Fish protein

Other Names

Blue whiting protein hydrolysateCod proteinCondensed fish solublesEnzymatic fish protein hydrolysateFish bioactive peptidesFish collagenFish connective tissue proteinFish gelatinFish hydrolysateFish mealFish muscle proteinFish myofibrillar proteinFish peptidesFish protein concentrateFish protein hydrolysateFish protein hydrolysatesFish protein isolateFish sarcoplasmic proteinFish silageFish solublesFish stroma proteinFish stromal proteinFish-derived proteinFishmealFPCFPHFPIHydrolyzed fish proteinLiquefied fish proteinMarine fish collagenMarine fish proteinMarine proteinMarine-derived proteinSalmon protein concentrateSurimi proteinWhole fish meal

Synopsis

Fish Protein: An Encyclopedic Reference

1. Identity: Names, Sources, and Forms

1.1 Nomenclature and Classification

Fish protein is a broad term encompassing the proteinaceous fraction derived from finfish and associated processing co-products. In nutritional science and food technology, it appears under several specific designations depending on preparation method and degree of processing:

Fish Protein Concentrate (FPC) — a stable, dried proteinous product in which the protein content is higher than in the original fish, manufactured for human consumption.
Fish Protein Hydrolysate (FPH) — a complex mixture of oligopeptides and free amino acids formed by partial or extensive proteolytic hydrolysis of intact fish proteins.
Fish Protein Powder (FPP) — a refined, dried product produced specifically for human food ingredient and supplement applications, typically with defined sensory and compositional standards.
Marine Protein Hydrolysate (MPH) — a term used interchangeably with FPH, sometimes inclusive of shellfish and other marine species.

Fish protein concentrate (FPC) is formally defined as any stable proteinous product in which the protein is more concentrated relative to the original fish and manufactured for human consumption. FPC is defined as a stable fish preparation in which the protein concentration is higher than in its fish origin and is purposed for human consumption; although fish protein hydrolysate (FPH) is similar to FPC, its oil and water have not been considerably removed.

1.2 Natural Sources

The marine environment is an excellent source of many physiologically active compounds due to its extensive biodiversity; among these, fish proteins stand out for their unique qualities, making them valuable in a variety of applications due to their diverse compositional and functional properties. Fish protein is sourced both from whole-fish species and from processing by-products. Fish protein hydrolysate (FPH) is sourced from various aquatic wastes such as bones, scales, skin, and others, and is rich in protein for value-added products.

Commercially exploited species include Atlantic cod (Gadus morhua), blue whiting (Micromesistius poutassou), Pacific whiting or hake (Merluccius productus), salmon (Salmo salar; Oncorhynchus spp.), tilapia, mackerel (Scomber scombrus), sardine (Sardina pilchardus), and anchovy (Engraulis spp.), among many others. By-products from these species — including heads, frames, skin, trimmings, viscera, and fins — represent a substantial fraction of total raw material. The average protein content in different fish waste materials has been reported as: guts and viscera 9–23%, heads 11–13%, backbones 10–15%, skin 8–12%, spleen and fish roe 14–27%, and trimmings 12–22%.

1.3 Common Forms and Preparations

Historically, the fish processing methods used for human consumption have been: fresh, canned, frozen, smoked or dehydrated — all of which would be used as a whole food rather than as an ingredient in other foods. Modern processing has created a distinct range of concentrated, refined, and functionally modified forms:

Fish Protein Concentrate (Type A): Produced by using chemical solvents and sometimes high temperatures to extract and separate proteins from other components of the raw material; solvent-extracted FPC (type-A FPC) is produced by extraction with isopropanol or azeotropic extraction with ethylene dichloride. In practice, FPC is usually produced from fish by separating the oil, removing the bones, and drying, from which the final product may contain higher protein content (85% to 95%) and lower ash and water contents than fish meal.
Fish Protein Hydrolysate (FPH): These biologically active peptides play a role in metabolic regulation and modulation and are increasingly seen as promising ingredients in functional foods, nutraceuticals, and pharmaceuticals. Hydrolysis is typically enzymatic, using proteases such as Alcalase, papain, pepsin, pancreatin, or thermolysin. Protein hydrolysates have been prepared from different parts (whole fish, skin, and head) of several species using Alcalase.
Fish Protein Powder (FPP): With the evolution of refining and processing technology and expanded research on the nutrition of fish proteins and peptides, a new industry has developed for the specific purpose of producing a fish protein powder for human consumption with the intent of reaching new ingredient uses and markets. The FPP end product is now used in a variety of food ingredient applications including sports nutrition, food additives, and supplements.
Microencapsulated forms: The hydrophobic peptides present in FPH have limitations like an unpleasant taste; microencapsulation techniques provide a scientific approach to address these limitations and safeguard bioactive peptides.
Fermented fish preparations: Traditional fermented fish products including sauces and pastes represent a historical precursor form. Fermentation is a commonly used process in both the standard food industry and in the nutraceutical field; fermented food products include those derived from fish and meats, and all have been consumed for centuries for their nutritional or medicinal properties; fermentation of fish was introduced as a means of preservation, and fish sauces and pastes are staples or condiments in Southeast Asian, Scandinavian, and other cuisines.

2. Traditional and Historical Use

2.1 Ancient and Pre-Modern Traditions

Fish as a protein-rich food source has been integral to human diets across coastal, riverine, and island cultures for millennia. How and why Europeans evidently ate fish during the medieval millennium is revealed in traditional verbal records, archaeological remains of fish in human waste deposits, and biochemical traces of fish proteins in human skeletal remains. Christian teachings allowed fish during regularly recurring religious taboos on mammal and bird meats; medical teachings inherited from classical Greco-Roman culture and further elaborated by Muslim and later Christian physicians both advised and constrained fish consumption, as did some folk beliefs.

In Spain, fish also held ethnomedicinal significance. Historical examination has documented the use of 54 medicinal fish species — 48 marine and six from inland waters — with 39 species recorded in ancient times. Species such as Anguilla anguilla, Engraulis encrasicolus, and Scyliorhinus canicula have survived over time as ingredients in Spanish folk remedies; most remedies used in the last century are empirical remedies based on the humorism theory and the principle of contraria contrariis curantur.

Fermented and dried fish preparations formed part of the traditional pharmacopoeia of multiple cultures. A method of preserving the essential nutritive elements of fish has been used for centuries in Vietnam, in the form of nuoc mam. Fermented fish pastes and sauces have been described as traditional remedies across Southeast Asia and Scandinavia for uses relating to strength, recovery, and digestive support.

2.2 Twentieth-Century Development for Nutritional and Public Health Purposes

The concept of concentrated fish protein as an ingredient was formally developed in the mid-twentieth century in response to global protein malnutrition. One of the earliest attempts to recover protein from by-products and under-utilized species for use as a human food was the production of fish protein concentrates; the National Marine Fisheries Service (NMFS) in the US initiated a large research program in the early 1960s with the goal of finding ways to produce FPC on a large scale to stimulate the seafood industry and fight the global protein malnutrition problem. In 1968 the United Nations published a paper entitled International Action to Avert the Impending Protein Crisis; by then, several projects had been set up with substantial funding to develop processes and machinery for the preparation of stable, solvent-extracted high protein powders from fish.

In addition to animal protein, FPC bears other important micronutrients, such as various vitamins, minerals, and trace elements, which are beneficial for child growth, keeping human well-being, and speeding up the recovery from malnutrition and various diseases. International organizations including FAO, WHO, UNICEF, and UNDP were involved in formulating foods for young children that incorporated fish protein concentrate as a high-quality protein source alongside cereals and legumes.

