Egg Protein
1. Identity, Chemical Nature, and Common Forms
Egg protein refers to the collection of proteins derived from the domestic hen's egg (Gallus gallus domesticus), sourced primarily from the egg white (albumen) and, in some formulations, the egg yolk. The term encompasses both whole-food consumption and concentrated or purified dietary supplement forms. In the context of commercial supplementation, "egg protein" most commonly refers to egg white protein powder (dried albumen), though whole-egg powders and egg yolk–derived preparations also exist.
The chicken egg consists of approximately 63% egg white, 27.5% egg yolk, and 9.5% eggshell. Whole chicken eggs are composed of water (approximately 74%), proteins (12%), lipids (11%), carbohydrates (1%), and minerals (0.6%). Unlike the yolk, which is high in lipids, egg white contains almost no fat, and carbohydrate content is less than 1%; egg whites contain just over 50% of the total protein in the egg.
Common commercial preparations include:
- Spray-dried egg white powder — the most prevalent supplement form, produced by pasteurizing and dehydrating liquid egg whites. Egg protein powder is made from dehydrated egg whites and offers a complete, dairy-free source of protein with all essential amino acids.
- Egg white protein isolate — further processed to achieve higher protein content per gram of powder.
- Egg white hydrolysates (EWH) — enzymatically pre-digested forms. The absorption rate of amino acids into the portal vein from egg white hydrolysate was found to be faster than with whey protein hydrolysate, despite the egg product's larger molecular weight.
- Lactic-acid-fermented egg white (LAFEW) — a fermented preparation used in some clinical investigations. Eligible interventions in clinical research have included intact egg white protein (powder, liquid, or cooked egg white), egg protein hydrolysates (e.g., NWT-03 ovalbumin hydrolysate), lactic-acid-fermented egg white, egg white extract, Fortetropin (egg yolk–derived proteo-lipid complex), and other specific egg-derived bioactive peptides.
- Fortetropin — a proprietary egg-yolk–derived proteo-lipid complex used in sports nutrition and aging research.
- Whole-egg powder — spray-dried whole eggs retaining both white and yolk fractions.
2. Traditional and Historical Use
Eggs have been consumed as a primary protein food by virtually every human culture throughout recorded history. While eggs were not isolated into supplement form in antiquity, their nutritional and restorative significance was recognized long before modern science.
The concept of consuming concentrated forms of protein is not entirely new. In ancient civilizations, warriors and athletes recognized the value of protein-rich foods to build strength and improve performance. Ancient Greek wrestlers and Roman gladiators consumed diets heavy on meat and legumes, aiming to maximize muscle and endurance. Whole eggs were a component of these high-protein diets, though the supplementation of isolated egg protein did not yet exist.
The transition from whole-food egg consumption to formulated egg protein supplementation occurred in the mid-20th century. During the Second World War, non-perishable goods became a necessity, and powdered milk, eggs, and even soy protein started to be manufactured — one of the main causes for the post-war boom in supplements. In the 1950s, with recreational and competitive bodybuilding becoming increasingly popular, Irvin P. Johnson began to popularize and market egg-based protein powders marketed specifically at bodybuilders and physical athletes.
Bodybuilding had become significantly more popular by the 1950s, and Irvin Johnson developed one of the first commercial protein powders, marketed as "Johnson's Hi Protein Food" — a milk and egg-based creation. In the 1960s, a notably higher-quality protein powder was released: "Blair Protein Powder," by nutritionist Rheo H. Blair (the same Irvin Johnson under a different name), became prominent on the market, containing both egg isolate and slow-release casein protein.
Egg protein powder was a popular supplement during the mid-20th century bodybuilding era (sometimes called the "Silver Era"). This powder was made from dried egg whites and was often used as a convenient way to add protein to shakes and smoothies. Some bodybuilders of this era also consumed raw eggs as a protein source, a practice made famous by bodybuilder and actor Steve Reeves.
