Protein Powder

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Key Facts

  • Protein powders can be made from whey, casein, egg, soy, pea, or rice. This article focuses on whey protein powders.
  • The protein in whey protein powder is derived from liquid whey, a byproduct of the cheese-making process.
  • Whey protein is a “complete protein,” meaning it contains all nine essential amino acids that the body must obtain through food or drink.
  • There have been no confirmed foodborne illness outbreaks linked to whey protein powder, although there have been precautionary recalls – one due to Clostridium botulinum and three due to Salmonella.
  • Between 2000 and 2020, at least 1 whey protein-associated outbreak was reported to CDC’s National Outbreak Reporting System (NORS), causing 2 illnesses, and 0 hospitalizations and deaths. 


Protein powders can derive their protein from a variety of sources such as whey, casein, egg, soy, peas, or rice. By


Nutrient compositions of sweet and acid whey. By the Handbook of Dairy Foods and Nutrition, Third Edition.

Protein powders are commonly marketed as a dietary supplement for those looking to increase protein intake. Among the most common proteins used in these products are whey, casein, egg, soy, rice, hemp, and pea proteins, accompanied by additives such as creatine, glutamine, sugar, artificial sweeteners, or herbal sweeteners. This article examines whey protein powders, the most popular among American consumers.

Whey is a byproduct of the cheese making process. Whey protein, derived from whey, is touted as an easily-digestible, complete protein because it contains all of the nine essential amino acids (EAAs) that the body cannot synthesize itself. Specifically, whey protein is composed of approximately 50% Beta-lactoglobulin proteins, 20% Alpha-lactalbumin proteins, 10% Bovine serum albumin proteins, lactoferrin, and immunoglobulins. Depending on the cheese-making process, either sweet whey or acid whey will be produced. Each of these  has varying nutrient compositions and chemical characteristics. Sweet whey is more commonly used in whey products, as it is produced in far larger quantities within the United States compared to acid whey (95 billion pounds of sweet whey compared to four billion pounds of acid whey were produced during 2011). Sweet whey has a pH of 5.6 or higher and is a byproduct from manufacturing cheddar, mozzarella, or Swiss cheeses. Acid whey has a pH lower than 5.1 and is a byproduct from manufacturing cottage or ricotta cheeses. (More information on the differences between these whey variations is presented in the above table.)

There are three main types of whey protein powder products: whey protein concentrate (WPC), whey protein isolate (WPI), and whey protein hydrolysate (WPH). Whey product labels include the type as well as the percent of whey protein the dry powder contains. For example, “WPC80” indicates a whey protein concentrate powder that is made up of 80% whey protein.

The three types of whey are often mixed along with added flavors and other ingredients to enhance nutritional value and palatability. Whey products include protein powders, baked goods, meats, processed cheeses, yogurts, and frozen desserts. The affordability and nutritional benefits of these whey proteins have contributed to their rise in popularity.

Whey Protein Concentrate (WPC):

Whey protein concentrate (WPC) has undergone various processes so that the final product contains low levels of fats and carbohydrates, yielding a whey protein concentration of approximately 30–90%. This variation tends to be cheaper than WPI or WPH because it undergoes less processing.

Whey Protein Isolate (WPI):

Whey protein isolate (WPI) is processed further so that all fat and lactose is removed, producing a whey protein concentration over 90%. The removal of all fat and lactose makes this an appealing option for those looking to reduce their carbohydrate intake.

Whey Protein Hydrolysate (WPH):

Whey protein hydrolysate (WPH) is considered by dietitians to be the “predigested” form of whey protein that has already undergone partial hydrolysis. Initial studies have indicated that consuming WPH may lead to faster and easier absorption of the proteins, although more research is needed. This process of partial hydrolysis breaks down the whey’s amino acids into smaller, simpler units called peptides. Peptides are much less likely to cause allergic reactions, making WPH a great, hypoallergenic alternative for individuals with milk allergies.

