Bioactive Peptides in Food: Naturally Occurring Sources

You are already eating peptides. Every glass of milk, every piece of grilled salmon, every bowl of fermented yogurt contains peptide fragments with measurable biological activity -- lowering blood pressure, scavenging free radicals, killing bacteria, or modulating your immune system. These are bioactive peptides: short amino acid sequences, typically 2 to 20 residues long, that do more than just provide calories. They do things.

The science of food-derived bioactive peptides has exploded over the past two decades. Researchers have cataloged thousands of these sequences from dairy, eggs, fish, meat, and plant proteins. Some, like the blood-pressure-lowering tripeptides VPP and IPP from fermented milk, have been commercialized as functional foods. Others are still in the lab, awaiting the clinical trials that will determine whether they work as well in humans as they do in test tubes and animal models.

This guide maps the major food sources of bioactive peptides, explains how they form, and separates the well-supported health claims from the ones that still need proof.

What Are Bioactive Peptides?
How Bioactive Peptides Form in Food
Dairy: The Most Studied Source
Eggs: Overlooked but Rich
Fish and Seafood
Meat-Derived Peptides
Plant Sources
Collagen Peptides from Bone Broth
Health Effects: What the Evidence Shows
Food Peptides vs. Therapeutic Peptides
Frequently Asked Questions
The Bottom Line
References

What Are Bioactive Peptides? {#what-are-bioactive-peptides}

Bioactive peptides are short chains of amino acids -- usually 2 to 20 residues -- that have a biological effect beyond basic nutrition. They are encrypted within the sequences of larger food proteins and become active when released through digestion, fermentation, or industrial processing.

The term "bioactive" means these peptides interact with cells or enzymes in ways that affect physiological function. A peptide that inhibits angiotensin-converting enzyme (ACE) lowers blood pressure. A peptide that scavenges free radicals reduces oxidative stress. A peptide that punctures bacterial cell membranes kills pathogens.

To be considered bioactive, a peptide must meet three conditions: it must be released from its parent protein, it must survive digestion long enough to reach its target, and it must have a measurable effect at physiological concentrations.

For background on how peptide bonds hold these molecules together, see our guide on amino acids, peptide bonds, and biochemistry basics.

How Bioactive Peptides Form in Food {#how-bioactive-peptides-form}

Bioactive peptides do not exist as free molecules in whole, unprocessed food. They are hidden inside intact proteins, waiting to be cut loose. Three processes release them:

Gastrointestinal digestion. Your stomach acid denatures food proteins, and digestive enzymes (pepsin, trypsin, chymotrypsin) cleave them into peptide fragments. Some of these fragments happen to have bioactive sequences. This is the oldest and most universal release mechanism.

Fermentation. Bacteria and fungi produce proteolytic enzymes that break down proteins during food processing. Lactic acid bacteria in yogurt and cheese, for example, generate ACE-inhibitory peptides from casein during fermentation. The specific peptides released depend on the bacterial strain, the protein substrate, and the fermentation conditions.

Enzymatic hydrolysis. Food scientists use purified enzymes (alcalase, pepsin, trypsin, flavourzyme) to deliberately break down food proteins into bioactive peptide mixtures. This is how commercial hydrolyzed protein products are made, including many sports nutrition supplements. The degree of hydrolysis -- the percentage of peptide bonds cleaved -- determines the size and activity profile of the resulting peptides.

Dairy: The Most Studied Source {#dairy}

Milk proteins are the most extensively studied source of bioactive peptides, and for good reason. A 2025 systematic review cataloged over 3,200 distinct bioactive peptides from dairy sources, with ACE-inhibitory sequences alone accounting for 1,237 entries (MDPI, 2025).

Casein-Derived Peptides {#casein-derived-peptides}

Casein makes up about 80% of milk protein and is the primary source of dairy bioactive peptides. Beta-casein is the most prolific precursor, followed by alpha-s1-casein.

