The ancient spice with potent health benefits

Turmeric is a spice that gives curry powder its characteristic pungent flavor. But it’s also an herbal remedy that’s been used as a traditional medicine in India for centuries. The main bioactive ingredient in turmeric is curcumin, a compound that gives the spice its bright yellow color. Curcumin has been a mainstay in ancient and modern herbal medicine due to its wide range of antioxidant, anti-inflammatory, analgesic, antiseptic, and anticarcinogenic properties.

In recent decades, investigators have researched this ancient compound’s potential to treat a variety of conditions and diseases. Here are just a few.

Diabetes

Curcumin has been shown to lower blood glucose levels in patients with type 2 diabetes. As long ago as 1972, in the first study of its kind, researchers demonstrated that turmeric powder lowered fasting blood sugar from 140 mg/dL to 70 mg/dL in a patient with a 16-year history of type 2 diabetes.

More recently, a randomized, double‐blind, placebo‐controlled clinical trial published in Diabetes Care in 2012 reported that curcumin may delay or prevent the development of type 2 diabetes. Among 240 patients with prediabetes, none who took a 9-month course of curcumin went on to develop type 2 diabetes while 16% of those given placebo did. Patients given curcumin also had higher adiponectin levels and lower insulin resistance, compared with the placebo group.

Hyperlipidemia and hypercholesterolemia

Speaking of patients with type 2 diabetes, in a small open-label trial of eight patients with type 2 diabetes who were on glyburide, those given a 10-day course of curcumin had significant reductions in low‐density lipoprotein (LDL), very‐low‐density lipoprotein (VLDL), and triglycerides, as well as an increase high‐density lipoprotein (HDL).

Curcumin has been linked to lower lipid levels in non-diabetic patients, too. A meta-analysis of seven studies involving 649 patients reported that curcumin/turmeric significantly reduced serum LDL cholesterol and triglyceride levels compared with those in control groups. Turmeric extract may also significantly reduce serum total cholesterol levels, the authors noted. The meta-analysis found no improvement in serum HDL cholesterol, however.

Asthma

Because curcumin is known for its anti-inflammatory properties, researchers have studied it for chronic inflammatory diseases, such as asthma. For instance, in a randomized trial of 77 patients with bronchial asthma, those who received standard asthma therapy plus twice-daily curcumin capsules for 30 days showed reduced airway obstruction compared with participants who received standard therapy alone. Specifically, patients given curcumin had significant improvement in average forced expiratory volume in 1 second (FEV1) values, although they also reported no improvement in clinical symptoms.

Inflammatory bowel disease

Curcumin’s anti-inflammatory properties have also shown to be effective against inflammatory bowel disease. In a recently published systematic review of six randomized clinical trials of patients with ulcerative colitis (UC), five of the studies showed that curcumin reduced symptoms, attained clinical remission, and/or prevented relapse when given in combination with standard mesalamine therapy. “The findings suggest that curcumin may be a safe, effective therapy for maintaining or inducing UC remission when administered with standard treatments,” the authors wrote.

Patients with Crohn's disease are frequently prescribed an immunosuppressant, such as infliximab, to reduce chronic inflammation. But drugs like infliximab tend to lose their effectiveness over time, and they have significant side effects, some severe. Enter curcumin. Patients with Crohn's disease who took infliximab along with curcumin experienced an average 55-point reduction in symptoms and severity (as measured by the Crohn’s Disease Activity Index), and reduced inflammatory markers such as IL-1, C-reactive protein, and TNF-a, according to a systematic review of 16 studies. Curcumin also improved outcomes in patients who developed colorectal cancer.

“Curcumin, even by itself, was found to be a cheap and safe way to reduce [Crohn's disease] symptoms and inflammatory markers,” the authors concluded.

Cancer

Curcumin has been studied in humans in a range of clinical trials against different types of cancers. “The main mechanisms of action by which curcumin exhibits its unique anticancer activity include inducing apoptosis and inhibiting proliferation and invasion of tumors by suppressing a variety of cellular signaling pathways,” noted the authors of a review article on curcumin and cancer.

Breast cancer. Earlier this year, researchers published results of the first clinical trial of chemotherapy plus intravenous curcumin for the treatment of cancer. The researchers administered curcumin intravenously because of its low bioavailability when taken orally.

In a randomized, double-blind, placebo-controlled study, 150 women with advanced and metastatic breast cancer were randomly assigned to receive either paclitaxel plus curcumin intravenously or paclitaxel plus placebo for 12 weeks. Four weeks after treatment, the women in the paclitaxel plus curcumin group achieved an objective response rate of 51% compared with 33% in women in the paclitaxel plus placebo group. Women given curcumin also reported less fatigue from treatment than women given placebo.

Colorectal cancer. In a small phase IIa open-label randomized controlled trial, 28 adults with metastatic colorectal cancer were randomly assigned to either folinic acid/5-fluorouracil/oxaliplatin chemotherapy or the same therapy plus daily oral curcumin. Results showed that the curcumin-treated group had median progression-free survival of 291 days compared with 171 days in the standard treatment group. Similarly, median overall survival was 502 days in the curcumin group and 200 days in the standard group.

Osteoarthritis

Another application of curcumin’s anti-inflammatory ability is its effect on osteoarthritis. Research has shown that curcumin reduces inflammation by down‐regulating various inflammatory cytokines, enzymes, and transcription factors. In a review article published in Drug Design, Development and Therapy, patients with osteoarthritis demonstrated improvements in pain, physical function, and quality of life after taking curcumin or curcumin derivatives. These patients also reported using fewer NSAID analgesics (and developing fewer NSAID-related side effects) while on curcumin therapy.

Gingivitis

Curry-flavored mouthwash, anyone? A randomized clinical trial of 100 patients with gingivitis and plaque showed that turmeric-infused mouthwash was as effective at reducing gingival inflammation as chlorhexidine gluconate (a prescription mouthwash for gingivitis), although the chlorhexidine mouthwash had a stronger effect in fighting plaque. Truth be told, the turmeric mouthwash was flavored with peppermint oil (ostensibly to cover any curry flavor), so that also puts the mouthwashes on an equal footing.

One big problem with curcumin

Despite all the promising research described here, curcumin has one big problem: low bioavailability. Up to 85% of an oral dose of curcumin slips through the gastrointestinal tract without being metabolized or absorbed.

To that end, researchers have begun to devise ways to make the compound more available. One basic solution has been to administer curcumin with another compound, such as piperine or bromelain, that enhances its absorption. Similarly, one curcumin supplement has been formulated with lecithin for better absorption—an idea inspired by the dietary use of turmeric in fatty foods like coconut milk or chocolate to increase absorption. Curcumin has also been encapsulated inside polymer or lipid-based colloidal particles—such as liposomes, nanoemulsions, biopolymeric microgels, solid lipid nanoparticles, micelles, and polymeric nanoparticles—to increase the compound’s solubility and bioavailability.

It may not be long before curcumin fully transforms from an ancient herbal remedy to a widely used therapeutic drug.