In the 1950s and 1960s, advancements in food processing technology enabled the creation of the first commercial protein powders. These early supplements primarily consisted of soy, milk, and egg-based proteins. Egg protein remained one of the dominant supplement forms until the commercialization of whey protein in the late 1980s and 1990s gradually shifted market dominance.
3. Constituent Proteins and Active Compounds
3.1 Egg White Proteins
Egg white is a remarkably complex mixture. According to a comprehensive review, egg white is best described as a system of globular proteins suspended in an aqueous solution, reinforced by the fibrous network of ovomucin. The protein component is divided into major and minor fractions. Major proteins include ovalbumin (54%), ovotransferrin (12%), ovomucoid (11%), ovomucin (3.5%), and lysozyme (3.5%). Minor proteins — avidin, ovoinhibitor, ovoglycoprotein, ovoflavoprotein, cystatin, and ovomacroglobulin — are present in smaller quantities but still carry significant biological relevance.
- Ovalbumin (Gal d 2) — ~54%: Ovalbumin is the single most abundant protein in egg white, accounting for roughly 54–58% of total egg white protein. It is a water-soluble glycoprotein made up of 385–386 amino acids with a molecular weight of 45 kDa. It is used primarily as a protein source in the food industry and has functional properties such as gelling, foaming, and emulsifying, which are important in meat processing, bakery, and baby food industries.
- Ovotransferrin (Gal d 3) — ~12%: A glycoprotein that binds iron, thereby sequestering it from microbial growth. A tripeptide IRW (Ile-Arg-Trp) has been characterized from ovotransferrin; this peptide showed anti-inflammatory, antioxidant, and angiotensin-converting enzyme (ACE) inhibitory properties in vitro.
- Ovomucoid (Gal d 1) — ~11%: A trypsin inhibitor that blocks certain digestive enzymes. Ovomucoid has been investigated for its potential to suppress tumor growth. It is also the most heat-stable and allergologically significant egg white protein (discussed in Section 7).
- Ovomucin — ~3.5%: Ovomucin, the protein believed to be responsible for the gel-like properties of fresh egg white, was first isolated by Eichholz (1898). This structurally important sulfated glycoprotein comprises approximately 3.5% of the total egg white proteins. Ovomucin has been investigated for antiviral and anti-inflammatory activity.
- Lysozyme (Gal d 4) — ~3.4%: An enzyme with antibacterial properties that hydrolyzes bacterial cell walls. Among its natural functions, lysozyme kills bacteria.
- Avidin — ~0.05%: Avidin binds biotin (vitamin B7), preventing its absorption. This property is significant for safety considerations and is discussed in Section 7.
- Minor proteins: Minor egg white proteins include ovoinhibitor (1.5%), ovoglycoprotein (1%), ovoflavoprotein (0.8%), ovomacroglobulin (0.5%), avidin (0.05%), and cystatin (0.05%).
3.2 Amino Acid Profile
Egg white protein is a complete protein, meaning it contains all nine essential amino acids the body cannot make on its own. These include the three branched-chain amino acids (BCAAs) — leucine, isoleucine, and valine — that play a major role in the muscle-building process. Egg whites have high amounts of sulfur-containing amino acids and branched-chain amino acids (BCAAs).
Comparison across different diets, breeds, and environments revealed no statistically significant differences in egg amino acid composition. The mean amino acid concentrations of egg protein showed little variation with breed, environmental conditions, or protein content of the diet.
3.3 Bioactive Peptides
Beyond whole proteins, enzymatic hydrolysis of egg proteins releases a variety of bioactive peptides with demonstrated functional activities. Hydrolyzed peptides derived from egg white proteins have shown angiotensin I-converting enzyme (ACE) inhibitory, anticancer, metal-binding, and antioxidant activities, opening up promising avenues in nutraceutical and pharmaceutical research.
Protein by-products from the extraction of lecithin from egg yolk can be converted into value-added products, such as bioactive hydrolysates and peptides that have potential health-enhancing antioxidant and antihypertensive properties. Specific egg yolk peptides (e.g., SDNRNQGY and YPSPV) demonstrated ACE inhibitory activity in laboratory assays, indicating substantial potential for producing valuable peptides with antioxidant and ACE inhibitory activity from egg yolk.