The most famous casein-derived peptides are the antihypertensive tripeptides VPP (Val-Pro-Pro) and IPP (Ile-Pro-Pro). These are released during fermentation by Lactobacillus helveticus and inhibit ACE, the enzyme that constricts blood vessels and raises blood pressure. Multiple clinical trials have shown modest blood pressure reductions (2-7 mmHg systolic) in mildly hypertensive subjects consuming fermented milk products enriched with these peptides.

Casein also yields casomorphins -- opioid-like peptides that bind to mu-opioid receptors. Beta-casomorphin-7, a seven-residue peptide from beta-casein, has been the subject of considerable debate regarding its absorption and physiological effects. More on this in the opioid section below.

Casein phosphopeptides (CPPs) are phosphorylated fragments that bind calcium, zinc, and iron, potentially improving mineral absorption in the gut. They are used as functional ingredients in some remineralization products for dental health.

Whey-Derived Peptides {#whey-derived-peptides}

Whey proteins -- beta-lactoglobulin, alpha-lactalbumin, and lactoferrin -- account for about 20% of milk protein. Enzymatic hydrolysis of whey produces peptides with antioxidant, antimicrobial, and immunomodulatory properties.

Lactoferricin, derived from lactoferrin by pepsin digestion, is one of the most potent antimicrobial peptides identified from food sources. It kills bacteria, fungi, and some viruses by disrupting their cell membranes -- a mechanism similar to the body's own antimicrobial peptides.

Alpha-lactorphin (Tyr-Gly-Leu-Phe) from alpha-lactalbumin has opioid activity and has been shown to lower blood pressure in animal models.

Fermented Dairy Products {#fermented-dairy}

Cheese, yogurt, kefir, and fermented milk drinks are natural peptide-generating systems. The longer and more complex the fermentation, the more peptides are released.

Aged cheeses like Parmesan and Gouda contain particularly high concentrations of bioactive peptides because months or years of bacterial proteolysis break casein into thousands of fragments. A 2025 study on fermented milk found that products rich in casein underwent higher degrees of proteolysis, producing peptides with stronger ACE-inhibitory activity (Singh et al., 2025). The specific bacterial strains used matter -- Lactobacillus helveticus is particularly efficient at generating antihypertensive peptides.

Eggs: Overlooked but Rich {#eggs}

Eggs contain multiple proteins capable of yielding bioactive peptides, and the research on egg-derived peptides has grown substantially.

Ovotransferrin from egg white yields antioxidant peptides when its structure is disrupted during cooking or enzymatic hydrolysis. Researchers have isolated 14 peptides from ovotransferrin, with two tetrapeptides -- Trp-Asn-Ile-Pro and Gly-Trp-Asn-Ile -- showing particularly strong free-radical-scavenging activity (PMC, 2012).

Ovalbumin, the most abundant egg white protein, yields ACE-inhibitory peptides under digestion by pepsin and trypsin. The peptide ovokinin (FRADHPFL) has demonstrated blood-pressure-lowering effects in spontaneously hypertensive rats.

Egg yolk peptides have shown immunomodulatory and antimicrobial activity in laboratory studies. A study by Jahandideh et al. showed that enzymatically pre-digested fried egg preparations significantly reduced blood pressure in hypertensive rats, while the same preparations without pre-digestion had no effect -- a strong argument that it is the peptide fragments, not the intact proteins, that produce the effect.

Fish and Seafood {#fish-and-seafood}

Fish muscle protein, fish skin collagen, and seafood processing byproducts are rich sources of bioactive peptides.

Mackerel hydrolysates contain peptides that inhibit lipid oxidation, quench DPPH free radicals, and reduce iron -- all markers of antioxidant capacity. The most active fractions have molecular weights around 1,400 Da (PMC, 2012).

Alaska Pollack frame protein hydrolysates contain the peptide LPHSGY, which quenched 35% of available hydroxyl radicals at a concentration of 53.6 micromolar -- potent antioxidant activity from a food-derived peptide.

Fish skin collagen hydrolysates are rich in hydroxyproline-containing peptides. These are structurally similar to the collagen peptides found in supplements and have demonstrated antioxidant and ACE-inhibitory activity.

