Nutrition Diet: How many amino acids can you get from plants?

October 29, 2025 •

5 min read

It is a widespread misconception that most edible plants lack one or more of the nine essential amino acids needed by humans. In reality, all edible plants contain all 20 amino acids, including the nine essential ones, though in varying concentrations. So, when exploring the question, how many amino acids can you get from plants, the answer is all of them, but the real key is understanding balance and variety.

Quick Summary

All edible plants contain the full spectrum of 20 amino acids, including the nine essential ones, though some are considered 'incomplete' due to lower proportions of certain amino acids. A varied intake of different plant foods throughout the day ensures all essential amino acid needs are met, making complex protein combining within a single meal unnecessary.

Key Points

All plants contain all 20 amino acids: Every edible plant, even those considered 'incomplete' protein sources, contains all 20 amino acids, including the nine essential ones.
Variety is key: A varied diet that includes different types of plant-based protein sources is the best way to ensure you get all essential amino acids in adequate amounts throughout the day.
Combining foods is not needed at every meal: The body maintains a pool of amino acids, so combining different complementary protein sources over the course of a day is sufficient, not necessarily in a single meal.
Complete plant proteins exist: Foods like soy products (tofu, edamame), quinoa, buckwheat, hemp seeds, and pistachios contain all nine essential amino acids in balanced proportions.
Plant protein offers extra health benefits: In addition to amino acids, plant sources provide fiber, vitamins, and antioxidants, while typically being lower in saturated fat than animal proteins.

The Amino Acid Foundation: Essential vs. Non-Essential

Amino acids are the fundamental building blocks of protein, which is vital for nearly every function in the body, from building muscle and tissue repair to creating enzymes and hormones. Our bodies require 20 different amino acids to function properly. These are categorized into two main groups:

Essential Amino Acids: There are nine essential amino acids that the human body cannot produce on its own. These must be obtained directly from dietary sources. The nine essential amino acids are histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, and valine.
Non-Essential Amino Acids: The other eleven amino acids can be synthesized by the body and do not need to be acquired through diet. These include alanine, arginine, asparagine, aspartic acid, cysteine, glutamic acid, glutamine, glycine, proline, serine, and tyrosine.

Additionally, some non-essential amino acids are considered “conditionally essential,” meaning that in times of illness, stress, or during growth phases, the body may not be able to produce enough of them, necessitating increased dietary intake.

Debunking the "Incomplete Protein" Myth

The idea that plant-based diets cannot provide all the necessary amino acids is a common myth. The term "incomplete protein" typically refers to a food that is relatively low in one or more of the essential amino acids when compared to human dietary needs. However, this does not mean that the amino acid is completely absent from the plant. A balanced and varied plant-based diet can easily provide all the amino acids required for health.

For example, cereal grains like wheat and rice are often considered low in the essential amino acid lysine. In contrast, legumes such as beans and lentils are rich in lysine but may be lower in methionine. By combining these different sources, all amino acid needs are easily met. The once-popular notion of meticulously combining specific foods at every meal is no longer considered necessary, as long as a variety of plant proteins are consumed throughout the day.

Complete Plant Protein Sources

While most plants contain all essential amino acids in varying amounts, a select few are recognized as "complete proteins" because they contain all nine essential amino acids in concentrations that are well-balanced for human needs. Incorporating these foods can provide additional assurance for those following a strictly plant-based diet.

Here are some well-known complete plant protein sources:

Soy Products: Edamame, tofu, and tempeh are excellent sources, providing all nine essential amino acids.
Quinoa: This ancient grain, technically a pseudocereal, is a complete protein source rich in fiber and minerals.
Buckwheat: Another gluten-free pseudocereal with a robust nutritional profile, including all essential amino acids.
Pistachios: Roasted American pistachios were classified as a complete protein source in 2019.
Hemp Seeds: These seeds are a complete protein and a good source of healthy fats.
Chia Seeds: The nutritional profile of chia seeds includes a complete set of essential amino acids.
Spirulina: This blue-green algae is a complete protein and a supplement rich in vitamins and minerals.
Amaranth: Like quinoa, this gluten-free grain is a complete protein.

Comparison: Plant vs. Animal Protein

While both plant and animal proteins can provide the necessary amino acids, they differ in several key nutritional aspects. Plant-based proteins generally offer additional health benefits, while animal proteins are often more easily absorbed by the body due to the absence of fibrous coatings and certain anti-nutrients.


