Exogenous Ketones
Summary
Ketone drinks raise blood BHB within an hour and lower blood glucose by about 0.5 mmol/L on average, more with esters than salts (grade C). They did not improve exercise performance across 13 trials, and one ester dose cut 20-minute time-trial power in trained cyclists by 2.4%. A 2026 analysis found a small thinking benefit, but several authors sell ketone products.
Key facts
- Beta-hydroxybutyrate taken as a ketone monoester ((R)-3-hydroxybutyl (R)-3-hydroxybutyrate) or as BHB mineral salts[2][3]
- Blood glucose (lower, C); exercise performance (no effect, C); thinking tests (small benefit, C, industry-linked authors); migraine (no effect, D)[2][3][7][10]
- About 0.35 g/kg as a single pre-exercise ester dose; 12 g BHB before each meal for 14 days; 3.75 g of salts twice daily for 90 days[6][8][11]
- FDA had no questions about a GRAS notice for the D-beta-hydroxybutyrate ester in bars, gels and drinks at 0.36 g/kg per serving[1]
- Authors of the 2026 cognition analysis hold equity or jobs at ketone companies (HVMN, BHB Therapeutics, Component Health); adolescent salt-trial authors receive honoraria from Pruvit; the monoester safety study's lead author is a non-executive director of TdeltaS (the ester's GRAS notifier) and the study was DARPA-funded[7][11][4][1]
- 7 graded human outcomes on this page
- October 10, 2026
How it works
EstablishedBHB is a fuel the body normally makes during fasting. Drinking it raises blood ketones directly, and in athletes this shifted muscle fuel use away from glucose and lowered lactate. In type 2 diabetes, a ketone ester appeared to slow glucose absorption after meals.[2][12][9]
What the human research says
Human trials only, one row per outcome. The form column shows what each trial actually tested. Grades follow our evidence-grading policy.
At a glance: strongest evidence per outcome
| Outcome | Grade | Effect | Strongest evidence | Rows |
|---|---|---|---|---|
| Cognition | Grade C | Improved | Meta-analysis of 29 trials · n = 1,117 · 2026 | 1 row |
| Blood glucose | Grade C | Improved | Meta-analysis of 43 trials · n = 586 · 2022 | 3 rows |
| Migraine | Grade D | No effect | Crossover RCT · n = 41 · 2022 | 1 row |
| Exercise | Grade D | Worsened | Crossover RCT · n = 23 · 2023 | 1 row |
| Safety | Grade D | No effect | RCT · n = 22 · 2021 | 1 row |
Every graded row
| Outcome | Effect | Grade | Best evidence | PMID |
|---|---|---|---|---|
| Thinking and memory test scores | Improved | Grade C | Meta-analysis · n = 1,117 · 2026 29 protocols in healthy adults and people with Alzheimer's disease or cognitive impairment Form: Ketone esters, salts and ketogenic MCT oils · Dose: Varied; higher daily doses linked to larger effects · Duration: Single dose to several months Exogenous ketones were associated with a small improvement in cognitive performance versus placebo (standardized mean difference 0.29), with no clear difference by product type or population. | 42063954 (opens PubMed)Source [7] |
| Blood glucose after a ketone drink | Improved | Grade C | Meta-analysis · n = 586 · 2022 43 trials in healthy people, athletes and people with metabolic conditions Form: Ketone monoesters or ketone salts · Dose: Varied; mostly single doses · Duration: Mostly single doses Compared with placebo, ketone drinks raised blood BHB by about 2 mmol/L and lowered blood glucose by 0.47 mmol/L; effects were larger with monoesters than salts. Evidence on longer use was limited. | 35380602 (opens PubMed)Source [2] |
| Migraine days | No effect | Grade D | Crossover RCT · n = 41 · 2022 Adults with episodic migraine Form: DL-beta-hydroxybutyrate · Dose: Dose not stated in the abstract · Duration: 12 weeks per treatment period No clinically significant change in migraine days or intensity versus placebo. | 34541914 (opens PubMed)Source [10] |
| 20-minute cycling time-trial power | Worsened | Grade D | Crossover RCT · n = 23 · 2023 Trained cyclists Form: Ketone monoester ((R)-3-hydroxybutyl (R)-3-hydroxybutyrate) · Dose: 0.35 g/kg body weight, 30 minutes before exercise · Duration: Single dose Mean power was 2.4% lower after the ketone ester than after placebo (255 vs 261 W). | 37185454 (opens PubMed)Source [6] |
