What are the benefits of the hazel tree (Corylus avellana)?

The common hazel, Corylus avellana, also known as the European hazel, is a fast-growing deciduous shrub belonging to the Betulaceae family. Corylus is derived from the Greek Korus, meaning ‘helmet’, referring to the shape of the cupules that surround the hazelnut. Avellana refers to the hazelnut and alludes to the Italian town of Avellino, where hazel trees were planted and grew in abundance. The genus Corylus comprises around fifteen species. Its origins are ancient, and traces of it can be found as far back as the Tertiary period. Corylus avellana became a dominant species in Europe around 9,000 years ago. The common hazel is cultivated in many countries, particularly in Turkey. It is a shrub 3 to 8 metres tall, which tends to produce suckers to varying extents; it is found in temperate regions and grows wild in the undergrowth or on the forest edge. Its roots are unique in that they live in symbiosis with truffles. The hazel has a bushy, spreading habit, often with several trunks arising from the base. When young, its bark is smooth, marked with pale lenticels; it cracks with age. The colour of the trunk varies from grey-brown to coppery brown. Its young branches are often downy. Its green, deciduous leaves are alternate, heart-shaped, with double-serrated margins. They turn yellow in autumn. It flowers early, from January to March, even before the leaves appear. The species is monoecious: it bears both male and female flowers on the same tree. The male flowers, or catkins, appear before the female flowers. The catkins are long and pendulous, resembling caterpillars and reaching lengths of 5 to 10 cm. They are composed of numerous male flowers clustered in spikes. In spring, they turn yellow before releasing their pollen. The female flowers are more inconspicuous and appear as small red buds. The fruit is well known, as it is the hazelnut. It grows in small clusters called ‘trochets’, consisting of two or three fruits. Its shell is hard, ovoid and green in colour; it dries out when ripe.

Hazelnuts are harvested in September–October. The hazel is a very hardy shrub that adapts to various soil types, although it prefers calcareous, well-drained soils. It tends to form dense coppices, making it a useful plant for soil stabilisation and the creation of hedges. Its wood is flexible, light and relatively strong, with a fine grain and a light colour ranging from creamy white to light brown. It has traditionally been used for making wickerwork, as well as walking sticks and canes. Several parts of the plant are used for herbal medicine and offer numerous benefits.

The properties of the fruit and its oil

Hazelnuts are rich in monounsaturated fatty acids, protein, vitamins (E, A) and minerals (potassium, magnesium, copper). They are a good source of nutrients, rich in antioxidants, and have a positive impact on cardiovascular health and metabolic regulation. Regular consumption of hazelnuts or hazelnut oil is thought to affect the nervous system, dopamine pathways and behaviour, notably reducing anxiety and improving working memory. The light, easily absorbed oil, obtained by pressing hazelnuts, has a lipid profile that is highly valuable in cosmetics, being rich in monounsaturated fatty acids. Nourishing, softening and regenerating, it regulates sebum production and has healing properties. It is an ingredient of choice for the care of acne-prone, oily and mature skin, and for reducing scars and stretch marks. What’s more, it makes an excellent base for massages.

The properties of the leaves

Hazel leaves are rich in tannins, proanthocyanidins and a flavonoid called myricitrin. This gives the leaves astringent, haemostatic and anti-inflammatory properties. The leaves are therefore used externally to help stop minor bleeding and aid the healing of minor wounds. The leaves are also recognised for their febrifuge, vasoconstrictive and circulatory tonic properties. When taken internally, the leaves are therefore used to treat disorders of the venous system, to reduce fever or to alleviate diarrhoea.

The properties of the bark

Hazel bark possesses similar benefits to the leaves, with astringent and febrifuge properties. Taken internally, the bark has long been used to reduce feverish conditions. Applied externally, it is used to promote healing.

The properties of the catkins

Hazel catkins possess diaphoretic properties, meaning they induce sweating. They are also traditionally recognised for their detoxifying properties. Catkins are rich in protein—accounting for up to 20 per cent of their composition—and in essential nutrients such as calcium, magnesium, silicon, phosphorus and potassium. They also contain vitamins B1, B2 and E, as well as unsaturated fatty acids. They can be eaten pickled or dried and ground into a flour used in various culinary preparations.

The hazel tree is a plant with multiple uses, both medicinal and nutritional. Its leaves, bark and nuts offer several benefits recognised in herbal medicine. It...:

• Promotes blood circulation and helps relieve heavy legs

• Has astringent properties, useful for mild diarrhoea or a sore throat

• Supports respiratory health thanks to the expectorant properties of its leaves

• Is beneficial for the heart and skin, hazelnuts are rich in unsaturated fatty acids, vitamin E and minerals

The buds are used in gemmotherapy for their draining and balancing effects, particularly on the liver and lungs.

1. As a herbal tea: dried hazel leaves can be steeped (1 tablespoon per cup of simmering water, for 10 minutes) to soothe circulatory problems, inflammation of the respiratory tract or as a venous tonic. Drink 1 to 3 times a day.

2. In cooking: Hazelnuts, from the hazel tree, are delicious whole, puréed or chopped into sweet or savoury dishes. They provide high-quality fatty acids, fibre, magnesium and antioxidants. Ideal as a snack or in baking. Hazelnut oil can also be used in cold dishes or for gentle cooking to add its distinctive flavour.

3. As a dietary supplement: the hazelnut tree is available in the form of bud macerates in gemmotherapy, often used for lymphatic drainage, chronic respiratory problems or liver imbalances. Always follow the recommended dosages.

4. In cosmetics: hazelnut oil is light, easily absorbed and non-comedogenic, making it ideal for combination to oily skin. It regulates sebum, softens the skin and prevents dehydration. It is found in many face care, hair care and massage products.

Balancing and soothing, this cosmetic- and food-grade oil has a non-greasy, quick-absorbing texture, making it ideal for preparing skincare products for oily and acne-prone skin. Its pleasant texture makes it a top choice for creating massage products.

The hazel tree has no major contraindications when used externally or as a leaf infusion, but its fruit, the hazelnut, is a common food allergen. People with nut allergies must avoid consuming it and check for the presence of hazelnut oil or extracts in cosmetics.

Native Americans used to make necklaces from young hazel twigs to relieve toothache in newborns. This ancient practice bears witness to traditional beliefs surrounding the soothing and protective properties of the hazel tree.

Catherine is passionate about plants and their properties. She studied natural cosmetics at the École Lyonnaise des Plantes Médicinales in the early 2000s. Driven by curiosity, she has continued to explore the richness and potential of plants. This led her to train in aromatherapy at the École Française d’Aromathérapie Intégrative. She discovered an almost unexplored world in olfactotherapy, and valuable tools for getting to know herself better and practising what she calls inner ecology.