For many centuries folk lore medicine has recommended the use of castor oil, either orally or transdermally for a wide range of complaints. Naturopaths and other practitioners continue to utilise its therapeutic potential for the management of the health of their clients and patients.
When confronted with the request for topical application by their health care provider many people will baulk and wonder why they should cover parts of their torso with the sticky oil – whilst blandishments may placate many, I felt that a dive into the literature to see what was currently understood about its purported mechanisms of action there were and how we might translate that alongside our therapeutic considerations.
Castor oil has many potential uses but the most common reasons for considering its application are:
- Gas and bloating
- Fibrocystic breasts
- Skin tonification
Castor oil is made from the plant Ricinus communis (castor bean). It has been used since ancient Egyptian times internally as a cathartic (stimulating laxative) and to induce labour. Topically, it has been used as a wound healer, anti-inflammatory agent, detoxifier, immunomodulator and has been found helpful in gastrointestinal complaints.,
The precise mechanisms of action for this remarkable plant have not been fully elucidated. Most of the traditional uses come from folk medicines and word of mouth in certain traditions around the world. ,,
What is known is the main component is considered to be ricinoleic acid (RA), which exerts analgesic and anti-inflammatory effects. Pharmacological characterisation has shown similarities between the effects of RA and those of capsaicin, suggesting a potential interaction of this drug on sensory neuropeptide-mediated neurogenic inflammation. It is thought to be effective in constipation via ricinoleic acid (RA), which constitutes 90% of castor oil, can bind to VR1 receptors and according to the literature acts to reduce straining.,
Members of the vanilloid receptor family (TRPV) are activated by a diverse range of stimuli, including heat, protons, lipids, phorbols, phosphorylation, changes in extracellular osmolarity and/or pressure, and depletion of intracellular Ca2+ stores. However, VR1 remains the only channel activated by vanilloids such as capsaicin. These channels are excellent molecular candidates to fulfil a range of sensory and/or cellular roles that are well characterised physiologically. Furthermore, as novel pharmacological targets, the vanilloid receptors have potential for the development of many future disease treatments.
A leading theory of how it positively affects the immune system is via T-cells in the skin and augmentation of prostaglandins. The T-11 (or CD2) antigen is an alternate pathway for antigen-independent activation of resting T cells. The respective cell increase represents a general boost in the body’s specific defense status. Lymphocytes actively defend the health of the body by forming antibodies against pathogens and their toxins. T-cell lymphocytes originate from bone marrow and the thymus gland as small lymphocytes that identify and kill viruses, fungi, bacteria, and cancer cells. T-11 cell lymphocytes supply a fundamental antibody capability to keep the specific defense system strong. The skin T-cell theory postulates that the absorption of castor oil into the skin triggers T-Iymphocytes embedded in the skin, causing them to activate a local and/or generalized immune reaction. ,
A well written and referenced review by Drs. Kennedy and Keaton, go into further detail in their April 2012 article titled, Evidence for the Topical Application of Castor Oil. Here they refer to a study in which 17 patients with fatigue were enrolled in a trial and “during the course of treatment, the mean total lymphocyte counts normalised within the group and were lower at the end of treatment vs. baseline. As an unexpected outcome, 2 participants with elevated liver enzymes and cholesterol levels normalised these variables by the end of the study.” Bit of an NAFLD link here?
It is known that transdermal absorption occurs, given that castor oil is fat soluble, but the exact biochemical pathway is not understood.
As this review has indicated, castor oil is of potentially high therapeutic value, with low odour, low side effect, low risk profile that is highly underutilised in today’s modern medical world.
The level of evidence for applicability from some of the published basis is weak, but what does exist suggests numerous explanations and extremely low risk to the individual applying the treatment. I personally have prescribed this to hundreds of patients for all of the reasons discussed in this article and have found profound therapeutic benefit in all capacities.
 McGarey, William A. The Oil That Heals: a Physician’s Successes with Castor Oil Treatments. Virginia Beach, VA: A.R.E., 1993
 Schmidt RE, et al. T11/CD2 activation of cloned human natural killer cells results in increased conjugate formation and exocytosis of cytolytic granules. J Immunol. 1988 Feb 1;140(3):991-1002. (View Abstract).