Iceberg lettuce is low in vitamin K compared to other leafy greens. A one-cup serving of shredded iceberg lettuce contains about 14 mcg of vitamin K, which is a small fraction of the 90 to 120 mcg adults need daily. If you’re watching your vitamin K intake because of a blood-thinning medication, iceberg lettuce is one of the safer greens to eat freely.
How Iceberg Compares to Other Greens
The gap between iceberg lettuce and darker greens is dramatic. One cup of raw spinach has 145 mcg of vitamin K, roughly ten times what you’d get from the same amount of iceberg. A half cup of cooked spinach jumps to 445 mcg. Kale is similarly packed: 82 mcg per cup raw and 247 mcg per half cup cooked. Even romaine lettuce, iceberg’s closest relative in the salad bowl, delivers 48 mcg per cup, more than three times the amount in iceberg.
The reason comes down to color. Vitamin K1 (the form found in plants) is concentrated in chlorophyll, the pigment that makes leaves green. Iceberg lettuce is pale and mostly water, so it simply doesn’t carry much of the vitamin. Darker, more intensely colored greens pack far more into every bite.
What This Means for Blood Thinners
People taking warfarin are often told to keep their vitamin K intake consistent, because the vitamin directly affects how the medication works. Foods are generally grouped into low, medium, and high vitamin K categories to make this easier. A single cup of iceberg lettuce falls squarely in the low category. However, an entire head of iceberg lettuce (roughly 700 to 800 grams) adds up to around 80 to 100 mcg total, which the University of Iowa Health Care classifies as a medium vitamin K food.
In practical terms, a normal salad portion of iceberg lettuce is unlikely to shift your vitamin K levels meaningfully. Just keep your intake roughly steady from week to week rather than swinging between no greens and large volumes. If you prefer darker greens like spinach or kale, you don’t need to avoid them, but consistency matters more than avoidance.
How Much Vitamin K You Actually Need
The recommended daily intake for vitamin K is 120 mcg for adult men and 90 mcg for adult women. A cup of iceberg lettuce covers about 12 to 16 percent of that range depending on your sex, so it contributes something but won’t get you close on its own. By contrast, a single cup of raw kale or half a cup of cooked spinach exceeds the full daily recommendation in one serving.
If iceberg is your go-to salad base and you don’t eat many other leafy greens, you may be falling short on vitamin K. Adding even a small handful of romaine, spinach, or kale to your bowl can close the gap quickly.
Getting More From Your Iceberg Salad
Vitamin K is fat-soluble, meaning your body absorbs it much more efficiently when you eat it alongside some dietary fat. A plain bowl of dry lettuce won’t deliver as much usable vitamin K as the same lettuce dressed with olive oil, topped with avocado, or paired with nuts and cheese. This applies to all leafy greens, but it’s especially worth noting for iceberg since the vitamin K content is already modest. A simple oil-based dressing can meaningfully improve how much of that 14 mcg your body actually takes in.
What Else Iceberg Lettuce Offers
Iceberg lettuce has a reputation as nutritionally empty, and while it’s true that it can’t compete with kale or spinach on most vitamins and minerals, it’s not worthless. It provides small amounts of vitamin A and folate, and its high water content makes it hydrating and extremely low in calories (about 8 calories per cup). It’s also naturally low in sodium.
Where iceberg really shines is as a gateway green. Its mild flavor and satisfying crunch make it easy to eat in large volumes, and it pairs well with more nutrient-dense ingredients. Mixing iceberg with a handful of spinach or romaine gives you the texture you like while boosting the vitamin K, folate, and vitamin A content of your meal significantly.