Small studies, mostly from Southeast Asia, suggest that drinking bay leaf tea or taking bay leaf extract can modestly lower blood pressure in people with hypertension. But there is an important catch that most online advice skips over: the “bay leaf” tested in nearly every promising blood pressure study is a completely different plant from the one sitting in your spice rack. Understanding that distinction changes the practical answer considerably.
Two Plants, One Common Name
The European bay leaf, Laurus nobilis, is the stiff, aromatic leaf used in soups, stews, and sauces across Western kitchens. The Indonesian bay leaf, called daun salam (Syzygium polyanthum), is a staple of Southeast Asian cooking and traditional herbal medicine. Both get called “bay leaf” in English, but they belong to entirely different botanical families and have different chemical makeups. This matters because nearly every human study reporting a drop in blood pressure after drinking bay leaf tea or taking a bay leaf extract used the Indonesian variety, Syzygium polyanthum. If you are tossing a European bay leaf into your pot roast and hoping it will lower your numbers, the research behind those claims was done on a different plant.
Laurus nobilis does contain a range of bioactive compounds, including flavonoids like quercetin, kaempferol, and catechin, as well as phenolic acids such as caffeic and ferulic acid, essential oils like cineole and eugenol, and various alkaloids.1International Journal of Secondary Metabolite. The botanical study, phytochemical composition, and biological activities of Laurus nobilis L. leaves: A review Many of these compounds have antioxidant activity and some have shown effects on blood vessels in lab settings.2PubMed Central. Isolation of Laurus nobilis Leaf Polyphenols: A Review on Current Techniques and Future Perspectives But having bioactive compounds in a leaf is not the same as proving that eating the leaf lowers blood pressure in a human being. For Laurus nobilis specifically, the human blood pressure evidence barely exists.
What the Blood Pressure Studies Actually Found
The most cited studies involve Indonesian bay leaf, typically prepared as a decoction (leaves boiled in water, essentially a strong tea). In one study of hypertensive patients, drinking Syzygium polyanthum decoction brought the average systolic reading down from about 154 mmHg to roughly 138 mmHg, and diastolic from about 94 to 84 mmHg, both statistically significant changes.3Journal of Health and Nutrition Research. The Effect of Bay Leaf (Syzygium polyanthum) Decoction on Lowering Blood Pressure in Hypertensive Patients Another study found an average systolic drop of 12 mmHg and a diastolic drop of 8 mmHg after two weeks of daily consumption in women using injectable birth control.4Jurnal Ilmiah Kesehatan Sandi Husada. Decoction of bay leaf (Syzygium polyanthum) against the reduction of high blood pressure in 3-month injectable birth control receptors
A community health program in Indonesia tracked members of a chronic disease management group (called Prolanis) before and after adding boiled bay leaves to their routine. The proportion of members with hypertension fell by about 30 percentage points, from roughly 77% down to 47%.5FICE (F Educator and Innovator in Community Service / ijahst.org). Efforts to Control Blood Pressure for Prolanis Hypertension Members through the Utilization of Bay Leaf Decoction A separate study in elderly hypertensive patients also found a statistically significant reduction in blood pressure after using an Indonesian bay leaf solution.6Jurnal Ilmiah Kesehatan (JIKA). The Differences in The Effectiveness of Indonesian Bay Leaves and Cucumbers in Elderly with Hypertension
These results are encouraging at face value, but they all share serious limitations. The sample sizes are small. Most lack a placebo control group, so it is hard to separate the bay leaf’s effect from the placebo effect, natural blood pressure fluctuation, or other lifestyle changes participants made during the study period. None are double-blinded randomized controlled trials, which is the gold standard for this kind of question. A comprehensive review of herbal interventions for hypertension identified bay leaves as one of the more frequently studied plants, alongside celery and black garlic, but acknowledged that the overall evidence base remains preliminary.7Huma Barigas: Journal of Medical and Health Sciences. Herbal Therapy for Hypertension: A Comprehensive Analysis of Effectiveness and the Identification of Promising Plants Based on Scientific Evidence
How Bay Leaf Might Affect Blood Pressure
The leading proposed mechanism involves nitric oxide, a molecule your body uses to relax blood vessel walls. When blood vessels relax, they widen, and blood pressure drops. A study of patients with abnormal cholesterol levels found that taking 600 mg of Syzygium polyanthum extract daily for 30 days significantly increased nitric oxide levels compared to a 400 mg dose. The higher-dose group saw a greater rise in nitric oxide, and the difference between the two groups was statistically significant.8International Journal of Research Science and Management. COMPARISON BAY LEAF (SYZYGIUM POLYANTHUM (WIGHT) WALP) EXTRACT WITH 400 MG AND 600MG DOSE ON NITRIT OXIDE CONCENTRATION IN DYSLIPIDEMIC PATIENTS If bay leaf extract genuinely boosts nitric oxide production, that would be a plausible pathway to lower blood pressure.
