TURMERIC

(pronounced /ˈtɜːrmərɪk/, also /ˈtuːmərɪk/ or /ˈtjuːmərɪk/)

Turmeric is a flowering plant, Curcuma longa of the ginger family, Zingiberaceae, the roots of which are used in cooking.

Turmeric is promoted as an alternative cancer treatment. There is some evidence that curcumin, a substance in turmeric, can kill cancer cells in certain cancers. But we need more research.

WHAT IS TURMERIC?

Turmeric is also known as Indian saffron, jiang huang, haridra and haldi. It is a spice grown in many Asian countries. It belongs to the ginger family and is a main ingredient of curry powder.

The main active ingredient in turmeric is curcumin or diferuloyl methane. Laboratory studies have shown curcumin has anti cancer effects on cancer cells.

Curcumin is purported to have multiple health-promoting effects, such as relieving inflammation, pain, and symptoms of metabolic syndromes. There are also claims that curcumin has anticancer properties.

WHY PEOPLE WITH CANCER USE IT?

Research has shown lower rates of certain cancers in countries where people eat more curcumin. This is at curcumin levels of about 100mg to 200mg a day over long periods of time.

A few laboratory studies on cancer cells have shown that curcumin has anti cancer effects. It seems to be able to kill cancer cells and prevent more from growing. It has the best effects on breast cancer, bowel cancer, and 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.

ANTICANCER EFFECTS

There are multiple studies that suggest that curcumin has anticancer properties, but the majority of these were conducted in vitro. These studies suggest that curcumin inhibits cell proliferation and induces cell cycle arrest, apoptosis, and senescence — through various mechanisms, across multiple different types of cancer cell lines. Curcumin has been shown to decrease the expression of multiple different enzymes, transcription factors, inflammatory cytokines, growth factors, and other cell-signaling components that are important for cancer growth and progression.

For example, a consistent finding across multiple studies of different cancer cell lines is that curcumin down regulates the expression of the transcription factor NF-κB, which is commonly highly expressed by cancer cells and is known to promote the development of cancer, metastasis, and tumor growth. In addition, curcumin arrests the cell cycle at the G1/S or G2/M phases by inhibition of different cyclins. Curcumin also induces apoptosis through caspase-dependent pathways, and decreases the expression of antiapoptotic proteins.

Curcumin has been evaluated in animal models of different cancer types. These studies have generally shown that curcumin has antiproliferative effects. For example, a mouse model of colorectal cancer (CRC) that was treated by intraperitoneal injection of curcumin or vehicle control demonstrated that curcumin prolonged life and inhibited tumor growth.⁴ These data also suggest that curcumin up regulated the Myrna miR-130a, which decreased the Wnt/β-catenin pathway and led to prolonged survival.

HOW YOU HAVE IT?

Turmeric can be taken raw, as a powder, a paste or extract. It is also available as an oil.

SIDE EFFECTS OF TURMERIC

It is important to remember that turmeric used in cooking is very safe. But we don’t know how safe curcumin is when used for medical reasons. So far, research studies seem to show that it causes few or no side effects. But we don’t know much about the side effects of taking it in large amounts to treat or prevent cancer.

People have reported stomach pain when eating too much turmeric. They have also reported skin problems when taking it for a long time. So, if you use curcumin for reasons other than cooking, talk to your doctor first.

The Medicines and Healthcare products Regulatory Agency (MHRA) has warned against Fortodol (also sold as Miradin). It is a turmeric-based food supplement. 

Fortodol contains the strong anti-inflammatory drug nimesulide. Nimesulide can cause severe damage to the liver. The signs include:

• yellowing skin (jaundice)
• dark urine
• feeling or being sick
• unusual tiredness
• stomach or abdominal pain
• loss of appetite

It does not have a licence as a medicine in the UK. The Food Standards Agency (FSA) in the USA states that products with unknown amounts of nimesulide could be very harmful.

RESEARCH INTO CURCUMIN AS A CANCER TREATMENT

Several studies have looked into whether curcumin could be a cancer treatment. These have had some promising results.

One of these in 2013 was an international laboratory study on bowel cancer cells. It looked at the effects of combined treatment with curcumin and chemotherapy. The researchers concluded that the combined treatment might be better than chemotherapy alone.

A problem highlighted by a number of review studies is that curcumin does not get absorbed easily. This makes it work less well as a treatment. Researchers are looking at ways of overcoming this problem.

We need more clinical trials in humans before we know how well it works as a treatment for cancer.

IN-HUMAN STUDIES

Some in-human studies of curcumin as an anticancer treatment have been conducted. These studies are primarily early pilot studies and have demonstrated that curcumin is safe and well tolerated, even at high doses.

Several studies suggest that continued evaluation is warranted. For example, a randomized, controlled trial of 4 doses of 8 g of curcumin decreased the free light-chain ratio, reduced the difference between the clonal and non-clonal light-chain and involved free light-chain, suggesting that curcumin may slow the disease process in patients with monoclonal gammopathy of undetermined significance and smoldering multiple myeloma.

Another trial treated 17 patients with advanced pancreatic with 8 g of curcumin daily concurrently with gemcitabine. Of the evaluable patients, 9% demonstrated a partial response, 36% stable disease, and 55% experienced progressive disease, and the median overall survival was 5 months. However, 5 patients discontinued curcumin due to abdominal fullness or pain and another 2 patients required a dose reduction of curcumin.

A pilot phase 2 trial evaluated the use of curcumin with docetaxel in 26 men with chemotherapy-naive metastatic castration-resistant prostate cancer.⁸ The men received 6 g of curcumin daily in addition to docetaxel and prednisone for 6 cycles. There was a prostate-specific antigen (PSA) response among 59% of patients and 40% experienced a partial response. There were no adverse events, and 100% of the patients were compliant with the curcumin.

A trial of 223 patients with leukoplakia randomly assigned patients to receive 3.6 g daily of curcumin or placebo for 6 months. Curcumin administration resulted in a significantly higher number of clinical responses compared with placebo (67.5% vs 55.3%, respectively; P = .03). However, there was no difference in histological response or durability of response among those who experienced a complete response. Curcumin was well tolerated and there were no safety concerns related to treatment.

In another trial, 44 patients with familial adenomatous polyposis were randomly assigned to receive 1500 mg of curcumin twice daily or placebo for 1 year. There was no difference in the number of polyps or size of the polyps between patients in the groups. There was also no difference in adverse events across groups.

Drug-Delivery Challenge

A major challenge in the use of curcumin as a treatment for cancer is its bioavailability. Curcumin is not water-soluble and has been shown to be poorly absorbed; it has also been shown to rapidly metabolize and be eliminated quickly. Different approaches to improving the bioavailability of curcumin are being investigated, including the development of synthetic analogs, enveloping it with liposomes or micelles, or combining it with bioavailability enhancers.