Ask Jen about lettuce


Hey Jen,

Every time I buy a head of lettuce at the grocery store, it turns brown within a couple of days. How can I get it to last longer?

Frustrated shopper

Hi Frustrated shopper,

While you may have heard that using a knife to cut lettuce causes its edges to wither and turn brown, it’s normal for lettuce to turn brown after it’s been exposed to air, not a knife blade. In scientific terms, it’s the chemical process called oxidation.

When leaves or stems are cut, enzymes produce compounds that create brown stains. This happens whether you cut a head of lettuce with a knife or tear it with your hands.

Also, lettuce is ethylene-sensitive, meaning it ripens quickly and therefore spoils faster when it’s around fruits and vegetables that produce ethylene, like apples, tomatoes and cantaloupes.

Want to keep your lettuce from turning brown? Store it away from the coldest part of your refrigerator and away from fruits like apples, pears, peaches, tomatoes and cantaloupe. Also, keep your lettuce dry. Dole recommends using whole head lettuce within two or three days of purchase.

To learn more, check out the San Francisco Chronicle’s article about what causes lettuce to turn brown and the University of California-Berkeley Wellness’ post.


Hey Jen,

Is there one kind of lettuce that’s healthier than another? I’ve been told that iceberg lettuce really isn’t that nutritious.

Greens lover

Hi Greens lover,

Lettuce is a vegetable, so all varieties have some nutritional value. Dark leaf lettuce, like romaine, contains more vitamins than lighter colored lettuce, like iceberg, so you’re right that iceberg isn’t the best choice if you’re set on getting the most nutritional value out of your salads.

That doesn’t mean iceberg doesn’t have a place in your diet, though. Iceberg lettuce is free of fat and saturated fat, contains low sodium, low cholesterol and low calories. You can mix other types of lettuce into an iceberg salad to make your meal more nutritious.

As a general rule of thumb, the darker the leaf, the more vitamins, fiber and flavor are packed into the lettuce. Lettuce varieties like romaine, butterhead and looseleaf offer vitamins A and C, potassium, calcium, iron and copper. The outer leaves of a head of lettuce contain the bulk of the vitamins and minerals, while the inner part of the head (the rib and spine) contain the dietary fiber.

Read more about lettuce’s nutritional content from the University of Minnesota Extension and South Dakota State University Cooperative Extension Service.

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