Whey protein
Encyclopedia
Whey protein is a mixture of globular protein
s isolated from whey
, the liquid material created as a by-product of cheese
production. Some preclinical studies in rodents have suggested that whey protein may possess anti-inflammatory
or anti-cancer properties; however, human data is lacking. The effects of whey protein on human health are of great interest and are currently being investigated as a way of reducing disease risk, as well as a possible supplementary treatment for several diseases.
Whey protein is commonly marketed and ingested as a dietary supplement
, and various health claims have been attributed to it in the alternative medicine
community. Although whey proteins are responsible for some milk allergies
, the major allergens in milk are the casein
s.
in water, with some minerals and lactalbumin
. It is removed after cheese is processed. The fat is removed and then is processed for human foods. Processing can be done by simple drying, or the protein content can be increased by removing lipid
s and other non-protein materials. For example, spray drying
after membrane filtration separates the proteins from whey.
Whey can be denatured
by heat. High heat (such as the sustained high temperatures above 72 °C associated with the pasteurization
process) denatures whey proteins. While native whey protein does not aggregate upon rennet
ing or acid
ification of milk, denaturing
the whey protein triggers hydrophobic interactions
with other proteins, and the formation of a protein gel
. Heat-denatured whey can still cause allergies in some people.
s isolated from whey
, a by-product of cheese
manufactured from cow's milk
. The protein in cow's milk is 20% whey protein and 80% casein protein, whereas the protein in human milk is 60% whey and 40% casein. Whey protein is typically a mixture of beta-lactoglobulin
(~65%), alpha-lactalbumin
(~25%), and serum albumin
(~8%), which are soluble in their native forms, independent of pH
. The protein fraction in whey (approximately 10% of the total dry solids within whey) comprises four major protein fractions and six minor protein fractions. The major protein fractions in whey are beta-lactoglobulin
, alpha-lactalbumin
, bovine serum albumin
, and immunoglobulins.
(WPC), isolate
(WPI), and hydrolysate
(WPH).
s and its effect on reducing the risks of diseases such as heart disease and cancer is the focus of ongoing research. Whey is an abundant source of branched-chain amino acids
(BCAAs), which are used to fuel working muscles and stimulate protein synthesis. In particular, leucine
plays a key role in initiating the transcription pathway that fires up protein synthesis. When leucine is ingested in high amounts, such as with whey protein supplementation, there is greater stimulation of protein synthesis, which may speed recovery and adaptation to stress (exercise).
Whey protein contains the amino acid cysteine
, which can be used to make glutathione
. However, this amino acid is not essential for the synthesis of glutathione, and some studies have suggested that the amount of cysteine in the diet may have little effect on glutathione synthesis. However, another study suggested that large amounts of whey protein can increase cellular glutathione levels. Glutathione is an antioxidant
that defends the body against free radical damage and some toxins, and studies in animals have suggested that milk proteins might reduce the risk of cancer.
It should be noted that similar symptoms can be caused by ingredients found in lower quality protein powders such as lactose
in whey protein concentrate or artificial sweeteners in most commercial protein powders. The effects of these substances can be distinguished from the effects of whey alone by switching to an unsweetened whey isolate or hydrolysate. If symptoms are not eliminated by switching to a more pure form of whey protein, many alternative powders, such as pea protein
or rice protein
may be suggested.
Globular protein
Globular proteins, or spheroproteins are one of the two main protein classes, comprising "globe"-like proteins that are more or less soluble in aqueous solutions...
s isolated from whey
Whey
Whey or Milk Serum is the liquid remaining after milk has been curdled and strained. It is a by-product of the manufacture of cheese or casein and has several commercial uses. Sweet whey is manufactured during the making of rennet types of hard cheese like cheddar or Swiss cheese...
, the liquid material created as a by-product of cheese
Cheese
Cheese is a generic term for a diverse group of milk-based food products. Cheese is produced throughout the world in wide-ranging flavors, textures, and forms....
production. Some preclinical studies in rodents have suggested that whey protein may possess anti-inflammatory
Anti-inflammatory
Anti-inflammatory refers to the property of a substance or treatment that reduces inflammation. Anti-inflammatory drugs make up about half of analgesics, remedying pain by reducing inflammation as opposed to opioids, which affect the central nervous system....
or anti-cancer properties; however, human data is lacking. The effects of whey protein on human health are of great interest and are currently being investigated as a way of reducing disease risk, as well as a possible supplementary treatment for several diseases.
Whey protein is commonly marketed and ingested as a dietary supplement
Dietary supplement
A dietary supplement, also known as food supplement or nutritional supplement, is a preparation intended to supplement the diet and provide nutrients, such as vitamins, minerals, fiber, fatty acids, or amino acids, that may be missing or may not be consumed in sufficient quantities in a person's diet...
