Turmeric has a long history of use as a traditional medicine and as a food ingredient. The turmeric you buy is the spice obtained by drying and grinding the root of the Curcuma longa plant. Curcumin is one of the natural chemical components of turmeric and is believed to be one of the ingredients that has medicinal benefits and effects. Turmeric sales have grown in recent years and it is now among the best-selling natural products in the US. It has also been receiving increased scrutiny from researchers and regulators, as serious reports of liver injury associated with consumption are becoming more frequent.
Clinical trials with turmeric have not been impressive from an efficacy perspective. There is some suggestion of benefit for conditions such as knee osteoarthritis, mucositis, high triglycerides, or allergic rhinitis, but persuasive evidence for routine medical use has not been established. The main challenge with using curcumin as a medication appears to be that the chemical is poorly absorbed. Manufacturers have come up with several different formulations (eg, nanoparticles, liposomes) that complicate the interpretation of any assay. Doses vary widely from 100 mg to several grams per day, and formulations include tablets, liquids, and root extracts. Malabsorption may also be responsible for its safety profile, which is generally considered safe by mouth even in gram daily doses when consumed over several weeks. However, some turmeric supplements are now marketed in combination with black pepper, which substantially improves its absorption. (If you haven’t already seen Marc Maron’s tidbit on turmeric and black pepper, it’s pretty funny.) Piperine, a component of black pepper, appears to inhibit glucuronidation (a metabolic process) in both the intestines and the liver. Through inhibition, the amount of curcumin available to the body is increased. Consequently, the potential risk of unwanted or harmful effects is also increased. Other means to increase absorption, such as nanoparticles, have also been developed.
Through better absorption, higher (effective) doses seem to be resulting in more cases of liver damage. Cases have occurred weeks or months after routine ingestion begins; it is reported to begin with fatigue, nausea, and lack of appetite, followed by dark urine and jaundice. Recovery is usually quick when turmeric consumption is discontinued.
A recent article published in the american journal of medicine describes ten cases of liver damage associated with turmeric. The Drug-Induced Liver Injury Network (DILIN) was established in 2003 as a cooperative agreement between academic centers and studies liver injury associated with drugs, herbal products, and other dietary supplements. In this work, all cases between 2004 and 2022 in which turmeric was implicated as a cause were reviewed. Causality was assessed and available product was tested for the presence of turmeric. Ten cases of turmeric injury have been reported, all since 2011, with six since 2017. Five of the ten were hospitalized and 1 patient died of acute liver failure. Chemical analysis confirmed turmeric in all seven available products tested. Three products also contained piperine.
Genetics may also play a role in putting some people at higher risk of liver damage from turmeric. Seven cases were found to carry the HLA-B*35:01 allele which has already been implicated as a potential biomarker predicting liver damage from other products such as green tea and Polygonum multiflorum, a Chinese herbal medicine. It is also associated with the risk of injury from regular medications. This allele is carried by 5-15% of the US population.
Based on concerns about health claims associated with turmeric and the potential but rare risk of serious harm, Italy recently banned turmeric-related health claims and placed a warning on turmeric-derived products. Curcuma longa root. This followed reports of around 20 cases of liver damage in the country attributed to use:
IMPORTANT WARNING In case of hepatic or biliary abnormalities or calculosis in the bile duct, the use of the product is not recommended. Do not use during pregnancy and lactation. Do not use for long periods without consulting your doctor. If you are taking medication, it is advisable to listen to the doctor’s opinion.
Bottom Line: Turmeric Has Rare But Serious Risks
Turmeric supplements show promise as medicines, but their role is not well established. The combination of turmeric with black pepper demonstrably increases the absorption of the drug. Liver damage is a rare but seemingly real consumption risk. If consumption is considered as a supplement, use with or without piperine should be consistent. Research into genetic risk factors for liver damage from supplements like turmeric is still preliminary, but has the potential to identify those most at risk for damage. Until then, whether it’s turmeric or any other dietary supplement, it’s important to carefully monitor for signs and symptoms of liver or other damage.