Glycomacropeptide Drug Interactions, Uses, Effectiveness, Safety & More
What is this page for?
First and foremost: how Glycomacropeptide interacts with medications. The heart of this page is the interaction list — every drug Glycomacropeptide is known to interact with, and how serious each one is.
But these pages have grown well beyond that into a full monograph — what Glycomacropeptide is, what people use it for and how strong the evidence is, its safety and side effects, and answers to the questions we’re asked most — written and reviewed by the clinical staff at HelloPharmacist. It’s educational information from our licensed clinical databases, not medical advice, and we don’t sell or endorse products. Our editorial policy
Check Glycomacropeptide against your medication
Add one medicationDrugs that interact with Glycomacropeptide
0 medications have a known interaction with Glycomacropeptide, graded by severity. Select any drug for the full evidence-based detail.
We don’t currently list any known drug interactions for Glycomacropeptide. This doesn’t guarantee none exist — always confirm with your pharmacist before combining supplements with your medications.
What Severity, Likelihood & Evidence Mean
Severity — How Serious It Can Be
- Major. Clinically significant; generally best avoided, or used only under direct professional supervision.
- Moderate. May need monitoring, a dose adjustment, or separating the times you take each one.
- Minor. Generally not clinically significant, but still worth noting and mentioning to your pharmacist.
- No known interaction. Checked against our sources with nothing documented — not the same as proven safety.
Likelihood — How Well It’s Documented
- Likely. Well-controlled human studies have demonstrated the likely existence of this interaction
- Probable. Interaction has not been documented in well-controlled studies, however, the interaction has been demonstrated in some small human studies or in controlled animal studies in conjunction with multiple case reports.
- Possible. Interaction has been documented in animal or in lab research, or the interaction has been documented in humans but is limited to case reports or conflicting clinical research exists
- Unlikely. Interaction has been demonstrated in animal or in lab research but has been shown not to occur in humans.
Where This Data Comes From
- Interaction records are evidence-graded and sourced from the Natural Medicines database (TRC Healthcare), the same reference used by pharmacists and hospitals.
- Each drug listed above links to the full report for that exact Glycomacropeptide combination — clinical detail, likelihood, evidence level, and citations.
- Content is reviewed by licensed HelloPharmacist pharmacists — see our data sources and editorial standards.
Glycomacropeptide: Uses, Safety & Side Effects
Glycomacropeptide (GMP) is a milk-derived protein fragment best known as a low-phenylalanine protein source used in medical foods for people with phenylketonuria (PKU). It is also being studied for gut health and appetite, but evidence for most non-PKU uses is still limited. Talk to your doctor or dietitian before using GMP products, especially if you have a metabolic condition.
- Part used
- Peptide derived from milk casein (whey-based)
- Common forms
- Medical foods, protein powders, capsules, ready-to-drink formulas
- Phenylketonuria (PKU) nutrition
- Protein source low in phenylalanine
- Gut and digestive health
- Prebiotic support
- Appetite and satiety
Popular and traditional uses — not proof it works. See “Uses & effectiveness” below for the evidence.
Generally well tolerated as a food protein, but it is milk-derived and not suitable for those with milk allergy.
Insufficient reliable information available; avoid using.
Read the full pregnancy detailInsufficient reliable information available; avoid using.
Read the full breastfeeding detailPregnancy & breastfeeding ratings are from Natural Medicines (Therapeutic Research Center). Safety guidance is general; always confirm with your pharmacist or doctor for your situation.
Overview
Glycomacropeptide (GMP) is a small protein fragment, or peptide, that comes from milk. It is released from a milk protein called casein during cheese-making, when an enzyme acts on the milk. GMP is found in the liquid whey that is left over.
What makes GMP special is that, in its pure form, it does not naturally contain the amino acid phenylalanine. This is why it is widely used in special medical foods for people with phenylketonuria (PKU), a genetic condition in which the body cannot break down phenylalanine properly.
Today GMP is sold in protein powders, drinks, bars, and capsules. It is most often used as a more pleasant-tasting protein source for people who need to limit phenylalanine, and it is also being explored for general gut and digestive health.
How it works
GMP is a peptide, meaning it is a chain of amino acids smaller than a full protein. Its key feature is that the pure peptide lacks phenylalanine, which is why it can replace ordinary protein for people who must avoid that amino acid.
Researchers think GMP may also influence the gut. It can resist some digestion and reach the lower intestine, where it may feed helpful bacteria, acting like a prebiotic. Some lab studies suggest it may bind to certain bacteria or toxins and affect immune signaling.
GMP may also affect appetite hormones, possibly increasing signals of fullness. Most of these mechanisms are based on laboratory or animal research, and it is not certain how strongly they apply to people.
Does Glycomacropeptide work?
How to read these evidence grades
Natural Medicines’ 7-point scale. We show each rating’s label word-for-word.
For Glycomacropeptide, current evidence isn’t strong enough to rate any specific use. The conditions it has been studied for are listed below.
