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Glycomacropeptide (Casein Glycomacropeptide)
A 64-amino-acid peptide released from kappa-casein during cheese-making, sold both as a whey-derived satiety supplement and (amino-acid-fortified) as a low-phenylalanine protein for PKU. Honest appraisal: the appetite/satiety evidence is genuinely mixed — several acute RCTs found NO effect of GMP itself on CCK, satiety ratings, or food intake, while a few found small reductions in energy intake. Its established, evidence-supported use is as a near-phenylalanine-free protein substitute in phenylketonuria, where it works as well as (not clearly better than) amino-acid formulas.
What the evidence says
Most Glycomacropeptide studies are mechanism or observational rather than RCTs that measure a clinical effect — keep findings provisional.
Most evidence is from mixed-quality meta-analyses and randomised trials published 2008–2023 with a typical study size of 24 participants.
Based on 12 studies · 1 meta-analysis · 7 RCTs · 270 total participants
Confidence
ModerateBy outcome
Glycomacropeptide has an evidence score of 3/10 — emerging evidence based on 12 indexed studies, including 1 meta-analysis. A 64-amino-acid peptide released from kappa-casein during cheese-making, sold both as a whey-derived satiety supplement and (amino-acid-fortified) as a low-phenylalanine protein for PKU. Honest appraisal: the appetite/satiety evidence is genuinely mixed — several acute RCTs found NO effect of GMP itself on CCK, satiety ratings, or food intake, while a few found small reductions in energy intake. Its established, evidence-supported use is as a near-phenylalanine-free protein substitute in phenylketonuria, where it works as well as (not clearly better than) amino-acid formulas. Representative study: PMID 30453665.
The commonly studied dose of Glycomacropeptide is Satiety/metabolic trials used ~15-30 g/day (e.g. 15 g GMP + 10 g whey, twice or thrice daily); acute preloads used 25-50 g. In PKU, GMP-AA replaces most daily protein per dietitian prescription. No validated dose for appetite or weight loss.. Individual needs vary — start at the lower end of the range and adjust based on how you respond.
Bonito Peptides
Mostly mechanism / observationalShort ACE-inhibitory peptides from enzyme-digested dried bonito (Katsuobushi) fish muscle — notably the dipeptide Val-Tyr ("VY") and the prodrug-type pentapeptide LKPNM — sold as a food-derived supplement for blood pressure. Honest appraisal: a handful of small, mostly Japanese, often industry-linked RCTs show a modest blood-pressure drop in people with mild/high-normal hypertension, on the same ACE-inhibition mechanism as related fish/sardine and milk (lactotripeptide) peptides. The effect is small, the trials are small, and benefit concentrates in (pre)hypertensive people — not normotensives.
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Last reviewed June 2026 · evidence from 12 studies · how we score
This information is for educational purposes only. It is not a substitute for professional medical advice. Always consult a qualified healthcare provider before starting, stopping, or changing any supplement or medication.
Appetite/satiety RCTs are mostly null, the single meta-analysis covers only niche PKU dietary use, and the promising glucose and gut effects come from one small RCT and preclinical data — keeping evidence emerging.
Glycomacropeptide (GMP), also called caseinomacropeptide (CMP) or casein macropeptide, is the hydrophilic C-terminal glycopeptide of kappa-casein, cleaved off and released into whey when chymosin clots milk during cheese-making.
In its native form it contains essentially no aromatic amino acids (phenylalanine, tyrosine, tryptophan), which is the basis for its two distinct uses.
As a satiety/weight supplement, GMP was promoted on the hypothesis that it stimulates cholecystokinin (CCK) release and underlies whey protein's reputed appetite-suppressing effect.
The honest evidence here is mixed and often null: in a 50-person crossover RCT (Lam 2009) there was no consistent satiety effect of GMP; an acute preload RCT in overweight men (Keogh 2010) found no difference in CCK, satiety ratings, or subsequent food intake; a normal-weight-women RCT (Chungchunlam 2014) found whey was more satiating than carbohydrate but GMP alone was not; and Burton-Freeman (2008) concluded GMP is 'not critical' to whey-induced satiety, with only sex-specific CCK patterns.
On the other side, Veldhorst (2009) found that whey *with* GMP lowered energy intake at the next meal versus whey without GMP, and a 2023 dose-finding crossover RCT in obese postmenopausal women (Hansen) reported higher postprandial amylin, improved glucose homeostasis, and shifts in the fecal microbiome with GMP supplementation.
Read together, GMP's satiety/appetite signal is weak and inconsistent — not a reliable weight-loss agent. GMP's better-established role is in phenylketonuria (PKU): when fortified with the limiting amino acids it lacks (CGMP-AA), it serves as an intact-protein alternative to amino-acid formulas.
