Home Ingredients Bay Leaf (Laurus nobilis)
Metabolic Health

Bay Leaf (Laurus nobilis)

Laurus nobilis
Evidence Level
Limited
4 Clinical Trials
5 Documented Benefits
2/5 Evidence Score

Bay leaf is the dried leaf of sweet bay laurel (Laurus nobilis), a Mediterranean evergreen used as a cooking herb and listed by the FDA among spices generally recognized as safe as a seasoning. It is not the same plant as mountain laurel or cherry laurel, whose leaves can look similar but are poisonous. Interest in bay leaf as a supplement rests mainly on one small 30-day trial in which 40 adults with type 2 diabetes took 1 to 3 g a day of ground leaf in capsules and had lower fasting glucose and cholesterol within the bay leaf groups; no larger trial has followed. A single-meal test in healthy adults found only a short dip in blood sugar, and two 10-day tea studies had no control group. The rest of the research is in cells and animals. Whole leaves used in cooking should be removed before eating, because swallowed leaves have lodged in the throat and gut.

Studied Dose 1, 2 or 3 g a day of ground dried leaf in 500 mg capsules, taken after meals for 30 days (the only capsule trial); cookies containing 6% bay leaf powder by weight in a single-meal test; tea from 5 g of dried leaves in 100 ml of water once daily for 10 days.
Active Compound Dried leaf of Laurus nobilis. It contains an essential oil in which 1,8-cineole is the main component, sesquiterpene lactones such as costunolide, dehydrocostus lactone and zaluzanin D, and phenolic compounds.

Benefits

Fasting blood sugar and blood lipids in a 40-person capsule trial

Forty adults with type 2 diabetes who stayed on their usual tablets took 1, 2 or 3 g a day of ground bay leaf or a corn flour placebo for 30 days, 10 per group. Fasting glucose fell 21 to 26% and LDL cholesterol 32 to 40% within the bay leaf groups, with no significant change on placebo. Higher doses did no better, blinding is not described, and no larger trial has followed.

Supported by Trial 1

Blood glucose after a carbohydrate meal with bay leaf baked in

In a randomized crossover test, 20 healthy adults ate cookies with 50 g of carbohydrate containing 0%, 3% or 6% bay leaf powder. Blood glucose was lower with the 6% cookie at 30 and 45 minutes, but the overall 2-hour glucose response did not differ between cookies. Appetite did not change and no digestive discomfort was reported.

Supported by Trial 2

HDL cholesterol in healthy adults drinking bay leaf tea

Thirty healthy adults aged 20 to 57 drank a tea made from 5 g of dried bay leaves in 100 ml of water once a day for 10 days. HDL cholesterol rose slightly from the start, while LDL cholesterol and triglycerides did not change significantly. There was no control group, so the change cannot be firmly credited to the tea.

Supported by Trial 3, Trial 1

Self-rated stress and blood cortisol in a 10-day tea study

Using the same tea and schedule in 30 healthy adults, the same research group reported lower plasma cortisol and lower scores on standard stress (PSS) and anxiety (STAI) questionnaires after 10 days. With no placebo or control group, expectation and repeat testing could explain much of the change.

Supported by Trial 4

Insulin-like activity of leaf extracts in laboratory tests

In a US Department of Agriculture screen of 49 herbs, spices and medicinal plants, bay leaf extract increased insulin-dependent glucose use in rat fat cells, and the effect disappeared when phenolic compounds were removed. Cinnamon was the most active plant in the same screen. These are cell results and do not show an effect in people.

Supported by Trial 4, Trial 1

Mechanism of action

1

Leaf chemistry: aroma oil and sesquiterpene lactones

The leaf's essential oil is dominated by 1,8-cineole. The leaf also contains sesquiterpene lactones such as costunolide, which in rats reduced the rise in blood alcohol after an alcohol dose without affecting glucose absorption, and which is also a strong skin allergen. Phenolic compounds appear to carry the insulin-like activity seen in cell tests.

2

Insulin signaling in liver cells under high glucose

In human liver cells (HepG2) exposed to high glucose and high insulin, pretreatment with an ethanol extract of the leaf lowered reactive oxygen species and markers of cell death and inflammation, and raised the expression of insulin-signaling genes (IRS1, IRS2, INSR). This is a single cell-culture model, not a clinical outcome.

3

Inflammasome signaling in immune cells

In mouse immune cells, a leaf extract and its main oil component 1,8-cineole suppressed activation of the NLRP3 inflammasome and the release of interleukin-1 beta, and the extract lowered inflammatory cytokines in a mouse lung injury model. These findings have not been tested in people taking bay leaf by mouth.

