plant-based sources like quinoa, buckwheat, and hemp seeds. You can also combine different plant foods, such as rice and beans, to ensure you get all essential amino acids.

Individuals with higher protein needs, such as athletes, pregnant women, and older adults, can particularly benefit from complete proteins. They efficiently support muscle synthesis and recovery after exercise.