Lettuce, cos or romaine, raw
Whole food · Vegetables and Vegetable Products
Photo: Wikipedia
Cos or romaine lettuce is a crisp, elongated leafy green with a sturdy, satisfying crunch and a subtly sweet, slightly nutty flavor. Its thick, pale ribs provide a refreshing watery bite, while the darker green leaves offer a milder taste. Nutritionally, it's exceptionally low in calories (just 17 kcal per 100g) and provides a good source of dietary fiber and vitamin K.
Calorie split: 24% protein · 63% carbs · 13% fat
↓ Full nutrition💚 Why it's loved
People adore romaine for its unparalleled crunch and structural integrity, which holds up beautifully in salads and sandwiches without wilting. Its mild, sweet flavor makes it a versatile canvas for bold dressings and a staple in iconic dishes like Caesar salad.
⚠️ Watch-outs & how to enjoy it better
The thick ribs can be tough and slightly bitter for some palates. Those with sensitive digestive systems might find the high fiber content causes gas. To counteract this, chop the ribs finely, massage them with a little dressing, or opt for the more tender inner leaves. Always wash thoroughly, as the layered structure can trap dirt.
Key benefits
- Excellent source of Vitamin K, crucial for bone health and blood clotting.
- Very low in calories, making it ideal for weight management.
- High water content (over 95%) aids in hydration.
- Provides dietary fiber to support digestive health.
- Contains antioxidants like beta-carotene and lutein.
🍽️ Popular dishes
🌍 Where it's eaten
💡 Did you know?
Ancient Egyptians cultivated romaine lettuce not just for food, but also for its seeds and oil, and it was a symbol of the fertility god Min.
Full nutrition (USDA data · scales with serving)
| Water | 94.6 g |
| Energy | 17.0 kcal |
| Energy | 72.0 kj |
| Protein | 1.2 g |
| Total lipid (fat) | 0.30 g |
| Ash | 0.58 g |
| Carbohydrate, by difference | 3.3 g |
| Fiber, total dietary | 2.1 g |
| Total Sugars | 1.2 g |
| Sucrose | 0.00 g |
| Glucose | 0.39 g |
| Fructose | 0.80 g |
| Lactose | 0.00 g |
| Maltose | 0.00 g |
| Galactose | 0.00 g |
| Starch | 0.00 g |
| Calcium, Ca | 33.0 mg |
| Iron, Fe | 0.97 mg |
| Magnesium, Mg | 14.0 mg |
| Phosphorus, P | 30.0 mg |
| Potassium, K | 247 mg |
| Sodium, Na | 8.0 mg |
| Zinc, Zn | 0.23 mg |
| Copper, Cu | 0.05 mg |
| Manganese, Mn | 0.15 mg |
| Selenium, Se | 0.40 ug |
| Vitamin C, total ascorbic acid | 4.0 mg |
| Thiamin | 0.07 mg |
| Riboflavin | 0.07 mg |
| Niacin | 0.31 mg |
| Pantothenic acid | 0.14 mg |
| Vitamin B-6 | 0.07 mg |
| Folate, total | 136 ug |
| Folic acid | 0.00 ug |
| Folate, food | 136 ug |
| Folate, DFE | 136 ug |
| Choline, total | 9.9 mg |
| Betaine | 0.10 mg |
| Vitamin B-12 | 0.00 ug |
| Vitamin B-12, added | 0.00 ug |
| Vitamin A, RAE | 436 ug |
| Retinol | 0.00 ug |
| Carotene, beta | 5226 ug |
| Carotene, alpha | 0.00 ug |
| Cryptoxanthin, beta | 0.00 ug |
| Vitamin A, IU | 8710 iu |
| Lycopene | 0.00 ug |
| Lutein + zeaxanthin | 2312 ug |
| Vitamin E (alpha-tocopherol) | 0.13 mg |
