How many amino acids should you take per day?: A Comprehensive Guide

October 16, 2025 •

4 min read

According to the World Health Organization (WHO), healthy adults need specific amounts of the nine essential amino acids per kilogram of body weight to meet baseline requirements. Knowing exactly how many amino acids should you take per day is crucial for building muscle, aiding recovery, and maintaining overall health.

Quick Summary

Daily amino acid requirements depend on factors like body weight, age, and activity level. Meeting these needs is typically achieved through a balanced, protein-rich diet, with supplements offering targeted benefits for specific populations like athletes.

Key Points

Prioritize whole foods: The safest and most effective way to meet your amino acid needs is through a diet rich in complete protein sources like meat, dairy, eggs, and soy.
Consider individual needs: Your specific amino acid requirements depend on body weight, age, and activity level, with athletes and older adults needing more than sedentary individuals.
Understand supplement roles: Amino acid supplements, like BCAAs for athletes or EAAs for the elderly, are most beneficial for targeted support rather than as a replacement for dietary protein.
Be mindful of dosage: Excessive intake of amino acid supplements can cause negative side effects and nutrient imbalances; always follow recommended guidelines.
Consult a professional: Before starting any supplement, speak with a doctor or dietitian to ensure your intake is safe and appropriate for your health goals.
Timing can matter: For athletes, consuming amino acids around workouts may improve performance and recovery, while older adults may benefit from supplementation timed to specific meals.

The Foundational Role of Amino Acids

Amino acids are the fundamental building blocks of proteins, which are essential for nearly every function in the human body, from creating muscle tissue to producing hormones and enzymes. There are 20 total amino acids, but only nine are classified as 'essential' because the body cannot produce them on its own. These must be obtained through food. The other amino acids are considered 'non-essential' or 'conditionally essential,' which the body can synthesize internally. The best way to ensure you're getting enough essential amino acids is to consume complete proteins, which contain all nine in sufficient amounts. Animal products like meat, eggs, and dairy are classic examples of complete proteins, but plant-based options like soy and quinoa also fit the bill.

Establishing Baseline Needs: WHO Guidelines

For a healthy, sedentary adult, the World Health Organization (WHO) provides baseline recommendations for essential amino acid intake per kilogram (kg) of body weight. These recommendations offer a starting point for understanding basic requirements:

Histidine: Recommended intake per kg of body weight
Isoleucine: Recommended intake per kg of body weight
Leucine: Recommended intake per kg of body weight
Lysine: Recommended intake per kg of body weight
Methionine: Recommended intake per kg of body weight
Phenylalanine (with Tyrosine): Recommended intake per kg of body weight
Threonine: Recommended intake per kg of body weight
Tryptophan: Recommended intake per kg of body weight
Valine: Recommended intake per kg of body weight

These recommendations are minimums and do not account for increased needs due to physical activity or other health factors.

How Activity Level Impacts Daily Requirements

An individual's lifestyle, particularly their level of physical activity, significantly alters their amino acid needs. Active individuals and athletes require more protein and, consequently, more amino acids to support muscle repair, growth, and performance.

Comparing Amino Acid Needs: Sedentary vs. Athlete


Population	General Protein Needs (g/kg BW)	Associated Amino Acid Needs	Primary Intake Source	Role of Supplements
Sedentary Adults	0.8–1.2 g/kg BW	Meets minimums for tissue repair and maintenance.	Balanced, complete-protein diet (meat, eggs, dairy, soy).	Typically unnecessary if consuming a balanced diet.
Moderately Active	1.2–1.6 g/kg BW	Supports increased tissue turnover and recovery.	Protein-rich meals and snacks.	May help meet higher targets, particularly around workouts.
Athletes/Intense Trainers	1.6–2.2 g/kg BW	Maximizes muscle protein synthesis and recovery.	High-quality complete protein sources throughout the day.	Useful for targeted benefits like recovery or fueling during exercise, especially BCAAs.
Older Adults	1.2–1.6 g/kg BW	Combats age-related muscle loss (sarcopenia) and supports strength.	Prioritize high-quality protein, especially leucine-rich sources.	EAA or leucine supplementation can stimulate muscle protein synthesis.

Targeted Supplementation: BCAAs and EAAs

While whole foods should be the foundation, certain supplements can help individuals meet increased or specific amino acid needs. Branched-chain amino acids (BCAAs)—leucine, isoleucine, and valine—are especially popular among athletes due to their role in stimulating muscle protein synthesis. BCAA supplements are often used around workouts. Research suggests a specific ratio of leucine, isoleucine, and valine may be effective for muscle recovery and growth. For those with lower total protein intake, such as the elderly or individuals on calorie-restricted diets, Essential Amino Acid (EAA) supplements containing all nine essential amino acids may be beneficial.

Risks and Considerations of Amino Acid Supplementation

Excessive supplementation of individual or specific amino acids can be harmful. Taking too much of one amino acid can create imbalances and interfere with the absorption of others. For example, high intake of BCAAs can compete with tryptophan, a precursor to serotonin. High doses can also lead to side effects such as nausea, headaches, and digestive issues. Importantly, amino acid supplements are not regulated as stringently as drugs by bodies like the FDA, so product quality and safety can vary. It is always recommended to consult a healthcare professional or registered dietitian before starting any supplement regimen to ensure it aligns with your health status and goals, especially if you have pre-existing conditions like kidney disease.

Conclusion

The question of how many amino acids you should take per day doesn't have a single answer, as the optimal amount depends heavily on individual factors like body weight and activity level. The priority for most people should be obtaining a complete set of essential amino acids through a balanced diet rich in high-quality protein sources. For athletes, the elderly, or those with specific needs, targeted supplementation with EAAs or BCAAs may offer additional benefits. However, responsible supplementation involves understanding potential risks and consulting a healthcare professional to avoid imbalances and negative side effects. Focusing on a well-rounded diet is the most effective and safest approach for ensuring adequate amino acid intake.

Frequently Asked Questions

Yes, it is possible to get all essential amino acids from a plant-based diet. While many plant proteins are 'incomplete,' combining different sources like rice and beans or consuming complete plant proteins like soy and quinoa ensures you receive a full amino acid profile over the course of a day.

For most people consuming adequate dietary protein, BCAA supplements are not necessary for muscle growth. While BCAAs, particularly leucine, are key for muscle protein synthesis, research does not show significant benefits over consuming sufficient complete protein from whole food sources.

A complete protein is a food source that contains all nine essential amino acids in sufficient amounts. Examples include meat, eggs, and dairy, as well as some plant-based options like soy and quinoa.

For athletes, supplements are often taken around a workout, either before, during, or after, to maximize energy and muscle recovery. For others, timing may be less critical and can depend on specific health goals, such as combating age-related muscle loss.

Taking excessively high amounts of amino acid supplements can lead to side effects like nausea, cramps, and diarrhea. It can also create imbalances, as high doses of one amino acid can interfere with the absorption of others.

Protein powders are typically complete proteins containing all essential amino acids and providing calories. Amino acid supplements contain specific, isolated amino acids and are often used for targeted effects, with negligible calories.

Yes, older adults have increased protein and amino acid needs, typically 1.2–1.6 grams per kg of body weight, to help prevent age-related muscle loss, or sarcopenia. EAA or leucine supplementation can also effectively stimulate muscle protein synthesis in this population.