Shrimp and crab processing waste contains peptides with antimicrobial and anti-inflammatory properties. The seafood industry generates enormous volumes of protein-rich waste, and bioactive peptide production is one strategy for converting waste into value.

Meat-Derived Peptides {#meat}

Muscle proteins from beef, pork, and poultry yield bioactive peptides during both cooking and digestion. The most studied effects are antihypertensive and antioxidant.

Dry-cured ham, which undergoes months of proteolysis during curing, is a particularly rich source. Spanish jamon iberico and Italian prosciutto contain ACE-inhibitory peptides generated naturally during the curing process. Similar to aged cheese, the extended processing time allows enzymes to release fragments that would remain encrypted in fresh meat.

Collagen-rich cuts of meat -- particularly connective tissue, tendons, and skin -- release hydroxyproline-containing peptides during slow cooking. This is the basis for the bioactive peptide content of bone broth, discussed below.

Plant Sources {#plant-sources}

Plant proteins are gaining attention as bioactive peptide sources, particularly as demand for plant-based nutrition grows.

Soy {#soy}

Soy protein is the most studied plant source. Soy peptides with ACE-inhibitory, antioxidant, and anticancer activity have been identified from both fermented soy products (miso, tempeh, soy sauce) and enzymatic hydrolysates of soy protein isolate.

The peptide lunasin, originally isolated from soy, has attracted attention for its anti-inflammatory and potential anticancer properties, though human clinical data remains limited.

Grains and Cereals {#grains-and-cereals}

Wheat gluten, rice bran protein, oat, and barley proteins all yield bioactive peptides when hydrolyzed. Wheat-derived peptides have shown ACE-inhibitory and antioxidant activity in laboratory studies. However, the allergenic potential of wheat peptides limits their use in people with celiac disease or wheat sensitivity.

Legumes and Seeds {#legumes-and-seeds}

Lentil, chickpea, pea, and chia proteins are emerging sources. A study on lentil protein found that alcalase hydrolysis produced peptides with strong ACE-inhibitory and antioxidant properties (Elisha et al., 2024). Sequential hydrolysis of chia expeller protein with alcalase followed by flavourzyme produced peptides with antioxidant, antihypertensive, and antithrombotic activity.

Hemp, flax, and pumpkin seed proteins are also under investigation, though the research is earlier-stage compared to dairy or soy.

Collagen Peptides from Bone Broth {#bone-broth}

Bone broth is one of the oldest food-derived sources of collagen peptides. Slow-simmering bones, cartilage, and connective tissue in water breaks down collagen -- primarily types I, II, and III -- into smaller peptide fragments.

The bioactive content of bone broth depends heavily on preparation: cooking time, temperature, acid addition (vinegar helps extract collagen), and the type of bones used. Commercial bone broth products vary widely in peptide content and are not standardized.

The peptides in bone broth are the same types found in hydrolyzed collagen supplements, though at much lower and more variable concentrations. If you are drinking bone broth specifically for its collagen peptide content, a standardized supplement will deliver a more consistent and higher dose.

For a broader look at collagen peptides, see our guide on collagen peptides explained.

Health Effects: What the Evidence Shows {#health-effects}

Blood Pressure Reduction (Antihypertensive) {#antihypertensive}

This is the best-supported health claim for food-derived peptides. The mechanism is straightforward: certain peptide sequences inhibit ACE, the enzyme that converts angiotensin I to the vasoconstrictor angiotensin II. Block ACE, and blood vessels relax, lowering blood pressure.

The tripeptides VPP and IPP from fermented milk are the gold standard. A meta-analysis of 12 randomized controlled trials found that daily consumption of milk products containing these peptides reduced systolic blood pressure by an average of 3.73 mmHg and diastolic blood pressure by 1.97 mmHg in mildly hypertensive subjects.

These are modest effects -- not enough to replace medication -- but meaningful as part of a dietary approach to blood pressure management. Several fermented milk products containing these peptides are sold as functional foods in Japan and Europe.