, and various health claims have been attributed to it in the alternative medicine
Alternative medicine
Alternative medicine is any healing practice, "that does not fall within the realm of conventional medicine." It is based on historical or cultural traditions, rather than on scientific evidence....
community. Although whey proteins are responsible for some milk allergies
Milk allergy
A milk allergy is a food allergy, an adverse immune reaction to one or more of the constituents of milk from any animal...
, the major allergens in milk are the casein
Casein
Casein is the name for a family of related phosphoprotein proteins . These proteins are commonly found in mammalian milk, making up 80% of the proteins in cow milk and between 60% and 65% of the proteins in human milk....
s.
Production
Whey is left over when milk coagulates and contains everything that is soluble from milk. It is a 5% solution of lactoseLactose
Lactose is a disaccharide sugar that is found most notably in milk and is formed from galactose and glucose. Lactose makes up around 2~8% of milk , although the amount varies among species and individuals. It is extracted from sweet or sour whey. The name comes from or , the Latin word for milk,...
in water, with some minerals and lactalbumin
Lactalbumin
Lactalbumin is the albumin contained in milk and obtained from whey. Lactalbumin is found in the milk of many mammals. There are alpha and beta lactalbumins; both contained in milk....
. It is removed after cheese is processed. The fat is removed and then is processed for human foods. Processing can be done by simple drying, or the protein content can be increased by removing lipid
Lipid
Lipids constitute a broad group of naturally occurring molecules that include fats, waxes, sterols, fat-soluble vitamins , monoglycerides, diglycerides, triglycerides, phospholipids, and others...
s and other non-protein materials. For example, spray drying
Spray drying
Spray drying is a method of producing a dry powder from a liquid or slurry by rapidly drying with a hot gas. This is the preferred method of drying of many thermally-sensitive materials such as foods and pharmaceuticals. A consistent particle size distribution is a reason for spray drying some...
after membrane filtration separates the proteins from whey.
Whey can be denatured
Denaturation (biochemistry)
Denaturation is a process in which proteins or nucleic acids lose their tertiary structure and secondary structure by application of some external stress or compound, such as a strong acid or base, a concentrated inorganic salt, an organic solvent , or heat...
by heat. High heat (such as the sustained high temperatures above 72 °C associated with the pasteurization
Pasteurization
Pasteurization is a process of heating a food, usually liquid, to a specific temperature for a definite length of time, and then cooling it immediately. This process slows microbial growth in food...
process) denatures whey proteins. While native whey protein does not aggregate upon rennet
Rennet
Rennet is a complex of enzymes produced in any mammalian stomach to digest the mother's milk, and is often used in the production of cheese. Rennet contains many enzymes, including a proteolytic enzyme that coagulates the milk, causing it to separate into solids and liquid...
ing or acid
Acid
An acid is a substance which reacts with a base. Commonly, acids can be identified as tasting sour, reacting with metals such as calcium, and bases like sodium carbonate. Aqueous acids have a pH of less than 7, where an acid of lower pH is typically stronger, and turn blue litmus paper red...
ification of milk, denaturing
Denaturation (biochemistry)
Denaturation is a process in which proteins or nucleic acids lose their tertiary structure and secondary structure by application of some external stress or compound, such as a strong acid or base, a concentrated inorganic salt, an organic solvent , or heat...
the whey protein triggers hydrophobic interactions
Hydrophobe
In chemistry, hydrophobicity is the physical property of a molecule that is repelled from a mass of water....
with other proteins, and the formation of a protein gel
Gel
A gel is a solid, jelly-like material that can have properties ranging from soft and weak to hard and tough. Gels are defined as a substantially dilute cross-linked system, which exhibits no flow when in the steady-state...
. Heat-denatured whey can still cause allergies in some people.
Composition
Whey protein is the collection of globular proteinGlobular protein
Globular proteins, or spheroproteins are one of the two main protein classes, comprising "globe"-like proteins that are more or less soluble in aqueous solutions...
s isolated from whey
Whey
Whey or Milk Serum is the liquid remaining after milk has been curdled and strained. It is a by-product of the manufacture of cheese or casein and has several commercial uses. Sweet whey is manufactured during the making of rennet types of hard cheese like cheddar or Swiss cheese...
, a by-product of cheese
Cheese
Cheese is a generic term for a diverse group of milk-based food products. Cheese is produced throughout the world in wide-ranging flavors, textures, and forms....
manufactured from cow's milk
Milk
Milk is a white liquid produced by the mammary glands of mammals. It is the primary source of nutrition for young mammals before they are able to digest other types of food. Early-lactation milk contains colostrum, which carries the mother's antibodies to the baby and can reduce the risk of many...
