Where Do Protein Powders Get Their Protein From? A Look at Animal and Plant Sources

November 24, 2025 •

4 min read

Over a third of American adults have used a dietary supplement, and for many, protein powder is a staple, but where do protein powders get their protein from? The sources are diverse, originating from both animal byproducts and concentrated plant matter, each with unique nutritional profiles and processing methods.

Quick Summary

Protein powders extract concentrated protein from diverse sources like milk (whey and casein), eggs, and various plants (soy, peas, rice). Manufacturers use processing methods like filtration and drying to create the fine powder, often adding flavors and other ingredients.

Key Points

Animal-based sources include whey and casein, both milk derivatives from the cheese-making process, and egg white protein.
Whey and casein have different absorption rates, with whey being fast-digesting and casein being slow-digesting, making them ideal for different times of day.
Plant-based proteins are derived from various plants such as peas, soy, brown rice, and hemp, offering options for vegans and those with dairy allergies.
Blended plant proteins are common to ensure a complete amino acid profile, compensating for the limitations of single plant sources.
The manufacturing process involves extraction, filtration, and drying to concentrate the protein and remove other components, converting the source into a fine powder.
Choosing the right protein powder depends on individual needs, including dietary restrictions, fitness goals, and desired absorption rate.

Unpacking the Animal-Based Protein Sources

Animal-based protein powders are derived primarily from milk and eggs, offering a complete amino acid profile, meaning they contain all nine essential amino acids necessary for the body. For many, they are the gold standard for muscle synthesis and recovery due to their high biological value and excellent digestibility.

Milk-Derived Protein: Whey and Casein

Both whey and casein are byproducts of the cheese-making process. When milk is curdled, it separates into solid curds (casein) and liquid whey.

Whey Protein: The liquid whey is collected and processed through filtration to remove water, lactose, and fat, leaving behind a protein-rich concentrate. For whey isolate, the filtration process is more extensive, resulting in a purer product with higher protein content and less lactose, making it suitable for those with sensitivities. Whey is known for its fast absorption rate, making it an ideal post-workout supplement for muscle repair.
Casein Protein: This makes up about 80% of the protein in cow's milk and is found in the curds. Because casein forms a gel in the stomach, it digests slowly, providing a sustained release of amino acids into the bloodstream over several hours. This makes it an excellent option for promoting muscle maintenance during sleep or prolonged periods without food.

Egg-Based Protein

Egg white protein powder is made by separating the egg whites from the yolks, filtering, and then pasteurizing and drying them into a fine powder. It is also a complete protein and is digested at a slower rate than whey but faster than casein. It serves as a great alternative for those with dairy allergies or intolerances.

Other Animal Sources

Collagen is another animal-based protein, typically sourced from the connective tissues, bones, and hides of animals. While it is popular for supporting joint and skin health, it is not a complete protein and lacks certain essential amino acids required for muscle growth. Beef protein isolates are also available, derived from beef for those seeking a dairy-free animal source.

Exploring the Plant-Based Protein Sources

Plant-based protein powders have grown in popularity, especially among vegans, vegetarians, and those with dairy allergies. While some plant proteins are incomplete on their own, manufacturers often create blends to achieve a complete amino acid profile. The process typically involves harvesting, cleaning, grinding, and then separating the protein from other plant components.

Common Plant Protein Examples

Pea Protein: Sourced from yellow split peas, this protein is hypoallergenic and rich in branched-chain amino acids (BCAAs). Its high digestibility makes it a popular choice for post-workout nutrition.
Soy Protein: Derived from soybeans, soy protein is one of the few complete plant proteins. It is widely available and has been extensively studied for its health benefits, including cholesterol reduction.
Brown Rice Protein: By itself, brown rice protein is not a complete protein due to low levels of lysine. However, it is easily digestible and often combined with pea protein to create a balanced amino acid profile.
Hemp Protein: Made from ground hemp seeds, this powder is a good source of fiber and omega-3 and omega-6 fatty acids. It contains all nine essential amino acids but in different proportions than animal proteins.
Blends: Many plant-based options are blends (e.g., pea and rice) to ensure a complete amino acid profile and a more balanced nutritional content.

