Turmeric: effectiveness, forms and interactions—what can we really conclude?

Turmeric (Curcuma longa) is both a culinary spice and a traditional medicinal plant. Curcumin has been widely studied, but products and doses are not interchangeable. Evidence does not support a general health claim. [1]

Food usually contains dried rhizome powder. Supplements may contain powder, standardised extracts, isolated curcumin or enhanced-bioavailability formulas. The EMA recognises traditional use of some rhizome preparations for mild digestive complaints such as fullness, slow digestion and flatulence; this is not proof that every curcumin product treats disease. [1][2][3]

NCCIH says evidence is insufficient for a definitive general benefit. Two 2021 reviews found possible improvements in osteoarthritis pain, function or stiffness, but doses, extracts and durations differed and the optimal formulation remained unclear. [1][6][7]

Conventional oral forms may cause nausea, reflux, stomach upset, diarrhoea or constipation. Some high-bioavailability curcumin products have been linked to liver injury reports. [1][3][4][8]

ANSES reports potential concerns with some anticoagulants, anticancer medicines and treatments affected by liver enzymes or transporters. Piperine can change bioavailability and complicate drug interactions. Use extra caution with anticoagulants, antiplatelets, chemotherapy, immunosuppressants, liver or bile-duct disease, gallstones, chronic disease or multiple medicines. [3]

Because safety data are insufficient, concentrated supplements should be avoided during pregnancy and breastfeeding unless a professional advises otherwise. Culinary use is different.

“Highly absorbed” does not mean “more effective for everyone.” A study of one extract does not validate a different capsule. Do not stop prescribed treatment to try a supplement.

Turmeric is a useful spice and some preparations have a recognised traditional digestive use. Curcumin extracts may help some osteoarthritis symptoms, but evidence depends on formulation and does not justify a general promise. Enhanced-bioavailability products require particular caution.

1. 01NCCIH, 2024 — https://nccih.nih.gov/health/turmeric
2. 02EMA/HMPC, 2018 — https://www.ema.europa.eu/en/medicines/herbal/curcumae-longae-rhizoma
3. 03ANSES, 2022 — https://www.anses.fr/fr/system/files/NUT2019SA0111.pdf
4. 04NIH LiverTox, 2024 — https://www.ncbi.nlm.nih.gov/books/NBK548561/
5. 05Cochrane, 2014 — https://www.cochrane.org/evidence/CD002947_oral-herbal-therapies-treating-osteoarthritis
6. 06Zeng et al., 2021 — https://pubmed.ncbi.nlm.nih.gov/34017975
7. 07Paultre et al., 2021 — https://pubmed.ncbi.nlm.nih.gov/33500785
8. 08Shrestha et al., 2025 — https://pubmed.ncbi.nlm.nih.gov/39995754