| Safety markers in adolescents | No effect | Grade D | RCT · n = 22 · 2021 Healthy adolescents Form: BHB salts · Dose: 3.75 g twice daily · Duration: 90 days No differences from placebo in fasting blood safety tests, bone density, blood pressure, happiness or emotional intelligence scores. | 33807731 (opens PubMed)Source [11] |
| Glucose control and blood vessel function | Improved | Grade D | Crossover RCT · n = 14 · 2021 Adults with obesity (mean age 56) Form: Ketone monoester drink · Dose: 12 g BHB 15 minutes before each meal · Duration: 14 days Average 24-hour glucose fell 7.8% and after-meal glucose 8.0% versus placebo; brachial artery flow-mediated dilation rose from 6.2% to 8.9%. The drink was well tolerated. | 33367782 (opens PubMed)Source [8] |
| Blood glucose after a meal in type 2 diabetes | Improved | Grade D | Crossover RCT · n = 10 · 2024 Adults with type 2 diabetes (mean HbA1c 7.1%) Form: Ketone monoester drink before a meal · Dose: Dose not stated in the abstract · Duration: Single dose Glucose was about 18% lower 2 hours and 12% lower 4 hours after the meal, mainly because glucose entered the blood more slowly; insulin did not differ, and no adverse effects were seen. | 38483543 (opens PubMed)Source [9] |
Forms
| Form | Elemental % | Absorption (human data) | GI tolerance | Studied for |
|---|---|---|---|---|
| Ketone monoester ((R)-3-hydroxybutyl (R)-3-hydroxybutyrate) | Varies[4][1] | Single doses raised blood BHB to 3.3 mmol/L within 1–2 hours at 714 mg/kg; BHB half-life was 0.8–3.1 hours.[4] | Generally well tolerated; some stomach and gut effects at the highest dose taken in large milk-based drinks.[4] | Glucose, exercise and safety studies |
| BHB mineral salts (sodium, calcium, magnesium or potassium BHB) | Varies[2][11] | Raise blood BHB less than monoesters.[2] | No safety-marker changes over 90 days in adolescents at 7.5 g/day.[11] | Exercise, migraine and safety trials |
| Ketogenic MCT oils (precursors, not BHB itself) | Varies[7] | The liver converts them to ketones; no blood-level figures in our sources.[7] | No tolerance data in our sources.[7] | Included with ketone esters and salts in the cognition analysis |
Studied doses
Doses studied in human trials ranged from 7.5 g/day of BHB salts for 90 days in adolescents to 12 g of BHB before each of three daily meals for 14 days, and single pre-exercise ester doses of about 0.35 g/kg. A 5-day safety study tested up to 2.14 g/kg/day of the monoester.[11][8][6][4]
Interactions
Published interactions only: each row cites a source. No row means none was found in our sources, not that a combination is safe.
Who should be careful
- People on glucose-lowering drugs
- Ketone drinks lower blood glucose, more with esters, so people on diabetes medicines should check with a clinician.[2][9]
- Endurance athletes before key efforts
- Ketone esters did not improve performance across 13 trials, and one dose lowered 20-minute cycling power by 2.4%.[3][6]
- Pregnancy and breastfeeding
- The trials cited here did not include pregnant or breastfeeding people.[2]
Talk to your pharmacist or clinician before starting a supplement, especially if you take prescription medicines.
Safety
Ketone drinks were generally well tolerated in short studies; most data cover single doses or days to weeks.
- Gut effects
- Some stomach and gut effects were reported at the highest monoester dose in large volumes of milk-based drink.[4]
- Longer use
- A pooled analysis found limited evidence on prolonged ketone supplementation; the longest trial cited here lasted 90 days.[2][11]
- Performance
- Ketone esters can lower short time-trial power in trained cyclists.[6]
How to read the label
- Ester vs saltMonoesters raise blood BHB and lower glucose more than salts; labels should name which form is used.[2]
- Label dose vs clinical doseTrials used about 0.35 g/kg of ester before exercise or 12 g of BHB per meal; many products contain less.[6][8]
- MCT is not BHBKetogenic MCT oils are ketone precursors and were pooled with true ketones in the cognition analysis.[7]
Cost per studied dose, without the sales pitch
Compare any product you already have by the amount it delivers, not by capsule count or front-of-pack weight.