ACE-inhibitory peptides have also been identified from fish, eggs, soy, and grains, though the clinical evidence for these sources is less extensive than for dairy.

Antioxidant Activity {#antioxidant}

Many food-derived peptides scavenge free radicals, chelate pro-oxidant metal ions, or inhibit lipid peroxidation in laboratory assays. Peptides containing histidine, tyrosine, tryptophan, methionine, and cysteine tend to be the most active antioxidants because these amino acid side chains can donate electrons to neutralize radicals.

The practical question is whether eating these peptides meaningfully reduces oxidative stress in the body. Most evidence comes from cell culture and animal studies. Human clinical trials specifically testing antioxidant food peptides are scarce. The body has its own antioxidant systems (glutathione, superoxide dismutase, catalase), and whether food-derived peptides meaningfully supplement these systems at dietary doses remains an open question (Kumari and Shahidi, 2024).

Antimicrobial Effects {#antimicrobial}

Some food-derived peptides kill bacteria, fungi, or viruses by disrupting their cell membranes. Lactoferricin from milk is the best-studied example. These peptides are structurally and mechanistically similar to the body's own antimicrobial peptides like LL-37 and defensins.

Most antimicrobial food peptide research has been conducted in vitro (in test tubes), and it is unclear whether dietary consumption delivers effective concentrations to target tissues. The potential for food-derived antimicrobial peptides as natural preservatives in the food industry may be more immediately practical than their direct health effects.

Opioid-Like Activity {#opioid}

Casomorphins from milk casein and exorphins from wheat gluten bind to opioid receptors in the gut and, potentially, in the brain. Beta-casomorphin-7 (BCM-7) has generated particular controversy.

In the gut, opioid peptides slow intestinal motility, affect mucus secretion, and may influence satiety. Whether they cross the intestinal barrier in sufficient quantities to reach the brain and produce systemic opioid effects is debated. BCM-7 has been implicated in everything from infant colic to autism in some claims, but systematic reviews have not found strong evidence for systemic opioid effects from dietary casomorphins in healthy adults.

The A1/A2 milk debate centers on beta-casein variants that preferentially release BCM-7 (A1) versus variants that do not (A2). Some consumers choose A2 milk to avoid BCM-7 exposure, though the clinical significance of this choice remains uncertain.

Other Bioactivities {#other-bioactivities}

Research has also identified food peptides with:

Immunomodulatory effects -- stimulating or suppressing specific immune cell functions
Antidiabetic properties -- inhibiting DPP-4 (the same enzyme targeted by drugs like sitagliptin) or improving insulin sensitivity
Mineral-binding capacity -- casein phosphopeptides that improve calcium absorption
Anti-inflammatory activity -- reducing production of inflammatory cytokines in cell models

For most of these, the evidence is primarily preclinical. Clinical trials in humans are needed before health claims can be confidently made.

Food Peptides vs. Therapeutic Peptides {#food-vs-therapeutic}

It is important to distinguish between the peptides you get from food and the therapeutic peptides used as drugs or research compounds.

Feature	Food-Derived Peptides	Therapeutic Peptides
Source	Released from food proteins during digestion, fermentation, or processing	Synthetically manufactured or recombinant
Dose	Variable, low, dependent on diet	Precise, standardized
Potency	Generally mild effects	Designed for strong, targeted effects
Purity	Mixtures of many peptides	Single, pure compound
Regulation	Food/supplement regulation	Drug regulation (FDA approval)
Evidence	Often preclinical; some clinical	Extensive clinical trials

Food-derived peptides produce real biological effects, but they are generally weaker and less targeted than therapeutic peptides like semaglutide or BPC-157. Eating yogurt for its ACE-inhibitory peptides might modestly reduce blood pressure. It will not replace an ACE inhibitor medication.

That said, food-derived peptides represent a science-backed rationale for the health benefits of whole, minimally processed foods -- particularly fermented dairy, fish, eggs, and legumes. The peptides are one piece of why these foods matter.