The Manufacturing Process: From Source to Scoop

Regardless of the source, the general manufacturing process follows several key steps to transform the raw ingredient into a supplement:

Sourcing and Preparation: Raw materials like milk or legumes are collected and tested for quality before processing.
Extraction and Separation: The protein is extracted from its source. For milk, enzymes separate whey from curds. For plants, milling and aqueous or enzymatic methods separate protein from starches and fibers.
Filtration and Concentration: The liquid protein is filtered to remove unwanted components like fat, lactose, and water, increasing the protein concentration. Techniques like microfiltration or ion exchange are used.
Drying: The concentrated protein solution is dried to create the fine powder. Spray drying is a common method, where the liquid is sprayed into a chamber of hot air.
Flavoring and Packaging: The final powder is blended with flavors, sweeteners, thickeners, and vitamins before being packaged for distribution.

Comparison: Animal vs. Plant Protein Powders


Feature	Whey Protein	Casein Protein	Blended Plant Protein	Egg White Protein
Source	Cow's milk	Cow's milk	Peas, rice, soy, hemp, etc.	Egg whites
Absorption Rate	Very Fast	Very Slow	Medium	Medium-Slow
Complete Protein	Yes	Yes	Often, when blended	Yes
Best Time to Use	Post-Workout	Before Bed	Post-Workout/Anytime	Anytime
Dairy-Free	No	No	Yes	Yes
Common Use	Muscle repair, recovery	Muscle maintenance, satiety	General nutrition, recovery	Dairy alternative, recovery

How to Choose the Right Protein Powder

Choosing the right protein powder depends on your dietary restrictions, fitness goals, and personal preferences. If you have no dairy sensitivities and want a fast-absorbing protein for immediate post-workout recovery, whey is an excellent choice. For sustained amino acid release, like before bed, casein is preferable. For those with dairy allergies or who follow a vegan diet, plant-based proteins offer a robust and complete option, especially when blended. Consider your overall diet and consult a healthcare professional to ensure the supplement fits your needs. As a reminder, supplements are not regulated as rigorously as food or medicine by the FDA, so it's wise to choose products from reputable brands that test for contaminants. Learn more about the potential risks and regulations concerning protein powders at Harvard Health Publishing.

Conclusion

Protein powders originate from diverse sources, with the most common being milk (whey and casein) and various plant materials (peas, soy, rice). The extraction and processing of these raw ingredients are key to producing the final powdered supplement. Each source offers distinct benefits and absorption rates, influencing when and why someone might choose it. Ultimately, understanding where your protein powder gets its protein from allows you to make an informed decision aligned with your health objectives and dietary requirements.

Frequently Asked Questions

Whey and casein are both derived from cow's milk. The primary difference is their digestion rate; whey is fast-digesting, making it ideal for post-workout recovery, while casein is slow-digesting, providing a prolonged release of amino acids, which is good for muscle maintenance over longer periods like overnight.

Yes, plant-based protein can be just as effective as whey for muscle building, especially when formulated as a blend of different sources (like pea and rice) to provide a complete amino acid profile. Some studies show similar muscle mass gains with both whey and soy protein when combined with exercise.

Whey protein is a byproduct of cheesemaking. After enzymes are added to milk to create curds (casein), the remaining liquid whey is collected. This liquid then undergoes filtration to remove fats and lactose, followed by evaporation and spray-drying to convert it into a fine powder.

Vegan protein powder gets its protein from a variety of plant sources. Common examples include yellow split peas, soybeans, brown rice, and hemp seeds. Blends are frequently used to create a complete amino acid profile.

Isolates, like whey protein isolate, undergo more extensive processing than concentrates. This additional filtration removes more of the fat and lactose, resulting in a purer protein powder with a higher percentage of protein per serving.

For most people, it's possible to meet protein needs through a balanced diet of whole foods like meat, eggs, and legumes. Protein powders offer a convenient and efficient way to supplement intake, especially for athletes or those with increased protein needs. Whole foods also contain other beneficial nutrients that powders may lack.

Besides the protein source, powders often contain additional ingredients to improve flavor, texture, and nutritional value. These can include sweeteners (natural or artificial), flavorings, thickeners, vitamins, and minerals.