Calendula Flower (Calendula Officinalis) Extract
Also known as: Calendula, pot marigold, marigold flower, Calendula officinalis L., Calendula officinalis
Overview
Calendula officinalis extract, commonly known as Calendula or pot marigold, is derived primarily from the flowers of the plant. It has a long history of traditional use in herbal medicine for its purported wound healing, anti-inflammatory, hepatoprotective, and antitumor properties. While commonly applied topically for various skin conditions and wounds, it has also been investigated for systemic effects such as liver protection and as an adjunct therapy in cancer. Research into Calendula's efficacy is ongoing, with a moderate but growing body of in vitro, animal, and human clinical studies. Systematic reviews, particularly concerning wound healing, suggest moderate benefits, though they often highlight the need for larger, more rigorously designed randomized controlled trials (RCTs) to definitively confirm its efficacy and safety across all claimed applications. The extract is available in various forms, including topical creams, ointments, and oral preparations, though standardized oral dosing is not yet established.
Benefits
Calendula officinalis extract shows several promising, evidence-based benefits: * **Wound Healing:** Moderate evidence supports the topical application of Calendula for accelerating acute wound healing. Systematic reviews, encompassing both animal and clinical trials, indicate its potential to reduce inflammation and promote granulation tissue formation. Some clinical trials have shown a decrease in venous ulcer size, though results are mixed for diabetic ulcers and burns. For instance, one RCT found no benefit for burn healing, while another reported mixed results for radiation dermatitis prevention. The strength of evidence is moderate, with calls for larger, well-designed RCTs to solidify these findings. * **Antitumor Activity:** Preclinical in vitro studies have demonstrated selective cytotoxicity of certain Calendula flower extracts against various cancer cell lines. Different extract types (e.g., methanolic, ethyl acetate) show varying degrees of selectivity and potency, with IC50 values ranging widely. While these findings are promising, they are currently limited to laboratory settings and require extensive clinical validation before any conclusions can be drawn regarding human cancer treatment. * **Hepatoprotective Effects:** Animal and in vitro studies suggest that Calendula extracts possess hepatoprotective properties. These studies indicate that the extracts can reduce liver cytotoxicity and oxidative stress induced by toxins. This protective effect is likely mediated by polyphenolic compounds, which help restore antioxidant enzyme levels and improve liver histology in a dose-dependent manner. The evidence for this benefit is primarily preclinical, warranting further research.
How it works
The therapeutic effects of Calendula officinalis extract are attributed to several mechanisms of action. For wound healing, its efficacy is linked to anti-inflammatory properties and the stimulation of granulation tissue formation, potentially through the modulation of cytokines and growth factors involved in the healing cascade. The observed antitumor effects in preclinical studies involve selective cytotoxicity to cancer cells, possibly by inducing apoptosis (programmed cell death) and inhibiting cell proliferation, although the precise molecular targets are still under investigation. Hepatoprotective activity is primarily mediated by its antioxidant effects, where compounds within the extract scavenge free radicals, enhance the activity of endogenous antioxidant enzymes like catalase (CAT), superoxide dismutase (SOD), and glutathione peroxidase (GPx), and reduce markers of lipid peroxidation such as malondialdehyde.
Side effects
Calendula officinalis extract is generally considered safe, particularly when used topically. Clinical trials focusing on wound healing have reported no significant adverse effects. However, comprehensive safety data for oral or high-dose systemic use are limited, and further research is needed to establish its safety profile in these contexts. Individuals with known allergies to plants in the Asteraceae family (e.g., ragweed, chrysanthemums, marigolds, daisies) may experience allergic reactions, though such occurrences are rare. These reactions could manifest as skin irritation, redness, or itching when applied topically. There are no major drug interactions documented in high-quality studies, but caution is always advised when combining herbal supplements with prescription medications. Pregnant or breastfeeding individuals should consult a healthcare professional before using Calendula due to insufficient safety data. Overall, while topical use appears safe for most, systemic use requires more extensive investigation to confirm its safety and rule out potential risks or contraindications.
Dosage
Dosage guidelines for Calendula officinalis extract are not fully standardized, particularly for oral administration. For topical applications, which are most commonly studied for wound healing, concentrations and dosing schedules vary widely across clinical trials, making precise recommendations challenging. Typical topical formulations include creams, ointments, or washes. For instance, some studies have used Calendula ointment applied twice daily for wound care. Oral dosing for potential hepatoprotective or antitumor effects is not standardized and remains largely in the realm of preclinical research, lacking established human dosages. The absorption and bioavailability of Calendula's active compounds can depend significantly on the extract preparation method (e.g., methanolic, aqueous, ethyl acetate), with different preparations showing varying activities in vitro. Due to the lack of standardized oral dosing and limited systemic safety data, it is crucial to consult a healthcare professional before considering oral Calendula supplementation, especially for specific health conditions. There are no established upper limits or safety thresholds for oral intake in humans.
FAQs
Is Calendula effective for wound healing?
Moderate evidence supports the topical use of Calendula for acute wounds and some chronic wounds like venous ulcers. However, results can vary by wound type and study quality, with mixed outcomes for burns and diabetic ulcers.
Can Calendula treat cancer?
Preclinical laboratory studies show Calendula extracts have potential cytotoxic effects against cancer cells. However, there is no clinical evidence to support its use as a treatment for cancer in humans, and it should not replace conventional therapies.
Is Calendula safe to use?
Topical use of Calendula is generally considered safe, with rare reports of allergic reactions in sensitive individuals. Systemic (oral) safety is less well-studied, and comprehensive data are needed before recommending widespread oral use.
What are the main benefits of Calendula?
The primary research-backed benefits of Calendula include promoting wound healing through anti-inflammatory actions and tissue regeneration, and showing hepatoprotective effects in preclinical studies. Antitumor activity is also observed in laboratory settings.
Research Sources
- https://journals.sagepub.com/doi/abs/10.1177/1534735418803766 – This review summarizes the in vitro and animal studies on Calendula officinalis, highlighting its diverse pharmacological activities including anti-inflammatory, antioxidant, and cytotoxic effects. It emphasizes the potential of different extract types and their varied chemical compositions in contributing to these effects, particularly noting selective cytotoxicity against cancer cell lines.
- https://pubmed.ncbi.nlm.nih.gov/31145533/ – This systematic review evaluated 14 studies (7 animal, 7 clinical) on Calendula's wound healing properties. It concluded that Calendula shows moderate evidence for improving acute wound healing, but results for chronic wounds, burns, and radiation dermatitis were mixed, indicating a need for larger, more robust clinical trials to confirm efficacy.
- https://pmc.ncbi.nlm.nih.gov/articles/PMC10142266/ – This review focuses on the therapeutic applications of Calendula, particularly its hepatoprotective effects. It discusses how Calendula extracts, primarily in animal and in vitro models, demonstrate liver protection by modulating antioxidant enzymes and reducing oxidative stress, suggesting its potential as a natural hepatoprotective agent.
- https://onlinelibrary.wiley.com/doi/abs/10.1111/wrr.12737 – This systematic review and meta-analysis specifically assesses the efficacy of Calendula in wound healing. It found some evidence supporting its use for certain wound types, but also highlighted the heterogeneity of studies and the need for more standardized, high-quality randomized controlled trials to provide definitive conclusions on its effectiveness across all wound types.