Curcumin

What is curcumin, and is it the same as turmeric?

Curcumin is a yellow-colored compound found in the rhizome (root stem) of the turmeric plant (Curcuma longa). Turmeric is a plant of the ginger family grown in Southeast Asia and India, and its root has been used in cooking, cosmetics, and traditional medicine. Its yellow color comes from curcumin. ^[1]

Curcumin is not the whole of turmeric. A medicinal chemistry review reports that curcumin makes up at most about 5% of turmeric. ^[2] In supplements, curcuminoid extracts isolated from turmeric are mostly used; the NCCIH states that the amount of curcumin that orally taken curcumin products actually contain varies and that they often also contain other plant substances such as piperine from black pepper. ^[1]

This difference matters in practice: turmeric used in the kitchen and a concentrated curcumin extract in a capsule do not provide the same dose of curcumin, and what is tested in studies is mostly the extract. What the evidence says about turmeric as a spice is covered on a separate page.

Detailed guideTurmeric benefits: what does the evidence say for use as a spice?→

Why is curcumin not absorbed well, and do piperine and special formulas change this?

Curcumin has low bioavailability because it is metabolized rapidly in the liver and the intestinal wall. In a 1998 study in India examining rats and healthy human volunteers, when 2 g of curcumin was given alone, human serum levels were found to be either undetectable or very low. When 20 mg of piperine was added to the same dose (piperine is a known substance that inhibits glucuronidation in the liver and gut), the authors reported a 2,000% increase in bioavailability. ^[3]

This result is frequently cited, but it should be read with its limits. The human part of the study was done in healthy volunteers, with a single dose and short-term measurement (in the first hours); it does not measure a clinical disease outcome. A serum level raised by piperine does not mean a better outcome in a disease.

There is a similar limit for special formulas. In a randomized, double-blind, crossover human study comparing a phospholipid (lecithin) formulation with an unformulated curcuminoid mixture, total curcuminoid absorption was found to be about 29 times higher; however, only phase-2 metabolites (conjugates) were detected in plasma, and plasma levels still remained markedly below what is needed to inhibit most of curcumin’s anti-inflammatory targets. The first author of the study worked at a dietary supplement company. ^[4] So a form that is “absorbed more” does not mean a form that “reaches a drug-like effective level.”

Another point emphasized by the NCCIH relates to safety: liver injury has been reported with curcumin products with enhanced absorption (high bioavailability). ^[1] So solving the absorption problem brings both hope and risk (detailed below).

Open the Deep view for details →

For which conditions has curcumin been studied, and how strong is the evidence?

The NCCIH states that many studies have been done on the safety and usefulness of curcumin and turmeric, but that it cannot be said with certainty that it is useful for any health purpose. The main areas are as follows. ^[1]

Individual studies and meta-analyses in areas such as depression, ulcerative colitis, blood sugar, CRP, cancer, and Alzheimer’s, together with who each examined and their limits, are collected on the page below.

Detailed guideCurcumin benefits: which claims are supported?→

Can curcumin harm the liver?

Yes, there are reported cases. In the Italian series, high-bioavailability, high-dose products stand out, and in the NCCIH’s assessment, products with enhanced absorption; the authors of the US series state that the rise may be linked to usage habits or to the spread of combinations with black pepper (piperine).

US (DILIN network). In the US Drug-Induced Liver Injury Network (DILIN), cases recorded between 2004 and 2022 in which turmeric was the associated product were examined; 10 cases were found (all enrolled since 2011, six since 2017). Eight of the ten were women, median age 56 (35–71). Injury was hepatocellular in nine and mixed in one; five were hospitalized and one died of acute liver failure. Turmeric was verified in seven of the products tested, and piperine was also detected in three. The authors report a latency of 1–4 months and that the cases were strongly associated with HLA-B*35:01: seven of ten patients carried this allele (allele frequency 0.450; 0.056–0.069 in population controls). According to the authors, turmeric-related liver injury appears to be rising in the US; the reason may be usage habits or increased combination with black pepper. ^[5] This is a case series; it gives no risk ratio among turmeric users.

Italy (Tuscany and the literature). In all seven cases of acute hepatitis reported in Tuscany up to September 2019, the injury was attributed to Curcuma longa formulations of high bioavailability and high curcumin/curcuminoid dose; in most, improvement on stopping the product (positive dechallenge) was seen. Of the 23 cases found in the systematic review, the majority had also been exposed to at least one other drug; 16 had positive dechallenge. The authors concluded, in the context of food supplements as products with weak oversight and regulation, that the Italian cases and the literature confirm the relationship between Curcuma longa and liver injury. ^[6]

NCCIH. Turmeric/curcumin taken orally in traditional formulation (without enhanced absorption) at recommended amounts is “likely safe” for up to 2–3 months; it can cause nausea, vomiting, reflux, stomach upset, diarrhea, or constipation. Liver injury has been reported with products with enhanced absorption; the NCCIH recommends stopping the product and talking to a health professional in the event of symptoms such as fatigue, nausea, loss of appetite, dark urine, or jaundice. ^[1]

These are case series: they do not show what proportion of users were injured (the risk ratio) and do not set a safe dose threshold. The contribution of piperine alone also cannot be separated from these data.

