Neem oil is a vegetable oil pressed from the fruits and seeds of the neem, an evergreen tree which is endemic to the Indian subcontinent and has been introduced to many other areas in the tropics. It is the most important of the commercially available products of neem for organic farming and medicines.
Neem oil varies in color; it can be golden yellow, yellowish brown, reddish brown, dark brown, greenish brown or bright red. It has a rather strong odor that is said to combine the odors of peanut and garlic. It is composed mainly of triglycerides and contains many triterpenoid compounds, which are responsible for the bitter taste. It is hydrophobic in nature; in order to emulsify it in water for application purposes, it must be formulated with appropriate surfactants.
The oil can be obtained through pressing (crushing) of the seed kernel both through cold pressing or a process incorporating temperature controls. Neem seed oil can also be obtained by solvent extraction of the neem seed, fruit, oil, cake or kernel. A large industry in India extracts the oil remaining in the seed cake using hexane. This solvent-extracted oil is of a lower quality as compared to the cold pressed oil and is mostly used for soap manufacturing. Neem cake is a by-product obtained in the solvent extraction process for neem oil.
Neem oil has been used for hundreds of years in controlling plant pests and diseases. Neem oil also works as a fungicide and helps control powdery mildew. Some people have also experienced good results with neem oil spray on black spot. As neem is very bitter in taste, it also works as an antifeedant thus making the leaves sprayed with it very distasteful for the bugs to eat and the bugs choose to starve themselves than eat the leaves treated with neem. Neem oil is bio-degradable and has proven to be non-toxic to mammals, birds, bees or earthworms. It is biodegradable and breaks down easily and quickly. Neem has also proven to be not harmful to adult beneficial insects, since it primarily affects only plant sap-sucking insects, which feed upon the treated plants. However it is recommended that care should be taken not to spray neem oil solution when honey bees and the larvae of beneficial like ladybugs, etc. are present. Neem oil spray like any other oil spray can also burn leaves if sprayed in sun.
Uses:
Neem oil is not used for cooking purposes. In India, it is used for preparing cosmetics (soap, hair products, body hygiene creams, hand creams) and in Ayurvedic, Unani and folklore traditional medicine, in the treatment of a wide range of afflictions. The most frequently reported indications in ancient Ayurvedic writings are skin diseases, inflammations and fevers.
Neem oil can be added to regular shampoo for controlling itchy scalp and dandruff.
For pets, neem oil can be added to pet shampoo to kill ticks and fleas or the area where the pets usually use can be treated with neem oil spray.
Neem oil should only be used externally on the skin and has been therapeutically used as folk medicine to control respiratory disorders, constipation, leprosy, as well as a general tonic. It has been used for the topical treatment of rheumatism, eczema, ringworm, athlete's foot, cold sores, psoriasis, warts, chronic syphilitic sores, infected burn wounds and slow-healing skin ulcers as well as controlling various skin infections.
It has anti-inflammatory, antipyretic (relieving fever) and analgesic (relieving pain) activity and possesses immunostimulant activity (increasing the body’s defense mechanism to fight infectious organisms and other foreign material) by selectively activating the cell-mediated immune mechanisms to elicit an enhanced response to subsequent mutagenic or antigenic challenge.
Application of Neem oil on the hair has been shown to kill head lice. A study was also done on various forms of cancer and tumors – and although the results were promising, this application needs more investigation.