Welcome to Issue 01 of The Kasivit Journal.
We started The Kasivit Journal because what clinical research shows and what people often hear about supplements can differ a great deal. Too much supplement advice is vague, overstated, or untethered from evidence. Every issue, we aim to close that gap, clearly and honestly. Kasivit sells supplements, so weigh our views accordingly and check the sources listed at the end of this issue.
GLP-1 medications like Ozempic and Wegovy represent a genuine advance in metabolic medicine. They also reduce appetite, and eating much less can lead to nutritional gaps; expert groups note that clinician and public knowledge of the nutritional side of treatment is limited.1 GLP-1 medications are also associated with a higher risk of gallbladder and bile duct problems;2 seek prompt medical care for severe upper-abdominal pain, fever or yellowing of the skin. This issue is largely about nutrition during GLP-1 treatment. Nothing in it is a reason to start, stop or change a prescribed medicine; ask your prescriber or pharmacist.
— The Kasivit Editorial Team
The gut lining is a single cell layer thick. In one trial in adults with post-infectious, diarrhea-predominant irritable bowel syndrome and increased gut permeability, glutamine improved symptoms and normalised permeability compared with placebo.3 It has not been tested in people taking GLP-1 medications.
Read the full article →Melatonin and magnesium have both been studied for sleep. In a meta-analysis of 19 trials in people with primary sleep disorders, melatonin shortened the time to fall asleep by about 7 minutes and lengthened total sleep time by about 8 minutes.4 For magnesium, a review found only three small trials in older adults with insomnia, and the evidence was low to very low quality.5
Read the full article →GLP-1 medications reduce appetite, and eating much less can lead to nutritional gaps.1 This article looks at five supplements people ask about on GLP-1 therapy and how strong the evidence is for each. Expert groups note that direct evidence on supplements in people taking these medicines is limited.6
Read the full article →Across 20 randomized trials (1,761 people), berberine lowered fasting glucose by about 0.5 mmol/L and HbA1c by about 4.5 mmol/mol compared with placebo.7 We did not find any trial of berberine combined with a GLP-1 medication. A 2026 review lists additive blood-glucose lowering (hypoglycemia) among berberine's possible drug interactions, along with effects on liver enzymes (CYP3A4, CYP2D6, CYP2C9) and drug transporters,8 so it could add to the effect of GLP-1 medications or other diabetes medicines. Berberine can also cause stomach upset: across trials, gastrointestinal side effects were reported in 2-23% of berberine groups versus 2-15% of placebo groups.9 Pregnancy has been flagged as a risk factor for berberine toxicity.10
In a small study of 15 adults with type 2 diabetes, gut bacteria composition changed between samples taken before and after 12 weeks of semaglutide. The study had no probiotic group, so it cannot say whether probiotics change these effects.11 We did not find trials showing that probiotics prevent these changes or reduce the side effects of GLP-1 medications.
Magnesium is involved in over 300 enzymatic reactions. About half of Americans (48%) consumed less than the required amount of magnesium from food in 2005–2006,14 and eating much less on GLP-1 therapy may widen that gap. That figure describes low intake, not measured deficiency. Magnesium oxide is poorly absorbed (about 4% in one study of healthy volunteers), while magnesium chloride, lactate and aspartate were absorbed better;15 glycinate was not tested in that study, and we did not find trials showing it is better absorbed or better tolerated. Magnesium supplements are not suitable for everyone. Data on magnesium supplements in chronic kidney disease are still limited and doses vary widely between studies,16 so ask a clinician before taking magnesium if you have kidney disease, and ask your prescriber or pharmacist whether it could interact with your medicines. The US upper limit for supplemental magnesium in adults is 350 mg/day of elemental magnesium; it was set because of diarrhea, and some researchers argue it should be re-evaluated.17 Check the label for how much elemental magnesium is in one serving, and do not exceed the labelled serving.
Magnesium has been studied for sleep in older adults with insomnia: in three small trials (151 people), the time to fall asleep was about 17 minutes shorter than with placebo, but the evidence was low to very low quality,5 and we found no studies in people taking GLP-1 medications, or on dose timing or muscle recovery. Take magnesium as directed on the product label. Ask a doctor or pharmacist first if you are pregnant or breastfeeding, and do not give magnesium supplements to children without medical advice.
