Neem oil is cold pressed or solvent-extracted from the seeds and fruit of Azadirachta indica, an evergreen species of tree native to India and South Asia. Unlike many other vegetable oils, neem oil is reserved for cosmetic use and is not used for culinary purposes. The oil is also used as an organic pesticide and in medicine to address a variety of disorders ranging from fever to acne. One traditional use of neem oil is to counter inflammatory skin conditions such as psoriasis.
Neem Oil Properties
Neem oil has a strong aroma reminiscent of rancid garlic, although it's also been described as smelling like stale peanut butter, burnt hair, onions boiled in coffee or spoiled Chinese food. In terms of color, the oil can range from a golden color to dark brown. Although neem oil is an abundant source of several fatty acids and is likely nutritious, the presence of various triterpenoid compounds imparts a very bitter taste.
Many traditional remedies used in Ayurvedic medicine contain neem extracts or neem oil. In fact, neem is so highly valued in Indian medicine that the tree has been dubbed "the village pharmacy." The oil is administered orally or topically as a contraceptive, pain and fever reducer, diuretic and antiseptic. It is also considered a traditional remedy for malaria, tuberculosis, tetanus infection, fungal and bacterial infections of the skin, hives, scabies, eczema and psoriasis.
As a cosmetic agent, neem oil is added to skin lotions, creams, salves and soaps. It is also found in hair care products.
More than 100 chemical compounds have been identified in neem oil. According to the "Physicians' Desk Reference for Herbal Medicines," neem oil contains several steroids, namely campesterol, beta-sitosterol and stigmasterol. The oil also contains triterpenoid saponins, the most significant of which is azadirachtin. This phytochemical is classified as a limonoid, the same type of agent that lends antibacterial and antiviral properties to many citrus fruits.
The PDR attributes azadirachtin with anti-inflammatory and antipyretic properties, the latter literally meaning to "put out the fire." In terms of proof of the effectiveness of neem oil in treating psoriasis specifically, the evidence is more anectodal than scientific. In addition, it should be noted that there is no cure for psoriasis, only management strategies.
However, the anti-inflammatory properties of azadirachtin, the active ingredient in neem oil, have been established. For instance, in 2009, scientists from Nihon University in Tokyo reported in the "Journal of Oleo Science" that 31 limonoid compounds isolated from neem demonstrated significant anti-inflammatory activity in mouse skin. A subsequent study published in the Feb. 19, 2010 issue of the "Journal of Biological Chemistry" showed that azadirachtin promotes an anti-inflammatory response in human skin cell lines by blocking the expression of certain enzymes involved in producing inflammation, such as cyclooxygenase 2.
Safety of Use
Generally speaking, neem oil is not associated with toxicity, even if taken internally. However, since neem oil is traditionally used as a contraceptive in Ayurvedic medicine, it may impair fertility or promote spontaneous abortion. Therefore, do not use neem oil if you are pregnant or trying to conceive. In terms of treating psoriasis, topical use is the safest and most effective mode of application.