Italian and US scientists point to the polyphenol compound as exhibiting anticancer properties in a review that draws on almost 5,000 studies that also highlight its anti-inflammatory and antioxidant properties.
The review finds this combination plays a role in halting tumour development, blocking the growth of eight types of cancers including breast, lung, pancreatic, bowel and prostate cancer.
“Curcumin belongs to the most promising group of bioactive natural compounds, especially in the treatment of several cancer types,” says researchers Antonio Giordano and Giuseppina Tommonaro.
“As reported in the present review, curcumin exhibits anticancer ability by targeting different cell signalling pathways including growth factors, cytokines, transcription factors, and genes modulating cellular proliferation and apoptosis.”
Forty years of research
As the team acknowledge, curcumin’s anticancer potential has been described in numerous papers with the polyphenol the focus of research for close to forty years.
In that time, its therapeutic benefits have been suggested in multiple chronic diseases such as inflammation, arthritis, metabolic syndrome, neurodegenerative diseases and in several cancers.
Its candidacy as an effective anticancer drug either alone or in combination with other drugs is strengthened by its effect on different signalling pathways and molecular targets involved in the development of several cancers.
However, as the team point out curcumin is not immune from side effects, such as nausea, diarrhoea, headache, and yellow stool.
Moreover, it showed poor bioavailability due to the fact of low absorption, rapid metabolism, and systemic elimination that limit its efficacy in diseases treatment.
Writing in the journal Nutrients, the review discusses the extent clinical development of curcumin has been hampered because of its scarce bioavailability and low aqueous solubility.
In clinical trials, it was reported that curcumin given orally at a dose of 8 grams per day (g/day) in humans, a rapid transformation into metabolites occurred resulting in a low level of free curcumin in plasma (less than 2.5 nanograms per millilitre (ng/mL)).
While curcumin analogues represent a good approach to improving the bioavailability of curcumin, many studies have been directed towards the development of innovative delivery systems for improving the pharmacokinetics of curcumin.
One example is curcumin encapsulated in protein nanoparticles that exhibited a better anticancer activity, reducing the breast cancer cell line MCF-7’s viability and an enhanced oral bioavailability in rats.
Two promising nanocurcumin formulations, Lipocurc (liposomal curcumin for infusion) and Meriva, have been shown to increase the bioavailability of curcumin and lead to better treatment outcomes in pancreatic and lymphocytic leukaemia patients, respectively.
“It is worth noting the study in which the patented formulation, BCM-95 CG (a mix of reconstituting curcumin with the non-curcuminoid components of turmeric) was tested on a human group of volunteers with the aim of estimating the bioavailability of curcumin in blood,” the review states.
“The increase in relative bioavailability of BCM-95 CG (Biocurcumax) was about 6.93 fold compared to free curcumin and about 6.3 fold compared to a curcumin–lecithin–piperine formula.”
Commenting on the review a Cancer Research UK spokesperson said, “There is some evidence that curcumin, a substance in turmeric, can kill cancer cells in certain cancers. But we need more research.
“It seems to be able to kill cancer cells and prevent more from growing. It has the best effects on breast cancer, bowel cancer, stomach cancer and skin cancer cells.
“At the moment there is no clear evidence in humans to show that turmeric or curcumin can prevent or treat cancer.”
Published online: doi.org/10.3390/nu11102376
“Curcumin and Cancer”
Authors: Antonio Giordano, Giuseppina Tommonaro