4. Protein Quality Metrics
Egg protein — and egg white in particular — is consistently rated among the highest-quality dietary protein sources across all established scientific scoring systems.
Egg white protein reportedly has Protein Digestibility Corrected Amino Acid Scores (PDCAAS) and Digestible Indispensable Amino Acid Scores (DIAAS) that are comparable to those of whey protein. Furthermore, the net protein utilization rate for unheated, half-boiled, and heated states of egg white protein is reportedly higher than that of whey protein, which is widely regarded as a high-quality protein source.
Based on the Digestible Indispensable Amino Acid Score (DIAAS), egg white protein has an excellent score comparable to that of whey protein, but with a lower amount of leucine. DIAAS is the newer, more precise metric the FAO recommends over PDCAAS — it measures actual ileal digestibility of individual amino acids rather than using a truncated fecal estimate. By that standard, egg white scores 101, higher than whey (85) and soy (91), according to Herreman et al. (2020).
In rat studies, the absorption rate of egg white hydrolysates was faster than that of egg white and whey proteins. According to both PDCAAS and DIAAS, the scores for egg white hydrolysates were equivalent to those of egg white and whey proteins, but higher than those of whey hydrolysates. These results indicate that egg white hydrolysates maintain the nutritional value of egg whites and are rapidly absorbed by the body.
The Protein Digestibility-Corrected Amino Acid Score (PDCAAS) is calculated using egg albumin as the reference protein for mammals due to its high biological value. The PDCAAS is calculated by multiplying the proportion of the limiting essential amino acid by protein digestibility, with a maximum value of 1.0 indicating a high-quality protein that meets essential amino acid requirements. This historical positioning of egg albumin as the scientific reference protein underlines its long-established status in nutritional science.
5. Mechanisms of Action
5.1 Muscle Protein Synthesis
Egg white protein stimulates muscle protein synthesis (MPS) primarily through the provision of essential amino acids — particularly BCAAs — that activate the mammalian target of rapamycin complex 1 (mTORC1) signaling pathway, which is central to anabolic signaling in skeletal muscle. Dietary patterns that include regular ingestion of high-quality, protein-dense foods are important to optimize the stimulation of postprandial muscle protein synthesis rates to improve skeletal muscle remodeling. Protein quality in human nutrition can be at least partly determined from the bioavailability of dietary protein-derived amino acids in the circulation to support whole-body and muscle protein metabolic needs. Various meal characteristics, such as protein source and ingested protein quantity, can influence the amount of dietary protein-derived amino acids available in the circulation to stimulate postprandial muscle protein synthesis rates.
5.2 ACE Inhibition and Blood Pressure
Bioactive peptides derived from egg proteins — particularly those released from ovotransferrin and ovalbumin upon hydrolysis — inhibit angiotensin-converting enzyme (ACE), a key regulator of vasoconstriction. ACE also indirectly influences the kallikrein-kinin system by promoting the inactivation and degradation of bradykinin, a vasodilator involved in blood pressure control. By repressing angiotensin II production and restraining bradykinin degradation, ACE inhibitory peptides control increases in blood pressure.
The tripeptide IRW (Ile-Arg-Trp), characterized from egg white ovotransferrin, showed anti-inflammatory, antioxidant, and ACE inhibitory properties in vitro. In spontaneously hypertensive rats, IRW treatment attenuated mean blood pressure by approximately 10 mmHg and 40 mmHg at low- and high-dose groups respectively compared to untreated controls. Heart rate was not affected. Reduction in blood pressure was accompanied by restoration of diurnal variations in BP, preservation of nitric oxide-dependent vasorelaxation, and reduction of plasma angiotensin II, other inflammatory markers, and tissue fibrosis. These findings are from animal models and have not yet been replicated in adequately powered human clinical trials.
