K
Kasivit Editorial Team
Evidence-based health research
May 2026 · 8 min read
🔬 Evidence-Based
📋 Quick Answer
GLP-1 medications like semaglutide (Ozempic, Wegovy) and tirzepatide (Mounjaro, Zepbound) reduce appetite, and eating less can lead to nutritional gaps1. Expert groups note that direct evidence on supplements in people taking these medicines is limited2. Options some people ask about are: Protein (expert groups point to resistance training and an appropriate diet for preserving muscle1), Magnesium Glycinate (for people whose diet is low in magnesium), Probiotics, L-Glutamine and Digestive Enzymes (the last three have not been tested in people taking GLP-1 medicines). Never delay, stop or change a prescribed medicine in order to start a supplement, and consult your prescriber or pharmacist before adding any supplement.
GLP-1 receptor agonists are among the most significant developments in metabolic medicine in recent years. The appetite suppression is real, the weight loss is real, and for many patients, the metabolic improvements are clinically meaningful. But there's a side of GLP-1 therapy that does not always come up in the prescribing conversation — the nutritional consequences of dramatically reduced food intake.
When appetite falls and someone eats much less than before, they don't just lose weight. They can also take in less protein and other nutrients. Expert groups list nutritional deficiencies due to calorie reduction, muscle and bone loss, and gastrointestinal side effects among the challenges of GLP-1 treatment, and note that nutrition and lifestyle therapy alongside these medicines is not yet widespread1.
This article looks at supplements that people on GLP-1 therapy often ask about, and what the evidence does and does not show for each. It is not a recommendation to take any of them.
🦠 The GLP-1 Gut Problem
What GLP-1 Medications Do to Your Gut
GLP-1 medications work partly by slowing gastric emptying — the rate at which food leaves your stomach. This contributes to fullness but also means slower digestion overall. In one study of tirzepatide, the delay in gastric emptying was greatest after the first dose and diminished with repeated dosing in healthy participants, with a smaller residual delay in people with type 2 diabetes3.
Glutamine is an amino acid that immune cells use heavily, and its availability in the body is largely controlled by the gut, liver and skeletal muscles4. Whether eating less on a GLP-1 medication affects the gut lining, and whether glutamine supplements help, has not been tested in people taking these medicines.
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In a trial of 106 adults who completed an 8-week study of post-infectious, diarrhea-predominant irritable bowel syndrome with increased intestinal permeability, glutamine 15 g/day improved symptoms and normalized permeability compared with placebo5. It was not tested in people taking GLP-1 medications or in gut-motility disorders generally.
Zhou Q, et al.
Gut. 2019;68(6):996–1002. ·
PubMed ↗
Gastrointestinal side effects — nausea, constipation, diarrhea, bloating — are among the most common adverse effects of GLP-1 medications. In the STEP 1 semaglutide trial, nausea and diarrhea were the most common adverse events, and 4.5% of people on semaglutide stopped treatment because of gastrointestinal events, compared with 0.8% on placebo6. Persistent or severe symptoms should be discussed with your prescriber. GLP-1 medications are also associated with a higher risk of gallstones and gallbladder inflammation, particularly in weight-loss trials7; seek medical care promptly for severe upper-abdominal pain, fever or yellowing of the skin.
💊 What the Evidence Shows
5 Supplements Worth Considering on GLP-1 Therapy
The following are not a recommendation for everyone, and direct evidence in people taking GLP-1 medications is lacking for most of them2. They are options some people consider. Discuss all of these with your prescriber or pharmacist, particularly if you take other medications, have kidney disease or diabetes, or are pregnant or breastfeeding.
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Gut Lining — limited evidence
L-Glutamine
Glutamine is an amino acid found in protein-rich foods. It has been studied as a supplement in post-infectious irritable bowel syndrome5, but not in people taking GLP-1 medications, so we cannot say whether it helps the gut on these medicines. Do not delay starting or adjusting a prescribed medication in order to take supplements first. Glutamine can change blood glucose and blood urea in people with type 2 diabetes (see the diabetes question below), so if you take insulin, a sulfonylurea or another glucose-lowering medicine, or have kidney disease, check with your clinician before using it. In a large trial in critically ill hospital patients with multi-organ failure, glutamine was associated with higher mortality8; it is not intended for people who are seriously ill.
Dose used in the irritable bowel trial: 5 g three times a day5. No dose has been tested for GLP-1 users; follow the product label.
