Which food has all 20 amino acids? Demystifying Complete Proteins

October 7, 2025 •

3 min read

The human body requires 20 different amino acids to function properly, with nine considered 'essential' because they cannot be produced internally. So, which food has all 20 amino acids? While no single food provides all 20 in perfect balance, sources known as 'complete proteins' contain all nine essential amino acids needed for optimal health.

Quick Summary

The body needs all nine essential amino acids, which must be obtained from food, to create the necessary proteins. Complete proteins are food sources containing all nine essential amino acids in sufficient amounts. The 11 non-essential amino acids are produced internally, so focusing on consuming a variety of complete and incomplete proteins is key for a balanced diet.

Key Points

Essential vs. Non-essential: The body needs 20 amino acids, but only 9 are essential and must come from your diet.
Complete Proteins Defined: A complete protein is a food source that contains all nine essential amino acids.
Animal Sources: Meat, eggs, dairy, and fish are all excellent complete protein sources.
Plant-Based Options: Quinoa, soy, buckwheat, and hemp seeds are examples of complete proteins from plant sources.
Complementary Proteins: Combining different incomplete proteins, like rice and beans, can create a complete amino acid profile.
Timing Is Flexible: It is a myth that complementary proteins must be eaten in the same meal; the body can combine them throughout the day.
Dietary Diversity is Key: Consuming a wide variety of protein sources, both complete and incomplete, is the best strategy for meeting all your amino acid needs.

What Are Amino Acids and Why Do They Matter?

Amino acids are the building blocks of protein and are vital for numerous bodily functions, including tissue repair and immune support. The body needs 20 different amino acids, but only nine are considered 'essential' and must be obtained through diet. The remaining 11 are non-essential and can be produced by the body.

The Definition of a 'Complete' Protein

A complete protein source contains all nine essential amino acids in adequate amounts. While some foods are more complete than others, consuming a variety of protein sources throughout the day is the best way to ensure you get all necessary amino acids. The body can combine amino acids from different foods eaten over the course of a day, so it is not necessary to consume all essential amino acids in a single meal.

Animal-Based Complete Protein Sources

Animal products are well-known sources of complete protein. These include:

Meat: Beef, chicken, pork, and turkey. Lean cuts are recommended for lower saturated fat intake.
Eggs: Highly regarded for their protein quality and nutrient density.
Dairy Products: Milk, cheese, and yogurt, offering protein and calcium. Greek yogurt is particularly high in protein.
Fish and Seafood: Salmon, tuna, and others provide complete protein and omega-3 fatty acids.

Plant-Based Complete Protein Sources

Contrary to a common myth, complete proteins are also found in plant-based foods, suitable for vegetarians and vegans.

Quinoa: A unique plant source containing all nine essential amino acids. One cup cooked has about 8 grams of protein.
Soy Products: Edamame, tofu, and tempeh are complete proteins derived from soybeans.
Buckwheat: A gluten-free seed with a complete amino acid profile.
Hempseed: Offers complete protein along with healthy fats.
Chia Seeds: Another source of all essential amino acids, also rich in fiber and omega-3s.
Spirulina: A blue-green algae, typically consumed as a supplement, that is a complete protein.

The Role of Complementary Proteins

Many plant foods are 'incomplete' proteins, lacking sufficient levels of one or more essential amino acids. Combining different incomplete protein sources throughout the day can create a complete protein profile.

Examples of complementary protein pairings can be found on {Link: Integris Health website https://integrishealth.org/resources/on-your-health/2022/august/how-to-eat-complete-proteins-in-vegetarian-and-vegan-diets}.

Complete Protein vs. Incomplete Protein: A Comparison


Feature	Complete Proteins	Incomplete Proteins	Complementary Proteins
Essential Amino Acids	Contains all nine essential amino acids in sufficient amounts.	Lacks one or more essential amino acids in sufficient amounts.	Combine two or more incomplete proteins to create a complete profile.
Common Sources	Meat, eggs, dairy, soy, quinoa, hempseed.	Legumes (most beans), nuts, seeds, grains (most).	Examples include combinations like rice and beans.
Dietary Flexibility	Provides all essential amino acids in one food source, simplifying planning.	Requires pairing with other foods to obtain all essential amino acids.	Offers a plant-based path to complete nutrition with simple food combinations.
Best For	Meeting daily protein needs efficiently, especially for muscle growth and repair.	Providing valuable nutrients like fiber and healthy fats.	Ensuring adequate essential amino acid intake on a vegetarian or vegan diet.

A Note on Protein Quality

Beyond being complete, the quality of protein also depends on its digestibility and how well the body can use it. While animal proteins are highly bioavailable, a well-planned plant-based diet can provide plenty of protein and other nutrients. Eating a variety of protein sources is the best approach for a full range of amino acids and other nutrients. A certified dietitian can help create a personalized nutrition plan, especially for specific diets or health goals. The {Link: National Institutes of Health https://www.ncbi.nlm.nih.gov/books/NBK234922/} is an authoritative source for more on protein needs.

Conclusion

Addressing the question of which food has all 20 amino acids highlights the importance of 'complete proteins,' which provide the nine essential amino acids. While many animal products are complete proteins, several plant-based foods like quinoa and soy also fit this description. For vegetarian or vegan diets, combining various plant foods throughout the day ensures a complete amino acid intake. A diverse diet with different protein sources is key to getting all the necessary building blocks for health.

Frequently Asked Questions

All 20 amino acids are vital for the body's function. However, the nine essential amino acids are particularly important because they must be obtained from food, while the other 11 can be synthesized by the body.

Yes, vegetarians can easily get all the necessary amino acids. While many plant proteins are incomplete, eating a variety of plant-based foods like legumes, grains, nuts, and seeds throughout the day ensures all essential amino acids are consumed.

No, soy is not the only plant-based complete protein. Other examples include quinoa, buckwheat, hempseed, chia seeds, and spirulina.

No, you do not need to combine complementary proteins in the same meal. The body has an 'amino acid pool' that can draw from different foods consumed throughout the day to meet its needs.

A deficiency in essential amino acids can impact muscle growth and repair, immune function, and overall tissue health. However, significant deficiencies are rare for individuals consuming a varied diet.

Complete proteins are highly effective for building muscle because they contain all the necessary amino acids for muscle protein synthesis. However, a varied diet with complementary incomplete proteins can also support muscle growth.

For most people consuming a balanced and varied diet, supplements are not necessary. Whole food sources provide all the required amino acids along with other important vitamins and minerals. Consult a healthcare provider before starting any supplement regimen.