3. Key Constituents and Active Compounds

3.1 Gross Compositional Profile

Fish protein hydrolysates typically have moisture and ash contents lower than 10% and 15% respectively; the fat content of FPH varies between 1.5% and 9.4%, and products have high protein content (69.8–76.6%); the amino acid profiles of FPH are broadly similar across species, with the most abundant amino acids being glutamic and aspartic acids.

Fish provides a low-caloric content, polyunsaturated fatty acids, many essential trace elements, and is also a rich source of protein, ranging from 10% to 25%.

3.2 Amino Acid Composition and Protein Quality

Fish protein is nutritionally considered a complete protein — it supplies all nine indispensable (essential) amino acids in quantities sufficient to support human protein synthesis. Fish protein hydrolysates (FPHs) are known for their excellent nutritional value, favorable amino acid profiles, and beneficial biological activities, generating significant interest for their potential health benefits.

In terms of standardized quality metrics, animal proteins including eggs, whey, chicken, and fish have complete amino acid profiles and 90–95% digestibility, and score 1.0 on the PDCAAS scale. Animal proteins (whey, egg, casein, fish) typically score highest on protein quality metrics (PDCAAS 0.92–1.0); plant proteins score lower due to limiting amino acids. The antihypertensive peptides isolated from FPH are noted to be rich in specific amino acids: purified antihypertensive peptides from FPH are known to be rich in arginine, valine, and leucine.

3.3 Bioactive Peptides

The principal bioactive constituents of fish protein supplements are short-chain peptides released during hydrolysis. FPHs contain bioactive peptides — peptide sequences known for their beneficial physiological effects — and these biologically active peptides play a role in metabolic regulation and modulation, and are increasingly seen as promising ingredients in functional foods, nutraceuticals, and pharmaceuticals.

Protein hydrolysates such as FPH, containing predominantly di- and tripeptides, are more readily absorbed than free amino acids and intact protein. These peptides, referred to as bioactive peptides, comprise 2–20 amino acid residues which are inactive within the sequence of many food proteins and exhibit biological activity when released by enzymatic hydrolysis.

Key classes of bioactive peptides identified in FPH include:

ACE-inhibitory (antihypertensive) peptides: Angiotensin I-converting enzyme (ACE) inhibitory activity is one of the most studied bioactive properties of fish protein hydrolysates. Notable short sequences include valine-tyrosine (Val-Tyr) from sardine muscle, as well as Ile-Val-Tyr (IVY), Val-Trp (VW), Ile-Tyr (IY), and Ile-Trp (IW) from various fish species. Reports reveal peptides with low molecular weight (<1 kDa) and shorter chain length (<20 amino acids) exhibit higher antihypertensive activity.
Antioxidant peptides: Hydrolyzed proteins demonstrate antioxidant capacity through several mechanisms: they can neutralize free radicals by donating electrons or hydrogen atoms, thus stabilizing radicals and preventing oxidative damage; they can chelate metal ions like iron and copper, inhibiting their ability to catalyze reactive oxygen species production through Fenton and Haber–Weiss reactions; and they can directly deactivate molecular oxygen, reducing the formation of reactive oxygen species.
DPP-IV inhibitory peptides (antidiabetic): Certain FPH-derived peptides inhibit the enzyme dipeptidyl peptidase-IV (DPP-IV), thereby prolonging the action of incretin hormones such as GLP-1. Eight peptides (VAPEEHPT, DLDL, MDLP, VADTMEVV, DPLV, FAMD, CSSGGY, GPFPLLV) demonstrated DPP-IV inhibitory activity after successfully passing through the intestinal barrier of a Caco-2 cell monolayer.
Satietogenic/incretin-stimulating peptides: Certain FPH-derived peptides stimulate the release of cholecystokinin (CCK) and glucagon-like peptide-1 (GLP-1), hormones involved in appetite regulation and glycemic control. Eleven novel biopeptides were isolated from a tilapia co-product protein hydrolysate, among which three (DLVDK, PSLVH, LKPT) exhibited the ability to stimulate hormonal regulation of CCK and GLP-1 in Caco-2 cells.
Antimicrobial, anti-inflammatory, immunomodulatory, and antithrombotic peptides: Protein hydrolysates have been found to exhibit diverse bioactive functions, including antioxidant, antimicrobial, antihypertensive, anti-inflammatory, immunomodulatory, and antithrombotic properties.

