Leek (Allium porrum): Benefits, Dosage, Safety & Evidence

Frequently asked questions

How does leek work as a medicinal herb?

Leek contains bioactive compounds including allicin, quercetin, kaempferol, and phthalides that contribute to its therapeutic effects. Allicin provides mild antimicrobial properties, while flavonoids like quercetin and kaempferol offer anti-inflammatory and antioxidant benefits. The phthalides may support cardiovascular health, and the high fiber content promotes digestive function. These compounds work synergistically to support respiratory and digestive health (Evidence Level C, Traditional use).

Can leeks interact with blood thinning medications?

Yes, leeks may interact with blood-thinning medications due to their vitamin K content and mild blood-thinning properties from allicin. Consuming large amounts of leeks could potentially affect blood clotting when taking anticoagulants like warfarin. While moderate consumption as food is generally acceptable, individuals on blood thinners should maintain consistent intake and consult their healthcare provider before significantly increasing leek consumption (Evidence Level C, theoretical interaction).

How much leek should I eat for health benefits?

For medicinal purposes, 100-200 grams of cooked leeks daily is traditionally recommended, equivalent to approximately 1-2 medium leeks. This amount can be incorporated into soups, stews, or consumed as a cooked vegetable. Leeks are primarily used as a food-medicine, so therapeutic doses align with normal culinary portions. Start with smaller amounts if not accustomed to high-fiber foods (Evidence Level C, Traditional use).

Is leek safe to eat during pregnancy?

Yes, leeks are considered safe to consume during pregnancy when eaten in normal food amounts. They provide beneficial nutrients including folate, fiber, and antioxidants that support maternal health. Leeks have a long history of use as a food and mild medicine without documented pregnancy-specific concerns. However, ensure thorough washing and proper cooking to avoid foodborne illness, and consult your healthcare provider for personalized advice (Evidence Level C, Traditional use).

What are the medicinal uses of leeks?

Leeks have been used traditionally for respiratory and digestive conditions since ancient Egyptian and Roman times. They may help thin and clear respiratory mucus, support healthy digestion through their fiber content, and provide anti-inflammatory benefits. Medieval European herbalists valued leeks as both food and medicine. Modern use focuses on respiratory support and digestive health, though clinical evidence remains limited (Evidence Level C, Traditional use).

Can leeks cause digestive problems?

Leeks contain FODMAPs (fermentable carbohydrates) that may cause digestive upset in sensitive individuals, particularly those with irritable bowel syndrome (IBS). Symptoms can include bloating, gas, and abdominal discomfort. If you have IBS or follow a low-FODMAP diet, consume leeks in small portions or avoid them. Most people tolerate leeks well when cooked thoroughly, which can improve digestibility (Evidence Level C, Traditional use).

PubMed-compiled information sheet

This sheet was compiled from PubMed (NIH) abstracts using AI assistance. Every factual claim is cited to a real PubMed article (see the source list). It has not yet been human-reviewed — confirm with a healthcare provider before use.

Compiled from 29 PubMed articles · model: gemma4:31b

Summary

Leek (Allium porrum) is a widely consumed vegetable and traditional medicinal herb known for its antioxidant, antibacterial, and anti-inflammatory properties [PMID:34420186, 37685158].

Background

Leek (Allium porrum), also referred to as Allium ampeloprasum var. porrum, is a non-bulb forming biennial species of the Liliaceae/Amaryllidaceae family grown for its pseudostem and leaves [PMID:38985927, 34270029]. It is an economically important crop used globally as a vegetable, food seasoning, and medicinal herb [PMID:34270029].

Traditional uses

Leek roots have a long history of medicinal applications and use as an edible food in China [PMID:37538865]. In Asia, leeks are used as traditional medicine to treat a variety of diseases [PMID:37685158].

Active compounds

Leeks contain organosulfur compounds (such as diallyl disulfide), flavonoids (specifically kaempferol derivatives), phenolic compounds, saponins, dietary fiber, steroid compounds, and inulin [PMID:11394858, 25036570, 34420186, 37685158]. They also have the ability to accumulate selenium from soil, biotransforming it into organo-selenium species like MeSeCys and SeMet [PMID:16480995, 34818737].

Mechanism of action

Chinese leek-derived extracellular vesicles (CL-EVs) may ameliorate sarcopenia by regulating mitochondrial biogenesis and autophagy via AMPK and maintaining myosin homeostasis [PMID:41261435]. Methanolic leek extract has been shown to decrease effector cell degranulation and prevent alterations in mRNA levels of NF-κB, c-Jun, and glutathione-S-transferase (GST) in airway epithelial cells [PMID:31181780].

Clinical evidence

Evidence DSarcopenia

Chinese leek-derived extracellular vesicles (CL-EVs) demonstrated dose-dependent restoration of myotube diameter and alleviated mitochondrial impairment in a dexamethasone-induced C2C12 myotube atrophy model [PMID:41261435].

Evidence DBacterial Infections

Aqueous extracts of A. porrum showed antibacterial activity against Staphylococcus aureus and Pseudomonas aeruginosa [PMID:37007285]. Leek leaf oil extract also demonstrated antibacterial activity with a minimum inhibitory concentration (MIC) of 0.20 μg/ml [PMID:35514610].

Evidence DLiver and Kidney Toxicity

Alcoholic extract of A. porrum leaves mitigated acute liver failure and nephrotoxicity induced by thioacetamide in male rats [PMID:32226246].

Evidence DInflammation/Allergy

Methanolic leek extract decreased the degranulation of human mast cells (LAD2) and humanized rat basophiles (RBL-2H3) [PMID:31181780].

Safety & adverse effects

Allium group plants contain active thiol groups that are suggested to potentially contribute to the induction of pemphigus [PMID:7873815]. Occupational rhinitis has been reported in relation to leek [PMID:15575950].

Evidence summary

The current evidence is primarily based on in vitro studies, animal models, and reviews; there is a lack of high-level clinical trial data (RCTs or meta-analyses) in humans.

PubMed sources

1.PMID: 38985927 (2012) — [Allergy to asparagus]. · CITED REFERENCES
2.PMID: 16480995 (2006) — Seleno-compounds in garlic and onion. · Journal of chromatography. A
3.PMID: 41261435 (2025) — Chinese leek-derived extracellular vesicles ameliorate sarcopenia by regulating mitochondrial biogenesis and autophagy via AMPK and maintaining myosin homeostasis. · Journal of nanobiotechnology
4.PMID: 36817114 (2022) — Genome-wide association and dissociation studies in Pantoea ananatis reveal potential virulence factors affecting Allium porrum and Allium fistulosum  ×  Allium cepa hybrid. · Frontiers in microbiology
5.PMID: 37007285 (2023) — Antibacterial Effect of Allium ampeloprasum and Allium porrum Extracts on Staphylococcus aureus and Pseudomonas aeruginosa.

Leek

Sources & Citations

Calculate a safe dose of Leek