The flavonoids and other phenolic compounds in both species of bay leaf are also part of the picture. These compounds act as antioxidants, which can protect blood vessel linings from damage caused by oxidative stress. Over time, oxidative damage to blood vessel walls contributes to stiffness and higher blood pressure. Laurus nobilis extracts have shown strong antioxidant activity in lab tests, with high concentrations of total phenolics and flavonoids.9Journal of Food Composition and Analysis. Lebanese bay leaves (Laurus nobilis): A unique chemotypic and pharmacological profile with culinary and medicinal potential Quercetin and kaempferol, both found in bay leaves, have independently been studied for their potential to relax blood vessels and reduce inflammation. But lab-dish antioxidant activity does not automatically translate into a meaningful effect inside the human body.
Traditional medicine systems also valued bay leaf as a diuretic, meaning it was believed to promote urine production and help the body shed excess fluid.10Medicinal Plants of South Asia. Chapter 5 – Bay Leaf If this effect is real, reducing fluid volume would be another way blood pressure could drop, similar to how prescription diuretics work. However, controlled studies confirming a meaningful diuretic effect in humans are lacking.
The Bioavailability Problem
Even if bay leaf compounds can relax blood vessels in a lab setting, the question is whether enough of those compounds actually reach your bloodstream when you eat or drink bay leaf. The answer, based on what we know right now, is not reassuring. A review of the literature found essentially no human studies examining the bioavailability of bay leaf constituents after ingestion. Animal studies of 1,8-cineole, a major component of bay leaf essential oil, showed that it is rapidly absorbed but has low bioavailability overall. In rats, the compound was quickly metabolized after an oral dose, and the resulting blood concentrations were measured in picograms per milliliter, which are extremely small amounts.11Nutrition Today. Bay Leaf: Potential Health Benefits
This is a gap that makes it hard to bridge the distance between “this compound relaxes blood vessels in a test tube” and “drinking this tea lowers your blood pressure.” There is also a dose question. Most of the studies showing blood pressure reductions used concentrated decoctions or capsulized extracts at specific doses, not the single leaf tossed into a pot of soup. The amount of bioactive material you get from a leaf simmering in stew for 30 minutes is likely far smaller than what participants received in clinical studies.
What About European Bay Leaf Specifically?
If your interest is in Laurus nobilis because that is what you have in your kitchen, the direct blood pressure evidence is thin to the point of being nearly absent. One study gave healthy volunteers a tea made from 5 grams of Laurus nobilis powder in 100 mL of boiled water daily for 10 days and measured metabolic markers before and after. It found no significant changes in fasting blood glucose, LDL cholesterol, total cholesterol, or triglycerides.11Nutrition Today. Bay Leaf: Potential Health Benefits Blood pressure was not a primary outcome in that study, but the absence of metabolic changes in healthy people after 10 days is worth noting. It suggests that at typical culinary or near-culinary doses, European bay leaf may not produce dramatic physiological shifts.
That does not mean Laurus nobilis is biologically inert. Its phenolic compounds and essential oils do show activity in laboratory experiments. It just means that human evidence for a blood pressure effect from the European species has not been established. Lumping the two species together, which happens constantly in online health articles and social media posts, creates a misleading impression of how strong the evidence really is for the bay leaf you are likely to use.
Bay Leaf and Blood Pressure Medications
If you are already taking medication for high blood pressure and you are thinking about adding bay leaf tea to your routine, there is a potentially serious interaction worth knowing about. A pharmacokinetic study in rats found that bay leaf infusion dramatically changed how the body handled captopril, one of the most widely prescribed blood pressure drugs. The peak concentration of captopril in the blood rose, the half-life of the drug nearly quintupled (from about 3.3 hours to over 16 hours), and the total drug exposure roughly doubled.12Jurnal Pharmascience. Pharmacokinetic Interaction Between Bay Leaf Infusion and Captopril in Rats In practical terms, that means the drug stayed in the body much longer and at higher levels than it was supposed to. If something similar happens in humans, combining bay leaf tea with captopril could amplify the drug’s effect and potentially cause blood pressure to drop too low.
