We use essential cookies (authentication, your saved goals/stack) by default. With your permission we’ll also enable privacy-respecting analytics (Vercel Web Analytics, anonymous load-time metrics) and error-replay diagnostics (Sentry — DOM snapshots only when an error fires) so we can fix bugs faster. Learn more about cookies
Glycerol (Glycerin)
Hyperhydrating agent that pulls extra fluid into tissue before competition — improves endurance and thermoregulation in heat.
What the evidence says
Glycerol doesn't have enough studies with structured effect-size data yet to pool a verdict. Browse the studies below for individual findings.
Most evidence is from high-quality meta-analyses and randomised trials published 1972–2026.
Based on 76 studies · 10 meta-analyses · 60 RCTs
Confidence
High confidenceWhat the studies found
By outcome
Meta-analyses show a small-to-moderate hyperhydration benefit for endurance and thermoregulation in heat, but direct glycerol trials are few and small, capping confidence at moderate.
63 randomised trials
every one checked individually
Every randomised or controlled trial of Glycerol indexed in PubMed, not a hand-picked subset. Meta-analyses and systematic reviews are deliberately excluded from this count: most of them cover many compounds at once, so counting them would inflate it.
PubMed · as of Jul 2026
44 trials ongoing or recruiting · 159 completed on ClinicalTrials.gov
43 of the completed trials have posted results
Registered trials show research momentum for Glycerol, not proof of effect — a registration is a plan, and posted results are sponsor-reported, not peer-reviewed. They are never counted toward the evidence rating above.
Browse these trials on ClinicalTrials.govClinicalTrials.gov · as of Oct 2026
Under EU law (Reg. 1924/2006), EFSA reviews whether a specific health claim for Glycerol meets the evidence standard. These are independent regulatory decisions on claims — not studies, and never counted toward the evidence score above.
Not authorised by EFSA
“Glycerol Soothing for mouth and throat. Reliefs in case of tickle in the throat and pharynx. Soothing and pleasant effect on throat, pharynx and vocal cords”
“Not authorised” means the specific claim wording did not meet the EU’s evidence standard — often a matter of dossier or phrasing, not proof of no effect. EFSA judges marketing claims and is kept separate from our study-based evidence score.
Source: EU Register of nutrition and health claims (European Commission / EFSA) · register snapshot Feb 2013
Glycerol is a naturally occurring compound that attracts and retains water in the body. When consumed before exercise, it creates a state of hyperhydration, allowing athletes to carry extra fluid into competition.
This is particularly beneficial for endurance events in hot conditions, where dehydration and overheating limit performance. Glycerol has been shown to improve endurance, delay fatigue, and enhance thermoregulation.
Increases total body water above normal levels
Better heat dissipation during exercise
More blood volume for cardiovascular function
How Glycerol 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.
Not recommended: maternal and infant safety of hyperhydration loading have not been reviewed, and it has no purpose in pregnancy or breastfeeding. A lack of data is not proof of harm. Glycerol in ordinary food or skincare is not covered by this.
Primary target population; practice before competition
Opposing effects on fluid balance — may affect electrolyte balance or enhance fluid loss
May affect blood sugar; monitor levels
Tip: Expected; should resolve as exercise begins
Tip: Ensure adequate electrolytes
Tip: Reduce dose; practice protocol in training
Tip: Practice in training; adjust dose
Glycerol has an evidence score of 5.8/10 — moderate evidence based on 77 indexed studies, including 3 meta-analyses. Hyperhydrating agent that pulls extra fluid into tissue before competition — improves endurance and thermoregulation in heat. Representative study: PMID 38198662.
The commonly studied dose of Glycerol is 1-1.5g per kg body weight (the cited trials used up to 1 g per kg). Individual needs vary — start at the lower end of the range and adjust based on how you respond.
Timing is flexible for Glycerol — consistent daily use matters more than the time of day. Glycerol is used primarily as a hyperhydrating agent before exercise or heat exposure.
Glycerol is generally well-tolerated and considered safe for most healthy adults at recommended doses. The most commonly reported side effects are bloating, headache, nausea. Use caution if any of these apply to you: Kidney disease; Diabetes (may affect blood sugar); Heart failure (fluid retention).
Caffeine
Probably helpsBlocks adenosine receptors to boost alertness, reaction time, and endurance — an umbrella review of 21 meta-analyses found it ergogenic for endurance, strength and power.
CoQ10
Likely helpsA lipid-soluble antioxidant central to mitochondrial energy production, with the strongest trial support for fertility/IVF outcomes and heart failure.
Sodium Bicarbonate
Likely helpsErgogenic aid that buffers metabolic acid. An umbrella review of meta-analyses found it improves peak anaerobic power and efforts lasting about 45 seconds to 8 minutes, on moderate to low quality evidence.
Tart Cherry
Likely helpsNatural melatonin and anthocyanin source with modest, fairly consistent small-RCT support for post-exercise recovery and sleep quality. Uric acid dropped only transiently in one trial, and did not fall after a purine-rich meal or beyond standard therapy in gout. Effects are real but small and not seen in every trial.
Explore: Best supplements for Athletic Performance
Reviewed by Dr. Baher Al Hakim · Last reviewed May 2026 · evidence from 76 studies · how we score · editorial policy
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.
Tap node to isolate • Pinch to zoom • Tap edge for research