Source  : Health Canada. Canadian Nutrient File , 2010.

The benefits of lettuce

• Cancer . Some studies have associated lettuce consumption with a reduced risk of developing various cancers ^3-5 . In one, eating lettuce several times a week was specifically associated with a lower risk of lung cancer ³ .
• Neurodegenerative diseases . According to an in vitro study , compounds contained in lettuce, more particularly in romaine lettuce, have neuroprotective effects and could help prevent the onset of certain neurodegenerative diseases, such as Alzheimer’s disease ³⁰ . However, clinical studies will be required to confirm these effects in humans.
• Blood lipids . A study in rats has indicated that a diet containing one-fifth of lettuce can lower their blood cholesterol . ²⁴ Another study in mice showed that a diet high in fat and cholesterol to which red leaf lettuce was added decreased the blood level of total cholesterol, “bad” cholesterol (LDL) and triglycerides ³³ . In humans, no data have been published on the effect that lettuce consumption may have on blood lipids.

Several epidemiological studies have shown that high consumption of vegetables and fruits lowers the risk of cardiovascular disease ²⁶ , certain cancers ²⁷ and other chronic diseases ^{1 , 2,28} . The presence of antioxidants in vegetables and fruits could play a role in these protective effects.

What does lettuce contain?

Phenolic compounds
Lettuce contains various phenolic compounds , mainly quercetin, as well as phenolic acids (caffeic acid and coumaric acid) ^7-9,29 . These antioxidant substances protect the cells of the body from damage caused by free radicals ^{6 , 20} .

However, research has shown that green lettuces have little antioxidant power ¹⁰ and little effect in preventing the growth of cancer cells in  vitro ¹¹ . Red lettuce is the only one with high antioxidant power. However, regular consumption of lettuce, regardless of its color, still provides a significant contribution to phenolic compounds, beneficial for health.

Carotenoids
Lettuce also contains carotenoids , mainly beta-carotene and lutein, but also different types of xanthines (for example zeaxanthin), depending on the variety ^17-19 . These compounds have antioxidant properties and the consumption of foods rich in carotenoids is linked to a lower risk of developing certain cancers ¹⁶ . Some studies have observed that consumption of lettuce increased concentrations of beta-carotene ^{8 , 21} in the blood, as well as concentrations of zeaxanthin and beta-cryptoxanthin in the blood of postmenopausal women ³¹ .

Fibers
Each variety of lettuce contains a different amount of fiber, of which approximately 15% to 35% is in soluble form. Romaine lettuce is the richest, followed by curly lettuce, iceberg and Boston. Soluble fibers are well known for their beneficial effect on blood lipids ²³ , those of lettuce have a certain cholesterol-lowering power .

Main vitamins and minerals

Precautions

All lettuce varieties, except iceberg lettuce, contain high amounts of vitamin K. This vitamin, which is necessary for blood clotting, among other things, can be produced by the body in addition to being found in certain foods . People taking blood thinners , such as those marketed under the names Coumadin®, Warfilone® and Sintrom®, should eat a diet with relatively stable vitamin K content from day to day. Lettuce is part of a list of foods that should be eaten no more than once a day and no more than 250 ml (1 cup)every time. People on anticoagulant therapy are strongly advised to consult a dietitian-nutritionist or a doctor in order to know the food sources of vitamin K and to ensure a daily intake as stable as possible.

To access other recipes, you can go to the CuisineAZ.com kitchen recipe site, which offers, among other things, the following recipes: lettuce soup, lettuce soup, lettuce recipes

Preparation

Wash lettuce only when preparing it, in very cold water. Wring it out in a cloth or in a salad basket. The vinaigrette will hold better on the leaves if they are dry.

The reddish oxidation of the tissue destroys vitamin C. To avoid this, it is better to tear the lettuce rather than cut it with a knife and do this operation only at the last minute.

Add the dressing to the lettuce just before serving. First pour the dressing in a large salad bowl and add the lettuce in small handfuls at a time, turning well to coat the pieces. In France, this operation is done directly at the table.