5.3 Antimicrobial and Antioxidant Activity
Egg peptides have been studied extensively for their antimicrobial activity. Specific peptides from egg yolk and egg white have been shown to have antimicrobial activity against various pathogens. Lysozyme exerts its antimicrobial effect by hydrolyzing the peptidoglycan layer of bacterial cell walls. Ovotransferrin starves microorganisms of iron by sequestering it. Research indicates that the amino acid cysteine has the potential as an antioxidant amino acid, and the combination of strong, weak, and non-antioxidant amino acids increases the overall antioxidant capacity of egg proteins.
6. Scientific Evidence by Area of Use
6.1 Muscle Protein Synthesis and Body Composition
Evidence strength: Moderate (human RCT evidence exists, some limitations)
The most well-studied clinical application of egg protein is its role in stimulating muscle protein synthesis, particularly in the context of resistance exercise. A 2026 systematic review and meta-analysis is the most comprehensive synthesis of the clinical evidence to date:
This meta-analysis aimed to evaluate the efficacy of oral egg-derived protein and peptide supplementation on health outcomes, including visceral fat area, blood pressure, muscle protein synthesis, and cognitive function in adults, by searching PubMed, Embase, Cochrane Library, and Web of Science through January 2026 for RCTs. Thirty RCTs (n = 1938 participants) were included. Evidence certainty was evaluated using the GRADE framework.
A key human crossover trial compared whole eggs to egg whites for post-exercise MPS. In crossover trials, 10 resistance-trained men (aged 21 ± 1 years) performed a single bout of resistance exercise, then consumed either intrinsically labeled whole eggs (18 g protein, 17 g fat) or egg whites (18 g protein, 0 g fat). Repeated blood and muscle biopsy samples were collected to assess whole-body leucine kinetics, intramuscular signaling, and myofibrillar protein synthesis. Whole-egg ingestion increased the postexercise myofibrillar protein synthetic response to a greater extent than did the ingestion of egg whites (P = 0.04). The ingestion of whole eggs immediately after resistance exercise resulted in greater stimulation of myofibrillar protein synthesis than did the ingestion of egg whites, despite being matched for protein content in young men. The data indicate that the ingestion of nutrient- and protein-dense foods differentially stimulates muscle anabolism compared with protein-dense foods.
This suggests that the food matrix of the whole egg — including the fat and micronutrient content of the yolk — may play a role in augmenting the muscle anabolic response, above and beyond what protein amino acid delivery alone achieves. The study was limited by its small sample size (n = 10), restriction to young resistance-trained men, and single-session acute design.
In animal research, the body protein level and gastrocnemius muscle weight in rats fed egg white protein were found to be significantly increased when compared to those fed casein, making it a promising protein supplement for muscle maintenance and building. Egg white protein feeding accelerated skeletal muscle gain under anabolism-dominant conditions more efficiently than casein and whey, and this stronger effect was not dependent on the arginine-rich composition of the protein source. These animal findings require cautious extrapolation to humans.
6.2 Egg Protein in Dialysis Patients (Serum Albumin and Phosphorus)
Evidence strength: Low to very low (GRADE) — preliminary clinical signal, high heterogeneity
In dialysis patients, egg white supplementation significantly increased serum albumin (mean difference: +0.42 g/dL [95% CI: 0.12–0.72]; I² = 82.4%; four RCTs; GRADE: very low). The very low GRADE rating and high statistical heterogeneity (I² = 82.4%) mean this finding should be interpreted with considerable caution, and it does not currently support firm clinical recommendations.
6.3 Blood Pressure (Antihypertensive Peptides)
Evidence strength: Preliminary (largely animal and in vitro; very limited human data)
As detailed in Section 5.2, egg-derived peptides — particularly IRW from ovotransferrin — have demonstrated ACE inhibitory and antihypertensive effects in animal models. Results from the animal study demonstrate antihypertensive effects of IRW in vivo, likely mediated through ACE inhibition, endothelial nitric oxide synthase, and anti-inflammatory properties. However, the human evidence for blood pressure reduction from egg protein supplementation remains limited. The 2026 meta-analysis included blood pressure as a primary outcome but comprised only a small number of relevant RCTs. Further well-powered RCTs in human hypertensive populations are needed before clinical conclusions can be drawn.
