If castor oil is a preferred ingredient in cosmetic formulation, it's because it possesses numerous benefits for the skin and hair. Can we, however, label this vegetable oil as a natural anti-inflammatory? That's the question we're addressing in this article.
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Castor oil, a natural anti-inflammatory?
Summary
Published August 23, 2024,
updated on October 4, 2024,
by
Pauline, Chemical Engineer
—
5 min read
An anti-inflammatory effect of castor oil?
The castor oil is a fatty substance derived from the seed of the plant Ricinus communis, commonly known as castor. Today cultivated worldwide, it is originally from Asia and tropical Africa. Organoleptically, the castor oil has a viscous and dense texture but nonetheless has good tissue absorption and is not considered comedogenic. This vegetable oil, rich in fatty acids, particularly ricinoleic acid, is best known for its hair benefits. It is also attributed with anti-inflammatory activity, which would come from its interesting biochemical composition.
Indeed, several studies have shown that oleic acid, found in castor oil, can inhibit the release of tumour necrosis factor alpha (TNF-α), as well as interleukins 1β and 6 (IL-1β and IL-6). These are pro-inflammatory cytokines, proteins that, as their name suggests, upregulate the body's inflammatory response. Furthermore, it has been shown on human monocyte TPH-1 cells that linoleic acid, also part of the composition of castor oil, could inhibit the effects of cyclooxygenases 1 and 2 (COX-1 and COX-2), enzymes catalysing the formation of prostaglandins. Just like pro-inflammatory cytokines, prostaglandins are chemical mediators contributing to the development of several inflammatory manifestations, such as vasodilation and pain.
The anti-inflammatory activity of castor oil doesn't stop there. It also appears that this botanical extract may suppress the activities of phospholipase A2 enzymes, some of which release arachidonic acid. Now, the metabolisation of this acid by a cyclooxygenase or a lipoxygenase leads to the formation of inflammation mediators such as prostaglandins and leukotrienes. Arachidonic acid can also act as a vasodilator, thereby exacerbating the redness and heat characteristic of an inflammatory reaction.
The anti-inflammatory effects of castor oil were evaluated on rats. Oedema in their paws was induced by injecting carrageenans, polysaccharides frequently used as triggers for the inflammatory response in experimental animal pharmacology. In some rats, castor oil was administered orally (250 mg/kg or 500 mg/kg) 30 minutes beforehand. In other animals, diclofenac, a non-steroidal anti-inflammatory drug, was used as a reference standard. The progression of the rats' paw volume was then monitored. The results are compiled in the table below.
| Group | Evolution of oedema after 60 minutes (mL) | Evolution of oedema after 120 minutes (mL) | Evolution of oedema after 180 minutes (mL) | Evolution of oedema after 240 minutes (mL) |
|---|---|---|---|---|
| Control | 0.37 ± 0.02 | 0.40 ± 0.01 | 0.38 ± 0.01 | 0.38 ± 0.01 |
| Castor Oil 250 mg/kg | 0.24 ± 0.001 | 0.19 ± 0.01 | 0.18 ± 0.01 | 0.15 ± 0.01 |
| Castor oil 500 mg/kg | 0.21 ± 0.004 | 0.17 ± 0.01 | 0.15 ± 0.01 | 0.14 ± 0.01 |
| Diclofenac 5 mg/kg | 0.16 ± 0.01 | 0.15 ± 0.01 | 0.13 ± 0.01 | 0.11 ± 0.01 |
Évaluation des effets de l'huile de ricin sur des œdèmes chez des rats
Source : VENKATARAMAN S. & al. Anti-inflammatory and free radical scavenging activity of Ricinus communis root extract. Journal of Ethnopharmacology (2006).
The results appear to suggest a certain efficacy of castor oil in reducing inflammation, comparable to that of diclofenac. However, this study presents two major limitations: it was conducted on rats and concerns the oral intake of vegetable oil. Thus, it is difficult to infer that the topical application of castor oil could reduce skin inflammation in humans, even though, according to some testimonies, it could be beneficial in soothing certain inflammatory skin conditions such as eczema. It is, however, important to note that the effects of the castor oil on eczematous skin have been very little studied to date.
The key takeaway:
Thanks to its rich biochemical composition, castor oil appears to have the potential to soothe inflammation. However, without clinical trials, it is difficult to assert this.
Sources
MANZINI S. & al. The Impact of Ricinoleic Acid on Acute and Subchronic Experimental Inflammation Models. Mediators of Inflammation (2000).
VENKATARAMAN S. & al. Anti-inflammatory and free radical scavenging activity of Ricinus communis root extract. Journal of Ethnopharmacology (2006).
PAULA ZURRON A. & co. Anti-inflammatory activity of polymer derived from Ricinus Communis. Brazilian Journal of Oral Sciences (2008).
KUMAR M. & al. A Review on Phytochemical Constituents and Pharmacological Activities of Ricinus communis L. Plant. International Journal of Pharmacognosy and Phytochemical Research (2017).
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