Leek, raw (organic?)

Leek ( Allium ampeloprasum var. porrum) is a healthy and aromatic vegetable, especially in organic quality. Raw leek stalks are available from local growers almost all year round.

Use in the kitchen

Leek, also called leeks, is popular in the kitchen as a vegetable or seasoning. Its taste is reminiscent of its relatives ( onions, chives and garlic), but it is milder and does not have a fully formed bulb or tuber. The low-calorie vegetable grows 60-80 cm high, with a distinctive white to light green stem made up of tubular leaves that grow together. ¹

What do you eat from leeks? Basically, all parts of the leek are edible. However, the root part is usually omitted when preparing the leek. Some people also discard the green part (= the leaves) when preparing dishes, as they taste a little more bitter/intense, and only use the white stem of the leek.

Can you eat leeks raw? All parts of the plant can be eaten fresh, raw or cooked. The general rule is: the younger the leek, the more tender it is. The older the leek plant, the darker and more fibrous its leaves become. Summer varieties have a milder taste and are therefore particularly suitable for eating raw. Winter leeks, with their fleshier, darker leaves, usually have a stronger and sharper taste and are used as a cooked winter vegetable.

The sulphur compounds contained in leeks give dishes a spicy note. It can be eaten raw in salads and with bread or used as a garnish. This preserves vitamins and other health-promoting ingredients.

The healthy vegetable goes well with vegan soups, stews, colorful vegetable side dishes, casseroles and quiches (also known in Germany as leek cake). If you like it spicy, try a hearty vegan leek omelette instead of muesli for breakfast. In summer, leeks even look good on the grill. As a soup green, leeks are a staple in the kitchen. Together with carrots, bulb fennel and parsley, you can easily make an aromatic instant soup seasoning or seasoning paste from them.

Vegan recipe for leek salad with apple

Ingredients (for 2 people): 1 raw leek (organic), 1 apple, 1 tbsp chopped hazelnuts, 100 g vegan sour cream, 2 tbsp lemon juice, ½ tsp mustard, 1 tsp agave or maple syrup, optionally 1 handful of fresh sprouts (e.g. alfalfa ).

Preparation: Remove the root and wilted leaves from the leek. Wash the apple and leek. To do this, cut the leek lengthways to the middle so that the different layers are well freed of sand and soil after washing. Cut the apple into small cubes and the leek into very fine rings. For the dressing, mix the vegan sour cream, lemon juice, mustard and agave or maple syrup well and season with pepper and salt. In a bowl, mix the dressing with the apple pieces and leek rings. Garnish with chopped hazelnuts and fresh sprouts. Serve the vegan raw vegetable salad with wholemeal bread, for example.

Vegan recipes with leeks can be found under the note: " Recipes that have the most of this ingredient ".

Shopping - Storage

Leeks are available at supermarket chains such as Coop, Migros, Denner, Volg, Spar, Aldi, Lidl, Rewe, Edeka, Hofer, Billa etc. usually all year round. A well-stocked market offers fresh leeks as individual leek stalks (in various sizes and weights). Sometimes, however, only the white, bleached part of the stalks is cut and packaged in the range. In combination with carrots and celery, leeks are available pre-portioned as soup vegetables. When you buy a leek, you can tell how fresh it is by its firm, deep green leaves without cracks or spots. The middle part of the stalk and the base of the roots should be white. If the leek is pre-cut, pay attention to the freshness of the cut parts. Make sure it is organic and buy fresh leeks in organic supermarkets (e.g. Denn's Biomarkt or Alnatura), at the weekly market, by buying directly from the farmer or in a subscription box.

The availability of leeks varies depending on the size of the store, catchment area, etc. Our recorded food prices for the DA-CH countries can be found above under the ingredient image - and by clicking you can see their development at different suppliers.

Storage tips

Fresh leeks are stored in the vegetable compartment of the refrigerator. They will keep for about two weeks there. The intense aroma of leeks can change the taste of delicate foods such as fruit or butter. If you have too much fresh leeks, they can be cleaned and pre-cut and frozen and kept in the freezer for up to 12 months.

