Walnut
Juglans regiaJuglone released into the soil from walnut roots and leaves stops other plants growing; this is why tomatoes struggle under a walnut tree.
What is Walnut?
Walnut (Juglans regia) is a plant of the Juglandaceae family. Traditions that use it: Anatolia and the Mediterranean, Asia and Siberia. Part used: kernel, leaf, green husk.
What is Walnut used for?
Traditional use: Green husks and leaves give a brown dye for wool and carpets and are rubbed into hair with henna to darken it. Scientific evidence: clinical. The nut itself is well studied: a meta-analysis of controlled trials (2018) showed that eating walnuts regularly lowers total and LDL cholesterol.
Is Walnut safe?
Safety label: generally safe. A serious allergy risk for people allergic to walnuts. Juglone in the green husk stains skin brown and can irritate it. There are no safety data for drinking leaf tea in large amounts over long periods; not recommended in pregnancy.
Traditional use
Green husks and leaves give a brown dye for wool and carpets and are rubbed into hair with henna to darken it. Green walnuts are made into jam. Leaf tea is drunk in folk medicine for blood sugar and eczema.
Walnut leaf is one of the leading anti-diabetic herbs of Iranian folk medicine. In the Caucasus, walnut sauces and green walnut jam are kitchen staples.
In nature
Mix-up risk
Black walnut (Juglans nigra) is a different species with a thicker shell and a stronger-tasting kernel.
Preparation
A dessertspoon of dried leaf is steeped in a cup of water for 10 minutes, or boiled for an external compress. The kernel is eaten raw or roasted.
What science says
The nut itself is well studied: a meta-analysis of controlled trials (2018) showed that eating walnuts regularly lowers total and LDL cholesterol. Evidence for the leaf is weaker; the EMA recognises walnut leaf only for external traditional use in minor skin inflammation and excessive sweating. A few small studies have looked at leaf extract and blood sugar in type 2 diabetes.
Safety
A serious allergy risk for people allergic to walnuts. Juglone in the green husk stains skin brown and can irritate it. There are no safety data for drinking leaf tea in large amounts over long periods; not recommended in pregnancy.
Similar plants
Sources
- EMA monographJuglandis folium: European Medicines Agency herbal assessment
- ResearchEffects of walnut consumption on blood lipids and other cardiovascular risk factors: meta-analysis (Am J Clin Nutr 2018)
- ResearchWalnut (Juglans regia) leaf extract on glycemic control and lipid profile in type 2 diabetes: a systematic review (Clin Nutr Res 2022)
- BookBaytop T. Türkiye’de Bitkiler ile Tedavi: Geçmişte ve Bugün. 2. baskı. İstanbul: Nobel Tıp Kitabevleri; 1999.
- Botanical recordKew Plants of the World Online: Juglans regia
- Titles of research sources are summarised in Turkish on the Turkish page; links open the original English publications.
Written by Edanaz Tınmazlar · Last reviewed: · Türkçe