Shop Magnesium Glycinate →Protein distribution may matter, but the evidence is limited. In a small crossover study of 8 healthy adults, spreading protein evenly across three meals gave 25% higher 24-hour muscle protein synthesis than eating most of it at dinner.18 A systematic review of 15 studies in healthy adults found an association between even protein distribution and higher muscle mass in 3 of 7 studies, and the evidence was insufficient for muscle strength or protein turnover.19 Neither looked at lean mass retention during calorie restriction or at people taking GLP-1 medications. Protein targets depend on kidney health and other conditions, so ask a clinician or dietitian.
Creatine has not been tested in people taking GLP-1 medications. A 2026 paper describes creatine as a biologically plausible but hypothesis-generating idea for GLP-1-associated muscle loss and states that no randomized clinical trial has directly evaluated it during GLP-1-based weight loss.20 In a meta-analysis of 26 trials, creatine raised blood creatinine (a marker doctors use to assess kidney function), but kidney filtration measured with a direct method did not change significantly; the authors judged this more likely to reflect altered creatinine metabolism than kidney injury.21 Tell your clinician if you take creatine before kidney blood tests.
Low magnesium intake is common. About half of Americans (48%) consumed less than the required amount of magnesium from food in 2005–2006.14 This figure describes intake from food, not measured deficiency.
References: (1) Mozaffarian D, et al. Am J Clin Nutr. 2025;122(1):344-367. PubMed · DOI (2) He L, et al. JAMA Intern Med. 2022;182(5):513-519. PubMed · DOI (3) Zhou Q, et al. Gut. 2019;68(6):996-1002. PubMed · DOI (4) Ferracioli-Oda E, et al. PLoS One. 2013;8(5):e63773. PubMed · DOI (5) Mah J, et al. BMC Complement Med Ther. 2021;21(1):125. PubMed · DOI (6) Sievenpiper JL, et al. Obes Pillars. 2026;17:100228. PubMed · DOI (7) Zhao JV, et al. J Nutr. 2023;153(10):2939-2950. PubMed · DOI (8) Dumitru CN, et al. Pharmaceuticals (Basel). 2026;19(8):1313. PubMed · DOI (9) Blais JE, et al. Drugs. 2023;83(5):403-427. PubMed · DOI (10) Ma J, et al. Phytomedicine. 2026;162:158782. PubMed · DOI (11) Chen Y, et al. Diabetes Metab Syndr Obes. 2025;18:3865-3881. PubMed · DOI (12) Doron S, et al. Clin Infect Dis. 2015;60 Suppl 2:S129-34. PubMed · DOI (13) Alshatari S, et al. Front Nutr. 2026;13:1895136. PubMed · DOI (14) Rosanoff A, et al. Nutr Rev. 2012;70(3):153-64. PubMed · DOI (15) Firoz M, et al. Magnes Res. 2001;14(4):257-62. PubMed (16) Vermeulen EA, et al. Nutrients. 2023;15(3):547. PubMed · DOI (17) Costello R, et al. Adv Nutr. 2023;14(5):973-982. PubMed · DOI (18) Mamerow MM, et al. J Nutr. 2014;144(6):876-80. PubMed · DOI (19) Jespersen SE, et al. Eur J Nutr. 2021;60(6):3185-3202. PubMed · DOI (20) Ostojic SM, et al. Clin Nutr. 2026;66:106805. PubMed · DOI (21) de Souza Almeida A, et al. Int Urol Nephrol. 2026. PubMed · DOI
This issue is general information, not medical advice, and is not intended to diagnose, treat, cure or prevent any condition. Do not start, stop, reduce or change a prescribed medicine because of anything in this issue; ask your prescriber or pharmacist. Supplements are not suitable for everyone: ask a doctor or pharmacist before use if you take medicines, have kidney disease or diabetes, are pregnant or breastfeeding, or are immunocompromised, and do not give supplements to children without medical advice. Individual responses vary; the studies summarized report population-level findings, not guaranteed individual outcomes.
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