What are turmeric and curcumin, and how much is in food?

Turmeric, called khamin chan (ขมิ้นชัน) in Thai, is the rhizome (underground stem) of Curcuma longa, a plant in the ginger family. Curcumin is one compound in it: the main yellow pigment, and one of a group of three called curcuminoids. A 2024 Thai study of 16 dried rhizomes found mostly 5–17% total curcuminoids, depending on where they were grown. Separately, ground turmeric sold as a spice averaged about 3% curcumin (curcumin alone) in a US analysis.

In short:

• What it is: the rhizome of Curcuma longa, family Zingiberaceae; Thai name khamin chan
• Curcumin: the main yellow pigment, one of three curcuminoids
• In dried Thai rhizomes: mostly 5–17% total curcuminoids (16 samples, 2023)
• In turmeric powder: about 3.14% curcumin on average (28 products)
• Not the same as: khamin oi (ขมิ้นอ้อย), which is Curcuma zedoaria
• Watch out for: people who are pregnant, breastfeeding or on regular medication should ask a doctor or pharmacist before using turmeric supplements

What plant is turmeric, and what else is it called?

Turmeric is Curcuma longa, a plant in the ginger family (Zingiberaceae). NCCIH, part of the US National Institutes of Health, says it is grown commercially in Southeast Asia and India, and that its rhizome has been used in cooking. Memorial Sloan Kettering adds that turmeric is now cultivated in tropical areas around the world and that the rhizome is used as a spice and as a colouring agent in food and cosmetics.

A spice in Southeast Asia for 2,000 years

A 2023 study by Wang and colleagues in Science Advances examined grinding stones from Oc Eo, an early port in southern Vietnam used during the early centuries CE. Of the starch grains from ginger-family plants found on the stones, turmeric made up the largest share, and many grains showed broken features from grinding, like the starch in modern curry powder. The researchers see this as evidence of curry-making in Southeast Asia about 2,000 years ago.

What is the difference between khamin chan and khamin oi?

They are different species in the same genus. Khamin chan is Curcuma longa and khamin oi is Curcuma zedoaria. Thai markets also sell other yellow rhizomes, such as phlai (ไพล, Zingiber montanum) and wan nang kham (ว่านนางคำ, Curcuma aromatica).

A 2024 study by Monton and colleagues at Rangsit University grew these plants in the same place, Chiang Dao District in Chiang Mai, and compared them.

Because the plants came from a single location, the table shows differences between species, not how much each one contains wherever it is grown.

What are curcumin and the curcuminoids?

Curcuminoids are the yellow compounds in turmeric. NCCIH says curcumin is a major component of turmeric and gives the spice its yellow colour. A 2025 study by Anukanon and colleagues at Mae Fah Luang University and Valaya Alongkorn Rajabhat University describes three: curcumin I (curcumin), curcumin II (demethoxycurcumin) and curcumin III (bisdemethoxycurcumin).

Source: formulas and molecular weights from PubChem. "Demethoxy" means one methoxy group (–OCH3) has been removed and "bisdemethoxy" means two have been removed, which is why each step down is about 30 g/mol lighter. Memorial Sloan Kettering also notes that turmeric contains an oil, turmerone oil, in addition to the curcuminoids.

How much curcuminoid is in Thai turmeric?

It varies a lot by where it is grown. Monton and colleagues (2024) bought 16 fresh turmeric rhizomes through online platforms in July 2023: four from the north, three from the centre, four from the west, two from the east and three from the south of Thailand. They dried and ground them and measured the curcuminoids by HPLC.

In most samples, curcumin was the most common curcuminoid. The limits: the 16 samples were bought in a single month, and only a few came from each region, so the results show how much turmeric can vary rather than which province always has the most.

What about turmeric extracts?

Anukanon and colleagues (2025) made ethanol extracts from turmeric grown in three regions of Thailand and found total curcuminoids of 15.1% in the extract from the east, 25.9% from the south and 31.6% from the north. Curcumin I was the main one, followed closely by curcumin II and III. These are percentages of a laboratory extract, not of the rhizome.

Does drying change the curcuminoids?

Yes. A 2022 study by Komonsing and colleagues at Silpakorn University dried 2 mm slices of turmeric at 40, 50, 60 and 70 °C under simulated sunlight, using either a cover that blocks ultraviolet light or one that lets it through. Curcumin and total curcuminoids depended on the total heat load during drying. The lowest curcumin was found at 40 °C under the cover that lets ultraviolet light through, where the total heat load was highest, and the researchers found 70 °C under the ultraviolet-blocking cover the best condition, with shorter drying and better colour and curcuminoids.

How much curcumin is in turmeric powder and curry?

Pure turmeric powder averaged 3.14% curcumin by weight (about 31 mg per gram) in a US analysis. The 2006 study by Tayyem and colleagues measured curcumin in 28 spice products sold as turmeric or curry powder.

The Thai rhizome figures include all three curcuminoids, while the powder figure is curcumin alone, so the two are not directly comparable. Memorial Sloan Kettering notes that turmeric is a major ingredient of curry powder. In Thai cooking, turmeric gives the yellow colour to dishes such as kaeng lueang (yellow sour curry), kaeng tai pla and fried chicken with turmeric.

How much curcumin do people get from food?

A 2014 study by Kwon used Korea's national nutrition survey (2008–2012) to estimate curcumin intake in a country where turmeric is not a common ingredient. Only 0.06% of Koreans reported eating curcumin-containing foods on a given day. The estimated average turmeric intake was about 0.47 g a day, equal to 2.7–14.8 mg of curcumin, and the author estimates that this is roughly a quarter of the daily curcumin intake in South Asia. No similar figure for Thailand was found for this article.

Is there a recommended daily amount of curcumin?

No. Turmeric and curcumin are not nutrients, so they have no value in the Thai Reference Daily Intakes (Thai RDIs), which cover nutrients such as vitamins and minerals.

Separately, curcumin is also used as a food colour, with the European code E 100. The European Food Safety Authority (EFSA) has assessed curcumin used as a food colour and uses an acceptable daily intake of 3 mg per kilogram of body weight a day for it. This is a figure for food colouring added to foods, not an amount to take.

Who should be careful with turmeric supplements?

Effects that have been reported

NCCIH lists possible effects of turmeric taken by mouth, such as nausea and vomiting, stomach upset, diarrhoea or constipation. Memorial Sloan Kettering lists stomach discomfort, skin rash and hives. NCCIH also says that liver damage has been reported in some people who took curcumin products made to be absorbed more easily, and that anyone who notices signs such as unusual tiredness, nausea, loss of appetite, dark urine or yellowing of the skin or eyes should stop and talk with a health care provider. Anyone with an ongoing health condition or taking regular medication should speak to a doctor or pharmacist before using turmeric supplements.

People who are pregnant or breastfeeding

NCCIH says the use of turmeric supplements during pregnancy may be unsafe, and that little is known about whether it is safe to use turmeric in amounts greater than those commonly found in food while breastfeeding.

People taking regular medication

NCCIH and Memorial Sloan Kettering both say that turmeric can interact with some medicines. Memorial Sloan Kettering adds that herbal supplements are stronger than the herbs used in cooking, and advises talking with your healthcare providers before taking turmeric supplements or higher amounts.

If you are pregnant, breastfeeding, take regular medication or are under a doctor's care, speak to a doctor or pharmacist before taking dietary supplements.

Dietary supplements are not intended to prevent, treat or cure any disease.