Vitamin K in lettuce: iceberg is lower, but not vitamin-K-free

Use the named lettuce type

The USDA SR Legacy record for raw iceberg lettuce contains 24.1 mcg vitamin K1 per 100 g. For comparison, the raw-spinach record contains 482.9 mcg per 100 g. Spinach is a comparison green, not another lettuce variety. These two values cannot establish the amount in romaine, butterhead or a mixed-leaf bag. [1]

The amount eaten still matters

A 50 g iceberg portion provides about 12.05 mcg K1 and 100 g provides 24.1 mcg by these reference values. Those amounts are lower than equal weights of spinach but are not zero. Dressings and other salad ingredients add separate contributions. The historical database is an estimate, not an assay of the exact salad. [1]

A hypothetical anticoagulation diet change

Imagine a person on warfarin replaces an ordinary iceberg salad with a much larger portion of concentrated leafy greens every day. The important issue is the changed vitamin K intake, not whether either food is inherently forbidden. NIH ODS advises consistency and clinical discussion of changes; the medication dose should not be adjusted from a salad calculation alone. [2]

Hypothetical example — interpret a specific hypothetical label or comparison
Hypothetical raw iceberg portion	K1 estimate
50 g	12.05 mcg
100 g	24.1 mcg

Vitamin K in lettuce: iceberg is lower, but not vitamin-K-free — original article outline diagram — Original editorial diagram of this article’s sections; no product photograph or clinical finding is depicted.

Sources for this article

USDA FoodData Central — SR Legacy April 2018 composition and portion tables
Source consulted: 2026-09-20. This is a reference resource, not a claim that we conducted the studies or tested a product.
Vitamin K - Health Professional Fact Sheet
Source consulted: 2026-09-20. This is a reference resource, not a claim that we conducted the studies or tested a product.