• Salads . Serve it alone, simply drizzled with a good vinaigrette or marry it with other greens such as arugula, lamb’s lettuce, watercress, chicory, etc. Play with colors, flavors, shapes, textures. You can also add other vegetables, cold meats or hard-boiled eggs to make a meal salad. If you serve it between the main dish and dessert, as in Europe, avoid overloading it with too heavy ingredients.
• Add a leaf or two of lettuce to sandwiches , burgers or hot dogs .

• We can make a fine julienne with which we will garnish the souvlaki or falafel presented in pita bread. Prepare the julienne at the last minute and serve immediately.
• You can also stuff raw leaves of cheese, ham or other meat, egg salad, seafood, vegetables or fruit.
• Cesar salad. Prepared with fresh ingredients, this elaborate dish is a very nutritious meal. First prepare the vinaigrette by passing the garlic, pepper and Parmesan cheese through a food processor. Add whole raw eggs, Dijon mustard, anchovy fillets, a little lime juice or vinegar and, if desired, Worcestershire sauce. Mix well and then gradually add olive oil or a mixture of olive oil and sunflower oil. Then prepare the croutons (use whole wheat or spelled bread and kamut) by coating them with a marinade made of oil, garlic and herbs. Bake them for about fifteen minutes at 180 ° C (350 ° F). Then tear romaine leaves, pour the vinaigrette, turning well, add the croutons and grated parmesan cheese and serve immediately.
• Add it to vegetable soups or make a cream. It is a good way to pass withered lettuce, still good, but not appetizing to the eye. Cook it for a few minutes in a covered pan with a little water. Drain, pass to the mixer. Brown finely minced onion in butter, thicken with flour, gradually add broth or milk, a little paprika and grated nutmeg. Salt, add the lettuce and reheat. If desired, garnish with grated parmesan.
• Braised. Put romaine or other firm lettuce hearts in a baking dish. Add a broth (vegetable, chicken or veal), a little butter and sugar and salt. Bring to a boil, cover and simmer until the lettuce is tender. Keep warm. Reduce the broth until there is only half a cup left, add a knob of butter and coat the lettuce with this sauce. Or simply braise it with stewed tomatoes.
• Papillotes . Blanch lettuce leaves for a few moments in boiling water or steam. Then spread them on the work surface, place 1 spoonful or 2 of precooked stuffing on each of the leaves, and roll after folding the two sides over the stuffing. Attach with a toothpick and steam the papillotes for a few minutes. Or, put them in a baking dish, cover them with hot broth and put them in the oven. The stuffing can be made of vegetables and tofu or minced meat (beef, veal, pork or lamb) seasoned with finely minced onion, parsley, garlic, thyme and, if desired, cayenne pepper.

• Asparagus lettuce marrow . Remove the bottom end and cut the top end with leaves. After peeling it, cut the stem into sections. Blanch for a few minutes in boiling salted water, wring out then brown in butter. Reserve in a hot dish with a layer of hot butter. Fry the garlic and then pour the juice of half a lemon into the pan. Add the upper end of the stem with its leaves and cook just long enough to warm up. Stir in the stem sections and serve.
• Make jump lettuce asparagus and serve it to the Chinese, with other vegetables and seasoning soy sauce.

To choose

The leaves should be firm, with no reddish discoloration at the tips and no rotting at the base.

Keep

Refrigerator . From a few days to 1 week in the vegetable drawer. Preferably keep in a perforated plastic bag. Avoid the proximity of apples , pears, and bananas that emit ethylene, a gas that causes lettuce to rot.

Freezer . Cooked lettuce can freeze, but not fresh.

The term ”  lettuce  ” appeared in the French language in the XI ^th  century. It comes from the Latin lactuca , which is derived from lake , “milk”, in reference to the milky white sap produced by the plant.

