Turmeric and curcumin: benefits and risks

Turmeric is not one standard product

Turmeric comes from the underground stem of a plant in the ginger family. Curcumin is one of its naturally occurring curcuminoids. A spoonful of spice, an extract, and a product designed to increase absorption are different exposures. Some supplements add piperine from black pepper to increase absorption; greater absorption does not by itself prove greater benefit or safety. Check the whole ingredient list and see how to read a supplement label.1

Can it help knee osteoarthritis?

In a 2020 Australian trial, 70 adults with painful knee osteoarthritis and fluid-related inflammation were assigned a particular turmeric extract or placebo for 12 weeks. On a 100-millimetre pain scale, the extract group improved by an average of 9.1 millimetres more than placebo. The trial did not find a clear difference in the measured volume of joint fluid and inflammation. It was small and short, and it did not demonstrate cartilage regrowth or long-term benefit. The University of Tasmania and Natural Remedies Private Limited funded the trial.

The US National Center for Complementary and Integrative Health describes early evidence for osteoarthritis as positive but says better-quality research is needed. Findings for one extract do not establish the effects of another product or a culinary serving. For another joint-supplement question, see glucosamine and chondroitin.21

What about liver injury?

Australia’s Therapeutic Goods Administration warns that medicines and herbal supplements containing turmeric or curcumin can rarely cause liver injury, sometimes severe. Its warning does not appear to apply to turmeric used in typical food amounts. Reports cannot establish the risk for every preparation or user; increased-absorption formulations raise particular questions. The Australian regulator advises people with current or past liver problems to avoid these supplements.

A US liver-injury research network described 10 cases judged associated with turmeric products; five people were hospitalised and one died. Seven products were chemically analysed, and three of those contained piperine as well as turmeric. The cases were selected because liver injury occurred: they cannot tell us how often injury happens in everyone taking these products, whether piperine caused or increased the risk, or whether a product without piperine is safe. The report does not show that ordinary culinary use has the same risk.

If taking such a product and experiencing symptoms such as yellow skin or eyes, dark urine, nausea, unusual tiredness or abdominal pain, the regulator advises stopping the product and seeking medical advice promptly. Symptoms have many possible causes, so a professional assessment matters.314

Medicines, pregnancy and labels

Products may cause digestive symptoms and can interact with medicines; the exact preparation and person matter. The US NCCIH says turmeric supplements may be unsafe during pregnancy. Little is known about the safety of amounts greater than those commonly found in food while breastfeeding. Discuss a supplement with your clinician if pregnant or breastfeeding. Ask a pharmacist or clinician about a specific product, especially with liver disease or regular medicines. Do not use a supplement to replace prescribed treatment. For practical context, see supplement and medicine interactions and the nutrition and supplements hub.1

New Zealand’s medicines regulator described a person taking warfarin whose INR—a blood test used to monitor its anticoagulant effect—rose markedly after starting a turmeric-containing product. The reporter suspected an interaction; a single report cannot prove the cause or show how often it happens. The regulator’s 2018 warning concerned turmeric or curcumin products and explicitly did not apply to turmeric used in food. If you use warfarin or another blood thinner, speak with the clinician or pharmacist managing it before starting or stopping a turmeric supplement; do not alter prescribed treatment on your own.56