Ingredients - Nutritional values - Calories

100 g of leek has an energy content of 61 kcal. The main nutrients consist on average of around 0.3 g fat, 1.5 g protein and 14 g carbohydrates. ² As with any unprocessed food, the nutrient content can vary due to natural fluctuations. (other databases assume an even lower energy value for leeks).

Particularly noteworthy is the vitamin K content (47 µg/100g), folic acid (64 µg/100g) and manganese (0.48 mg/100g). 100 g of fresh leek cover around 63% of the daily requirement of vitamin K, similar to bulb fennel (63 µg/100g) and pak choi (63 µg/100g). Particularly high levels of vitamin K can be found in fresh chard (830 µg/100g) and dandelion (778 µg/100g). ²

The amount of folate (precursor of folic acid, ex vitamin B₉, B₁₁) in 100 g of raw leek is around 64 µg, which corresponds to 32% of the daily requirement of an adult. Spring onions (64 µg/100g) and raw peas (65 µg/100g) have a similar folate content. Young spinach, which can be eaten raw as a salad, contains more folate. Raw spinach contains 194 µg per 100 g, which covers 97% of the daily requirement. ²

Is leek an important source of vitamin B₆ or vitamin C? Eating 100 g of raw leek covers around a quarter of your daily requirement of vitamin B₆ (0.23 mg/100g) and vitamin C (12 mg/100g). However, the foods richest in vitamin C include raw kale (120 mg/100g) and yellow bell peppers (184 mg/100g). ² You can read about higher vitamin C levels in organic leeks in the chapter on cultivation and harvest.

You can find the complete ingredients of leek, the coverage of the daily requirement and comparison values with other ingredients in our nutrient tables. In the article Nutrients explained you will get a detailed insight into the topic.

Health effects

Is raw leek healthy? The health effects of leek are due to the secondary plant substances it contains.

Secondary plant substances

Our article on secondary plant substances provides an overview of the classification of substance groups, their occurrence in foods and possible effects on humans. Leeks contain the following secondary plant substances:

• Isoprenoids: Steroidal saponins (neoporrigenins A and B, yayoisaponins A, B and C, agigenin, diosgenin, beta-chlorogenin, 24-ethylcholesta-(6-acyl)-3-O-β-D-glucoside), carotenoids ²⁸
• Polyphenols: Phenolic acids: hydroxybenzoic acids (gallic acid, protocatechuic acid, dihydroxybenzoic acid, vanillic acid, syringic acid), hydroxycinnamic acids (chlorogenic acid, rosmarinic acid, sinapic acid, ferulic acid, caffeic acid); Flavonoids: flavonols (quercetin, rutin, quercetin glucoside, kaempferol, kaempferol glucoside, myricetin), flavones (apigenin, luteolin), flavanones (naringenin); Tannins: proanthocyanidins, condensed tannins ^3,8,27,28
• Organic sulfur-containing compounds: sulfoxides (S-methyl-cysteine sulfoxide, S-propyl-cysteine sulfoxide, S-propenyl-cysteine sulfoxide, N-(γ-glutamyl)-S-(E-1-propenyl)-cysteine); Sulfides (isoalliin, methiine, propiine, dimethyl disulfide, methyl propenyl disulfide, propyl propenyl disulfide, dimethyl trisulfide, methyl propyl trisulfide, methyl propenyl trisulfide) ^3,27,28
• Other organic compounds: Hydroxycarboxylic acids (malic acid, oxalic acid, glutamic acid, citric acid, succinic acid) ²⁸

However, it should be noted that the composition of secondary plant substances in leek can vary depending on the variety, time of harvest and growing conditions. Therefore, quantities are only of limited use and should only be understood roughly.

The steroidal saponins and carotenoids contained in leek exhibit antimicrobial activity. ²⁸ Carotenoids are known for their antitumor, antidiabetic, anti-aging and anti-inflammatory properties.