Clinical trials

1
Ground Bay Leaf Capsules in Adults with Type 2 Diabetes: 30-Day Placebo-Controlled Trial
PubMed

Randomized, placebo-controlled trial of 1, 2 or 3 g a day of ground bay leaf in 500 mg capsules, or corn flour placebo, for 30 days followed by a 10-day washout; blinding is not described, and the placebo group took 2 capsules a day while the 2 g and 3 g groups took 4 and 6. (Khan et al. 2009, J Clin Biochem Nutr)

40 adults aged 40 or older with type 2 diabetes in Peshawar, Pakistan (18 men, 22 women), 10 per group, not on insulin and continuing their sulfonylurea and metformin tablets.

After 30 days, fasting glucose was 21 to 26% lower than at the start in all three bay leaf groups, total cholesterol 20 to 24% lower and LDL cholesterol 32 to 40% lower; HDL rose and triglycerides fell in the 1 g and 2 g groups. The placebo group showed no significant change. There was no dose response from 1 to 3 g, significance was reported within groups, the 3 g group started with higher HDL, and HbA1c was not measured.

2
Bay Leaf Powder Baked into Cookies: Single-Meal Glucose Crossover in Healthy Adults
PubMed

Randomized crossover study comparing plain wheat cookies with cookies containing 3% or 6% bay leaf powder by weight, each providing 50 g of available carbohydrate, eaten at breakfast 1 to 2 weeks apart. (Khan et al. 2017, J Am Coll Nutr)

20 healthy adults.

Blood glucose was significantly lower after the 6% bay leaf cookie than the plain cookie at 30 and 45 minutes, but the incremental area under the 2-hour glucose curve did not differ among the three cookies (p = 0.411). Appetite ratings did not differ, all cookies were rated acceptable, and no digestive discomfort was reported.

3
Daily Bay Leaf Tea and Blood Lipids: 10-Day Uncontrolled Study in Healthy Adults
PubMed

Single-group before-and-after study, with no control group, of a tea made from 5 g of dried bay leaves in 100 ml of boiled water once a day for 10 days. (Chbili et al. 2020, J Am Coll Nutr)

30 healthy Tunisian volunteers aged 20 to 57.

HDL cholesterol rose significantly between day 0 and day 11 (p = 0.01). LDL cholesterol and triglycerides fell slightly, a change the authors describe as not statistically significant. With no control group and only 10 days of use, the HDL change cannot be firmly attributed to the tea; the authors call for larger and longer studies.

4
Daily Bay Leaf Tea, Cortisol and Stress Scores: 10-Day Uncontrolled Study
PubMed

Single-group before-and-after study, with no control group, using the same tea (5 g of dried leaves in 100 ml of boiled water once a day for 10 days). (Chbili et al. 2022, Arch Ital Biol)

30 healthy Tunisian volunteers aged 20 to 57.

Plasma cortisol fell between day 0 and day 11 (p = 0.001), and scores on the PSS stress and STAI anxiety questionnaires also fell (p = 0.006 and p = 0.002). With no placebo or control group, expectation and repeat testing may account for part of these changes; the authors call for larger and longer studies.

Side effects and drug interactions

Common Potential side effects

Whole or broken leaves are a swallowing hazard: case reports describe bay leaves lodged in the throat and esophagus, a leaf blocking the duodenum, and a dried leaf causing upper gut bleeding. Remove whole leaves from food before eating; the capsules used in research contained finely ground leaf.
Liver: a 2026 case report described probable herb-induced liver injury, supported by liver biopsy and a standard causality score, in a 55-year-old woman who drank bay leaf tea twice a day for about three months, an estimated 0.8 to 1.2 g of dried leaf a day, similar to the lowest dose in the capsule trial; she improved after stopping. Stop and see a doctor if you notice yellowing of the skin or eyes, dark urine or unusual fatigue.
Allergy: costunolide in bay leaves is a strong contact allergen, and clinical reports including oral challenges show that eating it can trigger a widespread allergic skin reaction in people already sensitized. People with a known allergy to bay leaf or to sesquiterpene lactones (found in many daisy-family plants) should avoid it.
Mistaken identity: cherry laurel (Prunus laurocerasus) leaves look similar but contain cyanogenic glycosides, and mountain laurel (a Kalmia species) contains grayanotoxins that can cause dizziness, low blood pressure and heart block. Do not use leaves picked from garden shrubs unless the plant is reliably identified as Laurus nobilis.
Participants in the capsule trial (1 to 3 g a day for 30 days) reported no significant side effects, and no digestive discomfort was reported with bay leaf cookies, but these studies were small and short. Supplemental amounts have not been studied in pregnancy or breastfeeding.