6.4 Cognitive Function
Evidence strength: Preliminary (very limited human RCT data)
The 2026 systematic review and meta-analysis also aimed to evaluate the efficacy of oral egg-derived protein and peptide supplementation on cognitive function in adults. Some egg-derived peptide preparations have been investigated for potential cognitive benefits, but the body of evidence from human RCTs remains small and does not yet permit definitive conclusions.
6.5 Sarcopenia and Aging
Evidence strength: Preliminary (registered trials; limited published results)
Declining muscle mass (sarcopenia) in older adults is recognized as a major clinical concern, and adequate dietary protein intake is a primary nutritional intervention. Egg white protein has been investigated in this context. The health effects of egg protein components have been examined in relation to muscle protein synthesis and aging-related diseases. The role of eggs in sustainable nutrition strategies and their potential in addressing malnutrition and aging-related diseases has been highlighted in recent scientific literature.
Fortetropin, an egg yolk-derived proteo-lipid complex, has been studied for muscle protein synthesis in older adults. In one study, the overall magnitude of increase in muscle protein synthesis was 15%, indicating a stimulatory effect of the egg yolk powder composition. These effects were independent of gender or baseline muscle mass. The study comprised 10 control subjects and 10 Fortetropin subjects with an average age of 66.35 ± 4.45 years. Given the small sample size and proprietary nature of the preparation, these findings require independent replication.
6.6 Antioxidant Activity
Evidence strength: Preliminary (in vitro and animal; limited human data)
Eggs, in addition to being highly nutritious, have strong antioxidant activity due to yolk, egg white, and egg protein derivatives when broken down by enzymes (e.g., during digestion). The antioxidant effect of low-molecular-weight egg white hydrolysates generated from egg whites has been reported. These effects have primarily been documented in laboratory and animal settings; evidence from human intervention trials is sparse.
7. Body Systems and Health Areas
Based on the available scientific literature, egg protein is associated with the following body systems and health areas:
- Musculoskeletal system: Muscle protein synthesis, muscle mass maintenance, recovery from resistance exercise, sarcopenia prevention in aging. The health effects of egg protein components have been examined in relation to muscle protein synthesis.
- Cardiovascular system: Antihypertensive peptides (ACE inhibition); blood pressure regulation. Particular attention has been given to egg-derived peptides and their emerging roles in regulating blood pressure.
- Immune system: Egg-derived peptides have been investigated for roles in modulating the immune system.
- Renal/metabolic: Albumin repletion and phosphorus management in dialysis patients.
- Neurological/cognitive: Limited emerging evidence for cognition from peptide fractions.
- Antimicrobial defense: Lysozyme, ovotransferrin, and antimicrobial peptides. Several egg proteins have a strong effect against bacteria associated with food poisoning, and safe egg peptides are used in both the food and pharmaceutical industries as antimicrobials.
8. Dosage Forms and Dosages Reported in Studies
Egg protein supplements are available in several forms, and clinical dosages vary by indication and preparation. The following are dosages as reported in specific research contexts:
- Post-exercise muscle protein synthesis: In the crossover resistance exercise trial, participants consumed 18 g of protein, either as whole eggs (18 g protein, 17 g fat) or egg whites (18 g protein, 0 g fat) immediately after exercise.
- Fortetropin (egg yolk–derived proteo-lipid complex, older adults): The small-group study used 21 consecutive days of supplementation, though specific daily gram dosages were not detailed in the available excerpts.
- IRW tripeptide (animal antihypertensive model): Spontaneously hypertensive rats were orally administered IRW at either a low dose (3 mg/kg body weight) or a high dose (15 mg/kg body weight) daily for 18 days. This animal dosage has not been directly translated to confirmed human dosages in published clinical trials.
