Lettuce – ingredients, effects and application

Lettuce is a good all-round side dish for a healthy diet as it contains few calories and many nutrients and minerals. Other bioactive ingredients and fiber in green salad help reduce weight and prevent diabetes.

Characteristics

• Scientific name: Lactuca sativa
• Common names: garden lettuce, garden lettuce, lettuce; Variety group Lactuca sativa var. capitata: lettuce, green lettuce, butter lettuce, head lettuce (Austria)
• Family: Asteraceae (Asteraceae)
• Distribution: Originally probably in the Mediterranean region and the Near East, only since the early Middle Ages in Central Europe, today cultivated worldwide
• Plant parts used: lettuce head (leaves)
• Ingredients: Water (95%), vitamins A, B 1 / 2 / 5 / 7 / 9 and 12, C, D, E and K, minerals (calcium, potassium, magnesium, phosphorus and sodium) trace elements (iron and zinc) , bitter substances (lactucin and lactucopicrin), phenolic acids, flavonoids, carotenoids, sesquiterpene lactones, chlorophyll, fiber / fiber
• Areas of application: reduce weight, prevent inflammation and diabetes, balance cholesterol

Lettuce – an overview

• Lettuce probably comes from wild lettuce (Lactuca serriola) – a steppe plant that also occurs in southern Europe.
• The fresher the better: Fresh lettuce contains more vitamins and other healthy nutrients than if it has been stored longer.
• The outer leaves of lettuce are often thrown away because the inner ones taste milder, sweeter and are crunchier. The valuable ingredients, however, are mainly in the outer layers of the leaves.
• Lettuce has very few calories and is high in minerals and vitamins.
• Lactuca sativa has a positive effect on digestion and is a suitable food for weight loss.
• Bioactive substances in lettuce have an anti-inflammatory effect, prevent diabetes and lower cholesterol levels.
• Lettuce is easy to grow yourself, but needs a location with full sunlight and does not tolerate acidic soil.

ingredients

Lettuce contains vitamins A, B 1 / 2 / 5 / 7 / 9 and 12, C, D, E and K. These are mainly found in the outer leaves; only five percent of the vitamins are in the heart leaves inside.

The plant provides a rich spectrum of minerals such as potassium, calcium, magnesium, phosphorus and sodium. In addition, lettuce contains trace elements such as iron and zinc, polyphenols (phenolic acids, flavonoids), the bitter substances lactucin and lactucopicrin, carotenoids, sesquiterpene lactones, chlorophyll and fiber.

However, the salad mainly consists of water with a proportion of around 95 percent.

As with fruit and other vegetables, the fresher the salad, the more nutrients it contains. The valuable ingredients are mainly contained in the outer layers of the leaves.

Medical effect

Potassium is an electrolyte and necessary for cell metabolism (maintenance of osmotic pressure). Cells cannot grow without potassium because this mineral is involved in the formation of protein and glycogen. Other body functions that require potassium include the transmission of nerve impulses for muscle contractions, heart functions and the regulation of blood pressure.

The milky juice of lettuce contains the bitter substances lactucin and lactucopicrin. These improve digestion in different ways and have a positive effect on intestinal health and regulate the feeling of hunger.

Since lettuce is also about 95 percent water and contains very few calories, it is well suited to a healthy diet to lose or maintain weight. At the same time, lettuce provides the body with fluids. Other important ingredients for the health-promoting effects of lettuce include fiber and bioactive substances such as vitamins and phenols.

A comprehensive review (2022), published in the journal Antioxidants, discussed in 2022: Lettuce has a high nutritional value due to its ingredients. In particular, the antioxidant compounds that counteract free radicals and oxidation processes in the body may have potential health benefits. They can promote protective functions for the heart, help fight cancer, and have positive anti-diabetes and anti-aging effects. It was recommended that further clinical investigations be carried out to analyze this potential in more detail.

Another review (2022) also concludes that Lactuca sativa is an important dietary source of many bioactive compounds and promotes human health. However, there are still gaps in knowledge regarding a complete understanding of the bioactive ingredients in different types of lettuce and their actual benefits to human health. The effects of pre- and post-harvest procedures have not yet been fully researched.

