Allium ampeloprasum var. porrum (Leek)

Leek (Allium ampeloprasum var. porrum) contains organosulfur compounds and polyphenols that demonstrate antioxidant and antimicrobial properties. Research shows potential cardiovascular benefits through mechanisms involving blood pressure regulation and bacterial growth inhibition.

Origin & History

Leek (Allium ampeloprasum var. porrum) is a bulbous vegetable belonging to the Allium genus, cultivated as an important outdoor crop particularly in Belgium and other temperate regions. The plant is harvested for both its white shaft (bulb) and green leaves, which contain distinct bioactive compound profiles including organosulfur compounds, polyphenols, and saponins.

Historical & Cultural Context

The search results do not provide specific information about leek's historical use in traditional medicine systems or the duration of traditional use. While noted as having "low toxicity" in Allium species research, specific traditional applications were not documented in the available sources.

Health Benefits

• Anti-hypertensive effects demonstrated in animal models at doses of 250-500 mg/kg (preliminary evidence only)
• Antibacterial activity against P. aeruginosa (MIC 20 mg/mL) and S. aureus (MIC 29 mg/mL) in laboratory studies (in vitro evidence)
• Antioxidant properties through polyphenolic compounds and flavonoids, particularly in green leaves (mechanistic evidence only)
• Anti-inflammatory potential through suppression of COX-2 and iNOS pathways (theoretical based on compound analysis)
• Antifungal activity from spirostanol saponins and dibenzofurans including Porric acids A, B, and C (in vitro evidence)

How It Works

Leek's bioactive organosulfur compounds and polyphenolic antioxidants work through multiple pathways including free radical scavenging and bacterial cell membrane disruption. The anti-hypertensive effects likely involve vasodilation mechanisms, while antibacterial activity results from sulfur compounds interfering with bacterial protein synthesis and cell wall integrity.

Scientific Research

The available research consists primarily of in vitro studies and animal models, with no human clinical trials or meta-analyses found in the provided sources. One animal study demonstrated anti-hypertensive activity at oral doses of 250-500 mg/kg of alcoholic extract, while laboratory studies showed antibacterial efficacy with MICs of 20-29 mg/mL against common pathogens.

Clinical Summary

Current evidence for leek extract is primarily limited to animal and laboratory studies. Anti-hypertensive effects were demonstrated in animal models using 250-500 mg/kg doses, though human clinical trials are lacking. In vitro antibacterial studies show moderate activity against P. aeruginosa (MIC 20 mg/mL) and S. aureus (MIC 29 mg/mL). More robust human clinical research is needed to establish therapeutic efficacy and optimal dosing protocols.

Nutritional Profile

Leek (raw, per 100g edible portion): Macronutrients — Calories: ~61 kcal; Carbohydrates: ~14.2g (of which sugars ~3.9g); Dietary fiber: ~1.8g (predominantly fructooligosaccharides and inulin-type fructans acting as prebiotics); Protein: ~1.5g (containing all essential amino acids in modest amounts); Fat: ~0.3g. Key Micronutrients — Vitamin K1 (phylloquinone): ~47 µg (39% DV), among the highest in common vegetables; Vitamin A (as carotenoids): ~83 µg RAE, primarily from lutein (~1900 µg) and beta-carotene (~1000 µg) concentrated in green leaf portions; Folate (B9): ~64 µg (16% DV); Vitamin C: ~12 mg (13% DV); Vitamin B6: ~0.23 mg (18% DV); Manganese: ~0.48 mg (21% DV); Iron: ~2.1 mg (12% DV, non-heme form with moderate bioavailability enhanced by co-ingestion with vitamin C); Calcium: ~59 mg (6% DV); Potassium: ~180 mg; Phosphorus: ~35 mg; Magnesium: ~28 mg. Bioactive Compounds — Organosulfur compounds: allicin precursors (alliin ~0.02–0.05 g/100g), diallyl disulfide, and kaempferol-conjugated sulfur compounds; Polyphenols: kaempferol glycosides (primarily kaempferol-3-glucoside and kaempferol-4-glucoside, ~10–25 mg/100g), quercetin derivatives (~5–10 mg/100g), and ferulic acid; Anthocyanins: present in purple-tinged varieties (~1–5 mg/100g cyanidin equivalents); Fructans/Inulin: ~3–10 g/100g dry weight (significant prebiotic substrate for Bifidobacterium and Lactobacillus spp.). Bioavailability Notes — Lutein and beta-carotene absorption is fat-dependent (bioavailability increases ~3–5x when consumed with dietary fat); kaempferol bioavailability from leeks (~30–40%) is lower than from quercetin sources due to glycoside form; cooking (boiling) reduces vitamin C by ~30–40% and leaches water-soluble B vitamins but may mildly increase carotenoid bioaccessibility; iron absorption is inhibited by concurrent polyphenol intake (~25–75% reduction); fructan content may cause GI discomfort in FODMAP-sensitive individuals. Green leaf portions contain significantly higher concentrations of vitamins K, A, and polyphenols compared to white bulb portions.

Preparation & Dosage

Animal studies used alcoholic extract doses of 250-500 mg/kg for anti-hypertensive effects. Antibacterial research tested aqueous extracts at 35-40 mg per disk in laboratory settings. No standardized human dosage recommendations are available from clinical research. Consult a healthcare provider before starting any new supplement.

Synergy & Pairings

Garlic extract, Onion extract, Quercetin, Vitamin C, Aged black garlic

Safety & Interactions

Leek extract is generally considered safe when consumed in food amounts, but supplement safety data is limited. Potential interactions may occur with anticoagulant medications due to organosulfur compounds affecting platelet function. Individuals with existing hypotension should use caution given the anti-hypertensive effects observed in animal studies. Pregnant and breastfeeding women should avoid supplemental doses due to insufficient safety data.