Calendula as a healing oil?

According to studies conducted on animals, the calendula appears to contribute to the epithelial reconstruction process of wounds and accelerate the healing process, but what about in humans?

• A 2013 clinical study suggests that the use of analoe vera or calendula ointment, in addition to the standard hospital routine (Betadine), accelerates the healing rate of perineal wounds. In the study, women (n = 111) who used aloe vera or calendula ointment every eight hours for five days following anepisiotomy (a surgical procedure to widen the perineal muscles during childbirth) showed a reduction in symptoms, such as redness, swelling, and bruising. The addition of an aloe vera or calendula ointment to hospital care proved more effective than the use of Betadine alone. Finally, none of the women reported any auxiliary complications following the use of the ointments.

• The clinical examination of an ointment based on marigold extract was conducted on 34 subjects suffering from venous leg ulcers. These were divided into two groups.

  1. le groupe expérimentale, composé de 21 patients souffrant de 33 ulcères veineux, a été traité avec la pommade au calendula, avec une application deux fois par jour pendant trois semaines. La surface totale de tous les ulcères au début du traitement était de 67 544 mm2 ;

  2. le groupe contrôle, composé de 13 patients souffrant de 22 ulcères veineux sur une surface totale de 69 722 mm2 au début du traitement, a utilisé des pansements à base de solution saline.

  After the third week, the total surface area of all ulcers was 39,373 mm2 in the experimental group, representing a decrease of 41.71%, whereas in the control group the total surface area of all ulcers was 58,743 mm2 (a decrease of 14.52%). Furthermore, in the experimental group, complete epithelialisation was achieved in seven patients, while in the control group, four patients achieved complete epithelialisation. Consequently, a statistically significant acceleration in healing was observed in the experimental group. Although preliminary, these results suggest the positive effects of the calendula extract ointment on the epithelialisation of venous ulcers.

• In another comparative clinical study from 2016, researchers also evaluated the clinical efficacy of the extract of Calendula officinalis flowers in the treatment of chronic venous leg ulcers in 38 patients (n= 19 control patients) over a period of 30 weeks. They found that the proportion of treated patients who achieved complete epithelialisation (full wound closure) during the study period was 74% and 32% in the treatment and control groups, respectively. The average healing time was approximately 13 weeks in the treated group and 22 weeks in the group of patients treated with the standard treatment.

• A clinical trial conducted on the healing of caesarean section wounds has also proven successful with calendula. Indeed, a study examined the effectiveness of a calendula ointment in 72 primiparous women who had undergone a caesarean section. Compared to standard hospital care (saline solution), the women who received the calendula extract ointment (every 12 hours until complete healing) reported that their incisions were less red and less swollen. In addition, the results also showed that the caesarean wound was completely healed six days after childbirth (63.9% on day 3 post-operation) compared to ten days for the control group. According to the results, calendula could therefore offer a more effective solution to accelerate the healing of caesarean sections and thus avoid all common complications (infection, wound opening, serous, haematoma).

• In a randomised trial (n = 100; 50 in the experimental group and 50 in the control group), women who used a calendula ointment after episiotomy (4 hours after the procedure, then every 8 hours for 10 days), compared to the control group who received standard care, saw their pain levels significantly reduced from the second day and throughout the duration of the follow-up. The calendula ointment once again helped to improve the healing of perineal lacerations in terms of redness and swelling.

By what molecular mechanism?

Several previous studies have demonstrated that the healing properties of Calendula officinalis are associated with the action of various bioactive constituents, particularly triterpenic alcohols, triterpenic monoesters (faradiol, arnidiol, taraxasterol, etc.) and bioflavonoids (rutin, quercetin, kaempferol, etc.). The healing properties of the medicinal calendula plant come from several levels.

• Enhancement of Proteolytic Activity: A study using a hydroalcoholic extract of calendula on rat skin demonstrated an increase in the activity of two matrix metalloproteinases (MMP-2 and MMP-9), which are involved in tissue rearrangement.

• Activation of angiogenesis: Studies have shown increased angiogenic activity in chicken chorioallantoic membranes and skin wounds in rats following the use of calendula extract. Indeed, it promotes the expansion of new blood vessels in the injured tissue, thereby facilitating the entry of inflammatory cells and the supply of nutrients and oxygen to the wound area. These observed vascular proliferative effects would be linked to the increased expression of certain pro-angiogenic factors, such as fibroblast growth factors (FGF), angiogenic cytokines (IL-8), tumour necrosis factor (TNF-α) and transforming growth factor (TGF-ß), for which saponins and flavonoids appear to be responsible.

• Regulation of the inflammatory phase: A temporary inflammation is beneficial at the start of the healing process, but when prolonged, it can lead to chronic wounds. It has been demonstrated that calendula extract influences the inflammatory phase of healing by activating the transcription factor NF-κB, a central mediator of the immune system, and by increasing the production of the inflammatory chemokine IL-8, both at the transcriptional and protein level, in keratinocytes. This can intensify the inflammatory response after an injury and contribute to the acceleration of re-epithelialisation.

• Impact on granulation tissue formation: In a study on primary human fibroblast cell cultures, it was reported that calendula increases the synthesis of type I and III collagen by inhibiting matrix metalloproteinases, such as MMP-1. Studies using human and mouse fibroblast cultures have also shown that extracts of Calendula officinalis stimulate fibroblast proliferation by increasing the activity of mitochondrial dehydrogenase.

In addition to its healing properties, calendula has been found to possess anti-bacterial activity, thus helping to prevent secondary infections in wounds that could exacerbate the injury and delay the healing process.