A 2018 systematic review and meta-analysis (Pena) of eight short, small studies found no difference between GMP-AA and amino acids for blood phenylalanine control or other outcomes, while patients often prefer its palatability; three-year prospective PKU studies likewise found no clear advantage in body composition or growth, only non-significant trends.
Beyond humans, animal/in-vitro work suggests anti-inflammatory and gut-protective effects (e.g. down-regulating a type-2 immune response in a rat food-allergy model), but this has not been confirmed in clinical trials.
Overall the evidence is emerging/low for appetite and gut benefits, and established-but-niche for PKU dietary management.
GMP was hypothesized to stimulate cholecystokinin (CCK) release and other gut satiety hormones. Controlled trials have largely NOT confirmed a reliable CCK or satiety effect from GMP itself.
In one dose-finding RCT, GMP raised postprandial amylin and improved the insulin–glucagon ratio versus a soy meal, hinting at a glucose-homeostasis role that needs replication.
Native GMP contains essentially no aromatic amino acids, making it (once fortified with limiting amino acids) a low-phenylalanine protein source for PKU diets.
Animal and in-vitro studies report down-regulation of type-2 immune responses and oxidative/inflammatory stress, plus shifts in fecal microbiota — not yet validated in clinical digestive endpoints.
How Glycomacropeptide works — from molecular targets to health outcomes. Click an edge to see supporting research.This visualization is in beta — pathways are being refined and expanded.
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Satiety/metabolic trials used ~15-30 g/day (e.g. 15 g GMP + 10 g whey, twice or thrice daily); acute preloads used 25-50 g. In PKU, GMP-AA replaces most daily protein per dietitian prescription. No validated dose for appetite or weight loss.
Take with food
| Form | Type |
|---|---|
| 🧪GMP isolate / whey-derived GMP powder | Recommended |
| 💊GMP-AA medical food (PKU only) | Alternative |
| 💊Whey protein (broader satiety evidence than GMP alone) | Alternative |
For general protein/satiety goals, whole whey protein has more (and more consistent) evidence than the isolated GMP fraction. GMP's distinctive value is its near-absence of phenylalanine for PKU.
Compare Glycomacropeptide vs Whey Protein →Minimum: 1 weeks
Optimal: 4 weeks
Cycling: Not required
Note: Used as a pre-meal preload in satiety studies, or split across meals as a protein substitute. No weight-loss schedule is validated.
Dose-response data unavailable. The current published research for Glycomacropeptide does not provide sufficient dose-specific outcome data to generate reliable dose-response curves.
Refer to the Dosage & Timing section above for recommended dose ranges based on available evidence.
Across acute preload RCTs, GMP alone usually did NOT reduce hunger, CCK, or food intake; a minority of trials found small next-meal energy-intake reductions.
As an amino-acid-fortified protein substitute, GMP controls blood phenylalanine about as well as amino-acid formulas and is often better tolerated/preferred.
One small crossover RCT in obese postmenopausal women found improved glucose homeostasis and higher amylin — promising but unreplicated.
Animal/in-vitro data suggest anti-inflammatory and gut-protective effects; no confirmatory human digestive trials.
Relevant and potentially helpful — but only as an amino-acid-fortified medical food under metabolic-dietitian supervision; native GMP still contains residual phenylalanine and lacks some essential amino acids.
Avoid — GMP is derived from casein and may carry trace dairy proteins.
A food-derived milk peptide consumed in cheese/whey; likely safe in normal dietary amounts. No data for high supplemental doses — keep to food-level intake.
Tip: Take with food; reduce serving size
Tip: GMP forms are generally preferred over amino-acid formulas; try a different flavour/format
The best time to take Glycomacropeptide is with meals. Take it with food. Satiety trials dosed GMP as a preload before a test meal or split across meals; in PKU it is taken with meals as a protein substitute.
Glycomacropeptide is generally well-tolerated and considered safe for most healthy adults at recommended doses. The most commonly reported side effects are mild GI symptoms (bloating, fullness), taste/palatability complaints (medical-food forms). Use caution if any of these apply to you: Milk allergy (GMP is a dairy/casein-derived peptide); Galactosemia (contains glycosylated sugar residues including galactose).
Lactotripeptides
Mostly mechanism / observationalTwo milk-casein-derived tripeptides — Val-Pro-Pro (VPP) and Ile-Pro-Pro (IPP) — produced by fermenting milk with Lactobacillus helveticus or hydrolysing casein. They inhibit ACE in vitro and have been studied extensively for blood pressure. Honest appraisal: multiple meta-analyses find a small, statistically-significant drop in systolic/diastolic BP, but the effect is modest, heterogeneous, larger in Japanese than Western trials, and dented by clear publication bias plus outright-null trials (e.g. the Dutch Engberink RCT).