A separate study looked at hypertensive patients taking amlodipine (another common blood pressure medication) who also used herbal remedies including bay leaves, celery, and cucumber. The combination group showed a slightly higher clinical effectiveness rate than the amlodipine-only group, about 78% versus 69%, but the difference was not statistically significant.13Jurnal Riset Kesehatan Poltekkes Depkes Bandung. EFFECTIVENESS OF AMLODIPINE WITH CONCOMITANT HERBAL THERAPY (BAY LEAVES, CELERY, CUCUMBER) IN HYPERTENSIVE PATIENTS IN SURAKARTA That study mixed multiple herbs together, so it is impossible to attribute any effect to bay leaf alone. Still, the captopril interaction data from the rat study is a caution flag. If you take blood pressure medication, talk to your doctor before regularly drinking bay leaf tea in medicinal quantities.
Culinary Amounts Versus Therapeutic Doses
There is a wide gap between how bay leaf is used in cooking and how it was used in the studies showing blood pressure effects. A typical recipe calls for one or two dried leaves, which simmer in liquid and are removed before serving. You are not eating the leaf, and only a fraction of its compounds leach into the broth. The studies, by contrast, used preparations like boiling seven or more fresh leaves in water and drinking the resulting tea, or taking capsules containing hundreds of milligrams of concentrated extract daily for weeks.
This distinction is relevant because the dose-response relationship matters. The nitric oxide study, for example, found a significant effect at 600 mg of extract per day but not at 400 mg.8International Journal of Research Science and Management. COMPARISON BAY LEAF (SYZYGIUM POLYANTHUM (WIGHT) WALP) EXTRACT WITH 400 MG AND 600MG DOSE ON NITRIT OXIDE CONCENTRATION IN DYSLIPIDEMIC PATIENTS If the threshold for a measurable biological effect sits around several hundred milligrams of concentrated extract, the amount you get from a leaf in your soup is almost certainly too small to make a difference. Treating your dinner seasoning as a blood pressure treatment would be like expecting a splash of red wine to deliver the dose of resveratrol used in lab studies.
Safety at Higher Doses
Most people tolerate culinary amounts of bay leaf without any problems. But when the conversation shifts to drinking concentrated decoctions daily or taking extract capsules, the safety profile becomes less clear. There is a published case report of liver injury linked to Laurus nobilis consumption at higher-than-normal amounts.14DergiPark (Journal of Emergency Medicine Case Reports). Hepatotoxicity caused by bay leaf (Laurus nobilis): A case report A single case report does not prove that bay leaf commonly causes liver problems, but it does signal that treating it as completely harmless at any dose would be a mistake.
Bay leaf also contains eugenol and other essential oil components that can irritate the digestive tract in large amounts. Whole dried leaves are a well-known choking and bowel obstruction hazard if accidentally swallowed, which is why recipes always specify removing them. And as the captopril study showed, there is a real possibility of interactions with prescription drugs. The traditional use of bay leaf in many cultures has generally involved modest amounts over short periods, not the high-dose, long-term supplementation that would be needed to produce a reliable blood pressure effect.
Where This Leaves Practical Decisions
If you enjoy cooking with bay leaf, there is no reason to stop, and no reason to expect it is doing your blood pressure any particular good or harm. If you are searching for a natural approach to blood pressure management, the honest summary is that Indonesian bay leaf (Syzygium polyanthum) has shown some promising signals in small, methodologically limited studies. European bay leaf (Laurus nobilis), the one most readers have access to, has essentially no direct human evidence for blood pressure reduction. Neither species has been tested in the kind of rigorous, large-scale trials that would justify recommending it as a treatment or even a reliable complement to standard care.
The broader pattern here is familiar in herbal medicine research: a plant with genuine bioactive compounds, a plausible mechanism, some encouraging preliminary results, but a long road still ahead before anyone can confidently say it works. Blood pressure is too consequential a health marker to manage with unproven remedies alone. Lifestyle changes with strong evidence behind them, like reducing sodium intake, exercising regularly, maintaining a healthy weight, and limiting alcohol, remain the foundation. If those are not enough, medication with decades of clinical trial support is the next step. Bay leaf tea can be part of your day if you enjoy it, but it should not replace anything your doctor has prescribed.