Leeks have a particularly high polyphenol content. Studies have shown that the phenol content in the green leaves of the leek is higher than in the white parts. ⁸ The polyphenols contained in leeks have a strong antioxidant effect and protect the heart and blood vessels. Leeks show significant antioxidant and radical-scavenging properties due to the presence of phenolic acids and flavonols, especially rosmarinic acid and quercetin. Ethanolic extracts of leeks also show effective antimicrobial activity against various gram-positive and gram-negative bacteria and fungi in in vitro tests, especially Staphylococcus aureus, Bacillus subtilis and Aspergillus niger. ³

Leeks contain significant amounts of the flavonoid kaempferol. It is one of the antioxidants that protect our cells from free radicals (oxidative stress) and has anti-inflammatory properties. ⁹ Foods rich in kaempferol are associated with a reduced risk of developing some types of cancer, including skin, liver and colon cancer. ^9,10 Studies have shown that it significantly inhibits the growth and angiogenesis of cancer cells and induces apoptosis (programmed cell death) of cancer cells. Kaempferol appears to preserve the viability of normal cells and in some cases has a protective effect. ¹¹

Leeks also contain plenty of cysteine sulfoxides, which have antidiabetic and antioxidant effects. ²⁷ The medicinal properties of leeks are mainly due to the sulfur compounds that are responsible for the aromatic smell and taste of leeks. They have strong antibacterial and antifungal effects. ^3,27 Leeks mainly contain isoalliin and methiin, while alliin and propiin are present in trace amounts. ²⁸ The main focus of research is allicin. This is produced when onion and leek plants are cut or damaged from a chemical reaction between the amino acid alliin and the enzyme alliinase. ⁴ The resulting allicin not only serves plants as a defense mechanism against soil-dwelling pathogens such as fungi and microorganisms. In addition to the effects mentioned, allicin is also said to help against certain viruses and parasites. ⁵

Allicin is therefore considered a natural antibiotic and is even effective against antibiotic-resistant strains such as Staphylococcus aureus (MRSA). ⁴ In cancer research, allicin and other ingredients from leek and onion plants are also considered promising in the fight against cancer cells and as a health-promoting preventive measure. ^6,7

Epidemiological studies show that a higher consumption of alliums such as garlic, onions, wild garlic and leeks has a cancer-preventing effect through mechanisms such as inhibition of mutagenesis, modulation of enzyme activities, suppression of the formation of DNA adducts, scavenging of free radicals and influences on cell proliferation and tumor growth. One study found that garlic and onions block the formation of carcinogens better than the milder-tasting leeks. ⁷

Hydroxycarboxylic acids promote secretion in the gastrointestinal tract through their astringent effect. Thermal processing tends to reduce the content of polyphenols, sulfur compounds and carotenoids and has a negative effect on antioxidant activity. ²⁸

Dangers - Intolerances - Side effects

Cases of food allergies to leeks have only been described in isolated cases. Occasionally, inflammation of the nasal mucosa (rhinitis), conjunctivitis or swelling of the eyelids can occur. Cross-reactions with close relatives of leeks (such as onions, garlic, chives) do occur. ¹²

Like other alliums, leeks can cause flatulence. To avoid this, sensitive people should only eat small amounts of raw leeks, steam them briefly before eating them, or season them with caraway seeds.

Ecological footprint - animal welfare

In 2019, the Institute for Energy and Environmental Research Heidelberg ( ifeu) examined almost 200 foods in Germany for their environmental impact. The calculation of the ecological footprint is based on average values for agricultural production (including all upstream processes, such as fertilizer production), food processing, packaging (including disposal of the same) and distribution to the supermarket. Different cultivation methods (organic - conventional), domestic production vs. import by truck, ship or plane, etc. were also taken into account. For selected foods, the authors also point out the phosphate, water and land consumption. Leeks perform very well with 0.2 kg CO ₂ equivalents (CO ₂ eq for short) per kg. ¹³

Another positive aspect for the environmental balance is the possibility of growing leeks outdoors almost all year round. ¹⁹ In general, regional and seasonal fruit and vegetables are more climate-friendly than imported goods (the impact of air transport is particularly large), processed foods or vegetables from heated greenhouses. ¹⁴ For example, winter tomatoes from greenhouses in Germany have an impact of 2.9 kg CO ₂ eq/kg, whereas seasonal, regional tomatoes generate only 0.3 kg CO ₂ eq/kg and a much smaller _carbon footprint. ¹³

In conventional agriculture, synthetic pesticides and herbicides are generally used to combat unwanted insects and plants. However, these are often found in the end product, as a study of various types of fruit and vegetables by the Pesticide Action Network Europe shows. Residues of certain pesticides were also found in leeks. ²⁴ Ideally, you should buy leeks from organic farming, as the use of such products is prohibited there. In addition, this method of growing leeks has a better ecological balance: the savings in pesticides reduce emissions. ²⁵

For detailed explanations of various sustainability indicators (such as ecological footprint, _CO2 footprint, water footprint), see our article: What does the ecological footprint mean?