Foodborne Outbreaks and Recalls

Between 2000 and 2020, at least 1 whey protein-associated outbreak was reported to CDC’s National Outbreak Reporting System (NORS), causing 2 illnesses, and 0 hospitalizations and deaths. From 2011 to 2014, there was one international voluntary recall involving potential Clostridium botulinum contamination and three voluntary recalls due to potential Salmonella contamination within the United States. Furthermore, in July 2018 a precautionary recall was placed on a dry whey powder (a closely related product to WPC, WPI, and WPH) product from Minnesota, due to potential Salmonella contamination.

Clostridium Botulinim 

In 2014, there was an outbreak scare of Clostridium botulinum in a 3.78-ton batch of whey protein concentrate produced by the New Zealand dairy company, Fonterra. This outbreak scare originated in February 2012 when broken flashlight fragments were found in a batch of whey protein concentrate 80 (WPC80). While the fragments were eventually removed, the process used to rework the product was poorly planned and executed, resulting in further contamination of the batch. Specifically, the factory workers ran the WPC80 through improperly cleaned pipes, and they failed to disperse the reworked WPC80 among new, standard product up to a maximum of 10% reworked product. Dispersal of reworked product is an important safety step within the dairy industry that ensures if contamination does remain, the contaminated product (as well as the risks it may pose to consumers) are diluted to acceptable levels. When the suspected batch underwent routine testing during production of Danone’s nutritional powder, the results indicated the possible presence of Clostridium botulinum. In June 2013, a Fonterra manager approved testing for Clostridium botulinum by AgResearch, an independent agricultural research organization that did not have the required accreditation to conduct these tests. In August 2013, three months after approving these tests, Fonterra notified New Zealand’s Ministry of Primary Industries of AgResearch’s test results, which claimed that the presence of Clostridium botulinum was “likely” but not “confirmed,” setting off the coordinated tracing and recall efforts by Fonterra and the Ministry. It was later determined by two United States government laboratories that the WPC80 batch was contaminated with the non-toxic Clostridium sporogenes (associated with food spoilage), instead of Clostridium botulinum.


In 2011, a Minnesota supplier implemented a voluntary recall of WPI due to concerns of Salmonella contamination. An independent laboratory conducted tests for Salmonella, which all came back negative, eliminating concerns of a potential outbreak.

In 2018, Salmonella was found in 25kg and 50kg bags of dry whey powder during routine testing at a production facility. Although the specific cause of this precautionary recall has not been publicly reported as of July 2018, there are a several ways whey protein products can be contaminated by Salmonella. The introduction of moisture into the processing area produces an environment conducive to Salmonella growth, which could either directly contaminate or indirectly contaminate whey protein products via workers, equipment, or pests

Heavy Metals

In recent years, heavy metal contamination (e.g. arsenic, cadmium, lead, and mercury) has also been a concern with whey protein products. Heavy metals are sparse, naturally occurring elements that can be found in extremely high quantities due to human industrial activities such as mining/smelting, coal burning, agricultural use of heavy metals, or paper processing. These heavy metals, often found in soil, can be absorbed by plants and concentrate in grazing ruminants, like the dairy cows that supply the milk for whey protein production. The vast majority of whey protein products contain safe levels of these metals, but there are a few brands, including Muscle Milk Chocolate powder, Muscle Milk Vanilla Crème powder, and the ready-to-drink liquid EAS Myoplex Original Rich Dark Chocolate Shake, that may expose individuals to unsafe levels of heavy metal contamination if they are consuming three or more servings a day. Consumers may be unaware of this, as this information is not usually included on the nutritional labels of protein powders, except in certain states (such as in California) where toxic substance reporting is mandated.

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The whey protein in protein powders first originates as a byproduct from cheese-making. After being drained from sold curds (casein), it undergoes its own production steps.

The first steps of whey protein production coincide with commercial cheese making, as whey is often harvested as a byproduct of these processes. Please see our article on cheese-making here.