Feature	Plant Protein	Animal Protein
Completeness	Most sources are 'incomplete' (low in one or more essential amino acids) but can be combined. A few sources are 'complete'.	All sources are 'complete' proteins.
Amino Acid Profile	Varies by source; generally lower in certain essential amino acids like lysine or methionine depending on the food type.	Rich and well-balanced profile of all nine essential amino acids.
Fiber	Excellent source of dietary fiber, beneficial for digestion and overall health.	Contains no dietary fiber.
Fat Content	Typically lower in saturated fat and may contain healthy fats.	Often higher in saturated fat and cholesterol.
Digestion Rate	Can be slightly less digestible than animal proteins, partly due to fiber content and anti-nutrients. Cooking helps increase digestibility.	Generally highly digestible.
Additional Nutrients	Often provides antioxidants, vitamins, and minerals like iron, zinc, and B-vitamins.	Excellent source of nutrients like Vitamin B12, iron, and zinc.

Strategic Plant Protein Consumption

Ensuring adequate protein on a plant-based diet is simple and does not require complex meal planning. The key is to consume a variety of protein-rich plant foods throughout the day, rather than worrying about specific pairings in each meal.

A good strategy is to combine different food groups that complement each other's amino acid profiles. Examples include pairing grains with legumes, or nuts and seeds with vegetables. A simple lunch might be a sandwich on whole wheat bread with hummus, or a hearty dinner could consist of rice and beans.

Grains (e.g., rice, wheat, oats): Often lower in lysine but contain other essential amino acids.
Legumes (e.g., beans, lentils, chickpeas): Good sources of lysine but can be lower in methionine.
Nuts and Seeds: High in various amino acids, often complementing legumes and grains.
Nutritional Yeast: A deactivated yeast often fortified with Vitamin B12, it provides a cheesy flavor and is a complete protein.

For those with higher protein needs, such as athletes, supplementing with a plant-based protein powder (e.g., pea, rice, or a blended option) can be an easy way to boost daily intake. Cooking and other forms of processing can also help improve the digestibility of plant proteins.

Conclusion

Ultimately, the number of amino acids you can get from plants is all 20, including the nine essential ones. The perceived challenge of a plant-based diet lies not in the lack of any specific amino acid, but in the need for dietary variety to ensure all essential amino acids are consumed in sufficient quantity over the course of a day. By combining different plant foods, and incorporating the several naturally 'complete' plant proteins, you can easily meet your protein requirements. This approach also provides the added benefits of fiber, antioxidants, and a lower intake of saturated fats, contributing to improved long-term health. Eating a diverse diet is key to a healthy and nutritionally complete plant-based lifestyle.

Authoritative source for further reading: Academy of Nutrition and Dietetics

Frequently Asked Questions

Yes, it is entirely possible and simple for vegans to get all nine essential amino acids. The key is to consume a variety of protein-rich plant foods throughout the day, such as legumes, grains, nuts, and seeds.

While animal proteins are often slightly more digestible, the difference is minor and inconsequential for most people consuming a varied diet. A balanced plant-based diet can provide all necessary amino acids effectively for building and repairing tissues.

No, the need to combine complementary protein sources in a single meal is a debunked myth. As long as you consume a variety of protein sources over the course of the day, your body will have access to all the essential amino acids it needs.

Several plant foods are considered complete proteins, including soy products (tofu, tempeh), quinoa, buckwheat, hemp seeds, chia seeds, and pistachios. These foods contain all nine essential amino acids in sufficient amounts.

A limiting amino acid is an essential amino acid present in the smallest quantity relative to human needs. For example, legumes are often limited in methionine, while grains are often limited in lysine.

Plant proteins can be slightly less digestible than animal proteins due to their fiber content and certain plant compounds called anti-nutrients. However, cooking and proper preparation methods can significantly improve digestibility.

Yes, relying on a single plant-based protein source for a prolonged period could potentially lead to a deficiency in a specific amino acid. This is why variety in a plant-based diet is so important.

Plant proteins typically contain less saturated fat and no cholesterol compared to animal protein. They are also rich in fiber, which aids digestion, and contain beneficial antioxidants, vitamins, and minerals that support overall health.