What Are Essential Amino Acids? The Building Blocks of Protein
Essential amino acids are nine specific amino acids that the human body cannot produce. They must be obtained from food to build proteins, which are vital for growth, repair, and many other bodily functions.
At a glance
- Term
- Essential Amino Acids
- What it is
- Nutrient and protein component
- Section
- Food and nutrition
- Also called
- Indispensable amino acids
- In one line
- They’re the nine protein building blocks you have to get from food because your body can’t make them.
What Essential Amino Acids means
Proteins in your body are made from 20 different amino acids. Nine of these are called essential amino acids because your body cannot synthesize them from scratch. You must get them from the foods you eat. The nine essential amino acids are histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, and valine. Think of them as the crucial ingredients you have to buy at the store because you don’t have them in your pantry. Without a consistent supply of all nine, your body’s ability to build and repair itself can be compromised.
These amino acids are fundamental for more than just muscle growth. They are required for building and repairing all body tissues, including skin and hair. They also play a critical role in producing enzymes that facilitate chemical reactions, hormones that act as messengers, and neurotransmitters that regulate mood and sleep. A shortage of even one essential amino acid can disrupt these vital processes. This makes them a cornerstone of overall health, influencing functions from immune response to the production of neurotransmitters.
Foods that contain all nine essential amino acids in sufficient amounts are called complete proteins. These include animal products like meat, fish, eggs, and dairy, as well as some plant sources like soy and quinoa. Most other plant-based foods, such as beans, lentils, and grains, are considered incomplete proteins because they are low in one or more essential amino acids. However, by eating a variety of plant foods throughout the day, you can easily get all nine. For example, the classic combination of rice and beans provides a complete amino acid profile.
For someone eating a varied diet, getting enough essential amino acids is usually straightforward. The focus is less on tracking individual amino acids and more on a balanced dietary pattern that includes diverse protein sources. People following certain restrictive diets, such as a vegan diet, may need to pay closer attention to combining different plant-based protein sources to ensure they get an adequate supply of all nine. The goal is a consistent intake of varied proteins, not a perfect combination at every single meal.
What public guidance says
The National Academies recommend a daily protein intake of 0.8 grams per kilogram of body weight for adults.
How to get enough essential amino acids
- Include sources of complete protein in your diet. These include animal products like meat, fish, dairy, and eggs, as well as plant-based options like soy, quinoa, and buckwheat.
- Combine different plant-based proteins. You don’t need to eat them in the same meal, but aim to eat a variety throughout the day, such as beans with rice, lentils with bread, or hummus with pita.
- Eat a wide variety of foods. A diverse diet that includes legumes, nuts, seeds, and whole grains helps ensure you are covering all your amino acid needs without having to track them closely.
- Ensure your overall protein intake is adequate. Meeting your general protein needs usually means you are also getting enough of each essential amino acid.
Essential Amino Acids vs. similar terms
| Compared with | How Essential Amino Acids differs | What the other term means |
|---|---|---|
| Non-essential amino acids | Essential amino acids must be obtained from your diet because your body cannot produce them. | Non-essential amino acids can be synthesized by your body, so they are not required from food. |
| BCAA | Essential amino acids refer to all nine amino acids the body can’t make. | BCAAs are a specific group of just three essential amino acids: leucine, isoleucine, and valine. |
Common misconceptions
- Myth: You need to eat all nine essential amino acids in the same meal. Your body can pool amino acids from different meals. As long as you consume a variety of protein sources throughout the day, you can get all the essential amino acids you need.
- Myth: Plant-based diets are always deficient in essential amino acids. While many plant proteins are incomplete on their own, a well-planned diet with a variety of sources like legumes, grains, nuts, and seeds can easily provide all nine essential amino acids.
Related terms
When to bring in a professional
While dietary adjustments are often enough, a registered dietitian can provide personalized advice on meeting your protein needs.
- If you follow a restrictive diet, like a vegan diet, and are concerned about your protein intake.
- If you have a health condition that affects nutrient absorption or increases protein needs.
- If you are an athlete or have specific performance goals that might require a different protein intake.
- Before starting any new amino acid supplements.
How this entry was made: drafted with AI assistance from general, widely published definitions, checked in a separate verification pass for invented numbers and claims, and edited by the Millennials Wellness editors. General information only, not medical, financial or legal advice. Last checked October 2026. Our ground rules · Back to the glossary