Milk Intake

Milk arrives at the dairy processor where it is tested for purity, quality, fat content, and proper storage temperature to ensure the milk is free from harmful bacteria.

Milk Standardization and Pasteurization

Standardization includes determining the ratio of protein to fat in the milk or standardizing the solids and then weighing the milk. Various technologies, including ultrafiltration, are common in large cheese or dairy processing operations to ensure milk is cleared of debris and spores that could survive pasteurization. A specially designed centrifuge, called a Bactofuge, is often used to separate bacterial spores, which have a higher density than the milk. Unless raw milk cheese is being produced, pasteurization is carried out at this point in the process.


Milk after adding the enzyme, rennet. Solid casein proteins form curds while the whey proteins remain in a liquid form. 

Coagulation is the process of denaturing the milk proteins to form a gel network that facilitates the separation of milk solids (casein curds) from liquid (whey). However, coagulation itself does not separate curds and whey. Bacterial cultures are added to the milk before coagulation and after pasteurization. Streptococcus, Lactobacillus, and Lactococcus lactis are commonly used starter cultures that convert the lactose in milk to lactic acid via fermentation. A bovine-derived enzyme called rennet is added, which coagulates the milk protein, casein, forming a custard-like mass.

Whey Draining and Pasteurization

After separation, the whey is drained from the curds and then stored and transported to a protein manufacturing facility. After draining, the liquid whey is pasteurized again at 161 degrees Fahrenheit for at least five seconds to further ensure that the whey is free of harmful pathogens.

Whey Filtration

The liquid whey then undergoes filtration using a variety of methods, such as membrane filtration or ion exchange, which allow the whey proteins and other nutrients to selectively pass through while filtering out suspended solids (such as fine casein curd particles that remain from the draining step). In order to raise the concentration of whey protein (to 90% or higher) relative to all other dry matter, the liquid whey may undergo diafiltration, a process that adds water to the liquid whey during filtration to wash out lactose and minerals. Filtration steps may be repeated as necessary to reach the desired whey protein concentration. All the proteins and nutrients that pass through the filtration process are known as permeate. The permeate is then deposited in concentrated permeate storage to await the evaporation step.

After filtration, the whey permeate travels to the permeate evaporator (#2) for the evaporation step, then to the crystallization system (#3) for the crystallization step, and then to the permeate post-crystallization spray dryer (#4) for the spray drying step. Lastly, it is sent to permeate powder storage (#5) where it will then be packaged, transported, and sold. By The Dairy Processing Handbook.

Evaporation and Crystallization

Next, the permeate enters the evaporators, which siphon off more liquid in the whey product, further concentrating the whey proteins and nutrients.

After evaporation, the whey is flash cooled to 85 to 105 degrees Fahrenheit to facilitate the formation and growth of lactose crystals, a process known as nucleation. The whey is then held within the crystallizers for four to eight hours to achieve a uniform distribution of lactose crystals, a characteristic that prevents the final product from absorbing or attracting moisture from the air.

Spray Drying

The water in the whey permeate is siphoned off, and the dry product is then milled by the rotating drums. By The Dairy Processing Handbook.

The whey is then transported to a post-crystallization spray dryer where any remaining water in the whey concentrate is evaporated off and the product is milled into a powdered or flake form. Spray drying prevents the growth of microorganisms in order to protect the consumer and to better preserve the food product. The most widely-used method is drum-spray drying, by which the whey product is run over high-capacity, steam-heated, rotating drums to facilitate the grinding of the whey concentrate and siphoning of the whey’s excess liquid in the form of a vapor.


After drying, the powdered concentrate is transferred to Permeate Powder Storage, where the powdered whey protein product is then bagged, typically in approximately 25 kg, plastic-lined, industrial bags.