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Microbiome — not tested in GLP-1 users
Probiotic 40 Billion CFU with Prebiotics
Some people take a probiotic for digestive comfort. Probiotics have not been tested for GLP-1-related side effects. They are generally considered safe for most people, but serious infections have been described in susceptible individuals9, and in a trial in severe acute pancreatitis a multispecies probiotic was associated with higher mortality10. If you are seriously ill or have a weakened immune system, ask your clinician first.
Typical dose: 1 capsule daily, with or without food
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Digestion — not tested in GLP-1 users
Digestive Enzyme Pro Blend
Slower stomach emptying is a known effect of GLP-1 medications3. Digestive enzyme supplements (this blend contains Amylase, Protease, Lipase, and Lactase) have not been studied in people taking GLP-1 medications, so we cannot say whether they help with bloating or nutrient absorption. In one small trial in 16 healthy people, a lipase supplement taken before a fatty meal reduced the feeling of stomach fullness but not other symptoms11.
Typical dose: 1–2 capsules immediately before each main meal
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Mineral Intake
Magnesium Glycinate
Many people do not get enough magnesium from food: in the United States, 48% of the population consumed less than the required amount from food in 2005–200612. That is low intake, not a measured deficiency, and eating much less may widen the gap. Magnesium is involved in over 300 enzymatic reactions — including glucose metabolism, muscle function, sleep quality, and stress regulation. Magnesium oxide is poorly absorbed (about 4% in one study of healthy volunteers), while magnesium chloride, lactate and aspartate were absorbed better13. Glycinate was not tested in that study, and we did not find trials showing it is better absorbed or better tolerated. Magnesium supplements can cause loose stools or diarrhea at higher doses14. If you have kidney disease, ask your clinician before taking magnesium supplements, and ask your prescriber or pharmacist whether magnesium could interact with your medicines.
Upper limit for supplemental magnesium in adults: 350 mg/day of elemental magnesium (National Academies / NIH Office of Dietary Supplements)14,15. Check the product label, and ask your clinician if you have kidney disease.
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Muscle Preservation
High-Protein Supplementation
Losing weight on a GLP-1 medication can include loss of lean muscle as well as fat, and expert groups point to resistance training and an appropriate diet to help preserve muscle1. Higher-protein diets have been studied during calorie-restricted weight loss: in a meta-analysis of 24 trials (not in GLP-1 users), they modestly reduced loss of fat-free mass compared with standard-protein diets16. Your best protein target depends on your size, kidney health and other conditions, so ask your clinician or a registered dietitian what is right for you. In adults without kidney disease, a 2026 meta-analysis of 22 trials found no consistent evidence of kidney injury with high-protein diets, but most trials were short and long-term effects are uncertain17. If you have kidney disease, ask your clinician before using protein supplements.
Target: set with your clinician or dietitian, based on your size, kidney health and other conditions.
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In 24 trials of calorie-restricted diets (not in GLP-1 users), higher-protein diets modestly reduced loss of fat-free mass (by about 0.4 kg) and increased fat loss (by about 0.9 kg) compared with standard-protein diets16
Wycherley TP, et al.
Am J Clin Nutr. 2012;96(6):1281–98. ·
PubMed ↗
❓ What You Don't Need
Supplements to Skip on GLP-1 Therapy
The supplement industry has responded to the GLP-1 boom with a wave of "GLP-1 support" products that are, frankly, not well-evidenced for this specific application. Here's what to skip:
Berberine as an "Ozempic alternative" — Berberine has some evidence for modest blood sugar effects: in a 2023 meta-analysis of 20 trials it lowered fasting glucose and HbA1c (HbA1c by about 4.5 mmol/mol)18. But the viral framing of it as a "natural Ozempic" is misleading. Its mechanism is completely different from GLP-1 receptor agonism. Berberine can also interact with other medicines (it increased cyclosporine exposure in transplant recipients) and can add to the effects of other drugs, for example on blood sugar and blood pressure19, so ask your prescriber or pharmacist before taking it alongside a GLP-1 medicine or any other prescription drug.
Treating constipation on your own — Constipation is common on GLP-1 therapy. Expert consensus statements on managing GLP-1 side effects such as constipation are based mainly on indirect evidence2, and we did not find studies comparing fiber and magnesium supplements for constipation in people taking GLP-1 medicines. If constipation persists, ask your prescriber or pharmacist what is appropriate before adding fiber, laxatives or magnesium supplements, particularly if you have kidney disease.
