A category, not a vegetable — and the variety decides whether it is worth eating.
"Lettuce" covers wildly different vegetables. Iceberg is roughly 96% water with very
little nutrition. Romaine carries real vitamin A, vitamin K and folate. Butterhead sits between
them.
The rule of thumb is colour: the darker and greener the leaf, the more nutrition
in it. Pale, tightly packed heads are mostly water.
None of them are bad. But choosing
romaine over iceberg is a free upgrade that most people never make.
Per 100g raw. Values differ substantially between iceberg and romaine.
Based on the nutrients and fibre this food supplies. These are supporting foods, not treatments.
Darker is better. The single most useful thing about buying
lettuce.
Do not wash until you use it. Moisture is what makes leaves
collapse.
Add fat to the salad. The fat-soluble vitamins in lettuce
are largely wasted without it — a dressing with oil is doing nutritional
work.
Tear, do not cut, if you are serving it later — cut edges
brown faster.
Fat-soluble vitamin absorption from salad is a genuinely well-studied effect. Trials
feeding people salads with and without fat found dramatically higher carotenoid uptake when fat
was present. A fat-free dressing on a salad is close to self-defeating.
Lettuce's
water content is its other function — volume and crunch that make a meal feel larger for
almost no calories.
Kidney disease: potassium may need limiting. Ask your doctor for your
numbers.
IBS: several vegetables are high-FODMAP and commonly trigger
symptoms — tolerance is personal.
This is information, not a prescription. If you are managing a diagnosed condition or taking medication, talk to your doctor before making a large change to your diet.
Nutrition figures on this page come from standard food composition data. These links let you check the numbers and read the underlying research yourself rather than taking our word for it.