3.4 Structural Determinants of Bioactivity

The bioactivity of peptides derived from FPH depends heavily on their amino acid sequence, molecular weight, and hydrophobicity. The amino acid residues at the COOH- and NH2-terminals are important determinants of the ACE inhibitory potency of a fish protein hydrolysate; specifically, when glycine was at the NH2-terminal, the COOH- residues that most effectively inhibited ACE were tryptophan, tyrosine, or proline; when glycine was at the COOH-terminal, the NH2 residues most effective were valine, isoleucine, and arginine. The factors governing overall bioactivity of FPHs include the raw material species, the type of enzyme employed, degree of hydrolysis, processing temperature and pH, and molecular weight distribution of resulting peptides.

4. Scientific Evidence by Area of Use

4.1 Cardiovascular Health: Blood Pressure and Vascular Function

Mechanism: Blood pressure and fluid homeostasis in humans are regulated by different mechanisms including the renin–angiotensin system (RAS); RAS is mainly targeted pharmacologically to treat hypertension; ACE converts angiotensin-I into angiotensin-II, an octapeptide that acts as a potent vasoconstrictor; ACE also inactivates bradykinin, a vasodilator. Fish protein–derived peptides act as competitive inhibitors of ACE. These purified peptides have proven angiotensin-converting enzyme I inhibitory activity in vitro and in vivo.

Clinical (human) evidence: A double-blind, randomized, placebo-controlled, multicentre, parallel 8-week trial examined the efficacy of a daily dose of 1200 mg of protein hydrolysate from coldwater shrimp (Pandalus borealis). Treatment with the hydrolysate had a clinically relevant impact on lowering blood pressure compared to placebo in study participants, all of whom had mild to moderate hypertension at study entry.

A separate pilot study examined vascular endothelial function in humans. The study evaluated the effect of fish protein hydrolysate (FPH) ingestion on macro- and microvascular endothelial function and blood pressure in subjects at high risk of cardiovascular disease, using a randomized, placebo-controlled, double-blind, crossover design in which twelve individuals ingested a single dose of FPH or placebo. FPH ingestion produced a strong effect as observed by the large effect size for flow-mediated dilation (FMD) (d = 1.8) and a moderate effect for O₂ resaturation rate (d = 0.6); the result showed that a single dose of FPH ingestion improved macro- and microvascular reactivity; however, no change in blood pressure was observed. The small sample size (n = 12) and single-dose design limit the conclusions that can be drawn.

In vitro, ACE inhibitory sequences have been characterized from salmon protein hydrolysates prepared with both human and porcine gastrointestinal enzymes. During in vitro studies, peptides with sequences TVY, VFPS, VTVNPYKLWLP, YALPHA, and ALPHA were recognized as ACE inhibitors; peptides IVY, VW, IY, IW, VY, and IWHHT were experimentally recognized as antihypertensive in stroke-prone spontaneously hypertensive rats after oral administration.

Evidence strength: The ACE-inhibitory activity of fish protein–derived peptides is well established in vitro and in animal models. Human clinical evidence is limited to a small number of trials with variable designs and modest sample sizes, and some trials have been conducted with shellfish rather than strictly finfish hydrolysates. Overall, evidence in humans is preliminary and warrants larger, longer-duration trials.

4.2 Body Weight, Appetite, and Metabolic Health

Mechanism: Modulation of physiological pathways capable of suppressing appetite and thereby reducing energy intake provides an interesting approach to weight management strategies; molecules capable of stimulating the secretion of both CCK and GLP-1 provide a logical and natural approach to achieve this aim.

