Milk: The Best Example of a Complete Protein Source NASM

December 30, 2025 •

3 min read

Globally, sitting for extended periods is a common occurrence, increasing the importance of proper nutrition. The National Academy of Sports Medicine (NASM) often cites milk as a prime example of a complete protein source. It contains all nine essential amino acids necessary for bodily functions. This article explores complete proteins and other sources recommended by NASM.

Quick Summary

This guide explains why milk is a leading example of a complete protein source, as recognized by the National Academy of Sports Medicine. It also covers other complete protein examples and the importance of consuming all essential amino acids for health and fitness.

Key Points

Milk is a complete protein: NASM cites milk as a complete protein with all nine essential amino acids.
Animal proteins are generally complete: Proteins from animal sources, such as eggs, meat, and fish, are usually complete.
Some plant proteins are complete: Soy, quinoa, and buckwheat are exceptions, providing all essential amino acids for vegetarian and vegan diets.
Combine incomplete proteins: Pairing incomplete plant proteins like rice and beans can create a complete amino acid profile.
Protein needs vary by activity: NASM suggests higher protein intake for active individuals, especially those in resistance training, often 1.6 to 2.2 g/kg/day.
Focus on whole food sources: NASM encourages meeting protein needs through a varied diet of whole foods rather than supplements.
Timing is important for athletes: For performance athletes, timing protein intake can help muscle protein synthesis and recovery.

Understanding Complete Proteins

A complete protein is a food source with all nine essential amino acids (EAAs) that the human body cannot produce itself. EAAs must come from the diet. Fitness professionals certified by the National Academy of Sports Medicine (NASM) find understanding complete versus incomplete proteins essential for dietary recommendations. NASM materials emphasize that animal-based proteins are generally complete, while most plant-based sources are incomplete.

Milk and Other Animal Products

Milk is a top example of a complete protein because it naturally has both casein and whey proteins, providing a full spectrum of essential amino acids. Milk protein is used to evaluate the quality of other dietary proteins. Animal proteins are highly bioavailable, allowing the body to absorb and use them more efficiently than many plant-based options. Other top animal protein sources include:

Eggs: Whole eggs are often considered nature's perfect protein, with a high concentration of easily digestible, complete protein.
Meat and Poultry: Lean cuts of beef, pork, chicken, and turkey are dense sources of complete protein, plus iron and zinc.
Fish and Seafood: Salmon and tuna provide high-quality complete protein and omega-3 fatty acids.
Dairy Products: Greek yogurt and cheese are great sources of complete protein and calcium.

Plant-Based Complete Proteins

While most plant-based proteins are incomplete on their own, a few options contain all nine essential amino acids. NASM recognizes these as complete protein sources, which is important for those following vegetarian or vegan diets.

Examples of Complete Plant-Based Proteins

Soy: Products from soybeans, such as tofu, tempeh, and edamame, are a complete protein source for plant-based eaters.
Quinoa: This grain-like seed is a well-known plant-based complete protein, also rich in fiber and minerals.
Buckwheat: Buckwheat is a grain that offers a full amino acid profile and complex carbohydrates.
Hemp Seeds: Hemp seeds contain all nine essential amino acids and are rich in healthy fats.

Combining Incomplete Proteins

For those on a plant-based diet, NASM notes that combining different incomplete protein sources can ensure all essential amino acids are consumed daily. This strategy involves pairing legumes with grains, or nuts/seeds. Examples include rice and beans, or hummus with whole-wheat pita. The body maintains an amino acid pool, so these combinations don't necessarily need to be eaten in the same meal to be effective.

Complete vs. Incomplete Protein Sources: A Comparison


Feature	Complete Protein Sources	Incomplete Protein Sources
Essential Amino Acids	Contain all nine essential amino acids.	Missing one or more essential amino acids.
Common Sources	Animal products (milk, eggs, meat, fish), soy, quinoa, buckwheat.	Grains, legumes (except soy), nuts, seeds, and most vegetables.
Primary Goal for Consumption	Provides all building blocks in one food item.	Requires combining different sources to achieve a full amino acid profile over the day.
Muscle Building Efficiency	Highly efficient for muscle repair and growth due to high bioavailability.	Can be effective with proper planning and varied diet, but may be less bioavailable.
Example Combinations	N/A (single source sufficient)	Rice and beans, peanut butter on whole-wheat bread.

The NASM Perspective on Protein Consumption

NASM recommends that exercise professionals guide clients toward a balanced diet, with a focus on whole food protein sources. While supplements like whey and casein are convenient, NASM stresses that most protein needs can be met through varied food intake. For those in regular resistance exercise, protein intake is typically 1.6 to 2.2 grams per kilogram of body weight per day. For more detailed guidelines, especially regarding protein timing and supplementation, NASM provides extensive resources.

Conclusion

For NASM professionals, recognizing milk as a complete protein source is valuable knowledge. Complete proteins, whether from animal or plant sources, provide all essential amino acids for body repair, growth, and function. Understanding these sources helps create effective dietary plans tailored to individual needs. Prioritizing high-quality protein supports fitness goals and overall health.

Frequently Asked Questions

NASM identifies milk as the best complete protein source because it contains whey and casein proteins, providing all nine essential amino acids.

Generally, animal proteins like meat, eggs, fish, and dairy are considered complete because they contain all essential amino acids.

Complete plant-based proteins include soy (tofu, tempeh), quinoa, buckwheat, and hempseed.

Vegetarians can get complete proteins by eating various plant-based foods daily, such as combining legumes and grains (rice and beans) or nuts and seeds.

No, the body has an amino acid pool, so you can combine incomplete protein sources over the day to get the benefits of a complete protein.

Protein quality determines the availability of essential amino acids, which are crucial for muscle repair, growth, and immune function, especially for active individuals.

Casein and whey are milk proteins. Whey digests quickly, while casein digests slowly. Both are complete proteins.