Karanja Seeds

Karanja is a medium-sized, fast-growing, semi-evergreen tree with glossy compound leaves and clusters of white to pink pea-like flowers. Its pods are flat, woody and smooth, usually containing a single kidney-shaped seed about 2 cm long, with a reddish-brown skin. The kernel is oily, bitter and strong smelling. Seeds are sold crushed for oil, as seed cake and, in Ayurvedic markets, as dried kernels or powder. The pressed oil is reddish-brown to yellow, with a pungent, disagreeable odour, and is not used as a cooking oil. The tree is often planted along roadsides and canals for shade, soil improvement and nitrogen fixation.

Pongamia pinnata is native to the Indian subcontinent and Southeast Asia, extending to parts of northern Australia, and is commonly found near coasts, riverbanks and in monsoon forests. It has been widely planted in the tropics for shade and as a source of oil. Karanja is the name used in Sanskrit and several modern Indian languages, and honge is the Kannada name. The genus name Pongamia is thought to be derived from a Tamil name for the tree, and pinnata describes its leaves, which are arranged like a feather. Botanists have sometimes placed it in Millettia, which accounts for the double naming in older literature.

Karanja has a long record in Indian traditional medicine, and ancient Sanskrit texts mention its bark, seeds, leaves and oil for skin conditions, wounds, and parasitic infestations. Village communities in India burned the oil in lamps and used the seed cake as manure and, in some cases, as a natural pesticide or fish poison. In colonial times the oil was recorded as lamp fuel and for soap, and the tree was planted widely along roads. Since the early 2000s, karanja has drawn interest as a non-edible oilseed for biodiesel, particularly in India, which has promoted tree-borne oilseeds to reduce reliance on imported fuel. Large plantations and farmer schemes were set up, though yields and economics have often fallen short of the early optimism. Research continues into improved varieties, and the species is also grown in Australia as a biofuel and soil-restoration crop. Today it is a common landscape tree in tropical cities and an item in Ayurvedic pharmacopeias.

Karanja oil is used in traditional medicine for external application to skin conditions, in soap and leather treatment, as lamp oil, and as a biodiesel feedstock. The seed cake serves as fertiliser, and, when detoxified, may be used in feed in research settings. In Ayurveda, the seeds, oil, bark and leaves are prepared in specific formulations by trained practitioners. The tree's leaves and branches are used as green manure, and the flowers attract bees, supporting honey production. Wood is used for fuel and small tools.

Laboratory studies on karanja extracts have reported antimicrobial, anti-inflammatory and antioxidant activity, and compounds such as karanjin and pongamol have been investigated. These findings come mostly from cell and animal studies and are not proof of benefit in humans. Traditional uses on the skin remain popular, but robust clinical trials are scarce. Karanja should not be seen as a food supplement, and any medicinal use is best discussed with a qualified practitioner.