Clinical (human) evidence — weight and body composition: A clinical study supplemented participants with a blue whiting (Micromesistius poutassou) fish protein hydrolysate. Previous studies demonstrated the efficacy of a FPH obtained from blue whiting muscle on stimulating the release of CCK and GLP-1 in an STC-1 cell line, in rats, and in humans. Supplementation with 3 g fish protein (tablets) for 4 weeks had effects on body composition in overweight adults, including an increased percentage of body muscle and decreased percentage of body fat; marine protein hydrolysate (MPH) was also shown to have a positive effect on body composition in overweight adults in doses of 1.4 or 2.8 g.

Clinical (human) evidence — appetite and ghrelin: A double-blind crossover trial with 41 healthy individuals (15 males and 26 females, mean age 51 ± 6 years) assessed the effect of a single, low-dose of cod protein hydrolysate (CPH), where a test drink containing 20 mg CPH or casein (control) per kg body weight was given immediately before a standardized breakfast meal. No effect of a single dose of CPH on postprandial concentrations of acylated ghrelin or sensations related to feeling of hunger was found compared to control; further studies were recommended to evaluate the effect of a supplement with CPH given daily over a period of time.

A dose-ranging crossover study of cod-derived FPH in healthy older volunteers aged 60–78 years found that no differences in the estimated maximum value or AUC of serum GLP-1 were observed when comparing the lowest dose of FPH (10 mg·kg⁻¹ body mass⁻¹) against the higher doses (20, 30, or 40 mg·kg⁻¹ body mass⁻¹); the lack of a placebo control further complicates the interpretation of these findings.

Evidence strength: Despite wide methodological variation between studies, there is significant potential for the application of fish protein hydrolysates in the management of body weight and hyperglycemia. However, human evidence remains limited by small sample sizes, short durations, and inconsistent findings across studies. Evidence for appetite suppression via ghrelin modulation in humans is currently negative or equivocal.

4.3 Glycemic Control and Type 2 Diabetes

Mechanism: FPH-derived peptides may modulate postprandial glucose through (1) DPP-IV inhibition, prolonging active GLP-1 and thus stimulating insulin secretion; (2) inhibition of carbohydrate-digesting enzymes α-amylase (AAM) and α-glucosidase (AG); and (3) direct stimulation of CCK and GLP-1 secretion from enteroendocrine cells. The specific mechanism by which fish proteins and FPH or bioactive peptides exhibit antidiabetic activity remains unclear.

Clinical (human) evidence: Human intervention studies have shown positive impacts of bioactive proteins derived from fish in the management of type 2 diabetes through reductions in fasting blood glucose, hemoglobin A1c (HbA1c), and an increase in the Homeostatic Model Assessment of Insulin Resistance (HOMA-IR); the impact of varying doses of a cod protein hydrolysate (CPH) on postprandial glucose metabolism in older human adults has been explored in a double-blind crossover trial, where participants were administered daily doses of CPH at 10, 20, 30, or 40 mg/kg body weight for 1 week with one-week washout periods in between. The results did not demonstrate significant differences in the estimated maximum values of glucose, insulin, or GLP-1 between the lowest dose (10 mg/kg BW) and higher doses (20, 30, or 40 mg/kg BW) of CPH.

In vitro, enzyme inhibitory capacity has been demonstrated across multiple FPH preparations: the inhibitory activity of α-amylase (AAM) and α-glucosidase (AG) was evaluated in protein hydrolysates prepared from various parts of several species including blue whiting, hake, redfish, pout, sand eel, and mackerel; IC₅₀ values for AAM ranged from 5.70 to 84.37 mg/mL, and for AG ranged from 21.8 to 300 mg/mL.

Evidence strength: The antidiabetic mechanisms of FPH are supported primarily by in vitro and cell-model evidence. Human clinical trial evidence is sparse, inconsistent, and limited by small sample sizes. While in vitro and small animal in vivo studies have provided valuable information, translating these findings to human health requires comprehensive human intervention trials.

