phytochemicals Phytochemicals

More plants with phytochemicals



Corylus avellana

What is hazelnut?

The hazelnut is a shrub or small tree reaching up to 8 meter. The round leaves are deciduous, hairy on both sides and with shallow-toothed edges. The female and male flowers are formed in early spring. The male catkins are 5 to 10 cm long whereas the female flowers are very small and hidden in a green bud. The hazelnuts ripen in autumn. They are spherical to oval and 15 to 25 mm large. The hazelnut kernel has a dark brown skin with a bitter taste but containing many phytochemicals.

Parts used

The kernels and skin of the hazelnut nuts are consumed as a food. Medicinal extracts are traditionally made from leaves and bark. Other parts such as the hard shell and green leafy cover of the hazelnut contain significant amounts of phytochemicals and could be used as a cheap industrial source of antioxidant extracts.


These are typical phytochemicals found in hazelnut: the leaves and bark contain mainly hamamelitannin and proanthocyanidins as active phytochemicals. the hazelnut kernel contains following phytochemicals: 3-caffeoylquinic acid, 5-caffeoylquinic acid, p-coumaroyltartaric acid, myricetin, quercetin, gallic acid, kaempferol.

Benefits of hazelnut

Most scientific studies on hazelnuts have been focussed on their effect on heart health. One study showed a protective effect on cataract induced by the chemotherapeutic drug doxorubicin.

Heart health

Many studies have confirmed the link between the consumption of hazelnuts and nuts in general and improved heart health. Frequent consumption of nuts is associated with favourable plasma lipid profiles and reduced risk of coronary heart disease. A study published in the June 24, 2002 edition of the Archives of Internal Medicine, concluded that eating nuts regularly could lower your risk of sudden cardiac death. The researchers found that men who consumed nuts twice or more in a week had a 47 percent lower risk of sudden cardiac death than those who rarely or never consumed nuts. Another study published in the October 2004 edition of Bioscience, Biotechnology, and Biochemistry showed that the feeding of hazelnut oil reduces oxidative stress and cholesterol accumulation in the aortas of rabbits.


Atilla Bayer and collogues, who did many studies on the health benefits of hazelnuts, found that low doses of hazelnuts prevented cataract formation in rats. The cataract was induced by the administration of the chemotherapeutic drug doxorubicin. This protective effect of hazelnuts is probably due its antioxidants such as vitamin E and other phytochemicals.

Traditional use

Extracts from the bark or leaves are traditionally used to treat many conditions. Externally it is used to treat skin irritations, sunburn, diaper rash, scalds, bedsores, eczema and insect bites. Internally a tea can be used to relieve sore throat or diarrhea.

Other facts

The Hazelnut tree is deciduous to Europe and Asia. The Hazelnut tree is very common in hedgerows all over Europe and prefers damp soil. The hazelnut is cultivated for its nuts in orchards mainly in Turkey but also in USA, Italy and Caucasus. Hazelnuts are used as ingredient in confectionery products such as pralines, torts and chocolate paste.

Other names

Common hazel

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