Nutrition Diet: What are three examples of complementary proteins?

October 18, 2025 •

3 min read

Protein is a crucial component of every cell and tissue in the human body, but did you know that not all protein sources are created equal? For those following a plant-based nutrition diet, understanding what are three examples of complementary proteins is key to ensuring you get all nine essential amino acids your body needs from plant-based foods.

Quick Summary

This article explains how to create complete proteins by combining plant-based foods, detailing the science of amino acids. It provides three clear examples of complementary protein pairs and debunks the myth that combining must occur in the same meal, emphasizing the importance of daily dietary variety.

Key Points

Amino Acid Variety: Complementary proteins combine two or more incomplete protein sources, like grains and legumes, to provide all nine essential amino acids.
Rice and Beans: A classic example of complementary proteins, where the lysine-rich beans and methionine-rich rice combine to form a complete protein.
Nut Butter Sandwich: Pairing a nut spread (like peanut butter) with whole wheat bread creates a complete protein profile, combining legumes with a grain.
Hummus and Pita: The lysine from chickpeas in hummus perfectly complements the methionine found in whole wheat pita bread.
Dietary Flexibility: Modern science confirms that complementary proteins do not need to be eaten in the same meal; a variety of plant proteins throughout the day is sufficient.
Complete Plant Sources: Some plant foods, like soy (tofu, tempeh) and quinoa, are naturally complete proteins on their own.
Beyond Protein: Plant-based protein sources offer additional benefits, including being rich in fiber, vitamins, and minerals.

The Science Behind Complementary Proteins

Proteins are long chains of amino acids, and our bodies use 20 different kinds to build tissues and perform essential functions. Nine of these are considered 'essential' because our bodies cannot produce them, meaning we must obtain them from our diet. Foods are classified based on their essential amino acid profile:

Complete Proteins: These sources contain all nine essential amino acids in sufficient quantities. Most animal products are complete proteins, but some plant-based foods like soy and quinoa also fall into this category.
Incomplete Proteins: Most plant-based foods, including grains, legumes, nuts, and seeds, are 'incomplete' because they contain lower amounts of one or more essential amino acids.

For many years, it was a common misconception that individuals following a plant-based diet had to meticulously combine complementary proteins at every meal. The truth, however, is that the body maintains a 'pool' of amino acids, and by consuming a varied diet of plant-based foods throughout the day, you will naturally get all the essential amino acids you need.

What Are Three Examples of Complementary Proteins?

Combining two or more incomplete plant proteins can create a complete protein profile, crucial for a balanced plant-based diet. Here are three classic examples.

Example 1: Beans and Rice

A widely known complementary protein pairing, common in many global cuisines. Brown rice is often lower in lysine but high in methionine, while beans (like black or kidney) are high in lysine and lower in methionine. Consuming them together provides a complete set of essential amino acids and is a good source of fiber and complex carbohydrates.

Example 2: Peanut Butter and Whole Wheat Bread

This popular combination illustrates how nuts and grains complement each other. Whole wheat bread is typically lower in lysine, while peanuts (a legume) are rich in lysine. This pairing offers a complete protein and is a convenient snack option.

Example 3: Hummus and Pita Bread

This Mediterranean favorite is a flavorful example of protein combining. Hummus, made from chickpeas, is an excellent source of lysine. The wheat in pita bread provides methionine, which chickpeas are lower in. Together, they form a nutritionally complete option.

More Plant-Based Protein Combinations

Beyond these core examples, other effective complementary protein pairings include lentil soup with whole-grain bread, salads with chickpeas and sunflower seeds, and oatmeal with nuts or nut butter.

Complete vs. Complementary Proteins: A Comparison


Feature	Complete Plant-Based Proteins	Complementary Protein Pairs
Essential Amino Acids	All nine are present in a single food source.	Two or more foods are combined to supply all nine essential amino acids.
Examples (Single Food)	Soy (Tofu, Tempeh), Quinoa, Buckwheat.	Beans and Rice, Hummus and Pita, Peanut Butter and Whole Wheat Bread.
Preparation	Easiest to use, as no combination is necessary to get all essential amino acids.	Requires pairing different food groups (e.g., grains and legumes).
Dietary Context	Excellent to include regularly, especially for vegans and vegetarians.	Can be consumed together in one meal or throughout the day, as the body can store amino acids.

Debunking the Myth: Timing Isn't Everything

Modern nutritional science has disproven the need to combine proteins at every meal. The body maintains an amino acid pool, and a varied intake of plant-based foods throughout the day provides all essential amino acids. This offers greater dietary flexibility.

Conclusion: Practical Tips for a Balanced Protein Intake

A balanced diet, plant-based or otherwise, hinges on variety. Knowing what are three examples of complementary proteins is a great starting point. By eating a diverse range of plant foods—legumes, grains, nuts, and seeds—you naturally get all essential amino acids. Focus on daily variety rather than combining at each meal. For detailed nutritional data, the USDA Food Composition Databases are a useful resource.

Frequently Asked Questions

No, it is a myth that you must combine complementary proteins at the same meal. Your body maintains a pool of amino acids throughout the day, and as long as you eat a varied plant-based diet, you will get all the essential amino acids you need.

Complete proteins contain all nine essential amino acids, while incomplete proteins are low in one or more. Most animal products are complete, while most plant foods are incomplete, with notable plant exceptions like soy and quinoa.

Yes, several plant foods are complete proteins, meaning they contain all nine essential amino acids. Examples include soy products (tofu, tempeh), quinoa, and buckwheat.

Vegans can get enough protein by eating a wide variety of plant-based foods throughout the day, including legumes, grains, nuts, seeds, and vegetables. Including complete plant proteins like soy and quinoa is also helpful.

A simple and classic complementary protein meal is beans and rice. The combination of legumes and grains provides all the essential amino acids.

Some lesser-known combinations include lentil soup with whole-grain bread, or a salad with chickpeas and sunflower seeds.

Eating complementary proteins ensures that you consume all nine essential amino acids, which are vital for body function. This is especially important for those on plant-based diets.