Everything You Need To Know About Lettuce

By Sally Cameron

Everything You Need To Know About Lettuce

Everything You Need To Know About Lettuce. The humble lettuce has been cultivated for thousands of years, and is now grown in nearly every single country on Earth. And though it’s described as a ‘negative food source’- a food source that supposedly requires more calories to digest than it provides the body- this vegetable is one of the most positive foods to include in your daily diet. 

Everything You Need To Know About Lettuce

Often thought of as only a filler for salads & digest than it provides the body – this sandwiches, the humble lettuce can offer much vegetable is one of the most positive more. With a wide range of delicious varieties available, all offering myriad health benefits, it makes a fantastic addition to your daily diet.



  • There are many different types of lettuce (Lactuca sativa), and they all peak at different times of year. Some of the most commonly available varieties include iceberg, romaine and cos – but there are also butterhead lettuces, as well as an Asian version called celtuce, which tends to be grown primarily for its stem.
  • The common factors shared by every member of the lettuce group are their soft and bitter-tasting leaves, and the white sap that runs through the leaves and stems. This sap becomes visible once the stem is cut. Before lettuce was a highly cultivated plant, the sap contained narcotic properties – not dissimilar to the effects of the opium poppy. It caused a soporific stupor in bunnies as well as people.
  • The name ‘Lactuca’ (or ‘latex’) is derived from this sap, while ‘Sativa’ is the common term for being cultivated.
  • The ancient lettuce was a ‘weed-like’ plant that was originally harvested by early Egyptians, more than 6,000 years ago. They gathered it only for its seeds, which provided a rich oil that was used for both cooking and medicinal purposes.
  • The Greeks and Romans included lettuce in their diets as well – mostly for the milky sap that ran through the stems. The Romans would eat lettuce at the end of their meals to help create a sense of calm and bring on sleep. As lettuce was cultivated, however, this narcotic effect was reduced, and the leaves started to be eaten at the very beginning of the meal, as the bitter leaves would stimulate appetite.
  • In more modern texts from the 1500s, lettuce leaves were said to be adorned with a “seasoned oil” to make them more palatable – beginning what we now know as lettuce salads.



A lettuce leaf is around 96 per cent water by weight. The remaining four per cent is made up of dietary fibre, vitamins and minerals, and simple sugars. It is classified as a vegetable that takes more energy to chew and digest than the 55kjs per 100g it provides the body, which is why it is a staple in many weight-loss diets. The different types of lettuce all provide varying amounts of nutrients, however they can generally be said to be a good source of vitamins A and K. Most types are also high in vitamin B9, which forms folate – essential for fertility and reproductive health.



A properly harvested lettuce will have a firm ‘heart’ (the middle bunching of the leaves). An iceberg lettuce should have tightly layered leaves, whereas a butterhead lettuce will be more springy than solid to the touch.

Look for fresh, green, crisp leaves, which have a slightly sweet aroma like fresh air. If possible, you should try to buy your lettuce from local markets, where there has been very little time and transport from picking to point of sale. When buying lettuces that are wrapped in plastic, always check the best-before date, and inspect the contents to check for any brown marks or soggy leaves.



Lettuces grow quite fast, taking only 65 to 85 days to fully develop from seed. They are best planted in spring or autumn, rather than in the heat of summer or the frosts of winter. The lettuce plant will ‘bolt’ to flower and will then go to seed quite quickly if there is too much atmospheric heat. This is the plant’s survival technique to prevent it losing too much moisture from its soft leaves. Additionally, the seeds will not germinate in soil that is over 25°C – quite common in our hot antipodean summers. The plant also requires a very fertile soil with plenty of rotted compost, and needs lots of water to thrive.



Only buy fresh lettuces when you need them, and use them as soon as possible. A head of lettuce simply won’t last in a dehydrating refrigerated environment – and will also rapidly lose its crispness if left out at room temperature.

Listeria is a common bacterial contaminant of lettuce. If the leaves of lettuce are allowed to get too moist, or if they’re not stored in ideal chilled conditions, listeria can become highly problematic. It always pays to use the leaves when they’re as fresh as possible, and avoid eating leaves where there is visible browning or decomposition in the stem and leaves.



Lettuces have long been stored in plastic bags to assist with long-term preservation. Now, as we’re all trying to reduce our plastic consumption, buying commercially grown lettuces has become a challenge, as the plastic is all but essential. The plastic from a store-bought lettuce can be reused in the kitchen – providing it is cleaned thoroughly to prevent listeria bacteria from being passed on. Otherwise, the obvious alternative is to grow lettuce in your own garden space, and store in paper trays with wet paper towels.



Lettuce leaves aren’t traditionally cooked, as they break down quickly with excessive heat and turn soft and mushy – almost slimy, in fact. There are exceptions to this rule, however, and in French cooking lettuces are quickly braised with peas in the classic dish Petits Pois à la Française. The shredded leaves can also be used in broth-like soups, or creamed to use with egg dishes. But most commonly, the leaves are simply washed and torn or cut for uses in salads.

To prepare a lettuce, trim away any stalks, and remove discoloured outer leaves. Also make sure to wash the vegetable carefully, as dirt can easily get trapped in the curl of the leaves and stems.



It is best to dry lettuce leaves after washing, to get rid of any bacteria that may get trapped with the cleaning water. This can be done by leaving the lettuce to drain in a sieve or colander, or you can use a purpose-built lettuce spinner. Using dry, clean kitchen paper towels is another good option.


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