- Egg white hydrolysate (EWH, human bioavailability study): The absorption and nutritional value of egg white hydrolysate with a molecular weight of approximately 2500 Da (Egg White Peptide EP-3, Henningsen Foods Inc., Omaha, NE, USA) were assessed in comparison to whey protein hydrolysate.
- General supplement use: Commercial egg white protein powders typically provide approximately 20–25 g of protein per serving of powder; individual products vary. These commercial serving sizes are not derived from clinical trial protocols.
9. Safety Considerations and Interactions
9.1 Egg Allergy
Egg allergy is among the most common food allergies and represents the principal safety concern for egg protein supplements. Several egg white proteins are among the most common food allergens. The major allergens originating from egg white are ovomucoid (Gal d 1) and ovalbumin (Gal d 2), with ovotransferrin (Gal d 3) and lysozyme (Gal d 4) identified as minor allergens.
The protein component from egg white is the cause of the allergic response in children. The major allergens in egg white are ovomucoid and ovalbumin. Ovomucoid maintains its immunogenicity after 20 minutes of boiling. As a result of its resistance to heat and enzymatic digestion, and its physical characteristics, ovomucoid is the most important egg white protein capable of causing allergic reactions.
Hen's egg allergy is a common IgE-mediated allergy in childhood. Approximately 70% of children with hen's egg allergy are able to ingest extensively heated forms in baked goods. Ovomucoid is resistant to heat, and thus high levels of ovomucoid-specific IgE are associated with an increased likelihood of reactivity to baked egg.
Heat treatment during the production of commercial egg white powder denatures most heat-labile proteins, including ovalbumin, but ovomucoid may retain some allergenicity even after processing. Individuals with confirmed IgE-mediated egg allergy should avoid egg protein supplements entirely.
9.2 Avidin–Biotin Interaction
Egg protein contains a compound called avidin, which is well known to interfere with the absorption of biotin, a B-complex vitamin. Those who eat raw egg whites on a daily basis or people using large amounts of egg protein supplements might need to be concerned. Because of this issue, some egg protein supplements are heated during processing and are promoted as "avidin-neutralized."
Signs of frank biotin deficiency may be observed in individuals consuming large amounts of raw egg white; the biotin-binding protein avidin in raw egg white causes a substantial decrease in the bioavailability of biotin. Raw egg white contains avidin, which binds biotin and prevents its absorption from the intestine. Early studies produced biotin deficiencies by feeding subjects a low-biotin diet containing 15–20% egg white, requiring the raw whites of about 24 eggs per day for each volunteer. Cooking destroys the avidin; for the anti-biotin effect, the egg white had to be raw.
In practice, biotin deficiency results only from the prolonged consumption of an exceptionally large number of uncooked egg whites; symptoms include dermatitis and hair loss. Commercially processed, pasteurized, or heat-treated egg white protein powder effectively denatures avidin, eliminating this risk under normal use.
9.3 Drug Interactions
As of current available data, no reported interactions between egg protein supplements and pharmaceutical medicines have been documented. It is possible that unknown interactions exist.
9.4 Digestive Tolerance
Pasteurized and heat-processed egg white protein powder is generally well tolerated in individuals without egg allergy. Ovomucoid, a trypsin inhibitor present in raw egg white, is substantially denatured by heat treatment during commercial processing, reducing its potential to inhibit protein digestion. Raw egg white has long been known to have lower digestibility than cooked egg white, due to the activity of anti-nutritional factors such as ovomucoid and trypsin inhibitors; heating significantly improves protein bioavailability.
9.5 Salmonella and Microbial Safety
Raw egg products carry a risk of Salmonella contamination. Commercial egg white protein supplements are produced from pasteurized eggs, a process that eliminates viable Salmonella while substantially preserving protein integrity. Eating cooked eggs is recommended for optimal biotin absorption and to minimize the risk of foodborne illness from Salmonella.
9.6 Cholesterol Content
Egg white protein powder is free of cholesterol, since the cholesterol in eggs is located in the yolks, not the whites. Whole-egg powder formulations, by contrast, will retain the cholesterol content of the yolk fraction.
References
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