Saturday 13 June 2015

The Walnut Tree

The walnut tree (Juglans sp.) is a large deciduous tree which originates from south eastern Europe and western Asia. It has been introduced to many countries, including Britain, where it can be found growing wild, or is often grown for its fruit or ornamental value. The leaves of the walnut three are ovate to elliptical alternate green leaves, and the tree contains a smooth bark. In the late spring, the walnut tree produces male catkins and female flowers, the latter being small and inconspicuous. Fertilisation produces a green succulent drupe that contains a hardened nut that we know as the walnut. The outer green pericarp of the fruit and the leaves can both be used medicinally. The leaves and fruit contain tannins, organic acids, essential oils and bitter compounds such as juglone. The medicinal properties of the fruit and leaves include anti-inflammatory, antispasmodic and sedative properties. This makes extracts of the fruit and leaves useful in treating digestive disorders of the stomach and intestines. The leaves and fruits can also be used topically on the skin.
Figure 1. The walnut tree. Picture taken from: Stodola, J., Volak, J. and Severa, F. 1984. Illustrated Book of Medicinal Herbs. Octopus Books, London. First edition.

The nut of the walnut tree also possesses medicinal properties. The nut is a rich source of protein and fibre, and is also rich in the essential fatty acid alpha linolenic acid (ALA, C18:3 (n-3)). Alpha linolenic acid is essential to human health because it is used to synthesise a range of short lived chemicals called eicosanoids that regulate cells function. The eicosanoids synthesised from alpha linolenic acid have particular effects against inflammation, platelet adhesion and may be required to enhance immune function. The polyunsaturated fats in the walnut seed constitute a large proportion of the energy it contains, but much of this energy is never absorbed in humans. This is because the nutrients in the seed are contained within tough parenchymal cells walls that are indigestible to human enzymes. Most cells that survive the crushing action of the teeth are therefore immune to digestion and as such do not contribute to the energy needs of the individuals. The walnut seed also contains ellagic acid, along with other phytochemical antioxidants, in addition to high concentrations of vitamins and minerals.

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