4.4 Skeletal Muscle Mass, Strength, and Sarcopenia

Rationale: Ageing is associated with the loss of skeletal muscle mass and function, as well as increased oxidative stress, compromised vascularisation, neurological derangements, and immunosenescence; thus, there appears to be a potential application for FPH in older persons as a high-quality protein source that may also confer additional health benefits.

In vitro and ex vivo evidence: A study investigating a blue whiting–derived protein hydrolysate (BWPH) compared it against whey protein isolate (WPI) in an ex vivo, in vitro experimental design. This study investigated the impact of a blue whiting-derived protein hydrolysate on aminoacidaemia in vivo and skeletal muscle anabolism in vitro compared with whey protein isolate in an ex vivo/in vitro experimental design; blood was obtained from seven healthy older adults (two males, five females; age: 72 ± 5 years) in three separate trials in a randomised, counterbalanced, double-blind design. The study assessed mTOR pathway signaling and muscle protein synthesis markers.

Clinical (human) evidence: A randomized controlled trial assessed the effects of marine protein hydrolysate (MPH) supplements on physical function and strength in the elderly. The aim of this trial was to evaluate the effects of marine protein hydrolysate (MPH) supplements on physical function and strength in the elderly, representing one of the first long-term studies of MPH and age-related changes in muscle health.

Certain fish-derived peptides may exhibit antioxidant and anti-inflammatory activities, safeguarding muscle tissue from damage caused by oxidative stress and chronic inflammation; considering muscle wasting conditions such as cancer, diabetes, and aging-related disorders, fish-derived peptides with potential anabolic or anticatabolic effects could have therapeutic applications in preserving muscle mass and mitigating muscle loss.

Evidence strength: There is a dearth of human studies investigating the bioactivity of FPH, and as such, there is great opportunity for future research; despite the limited evidence available, the findings highlight potential beneficial outcomes related to skeletal muscle health and mass through supplementation with FPH; at present, only one registered clinical trial has been investigating the utility of FPH on measures of skeletal muscle health and function in older adults. Overall, evidence in this domain is preliminary, and robust human trials are lacking.

4.5 Gastrointestinal and Mucosal Integrity

Preclinical (cell and animal) evidence: A commercial fish protein hydrolysate product derived from Pacific whiting was studied in experimental models of epithelial injury. Effects on proliferation were determined using [³H] thymidine incorporation into rat intestinal RIE-1 and human colonic HT29 cells; effects on restitution were analysed using wounded HT29 monolayers and its ability to influence gastric injury was analysed using a rat indomethacin restraint model; partial characterization of bioactive agents was performed; both cell proliferation and cell migration were increased by about threefold when the supplement was added at 1 mg/ml (p<0.01). In addition to direct effects of bioactive peptides, glutamine constituents may have contributed to antioxidant activity via stimulation of glutathione production, and fatty acid constituents may have influenced the production of prostaglandins.

Human evidence — NSAID-induced intestinal injury: A small human study examined whether FPH could attenuate indomethacin-induced intestinal injury. In response to indomethacin during the placebo arm, gut permeability increased by approximately five-fold; however, in the FPH arm, the increase in gut permeability was truncated, suggesting a protective effect against indomethacin-induced injury; dyspepsia was present in 50% of participants in the placebo arm, but none in the FPH arm. These findings indicate that short-term supplementation with a Pacific whiting-derived FPH may be beneficial for preventing NSAID-induced intestinal injury, but the evidence for chronic supplementation is limited at present.

Human evidence — Irritable Bowel Syndrome (IBS): The effect of fish peptides in subjects with irritable bowel syndrome has been investigated; a double-blind, randomized parallel-intervention with six weeks of supplementation with 2.5 g cod protein hydrolysate (CPH) (n = 13) or placebo (n = 15) was conducted. It has been suggested that fish protein hydrolysates may have an immune-modulating effect with beneficial properties in the gut.