Important Drug interactions

Diabetes medicines (metformin, sulfonylureas, insulin): in the capsule trial, fasting glucose fell further while participants stayed on metformin and sulfonylureas, so the effects could add together; monitor blood glucose and talk to your doctor before combining.
Medicines that can strain the liver: given a reported case of liver injury from regular bay leaf tea, use caution and tell your doctor if you take such medicines. No formal drug interaction studies of bay leaf exist.

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Frequently asked questions about Bay Leaf (Laurus nobilis)

Is bay leaf the same as mountain laurel or cherry laurel?

No. Culinary bay leaf comes from sweet bay laurel, Laurus nobilis. Cherry laurel (Prunus laurocerasus) has similar-looking leaves that contain cyanogenic glycosides, and mountain laurel (a Kalmia species) contains grayanotoxins; both are poisonous. Buy bay leaf from a food or supplement source rather than picking leaves from garden shrubs.

Is it safe to swallow a whole bay leaf?

It is best not to. Case reports describe swallowed bay leaves lodged in the throat and esophagus, blocking the duodenum, or causing bleeding in the upper gut. Remove whole leaves before serving. The capsules used in research contained finely ground leaf.

How much bay leaf has been used in studies?

The only capsule trial used 1, 2 or 3 g a day of ground leaf for 30 days, with no extra effect from the higher doses. A single-meal test baked 6% bay leaf powder into cookies, and two short tea studies used 5 g of dried leaves steeped in 100 ml of water daily for 10 days. There is no established supplement dose.

How does bay leaf compare with cinnamon for blood sugar?

They are different plants with very different amounts of research. Cinnamon has been tested in many randomized trials. Bay leaf has one 40-person capsule trial, run by researchers who chose it because it behaved like cinnamon in their lab tests, plus one single-meal cookie study. Findings for one plant do not carry over to the other, and neither replaces medical care.

What is Bay Leaf?

Bay leaf is the dried leaf of sweet bay laurel (Laurus nobilis), a Mediterranean evergreen used as a cooking herb and listed by the FDA among spices generally recognized as safe as a seasoning. It is not the same plant as mountain laurel or cherry laurel, whose leaves can look similar but are poisonous.

What is Bay Leaf used for?

Bay Leaf is researched primarily for Metabolic Health. Forty adults with type 2 diabetes who stayed on their usual tablets took 1, 2 or 3 g a day of ground bay leaf or a corn flour placebo for 30 days, 10 per group.

What is the recommended dosage of Bay Leaf?

The clinically studied dose is 1, 2 or 3 g a day of ground dried leaf in 500 mg capsules, taken after meals for 30 days (the only capsule trial); cookies containing 6% bay leaf powder by weight in a single-meal test; tea from 5 g of dried leaves in 100 ml of water once daily for 10 days. Always follow the product label and check with a healthcare provider for personal advice.

Is Bay Leaf safe, and does it have side effects?

Side effects and cautions reported for Bay Leaf include: Whole or broken leaves are a swallowing hazard: case reports describe bay leaves lodged in the throat and esophagus, a leaf blocking the duodenum, and a dried leaf causing upper gut bleeding. It may also interact with some medications. Bay Leaf is not right for everyone, so check with a healthcare provider first if you are pregnant or breastfeeding, have a medical condition, or take prescription medication.

Does Bay Leaf interact with any medications?

Possible interactions include: Diabetes medicines (metformin, sulfonylureas, insulin): in the capsule trial, fasting glucose fell further while participants stayed on metformin and sulfonylureas, so the effects could add together; monitor blood glucose and talk to your doctor before combining. If you take prescription medication, check with a pharmacist or doctor before using it.

How strong is the scientific evidence for Bay Leaf?

NutraSmarts rates the evidence for Bay Leaf as Limited (2 out of 5). It is backed by 4 clinical trials and 16 cited references summarized on this page. A higher rating reflects more, larger, and better-designed human studies.

References(16 citations)

Evidence ratings on NutraSmarts are based on the totality of human clinical research, with emphasis on randomized controlled trials, meta-analyses, and systematic reviews. The references below directly support claims made throughout this page.