. The protein in cow's milk is 20% whey protein and 80% casein protein, whereas the protein in human milk is 60% whey and 40% casein. Whey protein is typically a mixture of beta-lactoglobulin
Beta-lactoglobulin
right|thumbnail|300px|Structure of a β-lactoglobulin subunit Ribbons denote the [[secondary structure]], with arrows for beta strands and spirals for alpha-helices. Rendered with [[Kinemage]]...
(~65%), alpha-lactalbumin
Alpha-lactalbumin
Lactalbumin, alpha-, also known as LALBA, is a protein that in humans is encoded by the LALBA gene.- Function :α-Lactalbumin is an important whey protein in cow's milk , and is also present in the milk of many other mammalian species...
(~25%), and serum albumin
Serum albumin
Serum albumin, often referred to simply as albumin is a protein that in humans is encoded by the ALB gene.Serum albumin is the most abundant plasma protein in mammals. Albumin is essential for maintaining the osmotic pressure needed for proper distribution of body fluids between intravascular...
(~8%), which are soluble in their native forms, independent of pH
PH
In chemistry, pH is a measure of the acidity or basicity of an aqueous solution. Pure water is said to be neutral, with a pH close to 7.0 at . Solutions with a pH less than 7 are said to be acidic and solutions with a pH greater than 7 are basic or alkaline...
. The protein fraction in whey (approximately 10% of the total dry solids within whey) comprises four major protein fractions and six minor protein fractions. The major protein fractions in whey are beta-lactoglobulin
Beta-lactoglobulin
right|thumbnail|300px|Structure of a β-lactoglobulin subunit Ribbons denote the [[secondary structure]], with arrows for beta strands and spirals for alpha-helices. Rendered with [[Kinemage]]...
, alpha-lactalbumin
Alpha-lactalbumin
Lactalbumin, alpha-, also known as LALBA, is a protein that in humans is encoded by the LALBA gene.- Function :α-Lactalbumin is an important whey protein in cow's milk , and is also present in the milk of many other mammalian species...
, bovine serum albumin
Bovine serum albumin
Bovine serum albumin is a serum albumin protein derived from cows. It is often used as a protein concentration standard....
, and immunoglobulins.
Major forms
Whey protein typically comes in three major forms: concentrateWhey concentrate
Whey protein concentrate is the cheapest and most common form of whey protein. Whey protein concentrate is a common athletic supplement used to increase dietary protein intake, often with the goal of maximizing muscle hypertrophy....
(WPC), isolate
Whey protein isolate
A whey protein isolate is a dietary supplement created by filtering milk protein. Whey is a by-product of the cheese-making process...
(WPI), and hydrolysate
Hydrolysate
Whey protein hydrolysate is considered the gold standard of protein powders. Unlike concentrate of isolate forms of whey protein, hydrolysates are enzymatically predigested for maximal speed of absorption. This additional processing often comes at an increased cost, but is considered superior for...
(WPH).
- Concentrates typically a low (but still significant) level of fat and cholesterolCholesterolCholesterol is a complex isoprenoid. Specifically, it is a waxy steroid of fat that is produced in the liver or intestines. It is used to produce hormones and cell membranes and is transported in the blood plasma of all mammals. It is an essential structural component of mammalian cell membranes...
but, in general, have higher levels of bioactiveBiological activityIn pharmacology, biological activity or pharmacological activity describes the beneficial or adverse effects of a drug on living matter. When a drug is a complex chemical mixture, this activity is exerted by the substance's active ingredient or pharmacophore but can be modified by the other...
compounds, and carbohydrates in the form of lactoseLactoseLactose is a disaccharide sugar that is found most notably in milk and is formed from galactose and glucose. Lactose makes up around 2~8% of milk , although the amount varies among species and individuals. It is extracted from sweet or sour whey. The name comes from or , the Latin word for milk,...
— they are 29%–89% protein by weight. - Isolates are processed to remove the fat, and lactose, but are usually lower in bioactivated compounds as well — they are 90%+ protein by weight. Both WPC and WPI are mild to slightly milky in taste.
- Hydrolysates are whey proteins that are predigested and partially hydrolyzedHydrolysisHydrolysis is a chemical reaction during which molecules of water are split into hydrogen cations and hydroxide anions in the process of a chemical mechanism. It is the type of reaction that is used to break down certain polymers, especially those made by condensation polymerization...
for the purpose of easier metabolizing, but their cost is generally higher. Highly-hydrolysed whey may be less allergenAllergenAn allergen is any substance that can cause an allergy. In technical terms, an allergen is a non-parasitic antigen capable of stimulating a type-I hypersensitivity reaction in atopic individuals....
ic than other forms of whey.