High-dose vitamin C — In a study of seven healthy volunteers, blood levels of vitamin C rose steeply between 30 and 100 mg a day and 200 mg a day was the first dose beyond the steep part of the curve, absorption of single doses of 500 mg and above fell (the absorbed excess was excreted), and urinary oxalate and urate excretion were higher at 1,000 mg a day. The authors concluded that daily doses above 400 mg have no evident value and that safe doses are less than 1,000 mg daily20. Higher-dose products are therefore best avoided.
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Important clinical note: GLP-1 medications slow gastric emptying, which can change how some oral medicines are absorbed. A 2025 review found most of these interactions clinically insignificant, but significant changes in exposure were seen with levothyroxine and oral semaglutide, and with oral contraceptives and tirzepatide21. In healthy volunteers, oral semaglutide raised total thyroxine exposure by 33% when taken with levothyroxine22, and a single dose of tirzepatide lowered peak levels of the contraceptive hormones by 55–66% and overall exposure by 20–23%; whether this changes contraceptive effectiveness has not been established23. If you take thyroid hormone, an oral contraceptive or any other oral medicine, ask your prescriber or pharmacist about timing and whether any extra precautions are needed before adding any new supplement. This includes all of the supplements listed above.
📊 Timing Protocol
When to Take Each Supplement
Timing is only one consideration, and none of this replaces advice from your prescriber or pharmacist. Here's one way to organize these supplements around your day, if you and your prescriber decide to use them:
Morning (before breakfast, on an empty stomach): L-Glutamine powder in water. Follow the directions on the product label.
With each main meal: Digestive Enzyme Pro Blend. These enzymes work actively on the food you're eating — timing with meals is essential.
Once daily, with or without food: Probiotic 40 Billion. Consistency of timing matters more than whether it's with food.
Evening (with dinner or a light snack): Magnesium Glycinate. Follow the directions on the product label.
Distributed throughout meals: Protein supplementation — use meal replacement shakes or protein powder, if needed, to help reach the protein target set with your clinician or dietitian.
🦠 Kasivit Gut Trio Bundle
The Kasivit Gut Trio Bundle brings the three gut-focused products together
L-Glutamine, Probiotic 40 Billion, and Digestive Enzyme Pro Blend, bundled and Kasivit-curated. These have not been tested in people taking GLP-1 medicines, so talk to your prescriber first. The bundle price is lower than purchasing individually.
View Kasivit Gut Trio Bundle →
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❓ Frequently Asked Questions
Your Questions, Answered
Can I take all of these supplements together with Ozempic?
Always check with your prescriber or pharmacist first. We did not find reports of direct interactions between these supplements and semaglutide or tirzepatide, but they have not been specifically studied21. In one small trial in people with type 2 diabetes, glutamine modestly lowered HbA1c24, and GLP-1 medications can change how some oral medicines are absorbed (see the clinical note above), so timing relative to your other medications should be discussed with your prescriber or pharmacist.
When should I start taking these supplements — before or after starting Ozempic?
There is no evidence that starting a supplement before a GLP-1 medication matters. Never postpone or change a prescribed medication in order to start supplements; discuss the timing of any supplement with your prescriber.
Do I need all five, or can I start with just one or two?
You do not need all five. Expert groups point to protein intake, resistance training and an appropriate diet as priorities for preserving muscle1; the other items here are optional and not backed by trials in people taking GLP-1 medicines2. If constipation, muscle cramps or sleep disruption are bothering you, discuss them with your prescriber first, because they can have many causes, before adding a supplement such as magnesium.
Are these supplements safe for people with diabetes?
Ask your physician or pharmacist before adding any of these if you have diabetes, especially if you take insulin, a sulfonylurea or another glucose-lowering medicine. In one small trial in type 2 diabetes (15 g twice daily for 4 weeks), L-Glutamine modestly lowered HbA1c and raised blood urea24; in another (30 g/day for 6 weeks) it did not improve post-meal glucose25. Probiotics are generally considered safe for most people9, but safety is less certain in some groups: a multispecies probiotic was associated with higher mortality in severe acute pancreatitis10, and a 2026 meta-analysis could not draw conclusions about long-term safety in at-risk populations26. We did not find evidence that probiotics prevent GLP-1 side effects.
My doctor never mentioned supplements with my Ozempic prescription. Is this unusual?