What other safety topics are there?

Iron absorption. In a single case report, a 66-year-old physician who used six capsules a day of turmeric extract (538 mg) for an osteoarthritis flare was reported to have hemoglobin that did not rise above 12 and iron and ferritin levels consistent with iron deficiency; endoscopy and fecal occult blood were negative; when turmeric was stopped and the usual iron supplementation was continued, hemoglobin and iron tests returned to normal after two weeks. The authors state that turmeric may bind iron in the small intestine and block its absorption and that this may be the first possible case documented in humans. ^[7] It is a single case; it is not evidence of frequency or cause and effect. For general information about iron deficiency, the iron guide can be used.

Gallbladder. In the randomized, double-blind, crossover study of 12 healthy volunteers by Rasyid and Lelo, gallbladder volume decreased compared with placebo after 20 mg of curcumin; the reduction was 11.8% at 0.5 hours, 16.8% at 1 hour, 22.0% at 1.5 hours, and 29.3% at 2 hours. The authors concluded that curcumin causes contraction of the human gallbladder. ^[8] This study did not examine people with gallstones; caution in those with gallstones or biliary obstruction is a logical inference drawn from the gallbladder contraction the study showed, not a demonstrated harm.

Drugs that affect clotting. In Wistar rats, high-dose curcumin given for 7 days increased the area under the curve (AUC) of warfarin and of the carboxylic acid metabolite of clopidogrel about 1.6-fold but did not change prothrombin time or platelet aggregation. ^[9] This is animal data and cannot be carried directly to humans; the interaction in humans would have to be measured separately.

Pregnancy and breastfeeding. The NCCIH states that turmeric supplements may not be safe in pregnancy and that very little is known about the safety of use above the amount in food during breastfeeding. ^[1]

Lead contamination. Lead chromate dye in turmeric powder sold as a spice is a documented public health problem in South Asia; the sources and what is known for Türkiye are covered on the turmeric page.

What is the status of curcumin supplements in Türkiye?

In Türkiye, curcumin supplements can be handled within the framework of “food supplements.” The Turkish Food Codex Communiqué on Food Supplements (Türk Gıda Kodeksi Takviye Edici Gıdalar Tebliği, 2013/49) defines “botanicals” as plants, herbs, fungi, algae, and their extracts, and a food supplement as products with a set daily intake dose, made from concentrates or extracts of plant substances and bioactive substances with a nutritional or physiological effect, in capsule, tablet, lozenge, single-use powder sachet, liquid ampoule, dropper bottle, or similar forms; capsules and tablets containing curcuminoid extract can fall under this definition. ^[10] The Restricted Substances List (21/09/2026) of the Ministry of Agriculture and Forestry sets the daily upper limit for turmeric-derived curcuminoids/curcumin at 20 mg at ages 4–10 and 600 mg at ages 11 and over. ^[11] This is the legal upper limit for food supplements; doses such as the 2 g used in pharmacokinetic studies are above this limit.

According to the 2013 text of the Communiqué, the label, presentation, and advertising of food supplements cannot include statements claiming to prevent, treat, or cure a disease; the label is required to carry the statements “Not a medicine. Not used for the prevention or treatment of diseases.” and “Consult your doctor in pregnancy and breastfeeding and when a disease or medicine use is present.” (the required Turkish label wording: “İlaç değildir. Hastalıkların önlenmesi veya tedavi edilmesi amacıyla kullanılmaz.” and “Hamilelik ve emzirme dönemi ile hastalık veya ilaç kullanılması durumlarında doktorunuza danışın.”). ^[10] The Communiqué was later amended; what is quoted here is the 2013 text in the Official Gazette.

For this reason, a statement such as “treats osteoarthritis” cannot appear on a supplement label under the Communiqué. The evidence picture also reflects this: this is a supplement whose evidence is limited to short-term and heterogeneous studies, not a drug.

What to look for on labels

This section is not a product recommendation but a label-reading framework. The NCCIH reports that the actual amount of curcumin in curcumin products varies and that they often contain other plant substances such as piperine. ^[1] Questions that can be asked of a label: what is the amount and source of curcuminoids (pure curcumin, turmeric powder, or extract); is there piperine or another absorption enhancer; are formula descriptions such as “phospholipid,” “micelle,” or “nano” used? Because the common point of the cases in Italy is “high bioavailability and high dose” ^[6], the presence of these two features together on a label can be read as a noteworthy sign.

Who needs extra precautions?

• People with a history of liver disease: cases of liver injury have been reported with turmeric and curcumin products. ^{[5] [1]}
• Pregnant and breastfeeding women: the NCCIH states that supplements may not be safe in pregnancy. ^[1]
• People with gallstones or biliary obstruction: gallbladder contraction has been shown. ^[8]
• People with iron deficiency or anemia: there is a single case report. ^[7]
• People using drugs that affect clotting: a pharmacokinetic change was seen in an animal study; human interaction should be measured separately. ^[9]
• People who take medicines regularly: the NCCIH recommends talking to a health professional before any herbal product. ^[1]

This guide does not set a personal dose, product, or drug interval; the drug leaflet and the physician or pharmacist take priority.