Lettuce goes beautifully in salads, wraps and sandwiches, but not all lettuces are created equal.

Lettuce first appeared near the Mediterranean basin more than 4000 years ago. Initially it was probably just regarded as a nuisance weed, but it wasn’t long before it was appreciated as a food and a medicine. Hippocrates, the father of modern medicine, advocated its use. In ancient Rome it was prescribed to relax the bowels and indeed Augustus (first emperor of the Roman Empire from 27 BCE to 14 CE) was so impressed with it that he erected a statue to it.

Lettuce’s name comes from the Latin and means milk (because of the white sap of the stem) and the name of its major chemical “lactucin” echoes this. In folk lore lettuce is said to have a calming effect on the body, so much so that if you can eat several heads of it you may become euphoric. Perhaps this is why rabbits always seem so happy … or is it why they breed so prolifically?

For years Australians ate only iceberg lettuce, but recently new types, such as cos (called romaine in the USA and the staple ingredient of Caesar salad), loose-leaf and butterhead lettuce have become very popular. Below is a brief guide to these lettuce types:

Iceberg (crisphead): Has green leaves on the outside and whitish ones on the inside. This variety of head lettuce has a crisp texture and a mild taste.

Cos (also known as romaine): This variety of head-forming lettuce has deep-green, long leaves with a crisp texture and deep taste.

Butterhead: This type of lettuce features tender large leaves that form a loosely arranged head that is easily separated from the stem. It has a sweet flavour and a soft texture.

Loose-Leaf: Featuring broad, curly leaf varieties that are green and/or red, the leaf lettuces offer a delicate taste and a mildly crispy texture. These lettuces do not form true heads, but have leaves joined at the stem. All coral, baby-leaf and salad mix lettuces belong to the “loose leaf” lettuce group.

Healing lettuce

As with any other green leafy vegetable, the darker the lettuce, the better when it comes to nutrition. If you eat the more bitter-tasting lettuces you are not only generally getting better nutrition, you are also stimulating your digestion. Bitter tastes stimulate the flow of digestive juices, which is why bitter salads (or even an aperitif) are a good idea prior to a meal.

If you eat the more bitter-tasting lettuces you are not only getting better nutrition generally, you are also stimulating your digestion.

As far as specific nutrient levels go, the United States Department of Agriculture (USDA) maintains a database called the USDA National Nutrient Database for Standard Reference, which shows nutrient levels in foods, and it illustrates that the different lettuce varieties have quite different nutritional profiles.

Iceberg lettuce, the most popularly consumed lettuce in Australia, has more fibre than some lettuces but it is low in vitamins and minerals. Cos (romaine) lettuce emerges as the best nutritional choice. It has more fibre than iceberg lettuce but is also a good source of vitamin C, folate and vitamin A. It also provides 10 times more beta-carotene than iceberg lettuce and almost as much as spinach. All of this combines to make cos one of the healthiest of all the lettuces.

Loose-leaf lettuce overall has the next best nutritional value. According to the USDA, loose-leaf lettuces deliver reasonable amounts of calcium, phosphorous, potassium, manganese, vitamin C, vitamin A and vitamin K.

Butterhead lettuces also surpass iceberg varieties in almost every nutrient category and have the highest amount of iron of all lettuces.

When you plan your salads it’s fine to include some iceberg lettuce, but spice up your palate and your health by making some of the other lettuces the staple parts of your lettuce diet.