What is the healthiest lettuce?
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Of the true lettuces, romaine. Per cup it has about three times iceberg’s vitamin K, three times its folate and eleven times its vitamin A. Spinach has about three times romaine’s vitamin K, but romaine has a little more folate and vitamin A per cup than spinach. The best plan is to rotate.
People tend to rank greens by how dark and how fashionable they are, with kale at the top and iceberg at the bottom. The real ranking depends on which nutrient you care about, and on whether you count by the cup or by weight. Per cup, romaine beats both kale and spinach on vitamin A, and kale comes last of the three on folate.
What we’d do
Use romaine or spinach as the base most days, since they’re the strongest all-rounders per cup, and mix in kale or arugula for flavor and vitamin C. Iceberg is fine for crunch, mixed with something darker. Change it up every few days, because no single green wins on everything.
Comparing greens by the cup is like comparing cereals by the bowl. The fluffy one fills the bowl with much less food in it, and a cup of chopped kale weighs only 21 g against 47 g for romaine.
Per cup, raw
| Green | Cup weighs | Calories | Vitamin K | Folate | Vitamin A | Vitamin C | Fiber |
|---|---|---|---|---|---|---|---|
| Spinach | 30 g | 7 | 145 mcg | 58 mcg | 141 mcg | 8.4 mg | 0.7 g |
| Romaine, shredded | 47 g | 8 | 48 mcg | 64 mcg | 205 mcg | 1.9 mg | 1 g |
| Kale, chopped | 21 g | 7 | 82 mcg | 13 mcg | 51 mcg | 19.6 mg | 0.9 g |
| Arugula | 20 g | about 5 | about 22 mcg | ||||
| Iceberg, shredded | 72 g | 10 | 17 mcg | 21 mcg | 18 mcg | 2 mg | 0.9 g |
From the USDA. Folate is in mcg of dietary folate equivalents and vitamin A in mcg of retinol activity equivalents. The USDA lists arugula only in small portions, so its numbers are scaled up and the rest are left out.
Which green wins what
- Vitamin K. Spinach wins by a lot, then kale. Vitamin K is the one people on warfarin need to keep steady.
- Folate and vitamin A. Romaine wins per cup, with spinach close behind. Kale is low per cup because a cup of it is so light.
- Vitamin C. Kale has more than twice spinach’s and ten times romaine’s.
- Fiber. They’re all about the same per cup, around 1 g, which is why beans or grains do the fiber work in a salad.
Iceberg is about 96% water and last on almost every vitamin, but it still counts. The US guidelines count two cups of any leafy greens as one cup of vegetables, iceberg included.
If you take warfarin, keep the amount of leafy greens steady week to week. Vitamin K changes how warfarin works. Talk to your doctor before a big change.
Compare more
Our greens comparison sorts the greens by any nutrient, per cup, per 2-cup bowl or per 100 g, and tells you when the ranking flips. For the most-asked matchup, see kale or spinach.
7 sources
- USDA Standard Reference, lettuce, cos or romaine, rawnutritionvalue.org
- USDA Standard Reference, lettuce, raw, iceberg (includes crisphead types)nutritionvalue.org
- USDA Standard Reference, spinach, rawnutritionvalue.org
- USDA Standard Reference, kale, rawnutritionvalue.org
- USDA Standard Reference, arugula, rawnutritionvalue.org
- Daily Servings by Calorie Level, Dietary Guidelines for Americans, 2025 to 2030cdn.realfood.gov
- MedlinePlus, Warfarin, US National Library of Medicinemedlineplus.gov