Also studied for 4 conditions — evidence insufficient to rate
Insufficient Reliable Evidence To Rate Gout
Preliminary clinical research in adults with recurrent gout flares shows that taking skim milk powder enriched with glycomacropeptide (Lacprodan CGMP-10, Arla Foods Ingredients) and G600 milk fat extract daily for 3 months modestly decreases the frequency of gout flares and patient-reported pain scores when compared with a lactose powder control.
Insufficient Reliable Evidence To Rate Obesity
Clinical research shows that consuming a meal-replacement supplement containing glycomacropeptide (NatraPep, MG Nutritionals) 13.5 grams twice daily for 6 months followed by once daily for an additional 6 months, along with energy restricted meals, does not increase weight loss in overweight or obese men and women when compared to using skim milk powder supplements. However, patients taking the glycomacropeptide meal-replacement supplement showed a significant reduction in weight of 10.8 kg when compared to baseline.
Insufficient Reliable Evidence To Rate Phenylketonuria (PKU)
Preliminary clinical research shows that replacing a phenylalanine-free amino acid supplement with a glycomacropeptide-based supplement containing glycomacropeptide plus essential amino acids, such as tyrosine, tryptophan, leucine, lysine, arginine, methionine, and histidine, for up to 1 year does not adversely affect health or renal status and maintains phenylalanine levels within the target range in adults and children with PKU. When used in children 5-16 years of age, the dose of the glycomacropeptide supplement is increased gradually, while the amino acid supplement dose is decreased, with regular monitoring to maintain phenylalanine levels in the desired range. About 48% of subjects are able to switch completely to glycomacropeptide supplements, while the remaining subjects require an individualized mixture of glycomacropeptide and standard amino acid supplements. Compared to the amino acid supplements, many subjects prefer glycomacropeptide-based supplements and report a subjective reduction in breath malodor. Replacing all or part of daily amino acid intake with glycomacropeptide also maintains height, lean body mass, percentage body fat, bone mineral density, blood pressure, and blood biochemistry including blood urea nitrogen.
Insufficient Reliable Evidence To Rate Tyrosinemia
Observational research shows that using glycomacropeptide as a substitute for all or part of daily protein intake in patients with tyrosinemia is effective and safe for reducing plasma tyrosine levels and maintaining them within the desired range.
Source & disclaimer. Effectiveness ratings and evidence summaries are provided by Natural Medicines (Therapeutic Research Center) and shown as licensed. Where Natural Medicines hasn’t rated a use, HelloPharmacist’s pharmacists may add their own reviewed rating and evidence (each such entry is labeled). This is educational information, not medical advice — talk with your pharmacist or doctor before starting, stopping, or changing a supplement.
Safety & precautions
As a food-derived protein, GMP is generally considered well tolerated when used as directed. However, because it is made from milk, people with a milk or dairy allergy should avoid it. People who are lactose intolerant should check labels, though purified GMP usually contains little lactose.
People with PKU should only use GMP products under the guidance of a metabolic doctor or dietitian, because GMP must be balanced with other amino acids and tracked carefully.
Pregnancy and breastfeeding: There is not enough reliable safety information on concentrated GMP supplements during pregnancy or breastfeeding. To be safe, use these products only if your doctor or dietitian recommends them. Women with PKU especially need close medical supervision during pregnancy.
Always talk with a pharmacist or doctor before starting any new supplement, especially if you have a chronic health condition.
Side effects
GMP is usually well tolerated. When side effects occur, they are typically mild and related to the digestive system, such as bloating, gas, or stomach discomfort, especially when first starting.
Because GMP comes from milk, an allergic reaction is possible in people sensitive to dairy. Signs can include rash, itching, swelling, or trouble breathing. Stop use and seek medical care right away if these occur.
There are no well-established serious side effects in healthy people, but high-protein products in general should be used cautiously by people with kidney problems.
Glycomacropeptide: Reported Adverse Effects
Documented safety reports on Glycomacropeptide from the evidence-graded Natural Medicines (TRC Healthcare) database, shown word-for-word from the licensed record.
Reports by conditionDiarrhea Gastrointestinal
Orally, the most common side effects of glycomacropeptide are abdominal discomfort, bloating, burping, and flatulence. Taking skim milk powder enriched with glycomacropeptide and G600 milk fat extract for 3 months has been associated with diarrhea, flatulence, and nausea. However, rates of these effects were similar in the control group. In another clinical trial, patients taking glycomacropeptide-containing supplements reported fewer gastrointestinal side effects than patients taking amino acid-based supplements.
- Delsoglio M, Capener R, MacDonald A, et al. Evaluation of a New Glycomacropeptide-Based Protein Substitute in Powdered and Liquid Format in Patients with PKU. Nutrients 2023;15(16):3580.
- Dalbeth N, Ames R, Gamble GD, et al. Effects of skim milk powder enriched with glycomacropeptide and G600 milk fat extract on frequency of gout flares: a proof-of-concept randomised controlled trial. Ann Rheum Dis. 2012;71(6):929-34.
- Ney DM, Stroup BM, Clayton MK, et al. Glycomacropeptide for nutritional management of phenylketonuria: a randomized, controlled, crossover trial. Am J Clin Nutr. 2016;104(2):334-45.