Cost per studied dose
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Frequently asked questions
Do exogenous ketones put you in ketosis?
They raise blood BHB within 1–2 hours, to about 3.3 mmol/L at high ester doses, without a ketogenic diet.[4][2]
Do ketone drinks improve exercise performance?
No clear effect across 13 trials, and one ester dose lowered 20-minute cycling power by 2.4%.[3][6]
Do exogenous ketones lower blood sugar?
Yes, acutely: by about 0.5 mmol/L on average, with larger drops from esters than salts.[2]
Do ketones help memory or focus?
A 2026 analysis found a small improvement in test scores, but several authors have financial ties to ketone products.[7]
Sources
- [1]GRAS Notice GRN No. 515: D-beta-hydroxybutyrate ester (notifier TdeltaS Limited; FDA has no questions, closed March 5, 2015). U.S. Food and Drug Administration, GRAS Notice Inventory, 2015. database
- [2]Effects of Exogenous Ketone Supplementation on Blood Glucose: A Systematic Review and Meta-analysis.. Adv Nutr, 2022. meta-analysis
- [3]Acute Ketone Supplementation and Exercise Performance: A Systematic Review and Meta-Analysis of Randomized Controlled Trials.. Int J Sports Physiol Perform, 2020. meta-analysis
- [4]Kinetics, safety and tolerability of (R)-3-hydroxybutyl (R)-3-hydroxybutyrate in healthy adult subjects.. Regul Toxicol Pharmacol, 2012. PK-study
- [5]Effects of ketone supplements on blood β-hydroxybutyrate, glucose and insulin: A systematic review and three-level meta-analysis.. Complement Ther Clin Pract, 2023. meta-analysis
- [6]Acute Ketone Monoester Supplementation Impairs 20-min Time-Trial Performance in Trained Cyclists: A Randomized, Crossover Trial.. Int J Sport Nutr Exerc Metab, 2023. crossover-RCT
- [7]The effect of exogenous ketone bodies on cognition across health and disease: a systematic review and meta-analysis.. Front Nutr, 2026. meta-analysis
- [8]14-Day Ketone Supplementation Lowers Glucose and Improves Vascular Function in Obesity: A Randomized Crossover Trial.. J Clin Endocrinol Metab, 2021. crossover-RCT
- [9]A ketone monoester drink reduces postprandial blood glucose concentrations in adults with type 2 diabetes: a randomised controlled trial.. Diabetologia, 2024. crossover-RCT
- [10]Efficacy and safety of exogenous beta-hydroxybutyrate for preventive treatment in episodic migraine: A single-centred, randomised, placebo-controlled, double-blind crossover trial.. Cephalalgia, 2022. crossover-RCT
- [11]The Effect of Exogenous Beta-Hydroxybutyrate Salt Supplementation on Metrics of Safety and Health in Adolescents.. Nutrients, 2021. RCT
- [12]Nutritional Ketosis Alters Fuel Preference and Thereby Endurance Performance in Athletes.. Cell Metab, 2016. RCT
What changed
- First draft. Every PMID checked against NCBI E-utilities esummary (title and year taken from the record) and abstracts read for the cited rows.
- Adversarial review pass: every evidence row re-read against its PubMed abstract. Official sources: FDA GRAS Notice Inventory GRN 515 record (opened 2026-10-10); no NIH ODS, NCCIH or EFSA monograph covers exogenous ketones. Industry ties: cognition meta-analysis authors with HVMN, BHB Therapeutics and Component Health interests (PMC13127162); adolescent BHB-salt trial authors paid by Pruvit; GRAS notifier TdeltaS; the 2012 monoester safety study was DARPA-funded and its lead author is a TdeltaS non-executive director (PMC3810007). The 2020 exercise meta-analysis gives no participant total, so it is cited in key facts, insights and FAQ, not as an evidence row. Retraction, expression-of-concern, erratum and withdrawn checks on all 11 PMIDs: none flagged. Page set indexable. Independent browser review (4 parallel reviewers, every evidence row checked against its abstract and official sources on the Vercel preview) found issues that were fixed: evidence direction now follows the site convention (up = improved, down = worsened), plus wording and disclosure corrections listed in the batch-14 PR review comment.