# Lactuca sativa var. longifolia (Romaine Lettuce)

**Canonical URL:** https://ingredients.hermeticasuperfoods.com/ingredients/lactuca-sativa-var-longifolia
**Data Source:** Hermetica Superfoods Ingredient Encyclopedia
**Updated:** 2026-03-23
**Evidence Score:** 2 / 10
**Category:** Vegetable
**Also Known As:** Lactuca sativa var. longifolia, Cos lettuce, Romaine, Roman lettuce, Mediterranean lettuce, Long-leaf lettuce

## Overview

Romaine lettuce (Lactuca sativa var. longifolia) contains phenolic compounds including caffeic acid and flavonoids such as quercetin and luteolin, which contribute to antioxidant activity by scavenging [reactive oxygen species](/ingredients/condition/antioxidant). It also provides phytosterols, vitamin K1, and beta-carotene, supporting vascular and bone-related metabolic pathways.

## Health Benefits

["\u2022 May support [antioxidant](/ingredients/condition/antioxidant) defenses due to its content of phenolic compounds like caffeic acid and flavonoids, though this is based on in-vitro chemical analysis, not human trials[1][2].", "\u2022 Potentially contributes to cholesterol management, as its stems are a source of phytosterols like \u03b3-sitosterol, but this effect has not been confirmed in clinical studies[3].", "\u2022 May offer [anti-inflammatory](/ingredients/condition/inflammation) activity, a potential benefit inferred from the presence of triterpenes such as \u03b1-amyrin and \u03b2-amyrin, although specific mechanisms in the plant remain unelucidated[3].", "\u2022 Provides foundational nutrients, including essential amino acids like lysine and phenylalanine, contributing to its classification as a nutrient-dense food[5].", "\u2022 Contains a variety of bioactive compounds, including flavonoids like japonicin A and phenolic acids, but their direct health impact from consuming romaine lettuce is not established by clinical evidence[1][6]."]

## Mechanism of Action

Caffeic acid and luteolin in romaine lettuce inhibit [lipid peroxidation](/ingredients/condition/antioxidant) and suppress NF-κB signaling, reducing [pro-inflammatory cytokine](/ingredients/condition/inflammation) expression at the cellular level. Phytosterols compete with dietary cholesterol for intestinal absorption via Niemann-Pick C1-Like 1 (NPC1L1) transporter sites, potentially lowering [LDL cholesterol](/ingredients/condition/heart-health). Beta-carotene undergoes enzymatic cleavage by beta-carotene 15,15'-monooxygenase to retinal, supporting retinoic acid receptor activation and cellular differentiation.

## Clinical Summary

Most evidence for romaine lettuce's bioactive effects derives from in-vitro chemical analyses and observational dietary studies rather than randomized controlled trials focused specifically on this cultivar. Population-based studies such as the PREDIMED trial associate high intake of dark leafy greens with reduced [cardiovascular risk](/ingredients/condition/heart-health) markers, though isolating romaine's independent contribution is not possible from such data. Phytosterol research broadly shows that 2 g/day of plant sterols reduces LDL cholesterol by approximately 8–10%, but romaine provides only modest sterol quantities per typical serving (~100 g). The overall clinical evidence for romaine lettuce as a standalone therapeutic agent remains preliminary, with nutritional benefit best understood in the context of whole dietary patterns.

## Nutritional Profile

Romaine lettuce (raw) per 100g: Calories 17 kcal, Water 94.9g, Carbohydrates 3.3g (of which sugars 1.2g), Dietary fiber 2.1g, Protein 1.2g, Fat 0.3g. Key vitamins: Vitamin K1 (phylloquinone) 102.5µg (85% DV) — notably high and bioavailability enhanced with dietary fat; Vitamin A (as beta-carotene ~1987µg, retinol activity equivalents ~166µg RAE); Folate (B9) 136µg (34% DV); Vitamin C 4mg; Vitamin B1 (thiamine) 0.07mg; Vitamin B2 (riboflavin) 0.07mg; Vitamin B6 0.07mg; Vitamin E (alpha-tocopherol) 0.13mg. Key minerals: Potassium 247mg, Calcium 33mg, Magnesium 14mg, Phosphorus 30mg, Iron 0.97mg (non-heme, low bioavailability ~5-12%, enhanced by co-consumption with vitamin C), Zinc 0.23mg, Manganese 0.18mg, Sodium 8mg. Bioactive compounds: Phenolic acids including caffeic acid (~8.5mg/100g), chlorogenic acid, and chicoric acid; flavonoids including quercetin (~0.2mg/100g) and luteolin; carotenoids lutein and zeaxanthin (~2312µg/100g combined, bioavailability fat-dependent); phytosterols including β-sitosterol (~7mg/100g) predominantly in stems; lactucin and lactucopicrin (sesquiterpene lactones, trace amounts, more concentrated in stems and outer leaves). Chlorophyll content approximately 8.2mg/100g. Fiber composition includes both soluble (pectin) and insoluble (cellulose, hemicellulose) fractions. Water content of ~95% means micronutrient density per calorie is high, though absolute quantities per serving are moderate.

## Dosage & Preparation

No clinically studied dosage ranges are available for Lactuca sativa var. longifolia in any form, including extracts, powders, or standardized products. Compositional studies do not specify therapeutic doses for its active compounds[1][3]. Consult a healthcare provider before starting any new supplement.