| Vitamin E, added | 0.00 mg |
| Tocopherol, beta | 0.00 mg |
| Tocopherol, gamma | 0.36 mg |
| Tocopherol, delta | 0.01 mg |
| Tocotrienol, alpha | 0.04 mg |
| Tocotrienol, beta | 0.00 mg |
| Tocotrienol, gamma | 0.00 mg |
| Tocotrienol, delta | 0.00 mg |
| Vitamin D (D2 + D3), International Units | 0.00 iu |
| Vitamin D (D2 + D3) | 0.00 ug |
| Vitamin K (phylloquinone) | 103 ug |
| Vitamin K (Dihydrophylloquinone) | 0.00 ug |
| Alcohol, ethyl | 0.00 g |
| Caffeine | 0.00 mg |
| Theobromine | 0.00 mg |
Fat & fatty acid profile (per 100g)
| Fatty acids, total saturated | 0.04 g |
| SFA 4:0 | 0.00 g |
| SFA 6:0 | 0.00 g |
| SFA 8:0 | 0.00 g |
| SFA 10:0 | 0.00 g |
| SFA 12:0 | 0.00 g |
| SFA 14:0 | 0.00 g |
| SFA 16:0 | 0.04 g |
| SFA 18:0 | 0.01 g |
| Fatty acids, total monounsaturated | 0.01 g |
| MUFA 16:1 | 0.00 g |
| MUFA 18:1 | 0.01 g |
| MUFA 20:1 | 0.00 g |
| MUFA 22:1 | 0.00 g |
| Fatty acids, total polyunsaturated | 0.16 g |
| PUFA 18:2 | 0.05 g |
| PUFA 18:3 | 0.11 g |
| PUFA 18:4 | 0.00 g |
| PUFA 20:4 | 0.00 g |
| PUFA 20:5 n-3 (EPA) | 0.00 g |
| PUFA 22:5 n-3 (DPA) | 0.00 g |
| PUFA 22:6 n-3 (DHA) | 0.00 g |
| Fatty acids, total trans | 0.00 g |
| Cholesterol | 0.00 mg |
Amino acid profile (per 100g)
| Tryptophan | 0.01 g |
| Threonine | 0.04 g |
| Isoleucine | 0.04 g |
| Leucine | 0.08 g |
| Lysine | 0.06 g |
| Methionine | 0.01 g |
| Cystine | 0.01 g |
| Phenylalanine | 0.07 g |
| Tyrosine | 0.03 g |
| Valine | 0.06 g |
| Arginine | 0.05 g |
| Histidine | 0.02 g |
| Alanine | 0.06 g |
| Aspartic acid | 0.14 g |
| Glutamic acid | 0.18 g |
| Glycine | 0.05 g |
| Proline | 0.04 g |
| Serine | 0.05 g |
FAQ
Is romaine lettuce nutritious?
Yes, despite being low in calories, it's a powerhouse for Vitamin K (over 100% DV per cup) and provides Vitamin A, folate, and antioxidants.
How do I keep romaine lettuce fresh?
Wrap the unwashed head in a dry paper towel, place it in a perforated plastic bag, and store in the crisper drawer. It should last 1-2 weeks.
What's the difference between romaine and iceberg lettuce?
Romaine has a longer, darker leaf with a sturdy rib and a sweeter flavor. Iceberg is round, pale, and has a milder taste but a very similar crunch.
Nutrient density (calculated · NRF9.3)
Nutrient Rich Foods index: beneficial nutrients (protein, fiber, vitamins, minerals) minus saturated fat, added sugar & sodium, per 100 kcal.
NRF9.3 index — Fulgoni, Keast & Drewnowski, 2009. Computed from USDA nutrients.
Weight-loss friendliness (composite index)
Energy density 0.17 kcal/g · 29% calories from protein · 2.1 g fiber · 1.2 g sugar per 100 g.
Composite of energy density (Rolls et al., 1999), protein & fiber satiety, minus sugar. A calculated heuristic — ranks satiety-per-calorie, not a clinical measure.
Dietary load (calculated from USDA values)
Potential renal acid load. Positive = acid-forming, negative = alkaline-forming.
Sodium-to-potassium ratio: 0.03 (lower is better — aim for ≤ 1)
Sodium:potassium per WHO potassium guidance. Computed from USDA nutrients.