  1. Khan A, Zaman G, Anderson RA. Bay leaves improve glucose and lipid profile of people with type 2 diabetes. J Clin Biochem Nutr. 2009;44(1):52-6. doi: 10.3164/jcbn.08-188.PubMedUsed to support: Randomized trial in 40 adults with type 2 diabetes in Pakistan (10 per group) taking 1, 2 or 3 g a day of ground bay leaf in capsules or a corn flour placebo for 30 days while continuing their usual tablets. Fasting glucose fell 21 to 26%, total cholesterol 20 to 24% and LDL cholesterol 32 to 40% within the bay leaf groups, with no significant change on placebo (the placebo group took 2 corn flour capsules a day; the 2 g and 3 g groups took 4 and 6 bay leaf capsules). No dose response; blinding not described; HbA1c not measured. The authors chose bay leaf because it acted like cinnamon in their earlier lab tests.
  2. Khan I, Shah S, Ahmad J, Abdullah A, Johnson SK. Effect of Incorporating Bay Leaves in Cookies on Postprandial Glycemia, Appetite, Palatability, and Gastrointestinal Well-Being. J Am Coll Nutr. 2017;36(7):514-519. doi: 10.1080/07315724.2017.1326324.PubMedUsed to support: Randomized crossover study in 20 healthy adults: cookies with 6% bay leaf powder lowered blood glucose at 30 and 45 minutes compared with plain cookies, but the 2-hour incremental area under the glucose curve did not differ among cookies. No effect on appetite and no digestive discomfort.
  3. Chbili C, Maoua M, Selmi M, Mrad S, Khairi H, Limem K, Mrizek N, Saguem S, Ben Fredj M. Evaluation of Daily Laurus nobilis Tea Consumption on Lipid Profile Biomarkers in Healthy Volunteers. J Am Coll Nutr. 2020;39(8):733-738. doi: 10.1080/07315724.2020.1727787.PubMedUsed to support: Uncontrolled before-and-after study in 30 healthy Tunisian adults drinking tea from 5 g of dried bay leaves daily for 10 days: HDL cholesterol rose significantly, while LDL cholesterol and triglycerides fell slightly without statistical significance. No control group; the authors call for larger, longer studies.
  4. Chbili C, Maoua M, Zaouali M, Selmi M, Kacem I, Mrizek N, Nouira M, Jihene M, Hedi K, Ben Fredj M. Evaluation of daily Laurus nobilis tea consumption on anxiety and stress biomarkers in healthy volunteers. Arch Ital Biol. 2022;160(3-4):136-146. doi: 10.12871/000398292022343.PubMedUsed to support: Uncontrolled before-and-after study in 30 healthy Tunisian adults drinking the same bay leaf tea daily for 10 days: plasma cortisol and PSS stress and STAI anxiety scores fell from baseline. No placebo or control group.
  5. Broadhurst CL, Polansky MM, Anderson RA. Insulin-like biological activity of culinary and medicinal plant aqueous extracts in vitro. J Agric Food Chem. 2000;48(3):849-52. doi: 10.1021/jf9904517.PubMedUsed to support: Laboratory screen of 49 herb, spice and medicinal plant extracts in rat fat cells: bay leaf extract was among the products that enhanced insulin-dependent glucose use, ranking below cinnamon and several others, and its activity was removed by stripping phenolic compounds. Cell assay only.
  6. Bourebaba N, Kornicka-Garbowska K, Marycz K, Bourebaba L, Kowalczuk A. Laurus nobilis ethanolic extract attenuates hyperglycemia and hyperinsulinemia-induced insulin resistance in HepG2 cell line through the reduction of oxidative stress and improvement of mitochondrial biogenesis - Possible implication in pharmacotherapy. Mitochondrion. 2021;59:190-213. doi: 10.1016/j.mito.2021.06.003.PubMedUsed to support: In human liver cells (HepG2) exposed to high glucose and insulin, a bay leaf ethanol extract reduced reactive oxygen species, apoptosis and inflammatory markers and increased expression of insulin-signaling genes (IRS1, IRS2, INSR). Cell culture only. Two errata to this paper were later published (2022 and 2023).
  7. Lee EH, Shin JH, Kim SS, Lee H, Yang SR, Seo SR. Laurus nobilis leaf extract controls inflammation by suppressing NLRP3 inflammasome activation. J Cell Physiol. 2019;234(5):6854-6864. doi: 10.1002/jcp.27434.PubMedUsed to support: In mouse bone marrow-derived macrophages, bay leaf extract and its major component 1,8-cineole suppressed NLRP3 inflammasome activation and interleukin-1 beta secretion; the extract also lowered proinflammatory cytokines in a mouse acute lung injury model. Cell and animal work only.