Evidence strength: Cell-based data and one small human study suggest potential protective effects on the intestinal mucosa. Human evidence is limited to very small studies and cannot yet support firm conclusions. Studies have shown that a fish hydrolysate product commercially available as a health food supplement possesses biological activity when assessed using several models of gut integrity and repair, but broader clinical validation is needed.

4.6 Antioxidant Activity

Growing scientific evidence suggests that hydrolyzed peptides and proteins derived from marine sources possess antioxidant and antimicrobial properties, promoting human health and preventing chronic diseases. Antioxidant capacity has been assessed both directly and via enhancement following digestion: the highest bioaccessibility of minerals was found in salmon and mackerel head hydrolysates for Fe (≥100%); the antioxidant capacity of all protein hydrolysate samples, measured by Trolox Equivalent Antioxidant Capacity (TEAC), increased 10–46% after in vitro digestion.

Evidence strength: Evidence for antioxidant activity is extensive at the in vitro level and has been confirmed in animal models. Controlled human clinical data specifically assessing antioxidant outcomes of FPH supplementation are scarce.

4.7 Malnutrition and Pediatric Nutrition

The safety of supplementation with fish protein hydrolysate (Amizate®) was examined in 438 malnourished children in a randomized, placebo-controlled, double-blind, and parallel study. This study was specifically designed to evaluate safety rather than efficacy. International organizations (FAO, WHO, UNICEF) have incorporated FPC into formulated foods for nutritional rehabilitation. Such foods were based on cereals, legumes, and a protein concentrate such as dried skimmed milk, soya bean flour, or fish protein concentrate.

5. Body Systems and Health Areas Associated with Fish Protein

Cardiovascular system: ACE inhibition and blood pressure modulation; endothelial vasodilation; antithrombotic peptide activity.
Musculoskeletal system: Muscle protein synthesis stimulation via mTOR pathway; potential anticatabolic effects; support for lean mass in ageing populations.
Metabolic system: Glycemic control through DPP-IV inhibition, incretin stimulation, and carbohydrate enzyme inhibition; appetite regulation via CCK and GLP-1; potential weight and fat mass management.
Gastrointestinal system: Support of intestinal epithelial proliferation and restitution; attenuation of NSAID-induced mucosal injury; potential immunomodulatory effects in the gut.
Immune system: In animal models, FPH have been shown to possess numerous beneficial properties for cardiovascular, neurological, intestinal, renal, and immune health.
Oxidative stress and inflammatory pathways: Free radical scavenging, metal chelation, and ROS suppression via antioxidant peptide activity.

6. Dosage Forms and Dosages Reported in Studies

The following dosages reflect what has been reported in published human clinical studies. They are presented for informational purposes and do not constitute dosing recommendations.

Tablets (fish protein): Supplementation with 3 g fish protein (tablets) for 4 weeks produced effects on body composition in overweight adults, including an increased percentage of body muscle and decreased percentage of body fat.
Marine protein hydrolysate (powder/tablet): Marine protein hydrolysate (MPH) had a positive effect on body composition in overweight adults in doses of 1.4 or 2.8 g.
Cod protein hydrolysate (liquid): A test drink containing 20 mg CPH per kg body weight was given immediately before a standardized breakfast meal in a single-dose crossover study. A dose-ranging study used daily doses of CPH at 10, 20, 30, or 40 mg/kg body weight for 1 week with one-week washout periods.
Cod protein hydrolysate (IBS trial): A double-blind, randomized, parallel-intervention used six weeks of supplementation with 2.5 g CPH.
Shrimp protein hydrolysate (blood pressure trial): A daily dose of 1200 mg of protein hydrolysate from coldwater shrimp (Pandalus borealis) was administered in a randomized, double-blind, placebo-controlled, multicentre, parallel, 8-week study.
Blue whiting muscle hydrolysate (satiety/CCK/GLP-1 trial): Subjects consumed 1 g of blue whiting muscle hydrolysate (BWMH) or placebo twice daily.
Marine protein hydrolysate (elderly, long-term trial): A daily intake of 3 g MPH for 6 to 12 months was tested as a preventive intervention against loss of physical performance in elderly persons.