Benefits for muscle building
Research indicates that the use of supplementary whey or soy protein combined with resistance training offers some benefit over no protein supplementation. The authors of this research concluded that "young adults who supplement with protein during a structured resistance training program experience minimal beneficial effects in lean tissue mass and strength.". In contrast, another study of elderly men found supplementation with whey protein before and after exercise to not have any significant effect on skeletal muscle hypertrophy compared to placebo. The timing of protein supplement ingestion may not have any significant effects on strength, power, or body-composition.Health effects
The use of whey protein as a source of amino acidAmino acid
Amino acids are molecules containing an amine group, a carboxylic acid group and a side-chain that varies between different amino acids. The key elements of an amino acid are carbon, hydrogen, oxygen, and nitrogen...
s and its effect on reducing the risks of diseases such as heart disease and cancer is the focus of ongoing research. Whey is an abundant source of branched-chain amino acids
Branched-chain amino acids
A branched-chain amino acid is an amino acid having aliphatic side-chains with a branch...
(BCAAs), which are used to fuel working muscles and stimulate protein synthesis. In particular, leucine
Leucine
Leucine is a branched-chain α-amino acid with the chemical formula HO2CCHCH2CH2. Leucine is classified as a hydrophobic amino acid due to its aliphatic isobutyl side chain. It is encoded by six codons and is a major component of the subunits in ferritin, astacin and other 'buffer' proteins...
plays a key role in initiating the transcription pathway that fires up protein synthesis. When leucine is ingested in high amounts, such as with whey protein supplementation, there is greater stimulation of protein synthesis, which may speed recovery and adaptation to stress (exercise).
Whey protein contains the amino acid cysteine
Cysteine
Cysteine is an α-amino acid with the chemical formula HO2CCHCH2SH. It is a non-essential amino acid, which means that it is biosynthesized in humans. Its codons are UGU and UGC. The side chain on cysteine is thiol, which is polar and thus cysteine is usually classified as a hydrophilic amino acid...
, which can be used to make glutathione
Glutathione
Glutathione is a tripeptide that contains an unusual peptide linkage between the amine group of cysteine and the carboxyl group of the glutamate side-chain...
. However, this amino acid is not essential for the synthesis of glutathione, and some studies have suggested that the amount of cysteine in the diet may have little effect on glutathione synthesis. However, another study suggested that large amounts of whey protein can increase cellular glutathione levels. Glutathione is an antioxidant
Antioxidant
An antioxidant is a molecule capable of inhibiting the oxidation of other molecules. Oxidation is a chemical reaction that transfers electrons or hydrogen from a substance to an oxidizing agent. Oxidation reactions can produce free radicals. In turn, these radicals can start chain reactions. When...
that defends the body against free radical damage and some toxins, and studies in animals have suggested that milk proteins might reduce the risk of cancer.
Digestive Issues
A significant portion of the population experiences severe digestive issues following consumption of whey protein powder. These may include gas, bloating, cramps, tiredness, weakness, fatigue, headaches, and irritability. The cause of these digestive problems has not yet been determined, but is reported frequently on strength training forums.It should be noted that similar symptoms can be caused by ingredients found in lower quality protein powders such as lactose
Lactose
Lactose is a disaccharide sugar that is found most notably in milk and is formed from galactose and glucose. Lactose makes up around 2~8% of milk , although the amount varies among species and individuals. It is extracted from sweet or sour whey. The name comes from or , the Latin word for milk,...
in whey protein concentrate or artificial sweeteners in most commercial protein powders. The effects of these substances can be distinguished from the effects of whey alone by switching to an unsweetened whey isolate or hydrolysate. If symptoms are not eliminated by switching to a more pure form of whey protein, many alternative powders, such as pea protein
Pea protein
Pea protein is a relatively new form of protein powder which is valued for its high digestibility , low potential for allergic responses, and remarkably low price...
or rice protein
Rice protein
Rice protein is a vegetarian protein that, for some, is more easily digestible than whey protein. Brown rice can be treated with enzymes that will cause carbohydrates to separate from proteins. The resulting protein powder is then sometimes flavored or added to smoothies or health shakes.Rice...
may be suggested.
External links
- Whey protein resources, National Dairy Council
- Whey Protein Healthnotes, University of California, San DiegoUniversity of California, San DiegoThe University of California, San Diego, commonly known as UCSD or UC San Diego, is a public research university located in the La Jolla neighborhood of San Diego, California, United States...