Animal protection - species protection

Although Allium plants are very healthy for humans, they are poisonous for dogs and cats (raw, cooked, dried and in powder form!). ²⁶

Worldwide occurrence - cultivation

According to Vavilov (1926), the primary genetic center of the leek is the Middle East (and the Mediterranean basin), while a more recent study suggests that cultivated forms originate from Asia Minor. ¹⁶ Today, Indonesia and Turkey produce the largest quantities of leek worldwide. ¹⁸ In addition, it is mainly grown in Western Europe and (to a lesser extent) North America. In Europe, France and Belgium are the main producers. ¹⁷

Wildly found

Field leek ( Allium ampeloprasum), from which the cultivated varieties of leek probably originated, can still be found in the wild in southern Europe, North Africa and the Middle East (native); as well as in North and South America and Australia (introduced). ¹⁵

Cultivation - Harvest

In Switzerland, Austria and Germany, leeks are grown both in conventional and organic farming and mostly outdoors. Depending on the growing season, a distinction is made between summer leeks, cultivated in the warm months, and autumn or winter leeks, which still grow even in snow and frost. ¹⁹ Due to the large variety of varieties, leeks are suitable for easy cultivation in your own garden almost all year round. They love nutrient-rich, deep soils and are heavy feeders. In order for the plants to develop long, white stems, they need to be covered with soil several times during the growth phase. ¹ Direct sowing in the field is possible; for early cultivation, heavy soils and in organic farming (due to weed pressure), pre-cultivation of young plants is more effective. The use of close-meshed crop protection nets is essential, especially in organic farming, to combat well-known pests such as thrips and the leek leaf miner. ¹⁹ In your own garden you can experiment with plant manure and mixed culture with odorous plants such as carrots, celery, dill, fennel, chamomile, lavender or parsley.

Leeks have a relatively long cultivation period; depending on the variety and the time of year when they are grown, they can be harvested after five to eight months. ²⁰

If you have planted summer leeks in your own garden, you should dig them up with the roots for storage before the first frosts. In a frost-free cellar or cool, dark storage room, the leeks will stay fresh for a long time in sand boxes. To do this, line the leeks up close to each other and cover the roots well with moist sand ("pack them in"). Since leeks are sensitive to the ripening gas ethylene, you should ensure that you store leeks and fruit separately. ²⁰

Most winter leek varieties are very frost hardy, they can often be left in the field over the winter and harvested fresh until spring as needed. ²¹

A field study conducted in Russia compared yield, quality and ingredients such as antioxidants between organically and conventionally grown leeks. In addition to major differences between varieties, it was found that the dry matter, sugar content and potassium content are higher in organic farming, while the nitrate concentration increases in conventional farming. The farming method had no influence on the yield, although the trial cultivation was carried out in greenhouses. Among the antioxidants, ascorbic acid (vitamin C) achieved higher values in organically grown leeks. Particularly interesting is the significant positive correlation found between ascorbic acid and polyphenol concentrations in the leek stems. The choice of variety and the cultivation method therefore have an influence on the content of antioxidants, which play an important role in health. ²²

Further information

Leek belongs to the genus Allium in the subfamily Allioideae. Several synonyms are used, including Allium porrum ^3,17 or Allium ampeloprasum ampeloprasum Porrum Group (or Leek Group).

Alternative names

In Switzerland and now also in large parts of Germany, the term leek is common. In the more rural northwestern and eastern Germany, people have stuck with leeks (from Old French, see also Latin porrum, porrus). Of the small-scale variants, only the name borage/poretsch has been retained in the Valais. ²³ In Austria, depending on the region, the term leek is also common. Leeks are also known as broad leek, winter leek, Welschzwiebel, common leek, Spanish leek, ash leek or meat leek. In English, it is called leek.