Adverse-effects data: Natural Medicines, Therapeutic Research Center
Dosing
There is no single standardized dose of glycomacropeptide for general use. The right amount depends on why it is being used. For PKU, the amount is carefully calculated by a metabolic dietitian based on a person's protein needs and phenylalanine limits.
For protein powders and other supplements, follow the directions on the product label. Because formulas and concentrations differ, check with a pharmacist, doctor, or dietitian before deciding how much to take. Avoid taking more than the label suggests.
Glycomacropeptide & Pregnancy
Glycomacropeptide & Breastfeeding
© 2026 Therapeutic Research Center
Pregnancy & lactation ratings: Natural Medicines, Therapeutic Research Center
References & further reading
The 12 references that drive our Glycomacropeptide monograph and interaction data, from the evidence-graded Natural Medicines (TRC Healthcare) database. Citations with a link open the study on PubMed or the publisher’s site.
- van Calcar SC, MacLeod EL, Gleason ST, et al. Improved nutritional management of phenylketonuria by using a diet containing glycomacropeptide compared with amino acids. Am J Clin Nutr 2009;89(4):1068-1077. PubMed
- Keogh, J. B. and Clifton, P. The effect of meal replacements high in glycomacropeptide on weight loss and markers of cardiovascular disease risk. Am J Clin Nutr 2008;87(6):1602-1605. DOI
- Dalbeth N, Ames R, Gamble GD, et al. Effects of skim milk powder enriched with glycomacropeptide and G600 milk fat extract on frequency of gout flares: a proof-of-concept randomised controlled trial. Ann Rheum Dis. 2012;71(6):929-34. PubMed
- Ney DM, Stroup BM, Clayton MK, et al. Glycomacropeptide for nutritional management of phenylketonuria: a randomized, controlled, crossover trial. Am J Clin Nutr. 2016;104(2):334-45. PubMed
- Daly A, Evans S, Chahal S, et al. Glycomacropeptide: long-term use and impact on blood phenylalanine, growth and nutritional status in children with PKU. Orphanet J Rare Dis 2019;14(1):44. doi: 10.1186/s13023-019-1011-y. PubMed
- Tiele A, Daly A, Hattersley J, et al. Investigation of paediatric PKU breath malodour, comparing glycomacropeptide with phenylalanine free L-amino acid supplements. J Breath Res 2019;14(1):016001. doi: 10.1088/1752-7163/ab4097. PubMed
- Larsen ER, Juel A, Jensen E, Hollyer TR, Wegener G. Dietary supplementation with casein glycomacropeptide, leucine and tryptophan reduces plasma amino acid levels in men. Acta Neuropsychiatr 2022;34(2):69-76. PubMed
- Delsoglio M, Capener R, MacDonald A, et al. Evaluation of a New 'Mix-In' Style Glycomacropeptide-Based Protein Substitute for Food and Drinks in Patients with Phenylketonuria and Tyrosinemia. Nutrients 2023;15(16):3598. PubMed
- Delsoglio M, Capener R, MacDonald A, et al. Evaluation of a New Glycomacropeptide-Based Protein Substitute in Powdered and Liquid Format in Patients with PKU. Nutrients 2023;15(16):3580. PubMed
- Daly A, Högler W, Crabtree N, et al. A Three-Year Longitudinal Study Comparing Bone Mass, Density, and Geometry Measured by DXA, pQCT, and Bone Turnover Markers in Children with PKU Taking L-Amino Acid or Glycomacropeptide Protein Substitutes. Nutrients 2 PubMed
- Pena MJ, Pinto A, de Almeida MF, et al. Continuous use of glycomacropeptide in the nutritional management of patients with phenylketonuria: a clinical perspective. Orphanet J Rare Dis 2021;16(1):84. PubMed
- Daly A, Högler W, Crabtree N, et al. Growth and Body Composition in PKU Children-A Three-Year Prospective Study Comparing the Effects of L-Amino Acid to Glycomacropeptide Protein Substitutes. Nutrients 2021;13(4):1323. PubMed
This information is for education only and is not a substitute for professional medical advice. Always check with your pharmacist or doctor before starting, stopping, or combining supplements and medications.
Parts of this content are provided by the Therapeutic Research Center, LLC.
DISCLAIMER: Currently this does not check for drug-drug interactions. This is not an all-inclusive comprehensive list of potential interactions and is for informational purposes only. Not all interactions are known or well-reported in the scientific literature, and new interactions are continually being reported. Input is needed from a qualified healthcare provider including a pharmacist before starting any therapy. Application of clinical judgment is necessary.
© 2021 Therapeutic Research Center, LLC
Glycomacropeptide: Common Questions
What is Glycomacropeptide used for, and does it work?
Does Glycomacropeptide interact with prescription medications?
How are Glycomacropeptide interactions rated?
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Where does this Glycomacropeptide interaction information come from?
What is Glycomacropeptide used for?
Is Glycomacropeptide safe?
Does Glycomacropeptide contain phenylalanine?
Can I take Glycomacropeptide while pregnant or breastfeeding?
Written and reviewed by the HelloPharmacist editorial staff. Our editorial policy
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