For millennia, hunter-gatherers harvested lettuce from one or more of dozens of Lactuca wild species . If one relies on paintings appearing on tombs dating from 2,500 years before our era, a primitive form of romaine lettuce was perhaps already cultivated by the Egyptians at that time. We did not consume its leaves, considered too bitter, but we used its seeds for its medicinal properties and we made an edible oil . However, the first documents relating to the cultivation of lettuce date from the year 450 BCE. The species L. serriola, originally from the Mediterranean basin and the Near East, is the ancestor of all forms of L. sativa that we consume today. The ancient Greeks would have been the first to domesticate it.

The first lettuce species quickly formed a tall stem on which small, very bitter leaves grew . Initially, the Romans set out to reduce this bitterness by removing the plant from light during part of its growth (as is still done today for endives). Then, by selection, they got varieties with shorter stems and larger leaves., which rose less quickly in seeds and were less bitter. In the first century AD, they had selected a dozen varieties, some of which were widely used. Like many other greens, they ate it raw, seasoned with oil and vinegar. However, in the Middle Ages, we began to see raw vegetables with a negative eye. Consumption of raw lettuce reappear in Western Europe in the XVI ^th  century only after a long period when it has been served only cooked in stews and pies.

The lettuce will cross the Atlantic with Christopher Columbus who will bring seeds during his first trips to America. Until the mid XX ^th  century, there will cultivate and consume all types of lettuce, many varieties are found today.

The introduction in 1941 of the iceberg (a firmer and larger variant of the European Batavia) completely transformed the markets. We had finally found a lettuce that supported the constraints of industrial culture, survived long journeys intended to make it cross a continent, even an ocean, and kept infinitely longer than all other known varieties.

Since then, iceberg lettuce has dominated the North American market (it occupied 73% of the market in 2000) and is on the way to establish itself in Europe, despite being much less nutritious than the other varieties. However, in recent years its consumption has decreased in favor of other varieties, the Roman in particular.

Lettuce with white seeds (there are browns and blacks) needs light to germinate. So we will not cover it with soil, but we will pack it well against the damp soil so that it does not dry out.

Plant of cool climate and short photoperiod , it is cultivated especially in spring and autumn. During the summer , you can try the culture of the Roman, slightly less sensitive to heat. It will be protected from hot rays with a shade house allowing only 50% of the light to filter through. We can also sow successive lettuce to cut every 2 weeks, and harvest the leaves when the plant is very young before it has time to go to seed. Finally, some cultivars are relatively resistant to the rise in seeds.

For early production , start the plants in containers indoors 6 to 8 weeks before the last gels. Transplant 3 or 4 weeks later into the ground (the plant is not afraid of frost). Protect against wind and extreme cold with a geotextile fabric.

pH: 6.0 to 7.0

Spacing: from 10 cm to 15 cm for the lettuce to be cut, from 15 cm to 20 cm for the others. When the plants expand until touching, remove 1 of 2.

Irrigation: contrary to what is recommended for most vegetable plants, lettuce prefers frequent, but shallow watering.

Insects: at the end of the season, aphids are to be feared, in particular because they are vectors of the mosaic virus, against which nothing can be done. Treat with insecticidal soap as soon as they appear. The slugs can also cause problems. Limit their proliferation with diatomaceous earth, eggshells or containers filled with beer and placed at the foot of the plants. Garlic extract has also been shown to be effective against this gastropod.

Diseases: scorching of the edge of the leaves and root rot can be minimized by ensuring that air circulates well between the plants and by watering the surface frequently.

Lettuce is one of the vegetables that receives the most chemical treatments – herbicides, insecticides and, most importantly, fungicides – during its growth. This encourages many people to look for organic products which, unfortunately, are generally more expensive. Indeed, organic market gardeners lose a large proportion of their lettuce due to diseases and insects that attack it, which inevitably leads to an increase in the retail price.

Various solutions are currently being tested in order to reduce the frequency and intensity of these attacks. The biofimugation , for example, is to bury in the ground, the year before growing lettuce plants with antifungal properties, particularly cruciferous (cabbage family).

Another approach is to practice on seed technology energy healing ( energy healing ) that some practitioners use to treat humans. This extremely controversial practice would aim to strengthen the immune defenses written into the plant’s DNA . The technique has been tried with some success, albeit on a small scale.