Which Vegetables Have All 9 Amino Acids? The Truth About Complete Plant Proteins

October 20, 2025 •

3 min read

While animal products are traditionally considered the primary source of complete proteins, it's a common misconception that all plant proteins are incomplete. The question of which vegetables have all 9 amino acids is more nuanced, as most true vegetables are incomplete, but a few key plant-based exceptions, including legumes and seeds, contain all the essential amino acids your body needs.

Quick Summary

This article clarifies which plant-based foods, including specific vegetables and pseudograins, provide all essential amino acids, explaining how to achieve a balanced protein intake on a plant-based diet through variety and strategic food choices.

Key Points

Complete Plant Proteins: Soy products (edamame, tofu, tempeh) and pseudograins (quinoa, amaranth, buckwheat) are key plant-based sources with all nine essential amino acids.
Combining Proteins: Combining incomplete proteins, like rice and beans, within the same day provides a complete amino acid profile, and it is not necessary to combine them in the same meal.
Seeds are Potent: Seeds like hemp and chia are complete proteins rich in essential amino acids, fiber, and healthy fats.
Potatoes' Profile: Research suggests potatoes contain all nine essential amino acids, but the quantity may vary, and a large portion is required for sufficiency.
Focus on Variety: A varied diet that includes a mix of legumes, grains, nuts, and seeds is the most effective way for vegans and vegetarians to ensure adequate intake of all essential amino acids.
Misconception Debunked: The idea that all plant proteins are automatically inferior or incomplete is false; several plant-based foods offer high-quality, complete protein.

Understanding Complete vs. Incomplete Proteins

Protein is made up of amino acids, which are the building blocks of every cell in your body. There are 20 different types of amino acids, but only nine are classified as "essential". These nine essential amino acids cannot be synthesized by your body and must be obtained from your diet.

Complete Proteins: These are foods that contain all nine essential amino acids in sufficient quantities. Animal sources like meat, eggs, and dairy are classic examples.
Incomplete Proteins: These foods lack or are low in one or more of the essential amino acids. Many plant-based foods, including most vegetables, grains, and nuts, fall into this category.

Historically, it was believed that people on a plant-based diet had to meticulously combine complementary proteins at every meal to ensure they got all nine essential amino acids. However, modern nutritional science has proven this unnecessary. As long as you eat a varied diet throughout the day, your body is very efficient at utilizing the available amino acid pool to construct the proteins it needs.

Plant-Based Foods with All 9 Amino Acids

While the list of true vegetables with a complete protein profile is short, there are several plant-based foods that qualify. It's important to distinguish between vegetables and other plant-based categories like legumes and pseudograins, which are often grouped together in casual discussions about plant-based diets.

Soybeans and Their Derivatives

Soybeans are one of the few plants that contain all nine essential amino acids, making them a complete protein source. This includes edamame, tofu, and tempeh, all versatile options for plant-based diets.

Pseudocereals

Several pseudocereals, which are seeds consumed like grains, are complete protein sources. Quinoa is a well-known example, providing a high-quality protein profile along with fiber, magnesium, and iron. Amaranth and buckwheat are other gluten-free pseudocereals that offer all nine essential amino acids, fiber, and various minerals.

Seeds

Some seeds also provide all nine essential amino acids. Hemp and chia seeds are notable examples, offering a complete protein along with healthy fats and fiber. They can be easily added to various dishes for a nutritional boost.

Potatoes and Mushrooms

Potatoes and certain mushrooms may contain all nine essential amino acids. However, the protein content and sufficiency can depend on factors like variety and serving size. While not typically relied upon as primary protein sources, they contribute to a nutrient-dense diet.

Comparison of Plant-Based Complete Proteins


Source	Type	Complete Protein Status	Notes
Soybeans (Edamame, Tofu, Tempeh)	Legume	Complete	Versatile, high protein.
Quinoa	Pseudocereal (Seed)	Complete	Gluten-free, nutty flavor, good for meals.
Amaranth	Pseudocereal (Seed)	Complete	Gluten-free, used in porridge or baking.
Buckwheat	Pseudocereal (Seed)	Complete	Gluten-free, often used as flour.
Hemp Seeds	Seed	Complete	Adds nutty flavor, rich in omega-3s.
Chia Seeds	Seed	Complete	Used in puddings, thickener, high in fiber and omega-3s.
Potatoes	Vegetable	Nearly Complete	Contains all 9 essential amino acids, but requires sufficient quantity.
Mushrooms	Fungus	Nearly Complete	Some varieties, but generally low in protein quantity.

How to Combine Incomplete Proteins

For most vegetables, achieving complete protein status involves pairing them with other food groups. A varied diet throughout the day is sufficient to ensure all essential amino acids are consumed. Classic combinations include rice and beans, hummus and whole-wheat pita, peanut butter on whole-wheat toast, lentil soup with bread, and salads with nuts or seeds.

The Nutritional Big Picture: Variety is Key

A healthy diet, especially plant-based, emphasizes variety. Consuming a mix of legumes, whole grains, nuts, seeds, fruits, and vegetables ensures you naturally get all essential amino acids. While complete plant proteins simplify meal planning, consuming incomplete proteins occasionally is fine as your body uses amino acid stores throughout the day. For more on plant-based benefits, consult resources like the Harvard T.H. Chan School of Public Health.

Conclusion

Few true vegetables are complete proteins alone, but plant sources like soybeans (edamame, tofu, tempeh), quinoa, amaranth, buckwheat, hemp seeds, and chia seeds offer all nine essential amino acids. Combining vegetables with grains and legumes over the day creates a complete protein profile. A varied, balanced plant-based diet provides all necessary nutrients and essential amino acids without strict meal planning.

Frequently Asked Questions

Few true vegetables are complete proteins. Key examples that contain all nine essential amino acids are generally not vegetables but other plants like soybeans (edamame) and pseudograins (quinoa, amaranth). Some research suggests potatoes and mushrooms may also contain them, but often in lower quantities.

No, this is a misconception. While many plant proteins are incomplete, there are several exceptions, including soy products, quinoa, amaranth, buckwheat, and some seeds, that provide all nine essential amino acids.

No, it is not necessary to combine complementary proteins at every meal. Your body maintains a pool of amino acids, and as long as you eat a varied diet over the course of a day, your body will get all the essential amino acids it needs.

Quinoa is technically a seed, but it is often classified as a whole grain because it is used and prepared similarly. It is not a vegetable.

You can easily incorporate complete plant proteins by adding foods like edamame, tofu, quinoa, hemp seeds, or chia seeds to your daily meals. For example, add edamame to a salad, use tofu in a stir-fry, or sprinkle hemp seeds on your breakfast.

Most beans are incomplete proteins, as they lack sufficient amounts of certain essential amino acids. However, they can be paired with other foods, like grains (e.g., rice), to form a complete protein.

The nine essential amino acids are histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, and valine. Your body cannot produce these, so they must come from your food.

Yes, it is entirely possible to get enough protein on a well-planned vegetarian or vegan diet. By consuming a wide variety of plant foods, including legumes, nuts, seeds, and grains, you can easily meet your protein needs.