The evidence for herbal and botanical remedies, Part 2

More than a third of American adults use complementary and alternative medicine.¹ Unfortunately, the public’s enthusiasm for herbal products is not always consistent with the scientific evidence supporting their use. In part one of this series, we discussed the studies that have been done on capsaicin, butterbur, green tea, and peppermint. In this installment, we outline the research on 5 additional remedies: turmeric/curcumin, which may be of benefit in ulcerative colitis; chamomile, which appears to offer relief to patients with anxiety; rosemary, which may help treat alopecia; as well as coffee and cocoa, which may have some cardiovascular benefits (TABLE).

Turmeric/curcumin

Overview

Turmeric (Curcuma longa), a relative of ginger, has been used for 4000 years to treat a variety of conditions.^2,3 Curcumin is the yellow pigment isolated from the rhizomes of Curcuma longa, commonly known as turmeric.³ Turmeric powder contains 5% curcumin, which is the main biologically active compound. Although it grows in many tropical locations, most turmeric is grown in India, where it is used as a main ingredient in curry. The roots and bulbs of turmeric that are used in medicine are generally boiled and dried, which results in a yellow powder.

Turmeric has been used in both Ayurvedic and Chinese medicine for its anti-inflammatory properties, in the treatment of digestive and liver problems, to fight infections, and to help heal skin diseases and wounds.^3-7

Functional GI disorders. A recent review noted that curcumin has been shown in several preclinical studies and uncontrolled clinical trials to have effects on gut inflammation, gut permeability, and the brain-gut axis, especially in functional GI disorders.⁷ A double-blind, placebo-controlled study from 1989 found that turmeric reduced symptoms of bloating and gas in subjects suffering from undifferentiated dyspepsia.⁸

Ulcerative colitis (UC). A 2012 Cochrane review noted that curcumin appears to be a safe and effective therapy for maintenance of remission in quiescent UC when given as adjunctive therapy along with mesalamine or sulfasalazine.⁹ In a 2015 randomized controlled trial (RCT), the addition of curcumin to mesalamine therapy was superior to the combination of placebo and mesalamine in inducing clinical and endoscopic remission in patients with mild-to-moderate active UC, producing no apparent adverse effects.¹⁰

Osteoarthritis (OA). Because of turmeric’s ability to reduce inflammation, it may help relieve OA pain.³ Clinical evidence is scant for the anti-arthritic efficacy of turmeric dietary supplements, although animal studies indicate that turmeric prevents inflammation through regulation of NF-kappaB-regulated genes that regulate the immune and inflammatory response.⁶ Inflammatory cell influx, joint levels of prostaglandin E2, and periarticular osteoclast formation were also inhibited by turmeric extract treatment.⁶

A 2013 review of turmeric for OA concluded that observational studies and in vitro results are promising for the use of curcumin for OA, but well-designed clinical studies were lacking and are needed to support the efficacy of curcumin in OA patients.¹¹ How­ever, in a 2014 randomized trial of 367 patients, turmeric appeared to be similar in efficacy to ibuprofen for the treatment of pain and disability in adults with knee OA.¹² The curcumin (turmeric) group also had fewer adverse effects.¹²

Cancer. There has been a great deal of research on turmeric’s anti-cancer properties, but clinical evidence is lacking. In vitro evidence, animal studies, and small clinical trials suggest that curcumin may help prevent or treat several types of cancers, but the overall evidence is poor. Nonetheless, curcumin and turmeric have been or are currently being evaluated for the treatment or prevention of prostate, liver, breast, skin, gynecologic, hematologic, pulmonary, thymic, bone, brain, and colon cancer.^13-18

Oral submucous fibrosis. A small randomized trial found improvement in oral function with curcumin lozenges, when compared to placebo, indicating that turmeric may hold promise as a treatment of oral submucous fibrosis.¹⁹

Uveitis. A small pilot study of 32 patients suggested that oral curcumin may be as effective as corticosteroids for uveitis.²⁰

Heart disease. Curcumin may have a cardiovascular protective role, as it has been shown to reduce atherosclerosis, but a reduction in myocardial infarction or stroke has not been documented.²¹

Alzheimer’s dementia. Animal studies have shown a reduction in amyloid plaque formation with curcumin.²²

Adverse effects (and precautions)

Turmeric in food is considered safe. A variety of animal and human studies have also indicated that curcumin is safe and well tolerated, even at very high doses.¹³ However, taking large amounts of turmeric for long periods of time could cause stomach upset and gastric ulcers. In addition, patients with gallstones or bile obstruction should use it with caution due to increased bile production.⁷

Because turmeric may lower blood sugar levels, patients with diabetes should monitor for hypoglycemia when using turmeric in combination with diabetic medications. Similarly, those with bleeding disorders taking blood thinners should use turmeric and curcumin with caution, because it can inhibit platelet aggregation.²³

Although it is safe to eat foods with turmeric during pregnancy, pregnant and breastfeeding women should not take turmeric supplements, as the safety of large doses in pregnancy is unknown.

The bottom line

Turmeric/curcumin has anti-inflammatory properties and may be useful as an adjunct for ulcerative colitis and to improve the symptoms of OA. It may also have anti-carcinogenic properties, although definitive data are lacking. Those with a history of gastrointestinal conditions such as gastric ulcer, patients taking blood thinners, and patients with diabetes who are prone to low blood sugar levels should use turmeric/curcumin with caution.