  8. Yoshikawa M, Shimoda H, Uemura T, Morikawa T, Kawahara Y, Matsuda H. Alcohol absorption inhibitors from bay leaf (Laurus nobilis): structure-requirements of sesquiterpenes for the activity. Bioorg Med Chem. 2000;8(8):2071-7. doi: 10.1016/s0968-0896(00)00127-9.PubMedUsed to support: Isolated sesquiterpene lactones from bay leaf, including costunolide, dehydrocostus lactone and zaluzanin D, that reduced the rise in blood ethanol in alcohol-loaded rats; costunolide and dehydrocostus lactone did not significantly affect glucose absorption. Animal and chemistry work only.
  9. Malaspina P, Betuzzi F, Ingegneri M, Smeriglio A, Cornara L, Trombetta D. Risk of Poisoning from Garden Plants: Misidentification between Laurel and Cherry Laurel. Toxins (Basel). 2022;14(11):726. doi: 10.3390/toxins14110726.PubMedUsed to support: Laurel (Laurus nobilis) is considered a non-toxic flavoring plant, while cherry laurel (Prunus laurocerasus) has similar-looking leaves that contain toxic cyanogenic glycosides; the paper sets out microscopic and chemical features for telling them apart.
  10. Jansen SA, Kleerekooper I, Hofman ZL, Kappen IF, Stary-Weinzinger A, van der Heyden MA. Grayanotoxin poisoning: 'mad honey disease' and beyond. Cardiovasc Toxicol. 2012;12(3):208-15. doi: 10.1007/s12012-012-9162-2.PubMedUsed to support: Review: many Ericaceae plants, including the Kalmia genus to which mountain laurel belongs, contain grayanotoxins; eating their leaves, flowers or honey can cause dizziness, low blood pressure and atrioventricular heart block.
  11. Soare M, Călugăr-Șolea SF, Brisc C, Rus M, Bodog TM, Becheanu G, Brisc CM, Brisc MC. Herb-Induced Liver Injury by Laurus nobilis: A Case Assessed for Causality Using the Updated RUCAM. Life (Basel). 2026;16(1):180. doi: 10.3390/life16010180.PubMedUsed to support: Case report of a 55-year-old woman who regularly drank bay leaf tea and developed rising liver enzymes; after other causes were excluded and a biopsy pointed to toxic hepatitis, the updated RUCAM scale rated the link as probable herb-induced liver injury. She improved after stopping the tea. The full text estimates her intake at about 0.8 to 1.2 g of dried leaf a day (infusions twice daily for about three months) and cites earlier published bay leaf liver-injury case reports, including a fatal one. A single case.
  12. Tsang TK, Flais MJ, Hsin G. Duodenal obstruction secondary to bay leaf impaction. Ann Intern Med. 1999;130(8):701-2. doi: 10.7326/0003-4819-130-8-199904200-00022.PubMedUsed to support: Case report (letter) of a swallowed bay leaf lodging in and obstructing the duodenum.
  13. Buto SK, Tsang TK, Sielaff GW, Gutstein LL, Meiselman MS. Bay leaf impaction in the esophagus and hypopharynx. Ann Intern Med. 1990;113(1):82-3. doi: 10.7326/0003-4819-113-1-82.PubMedUsed to support: Case report of swallowed bay leaf becoming lodged in the esophagus and the lower throat (hypopharynx).
  14. Skok P. Dried bay leaf: an unusual cause of upper gastrointestinal tract hemorrhage. Endoscopy. 1998;30(3):S40-1. doi: 10.1055/s-2007-1001270.PubMedUsed to support: Case report of a swallowed dried bay leaf causing bleeding in the upper digestive tract.
  15. Paulsen E. Systemic allergic dermatitis caused by sesquiterpene lactones. Contact Dermatitis. 2017;76(1):1-10. doi: 10.1111/cod.12671.PubMedUsed to support: Review: clinical reports and oral challenges show that eating sesquiterpene lactone-containing plants can cause systemic allergic skin reactions in sensitized people, most convincingly for strong contact allergens such as costunolide in bay leaves.
  16. US Food and Drug Administration. 21 CFR 182.10 Spices and other natural seasonings and flavorings. Code of Federal Regulations (eCFR). 2026;Title 21, Part 182, Section 182.10 (accessed 2026)..SourceUsed to support: Not PubMed-indexed. The FDA list of spices and natural seasonings generally recognized as safe for their intended use includes bay (Laurus nobilis L.). This covers use as a food seasoning, not concentrated supplement doses.