Dosage forms include tablets, capsules, powder dissolved in liquid (beverages), and encapsulated powder formulations. These peptides have various practical applications, including being used as additives in food and medicinal supplements, contributing to improved consumer health and increased shelf life of food and healthcare products.

7. Safety Considerations and Interactions

7.1 Allergenicity

Fish is one of the major food allergens regulated under food labeling law in numerous jurisdictions, including the United States and the European Union. Individuals with confirmed fish allergies may react to fish protein concentrates or hydrolysates regardless of the degree of processing, as allergenic epitopes may survive partial hydrolysis. The degree to which extensive enzymatic hydrolysis destroys allergenic sequences varies and is not universally characterized for all fish species and product types.

7.2 Heavy Metal and Contaminant Risk

Few studies have investigated the relationship between the initial microbial and chemical quality of by-products and the safety of the resulting protein hydrolysates for food applications; residual antibiotics in protein hydrolysates from intensive fish/shrimp farming, the amount of biogenic amines such as histamine, and the presence of contaminants (such as cadmium, arsenic, mercury, and lead) caused by pollution of the sea or culture water are safety issues that should be considered when selecting by-products.

Testing of specific salmon and mackerel hydrolysates found: the heavy metals arsenic, mercury, cadmium, and lead were determined in raw hydrolysates to confirm harmlessness; except for cadmium in mackerel hydrolysates, all toxic elements were below the legislation levels for fish commodities. There is currently limited information regarding heavy metal contamination in fish by-products; however, FPHs being subjected to a concentration process during drying could become a risk.

7.3 Biogenic Amines (Histamine)

Histamine can accumulate during fish processing, particularly in fermented or poorly temperature-controlled products. The histamine content obtained in whole anchovy (Engraulis ringens) protein hydrolysates was 14.91 mg/kg — a very low content considering the maximum limit (100 mg/kg) according to Commission Regulation (EC) no. 2073/2005 on Microbiological Criteria for Foodstuffs. Good manufacturing practice is critical: good manufacturing practices are essential to obtain hydrolysates with maximum food safety.

7.4 Microbial and Antibiotic Residue Risk

Few studies have investigated the relationship between the initial microbial and chemical quality of by-products and the safety of the resulting protein hydrolysates for food applications; residual antibiotics in protein hydrolysates from intensive fish/shrimp farming, the amount of biogenic amines such as histamine, as well as the presence of contaminants caused by pollution of the sea or culture water are safety issues that should be considered when selecting by-products. By-product processing should be carried out near fish production and processing centers so that hydrolysis of by-products can be performed within the shortest possible time.

7.5 Sensory and Palatability Limitations

The nature of the study product (food product produced by using fish waste) impaired participant recruitment and adherence due to the characteristic fish flavor. Bitter taste from hydrophobic peptides is a recognized challenge in FPH formulation. The hydrophobic peptides have limitations like an unpleasant taste. Microencapsulation has been proposed to address this.

7.6 Interaction with Antihypertensive Drugs

Because certain fish protein–derived peptides act as ACE inhibitors through the same mechanistic pathway as pharmaceutical ACE-inhibitor drugs (e.g., captopril, lisinopril), theoretical additive effects on blood pressure could occur when FPH is used concurrently with antihypertensive medications. No formal drug interaction studies in humans have been published as of the current evidence base.

7.7 Evidence of Safety in a Pediatric Population

The safety of supplementation with fish protein hydrolysate (Amizate®) was examined in 438 malnourished children in a randomized, placebo-controlled, double-blind, and parallel study, representing one of the larger controlled evaluations of FPH safety in a vulnerable population.

References

Health Conditions

Health conditions that Fish protein may help support.

No conditions available.

Body Systems

Body systems that Fish protein may help support.

No body systems available.