Food Safety

Packaging, Transportation, and Storage

It is important that both consumer and producer understand the biggest risks associated with whey protein powder and how to mitigate those risks to protect consumer safety. After production, the whey protein powder should be properly sealed to prevent contamination from the outside environment. Whey protein powders should be packaged, shipped, and stored in cool, dry environments with temperatures and relative humidity not to exceed 80℉ and 65%, respectively. It is recommended that whey protein products be consumed within nine months to a year of production.

Environmental Contaminants

Spore-forming bacteria (such as Clostridium botulinum) can withstand stresses, such as UV radiation, drying, or high temperatures, that kill other pathogens. Bacterial spores can be present in the environment as biofilms on the surfaces of processing plant equipment or even on the udders of dairy cows (cleaning the udders may reduce the spore count in milk). In addition, if the product is rehydrated and kept at room temperature in anaerobic conditions, dormant Clostridium botulinum bacteria could be stimulated to produce the harmful neurotoxin that causes botulism illness in humans. Other non-spore forming bacteria, such as Salmonella, Escherichia coli, or Listeria monocytogenes, can also contaminate whey products at different stages of production. Pasteurization can effectively eliminate most, but not all pathogens of concern. However, contamination can still occur later in production during transportation and retail storage or in the consumer’s home.

Allergies and Sensitivities

Individuals that are lactose intolerant are advised to avoid consuming protein powders that contain WPC and, instead, consume protein powders containing WPI because it has much lower lactose content. Those with milk allergies are recommended to use protein powders with WPH, as they are less likely to cause allergic reactions.


Whey protein powder is used in a wide variety of products, such as infant formula, emergency food rations, bakery items, cereal products, and sports nutrition products. As of 2015, whey protein had been used in over 6,000 products launched globally, and this number is expected to continue rising given the 4% annual increase in sales of whey protein powder every year from 2009 to 2016.


Whey protein powder contains all nine essential amino acids that individuals need to obtain from their diet and can easily be incorporated and mixed into virtually any food or drink. Protein powders made from WPC, WPI, and WPH vary in the amounts of lactose, minerals, and other nutritional additives they contain, but they are all composed of basic whey proteins (beta-lactoglobulins, alpha-lactalbumins, bovine serum albumins, lactoferrins, and immunoglobulins). For some individuals, whey protein powders may play a key role in supplementing or substituting food-based protein to follow the National Institute of Health’s recommended protein consumption guidelines of 0.8 grams of protein per kg of body weight.

Furthermore, many individuals elect to exceed these guidelines in order to increase muscle mass and strength. Whey protein has a high concentration of proteins and amino acids and can increase the release of hormones that facilitate muscle growth. High protein diets also have a high satiety value and have been shown to aid individuals in weight loss by boosting their metabolic rate and decreasing appetite. Beyond these two primary uses of whey protein powder, recent studies have identified associations between whey protein intake and various health outcomes such as lowered blood pressure, moderation of blood sugar in type II diabetics, inflammation reduction, improved mood and serotonin levels, boosting of the body’s immune system as well as anti-tumor and anticarcinogenic effects, although more research on the health benefits of protein powders is needed.

In recent years, the American Heart Association’s Nutrition Committee has claimed that high protein diets, such as those supplemented by whey protein products, put consumers at risk of bone, kidney, and liver problems. However, there is no consensus on the health effects of these products, with some studies indicating that high protein diets may be beneficial to these same aspects of human health. Individuals with current kidney or liver conditions have traditionally been advised to consult with a healthcare provider before including whey protein powder into their diet. Limiting dietary protein has been standard practice to avoid further complications among these patients, though recent studies have called this practice into question. Lastly, some individuals consuming too much whey protein powder may experience nausea, cramping, flatulence, or diarrhea.


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Tyler Bonnell

Tyler Bonnell

BS Public Health, BA Spanish Student; University of Washington

Kathleen Conery

Kathleen Conery

MPH One Health; University of Washington

Maayan Simckes

Maayan Simckes

PhD Epidemiology; University of Washington

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