A 2016 review noted that studies have shown anti-inflammatory, cholesterol-lowering and anti-diabetic effects of Lactuca sativa, although the ingredients and therefore the effects vary between different types of lettuce.

Lettuce offers a variety of nutrients and bioactive substances that have positive effects on health. (Image: mae-mu/unsplash/own editing heilpraxis.de)

Lettuce against diabetes and obesity

Lettuce contains cellulose as an insoluble fiber that remains in the intestines longer and has a positive effect on digestion. Carbohydrates from the intestine enter the blood more slowly and the glycemic response is improved. This means that blood sugar levels rise more slowly after eating – this is particularly important in the diet of diabetics.

Eating salad before a main meal that is high in carbohydrates reduces the post-meal spike in blood sugar. The combination of extremely low calories and lots of fiber is useful for a diet. The intestines are kept busy, cravings are reduced and the feeling of hunger is generally regulated (also due to bitter substances). This eliminates the need to consume larger amounts of food during the main meal.

What characterizes lettuce?

Lettuce grows herbaceously on the surface and a long taproot forms underground. It has a strongly compressed shoot axis and at the same time large leaves. This way the leaves overlap each other and form a head of lettuce.

The lettuce leaves are wide and have a soft surface that appears oily. This is where the name “butter lettuce” comes from. When the flower is in bloom, the shoot axis grows upwards and many yellow flowers are formed.

Always wash lettuce

Lettuce accumulates nitrates from the soil. The nitrate itself is not a problem for humans, but can be converted into nitrite in the food if it is stored improperly or has problems with transport and common hygiene practices. Under certain circumstances, nitrate can also be partially converted into nitrite in the human body. Nitrite is considered a carcinogen in higher concentrations.

You can reduce this risk with freshly harvested lettuces from the field. When harvested, lettuce contains less nitrates if it is picked in the evening after a hot sunny day. Light and heat reduce the amount of the substance. Lettuce, along with rocket and lamb’s lettuce, is one of the salad plants that contain higher concentrations of nitrates than others.

In general, lettuce can contain residues of cadmium, mercury, lead and pesticides. That’s why you should always wash it thoroughly before consumption.

Lettuce leaves, both lettuce and other salad plants, often contain bacteria and other germs. Many of them cause diseases in humans: listeria, salmonella or Escherichia coli. Multi-resistant germs are also sometimes included, which get onto plants when fertilized with manure from industrial animal husbandry. Lettuce must always be washed thoroughly before consumption to avoid infection.

Where does lettuce come from?

The wild form of lettuce is a steppe plant common in southern Europe and western Asia, the wild lettuce or prickly lettuce (Lactuca serriola). Salad was already cultivated in ancient times and eaten by Egyptians, Greeks and Romans, for example.

Today it is grown all over the world. The most important growing countries are Central Europe, the Netherlands and the USA. Cultivation has been documented for around 6,500 years.

Red and green lettuce

There is green and red lettuce. The red color is caused by the flavonoid anthocyanin. This occurs particularly when there is strong and long-term exposure to the sun. That’s why red lettuce is particularly well known from sunny regions such as southern France.

Red-leaved lettuce also usually has a higher proportion of phenols, so it is considered healthier compared to green-leaved lettuce. Since environmental and storage conditions also have an influence on the ingredients and the studies on this are still sparse, this statement is not fully proven.

Buy and store lettuce

Lettuce is commercially available in sizes ranging from around 100 grams to around 500 grams, with outdoor lettuce usually being larger. Greenhouse lettuce is often sealed in foil to prevent evaporation and falling apart.

Lettuce from the local field is available from May to November. When fresh, it contains all the nutrients and vitamins.

Lettuce is delicate. Because it contains so much water, it reacts significantly to pressure, sun and heat. Without coolness and shade, the leaves quickly wilt and become limp. Freshly purchased lettuce that you do not use immediately should be wrapped in a damp cloth. Then the taste lasts.

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