No — it is common. Expert groups note that nutrition and lifestyle therapy alongside GLP-1 medications is not yet widespread in practice1. A registered dietitian or your prescriber can tailor advice to you.
📝 Final Thoughts
The Bottom Line
GLP-1 medications are a genuine clinical advance. But they work by dramatically reducing the amount of food you eat — and that has downstream consequences for nutrition that are not automatically addressed by the prescription. The supplements covered in this article are options some people consider; for most of them, direct evidence in people taking GLP-1 medications is lacking2.
None of these replace a conversation with your prescribing physician. But if your prescriber hasn't discussed these issues with you, this article gives you the language and the evidence to raise them at your next appointment.
If you're not sure where your biggest nutritional gaps are, the free Kasivit Wellness Quiz scores you across five health dimensions — including body habits, lifestyle routines, and rest — and recommends the supplements most relevant to your specific profile.
Medical Disclaimer: This article is written for educational purposes by the Kasivit Editorial Team. It does not constitute medical advice and is not a substitute for consultation with your prescribing physician or a qualified healthcare provider. GLP-1 medications are prescription drugs; any changes to your supplement regimen should be discussed with your prescribing team or pharmacist, and no prescribed medicine should be started, stopped or changed on the basis of this article. These statements have not been evaluated by the Food and Drug Administration. Products mentioned are not intended to diagnose, treat, cure, or prevent any disease.
References: (1) Mozaffarian D, et al. Am J Clin Nutr. 2025;122(1):344-367.
PubMed ·
DOI (2) Sievenpiper JL, et al. Obes Pillars. 2026;17:100228.
PubMed ·
DOI (3) Urva S, et al. Diabetes Obes Metab. 2020;22(10):1886-1891.
PubMed ·
DOI (4) Cruzat V, et al. Nutrients. 2018;10(11):1564.
PubMed ·
DOI (5) Zhou Q, et al. Gut. 2019;68(6):996-1002.
PubMed ·
DOI (6) Wilding JPH, et al. N Engl J Med. 2021;384(11):989-1002.
PubMed ·
DOI (7) He L, et al. JAMA Intern Med. 2022;182(5):513-519.
PubMed ·
DOI (8) Heyland D, et al. N Engl J Med. 2013;368(16):1489-97.
PubMed ·
DOI (9) Doron S, et al. Clin Infect Dis. 2015;60 Suppl 2:S129-34.
PubMed ·
DOI (10) Besselink MG, et al. Lancet. 2008;371(9613):651-659.
PubMed ·
DOI (11) Levine ME, et al. Gut Liver. 2015;9(4):464-9.
PubMed ·
DOI (12) Rosanoff A, et al. Nutr Rev. 2012;70(3):153-64.
PubMed ·
DOI (13) Firoz M, et al. Magnes Res. 2001;14(4):257-62.
PubMed (14) Costello R, et al. Adv Nutr. 2023;14(5):973-982.
PubMed ·
DOI (15) National Academies / NIH Office of Dietary Supplements, tolerable upper intake levels.
ods.od.nih.gov (16) Wycherley TP, et al. Am J Clin Nutr. 2012;96(6):1281-98.
PubMed ·
DOI (17) Teixeira Silva PR, et al. Diabetes Obes Metab. 2026;28(9):7672-7683.
PubMed ·
DOI (18) Zhao JV, et al. J Nutr. 2023;153(10):2939-2950.
PubMed ·
DOI (19) Dumitru CN, et al. Pharmaceuticals (Basel). 2026;19(8):1313.
PubMed ·
DOI (20) Levine M, et al. Proc Natl Acad Sci U S A. 1996;93(8):3704-9.
PubMed ·
DOI (21) Min JS, et al. Drug Des Devel Ther. 2025;19:3509-3537.
PubMed ·
DOI (22) Hauge C, et al. Expert Opin Drug Metab Toxicol. 2021;17(9):1139-1148.
PubMed ·
DOI (23) Viana DPDC, et al. Maturitas. 2026;214:109116.
PubMed ·
DOI (24) Samocha-Bonet D, et al. PLoS One. 2014;9(11):e113366.
PubMed ·
DOI (25) Mansour A, et al. Int J Vitam Nutr Res. 2020;90(5-6):425-429.
PubMed ·
DOI (26) Alshatari S, et al. Front Nutr. 2026;13:1895136.
PubMed ·
DOI