## Safety & Drug Interactions

Romaine lettuce is generally recognized as safe for most adults when consumed in typical food amounts, with no established tolerable upper intake level for its micronutrients at dietary doses. Its substantial vitamin K1 content (~48 µg per 100 g) may interfere with anticoagulant medications such as warfarin by competing with vitamin K-dependent clotting factors II, VII, IX, and X, necessitating consistent intake monitoring in patients on such therapy. Individuals with latex-fruit syndrome or sensitivity to other Asteraceae family plants may experience cross-reactive allergic responses. Romaine is considered safe during pregnancy as a food source; however, raw romaine has been associated with multiple E. coli O157:H7 outbreaks, making thorough washing or avoidance of raw consumption a relevant safety consideration for immunocompromised individuals and pregnant women.

## Scientific Research

No human clinical trials, randomized controlled trials, or meta-analyses specific to Lactuca sativa var. longifolia were identified in the research dossier. Existing studies (e.g., PMC10701912, PMC12988707) focus on nutritional profiling, chemical composition, and in-vitro [antioxidant activity](/ingredients/condition/antioxidant) rather than clinical efficacy in humans[2][4][5].

## Historical & Cultural Context

The provided research dossier contains no information on the historical or traditional medicinal use of Lactuca sativa var. longifolia. Sources emphasize modern phytochemical analysis rather than its role in traditional systems like Ayurveda, TCM, or folk medicine[1][3][5].

## Synergistic Combinations

Vitamin C, Omega-3 Fatty Acids, Green Tea (EGCG), Turmeric (Curcumin)

## Frequently Asked Questions

### What vitamins and minerals are in romaine lettuce?

Romaine lettuce (100 g raw) provides approximately 48 µg of vitamin K1, 436 µg of beta-carotene (provitamin A), 64 µg of folate, 24 mg of vitamin C, and 33 mg of calcium. It also contains smaller amounts of potassium (~247 mg), magnesium (~14 mg), and iron (~0.97 mg), making it a micronutrient-dense, low-calorie food at roughly 17 kcal per 100 g.

### Does romaine lettuce help lower cholesterol?

Romaine lettuce contains phytosterols, plant-based compounds that compete with cholesterol at NPC1L1 intestinal absorption sites, theoretically reducing LDL uptake. However, a typical 100 g serving provides only a fraction of the 2 g/day phytosterol threshold shown in clinical trials to reduce LDL by 8–10%, meaning romaine alone is unlikely to produce measurable cholesterol-lowering effects without very high or concentrated consumption.

### Is romaine lettuce good for inflammation?

Romaine lettuce contains luteolin and caffeic acid, flavonoids and hydroxycinnamic acid derivatives that inhibit NF-κB pathway activation and reduce production of pro-inflammatory mediators such as IL-6 and TNF-alpha in cell culture studies. While these findings are promising, no human clinical trials have specifically measured romaine lettuce's anti-inflammatory effects in vivo, so conclusions about its direct anti-inflammatory benefit in humans remain speculative.

### Can people on blood thinners eat romaine lettuce?

People taking warfarin (Coumadin) or other vitamin K antagonists should eat romaine lettuce in consistent, moderate amounts rather than eliminating it, since sudden changes in vitamin K1 intake (~48 µg per 100 g in romaine) can destabilize INR levels and alter anticoagulation control. Patients should inform their prescribing physician of their typical dietary intake so warfarin dosing can be appropriately calibrated; they do not need to avoid romaine entirely.

### What antioxidants does romaine lettuce contain?

Romaine lettuce provides several classes of antioxidants including flavonoids (quercetin, luteolin, apigenin), hydroxycinnamic acids (caffeic acid, chlorogenic acid), carotenoids (beta-carotene, lutein, zeaxanthin), and ascorbic acid (vitamin C). These compounds collectively neutralize reactive oxygen species and chelate redox-active metals in laboratory assays, though their bioavailability and in-vivo antioxidant potency after digestion depend on factors like food matrix, cooking method, and individual gut microbiome composition.

### Is romaine lettuce safe to eat raw, or should it be cooked?

Romaine lettuce is safe to eat raw and is commonly consumed in salads, where its crisp texture is most appreciated. Raw consumption preserves heat-sensitive vitamins like vitamin C and folate, though cooking can improve the bioavailability of fat-soluble nutrients like lutein and beta-carotene when paired with dietary fat. Both raw and cooked preparations are nutritionally valuable; the choice depends on personal preference and intended nutrient focus.

### How much romaine lettuce should I eat daily to get health benefits?

General dietary guidelines recommend consuming 2–3 cups of raw leafy greens like romaine lettuce per day as part of a balanced diet, though no formal clinical studies have established an optimal dose for specific health outcomes. A typical serving of romaine (about 2 cups raw) provides meaningful amounts of vitamins K, A, and folate, but romaine alone cannot serve as a complete nutrient source. Consistent inclusion in meals as part of a varied diet, rather than isolated dosing, is the practical approach supported by nutritional science.

### Does cooking or storing romaine lettuce affect its nutrient content?

Storage conditions significantly impact romaine lettuce's nutrient retention; keeping it refrigerated in a plastic bag can preserve vitamin C and folate for up to a week, while room-temperature storage causes rapid nutrient degradation. Cooking methods vary in impact: boiling may leach water-soluble vitamins like folate and vitamin C into water, while steaming or light sautéing better preserves overall nutrient density. For maximum nutrient preservation, fresh consumption within 3–5 days of purchase is recommended.

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