Frequently Asked Questions {#faq}

Can I get enough bioactive peptides from food alone?

Yes, for the modest health effects documented in clinical trials (like small blood pressure reductions). Diets rich in fermented dairy, fish, and legumes naturally deliver bioactive peptides. However, the doses are much lower and less consistent than what you would get from a standardized supplement or hydrolysate product.

Do bioactive peptides survive digestion?

Some do, some do not. Peptides that are resistant to GI enzymes -- particularly those rich in proline -- can survive digestion and reach the intestinal wall, where they may be absorbed or exert local effects. Others are further broken down into inactive fragments. The bioavailability of food-derived peptides is one of the biggest challenges in the field.

Are fermented foods a better source than cooked foods?

Fermentation typically generates more bioactive peptides than simple cooking because bacterial proteases systematically break down proteins over hours or days. However, cooking (especially slow cooking of collagen-rich foods) also releases peptides. The best approach is to include both fermented and well-cooked protein-rich foods in your diet.

Are plant-derived bioactive peptides as effective as dairy-derived ones?

The research on plant-derived peptides is less mature. In laboratory assays, some plant peptides show comparable ACE-inhibitory and antioxidant activity to dairy peptides. But dairy peptides -- particularly VPP and IPP from fermented milk -- have far more human clinical trial data supporting their effects. The gap is narrowing as more plant-based studies are published.

Do bioactive peptides have side effects?

At dietary doses from food, no significant adverse effects have been reported. The concentrations of bioactive peptides in food are far below the levels that would be needed to produce drug-like side effects. However, people with milk allergies should avoid dairy-derived peptide products, and those with celiac disease should avoid wheat-derived peptides.

The Bottom Line {#the-bottom-line}

Bioactive peptides in food are real, measurable, and supported by a growing body of research. Dairy proteins -- particularly casein in fermented milk -- are the most extensively studied and validated source, with ACE-inhibitory tripeptides showing consistent blood pressure reductions in clinical trials. Fish, eggs, meat, and plant sources also yield peptides with antioxidant, antimicrobial, and other bioactivities, though the clinical evidence for these sources is earlier-stage.

These are not magic bullets. Food-derived peptides produce modest effects that complement a healthy diet -- they do not replace medications or therapeutic peptides. But they represent one of the science-backed reasons why nutritionists emphasize whole, protein-rich, and fermented foods. Every time you eat a piece of aged cheese, a bowl of yogurt, or a serving of fish, you are consuming a complex mixture of peptides whose health effects are only beginning to be understood.

References {#references}

Singh A, et al. "Investigating the antioxidative and antihypertensive properties of milk-derived bioactive peptides fermented by lactic acid bacteria." Food Safety and Health. 2025. Wiley
Elisha D, et al. "Emerging production techniques and potential health promoting properties of plant and animal protein-derived bioactive peptides." Critical Reviews in Food Science and Nutrition. 2024. Tandfonline
Kumari S, Shahidi F. "Bioactive peptides as antioxidants and antimicrobials: fundamentals and applications." Journal of Food Bioactives. 2024. Sciopen
"Bioactive peptides from dairy products: a systematic review of advances, mechanisms, benefits, and functional potential." MDPI. 2025. MDPI
Udenigwe CC, Aluko RE. "Food protein-derived bioactive peptides: production, processing, and potential health benefits." Journal of Food Science. 2012.
Ryan JT, et al. "Bioactive peptides from muscle sources: meat and fish." Nutrients. 2011. PMC
Hartmann R, Meisel H. "Food-derived peptides with biological activity: from research to food applications." Current Opinion in Biotechnology. 2007.
FitzGerald RJ, et al. "Hypotensive peptides from milk proteins." Journal of Nutrition. 2004.
"Food-derived bioactive peptides in human health: challenges and opportunities." Nutrients. 2018. PMC
"Food-derived bioactive peptides: the gateway to reach the full potential of food proteins for human health." Trends in Food Science & Technology. 2025. ScienceDirect

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