How many amino acids does the body need to get from food? The Essential Nine

December 13, 2025 •

4 min read

The human body requires 20 amino acids to function properly, but research confirms it can only produce 11 of these on its own. This means you must understand how many amino acids does the body need to get from food to ensure proper nutrition and health. A balanced diet is critical for obtaining the remaining nine, known as essential amino acids.

Quick Summary

The body must get nine essential amino acids from food, as it cannot produce them itself. A balanced diet with complete proteins or varied plant sources ensures proper intake for health.

Key Points

Nine Essential Amino Acids: The body must obtain nine specific amino acids—histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, and valine—from food because it cannot produce them internally.
Complete vs. Incomplete Proteins: Complete protein sources, like meat, eggs, and soy, contain all nine essential amino acids. Most plant-based foods are incomplete but can be combined to form a complete profile.
Balanced Diet is Sufficient: Most people can get all the essential amino acids they need by eating a healthy, varied diet, without the need for supplements.
Amino Acid Deficiency Symptoms: A lack of essential amino acids can lead to fatigue, poor immunity, slow wound healing, and mood disorders.
Conditionally Essential Amino Acids: Some non-essential amino acids can become essential during times of stress, illness, or rapid growth, when the body's natural production is insufficient.
Vital Body Functions: Amino acids are crucial for building protein, repairing tissue, creating hormones, supporting immune function, and providing energy.

Amino acids are the fundamental building blocks of protein, and they are critical for numerous bodily functions, including repairing tissue, supporting muscle growth, and creating hormones. While there are 20 total amino acids, their source and importance can be categorized into three distinct groups: essential, non-essential, and conditionally essential. Understanding this classification is key to knowing precisely how to meet your body's nutritional requirements through your diet.

The Three Classes of Amino Acids

To grasp why only certain amino acids must come from your diet, it's helpful to first understand how they are classified.

Essential Amino Acids: The Non-Negotiables

There are nine amino acids that the human body cannot produce on its own or cannot produce in sufficient quantities. These are known as essential or indispensable amino acids and must be obtained directly from the foods we eat. The nine essential amino acids are histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, and valine. A deficiency in even one of these can negatively impact the body's ability to create the necessary proteins and perform its vital functions.

Non-Essential Amino Acids: What Your Body Makes

In contrast, non-essential amino acids are those that the body can synthesize internally, meaning they do not have to be consumed through food. The eleven non-essential amino acids are alanine, arginine, asparagine, aspartic acid, cysteine, glutamic acid, glutamine, glycine, proline, serine, and tyrosine. Despite the name, these amino acids are still vital for your health and serve many crucial roles in the body, such as regulating digestion and removing toxins.

Conditionally Essential Amino Acids: When Needs Increase

A third category, conditionally essential amino acids, refers to non-essential amino acids that can become essential under specific circumstances, such as stress, illness, or rapid growth. For example, while a healthy adult can synthesize arginine, a person recovering from severe trauma or dealing with a serious illness may not produce enough to meet their increased demands.

How to Get All the Essential Amino Acids from Food

Meeting the body's need for essential amino acids is straightforward with a balanced diet. The key is to consume either complete protein sources or a variety of incomplete ones.

Complete Protein Sources

A complete protein is a food item that contains all nine essential amino acids. Animal products are a classic example, but several plant-based options also provide a full profile.

Animal-Based: Meat, poultry, fish, eggs, and dairy products like milk and cheese.
Plant-Based: Soy products (tofu, tempeh, edamame), quinoa, and buckwheat.

Complementary Proteins for Plant-Based Diets

For those following a plant-based diet, combining different incomplete proteins throughout the day can provide all nine essential amino acids. This does not need to happen within the same meal. Examples of complementary pairings include:

Rice and beans
Hummus and whole-grain bread
Peanut butter and whole-wheat toast
Lentils and almonds

Understanding Complete vs. Incomplete Proteins


Feature	Complete Proteins	Incomplete Proteins
Contains all 9 EAAs?	Yes	No, lacks one or more EAAs
Primary Sources	Animal products (meat, eggs, dairy); a few plant sources (soy, quinoa)	Most plant sources (grains, legumes, nuts, seeds)
Dietary Strategy	Simple; consume a variety for balanced intake	Intentional combination; pair different plant proteins over the day
Protein Quality	High biological value; easily absorbed and utilized	Lower biological value; requires pairing to form a complete profile
Common Examples	Chicken, eggs, milk, tofu, quinoa	Beans, lentils, nuts, most grains

The Vital Role of Amino Acids in the Body

Amino acids are involved in virtually every physiological process. They aid in numerous functions:

Muscle Growth and Repair: Critical for building and repairing muscle tissue, especially during and after exercise.
Hormone Production: Precursors for many hormones, such as epinephrine and thyroid hormones.
Immune System Support: Essential for a healthy immune response and the production of antibodies.
Brain Function: Synthesize neurotransmitters like serotonin and dopamine that regulate mood, sleep, and appetite.
Tissue Repair and Healing: Necessary for wound healing and forming structural proteins like collagen.
Energy Source: Can be used as an energy source when other macronutrients are insufficient.
Digestion: Help break down food and maintain a healthy digestive system.

What Happens When You Have an Amino Acid Deficiency?

Because of their widespread roles, a deficiency in one or more essential amino acids can have serious health consequences. Symptoms can include:

Fatigue and Weakness: Due to impaired energy production and muscle synthesis.
Poor Wound Healing: Collagen production is hindered, slowing recovery.
Decreased Immunity: The body's ability to fight off infections is compromised.
Mood Disorders: Low levels of neurotransmitters like serotonin can lead to depression and anxiety.
Stunted Growth: Especially in children, a lack of essential amino acids can slow development.
Digestive Issues: Poor gut health and an inability to break down food efficiently.
Skin and Hair Problems: Compromised health of structural proteins can affect skin, hair, and nails.

Conclusion: Eating a Varied Diet is Key

In conclusion, your body needs to get nine essential amino acids from food, while producing eleven others on its own. While the distinction between essential and non-essential may exist, all amino acids are crucial for overall health. The good news is that most people can meet their daily needs through a balanced diet without needing to meticulously track individual amino acids. By incorporating a variety of complete protein sources or combining different plant-based proteins, you can ensure your body has all the necessary building blocks to function optimally. For more detailed information on specific amino acids and their roles, the Cleveland Clinic offers a great resource on their website: Amino Acid: Benefits & Food Sources - Cleveland Clinic.

Frequently Asked Questions

There are 20 different amino acids that the human body needs to function correctly. These are categorized into three groups: essential, non-essential, and conditionally essential.

You can get all nine essential amino acids by eating a balanced diet that includes complete protein sources, such as meat, eggs, dairy, soy, and quinoa. Vegetarians and vegans can combine different incomplete plant-based proteins, like rice and beans, to get a full amino acid profile.

The main difference is that the body cannot produce essential amino acids, so they must be obtained from food. Non-essential amino acids can be synthesized by the body internally, but are still vital for various functions.

Complete proteins are foods that contain all nine essential amino acids. Examples include animal products like meat, eggs, and dairy, as well as plant-based options such as soy, quinoa, and buckwheat.

For most people with a healthy, balanced diet, amino acid supplements are not necessary to meet daily needs. You should consult a healthcare provider before taking any supplements.

A deficiency in essential amino acids can lead to various health problems, including fatigue, decreased immunity, digestive issues, poor wound healing, and mood disturbances.

Yes, a well-planned plant-based diet can provide all the amino acids you need. While most individual plant proteins are incomplete, combining different sources like legumes, nuts, and grains throughout the day ensures you get all nine essential amino acids.