Is There A Nutritional Difference Between Iceberg And Romaine Lettuce?

The kind of lettuce you choose is often determined by the kind of dish you're preparing. If you're making a wedge salad, then iceberg is what you're after. For a grilled Caesar salad, you're almost certainly going with romaine. Though many recipes give you a choice when it comes to the kind of lettuce you select, and The University of Illinois Extension explains that lettuce comes in five basic kinds: leaf lettuce, crisphead, butterhead, cos or romaine, and stem or asparagus lettuce.

Salads, according to Lettuce Info, provide a number of proven nutritional benefits. For example, blood tests of those who recently ate salads demonstrated higher levels of important nutrients. Since lettuce is typically the foundation upon which great salads are composed, it makes sense to understand which lettuce varieties are healthiest. If nutrition is your primary concern when selecting lettuce, what should you know? Let's see how the two most popular kinds of lettuce stack up nutritionally.

Iceberg lettuce is the most popular type of lettuce in the U.S., with 1.6 million tons harvested annually in California alone, according to Lettuce Info. One of the reasons iceberg lettuce is so popular is because of all the fragile, highly perishable lettuce varieties, iceberg travels best, per the University of Illinois Extension. The rule of thumb for lettuce and other greens is the darker the color, the more nutritious the green. But is that true? Is the typically light green iceberg lettuce less nutritious than romaine?

Iceberg lettuce is low in calories, with a mere 10 calories per 1 cup serving. Lettuce Info explains that a serving provides about 1 gram of fiber, as well as 15% of the recommended dietary allowance (RDA) of vitamin K and 6% of vitamin B9. Other vitamins, like A and C, along with potassium, magnesium, and phosphorus are also present in small quantities — about 2% of the RDA. So overall, iceberg lettuce doesn't have any fat and contains few calories, so it isn't costly in dietary terms. On the other hand, it doesn't provide much nutrition either. 

Romaine lettuce is the second most popular lettuce in the U.S. Since romaine is darker than iceberg, our rule of thumb tells us it should contain more nutrients. Does it? Like iceberg lettuce, romaine is low in calories, according to Lettuce Info. And like iceberg, it contains 1 gram of fiber, and is fat-free. Romaine also has the same 2% of the RDA of potassium, vitamin C, magnesium, and phosphorus. But romaine lettuce becomes the standout when we look at vitamin A, with 25% of the RDA, and vitamin K, with a whopping 40% of the RDA in every cup. So romaine lettuce is indeed more nutritious than iceberg lettuce. 

Romaine may have the nutritional edge, but you still may want to grab iceberg from time to time because it lasts. Iceberg lettuce not only keeps better than romaine in transit, but also in your refrigerator. However, you can keep any lettuce fresh after purchase by giving it some air. If you open the original packaging, wash, dry, and store your lettuce in a way that allows for air circulation, you will get the best life out of your greens. Lettuce should also be stored in your crisper drawer and away from fruits like apples and bananas that emit ethylene gas and cause the lettuce to spoil more quickly.

If it's nutritional data that guides your choice of lettuce, that fresh, crisp romaine is the better bet, and the rule of "green" holds firm.