including in India and among people of the African diaspora. Hair oiling typically entails combing the hair, followed by applying oil from the roots to the ends about once a week prior to shampooing. Hair oiling daily or every other day, often with a hair braid, is also practiced, using coconut oil or other oils. Oil is found in various hair products and has been popular in the United States, particularly as hot oil treatments in the 1980s.
Dr. Naissan O. Wesley
Oils are used as part of Abhyanga massage, either by an Ayurvedic practitioner or as self-massage, as part of ancient Indian Ayurvedic medicine practice. The type of oil used is determined by the practitioner depending on the individual’s needs; cold-pressed sesame oil or coconut oil is often used as the base oil. Abhyanga is often performed with oil on the entire body as an act of self-care, which includes massage of the hair and scalp. The oil and herbs that are often added to the oil, as well as the scalp massage itself, are explained by practitioners as having therapeutic effects on the hair, including exfoliation of a dry scalp and on overall well-being. Outside of Ayurvedic medicine, hair oiling is also sometimes performed in India as part of routine hair care and can be a bonding experience among parents, grandparents, and children.
Amla oil, which is derived from Indian gooseberry (Phyllanthus emblica L.) and is often used in India on the hair, contains Vitamin C and has been shown to have activity against dermatophytes. In a study conducted in India, amla oil was found to have the most activity against Microsporum canis, M. gypseum, and Trichophyton rubrum, followed by cantharidine and coconut oil, while T. mentagrophytes was most susceptible to coconut oil, followed by amla and cantharidine oil.1 A study conducted in mice in Thailand found that 5-alpha-reductase was reduced with the dried form of the herb Phyllanthus emblica L, as well as with some other traditional Thai herbs used as hair treatments.2
Castor oil has been utilized in many cultures to promote hair growth. Ricinoleic acid, an unsaturated omega-9 fatty acid and hydroxy acid, is the major component of seed oil obtained from mature castor plants. It has anti-inflammatory and antimicrobial effects, and in one study,3 was found to inhibit prostaglandin D2, which has been implicated in the pathogenesis of androgenetic alopecia.4 Jamaican black castor oil is darker in color and has a more alkaline pH compared with traditional castor oil (both contain ricinoleic acid). To produce Jamaican black castor oil, the seed is roasted, ground to a thick paste, boiled in a pot of hot water, then the oil is skimmed off of the top into individual bottles, whereas regular castor oil is cold pressed. The alkalinity of Jamaican black castor oil may play a role in opening up the hair cuticle, which may be beneficial, but application also needs to be followed by a routine that includes closing the cuticle to avoid increasing hair fragility; such a routine could include, for example, leave-in conditioner or rinsing conditioner with colder water.
Castor oil is sometimes used on its own or in combination with other oils, and it is also an ingredient in some hair care products. However, publicly available peer-reviewed research articles demonstrating the effects of castor oil when applied directly to the hair and scalp for hair growth are needed.
Dr. Lily Talakoub
Different types of hair oils are used in African American hair care products and, worldwide, by people of the African diaspora as part of regular hair care and hair styling. Common oils include jojoba, coconut, castor, argan, olive, sunflower, and almond oils. Very curly hair often dries out more easily, especially in drier climates; and sebum build-up on the scalp does not occur as quickly, so hair typically does not need to be shampooed frequently. As such, over-shampooing also often dries the hair out faster, especially if hair has been chemically processed. Thus, oils help to coat and protect the hair, and smooth the cuticle. Oils themselves do not moisturize, but can seal moisture into the hair or act as humectants and draw moisture in. Rather than applying on dry hair, oils, when used as daily care as opposed to before shampooing, are often applied on clean hair after shampooing and after a leave-in conditioner has been applied to help seal in moisture for the most benefit. For treatment of scalp conditions, depending on the type of hair care practice performed at home, oils may be preferred over potentially drying solutions and foams if available, for optimum hair care.
Hair oiling is a long-standing practice which, when used correctly, can be beneficial for hair management and health. There are, however, caveats to hair oiling, which include being careful not to excessively brush or comb hair that has a lot of oil in it because the hair is slick, which can cause hair to fall out during combing. Some oils have elevated levels of lauric acid (coconut oil has 50%), which has a high affinity for hair proteins.5 While this can support hair strength, care should be taken not to overuse some oils or other products known as “protein packs,” which should be used as directed. Since hair is protein, excess protein build-up coating the hair can block needed moisture, making the hair more knotted and brittle, potentially resulting in more breakage with brushing or other hair care practices.
Some oil-containing hair products also contain artificial fragrances and/or dyes, which in some individuals, may promote an immunogenic effect, such as contact dermatitis. Certain oils, particularly olive oil, can promote an environment favorable to yeast growth, especially Malassezia species, implicated in seborrheic dermatitis. Practices that involve excessive application of oil to the scalp can also result in build up if not shampooed regularly. Sulfonated castor oil (also known as Turkey Red oil) has been reported to cause contact dermatitis.6
Dr. Wesley and Dr. Talakoub are cocontributors to this column. Dr. Wesley practices dermatology in Beverly Hills, Calif. Dr. Talakoub is in private practice in McLean, Va. This month’s column is by Dr. Wesley. Write to them at dermnews@mdedge.com. They had no relevant disclosures.