D r. Amit X. Garg, a professor of medicine at Western University in London, Ontario, knew about turmeric’s medicinal use because of his Indian heritage. He knew firsthand of its rich cultural significance too: On his wedding day, his relatives rubbed the spice all over him because it is believed to be cleansing.

After seeing the effectiveness of curcumin, in smaller studies, Dr. Garg and his colleagues decided to test it on a larger scale in hopes it would make elective aortic surgery safer by reducing the risk of complications, which include heart attacks, kidney injury and death. In the randomized clinical trial that followed, about half of the 606 patients were administered 2,000 milligrams of curcumin eight times over for four days, while the others were given a placebo. “It was a bit disappointing, but we couldn’t demonstrate any benefit used in this setting,” Dr. Garg said of the study, published last year in the Canadian Medical Association Journal.

In fact, there is not enough reliable evidence in humans to recommend turmeric or curcumin for any condition, according to the National Center for Complementary and Integrative Health. Turmeric became a nutritional golden child partly because of its promise in laboratory studies — cellular and animal. Some research indicates that both turmeric and curcumin, the active ingredient in turmeric supplements, have anti-inflammatory, antioxidant, antibacterial, antiviral and antiparasitic activity. But this has mostly been demonstrated in laboratory studies, and, in many cases, the benefits of preclinical research isn’t observed in clinical trials.

According to Natural Medicines, a database that provides monographs for dietary supplements, herbal medicines, and complementary and integrative therapies, while some clinical evidence shows that curcumin might be beneficial for depression, hay fever, hyperlipidemia, ulcerative colitis, osteoarthritis and nonalcoholic fatty liver disease, it’s still too early to recommend the compound for any of these conditions.

And Natural Medicines has found there isn’t enough good scientific evidence to rate turmeric or curcumin’s use for memory, diabetes, fatigue, rheumatoid arthritis, gingivitis, joint pain, PMS, eczema or hangovers.

Physicians say more research is needed. D r. Gary W. Small, a professor of psychiatry and biobehavioral sciences at the David Geffen School of Medicine at the University of California, Los Angeles, who studies curcumin’s effect on memory, sees a lot of therapeutic potential. He also states that existing research demonstrates curcumin’s biological effects.