Turmeric and Curcumin

What It Does

In cell studies, curcumin inhibits NF-kB signaling, COX-2, lipoxygenase, and dozens of other targets. That breadth is part of the problem. A 2017 review by medicinal chemists argued that curcumin is chemically unstable, reactive, and prone to interfering with laboratory assays, so many of its in vitro "hits" are artifacts, and that it is an unpromising drug candidate (Nelson 2017). The laboratory literature overstates what curcumin does in people.

The clinical evidence is narrower and more modest. A 2016 meta-analysis of eight trials found that turmeric extracts, usually about 1,000 mg of curcumin daily, reduced joint pain in arthritis, with small trials and some risk of bias (Daily 2016). In the largest trial, 367 people with knee osteoarthritis took 1,500 mg of turmeric extract or 1,200 mg of ibuprofen daily for four weeks; pain and function improved similarly, and the turmeric group had fewer GI complaints (Kuptniratsaikul 2014). Claims for depression, metabolic disease, and cancer rest on weaker data.

Liver injury is uncommon but documented. In ten cases from the US Drug-Induced Liver Injury Network, most patients carried the gene variant HLA-B*35:01, and cases have risen as turmeric sales have grown (Halegoua-DeMarzio 2023). EFSA set an acceptable daily intake for curcumin as a food coloring of 3 mg/kg body weight, about 210 mg for a 70 kg adult (EFSA 2010). Supplements routinely exceed that, and enhanced forms deliver more curcumin to the blood than the safety data assumed.

Forms and Bioavailability

Absorption ratings are broad tiers. Head-to-head human trials rarely support a finer ranking among well-absorbed forms.

Labels column: number of labels named as turmeric and curcumin products that list this form. A product can list more than one form, and some labels do not state a form at all.

Unformulated curcumin is poorly soluble and rapidly conjugated in the gut wall and liver, so blood levels after gram doses are often near the detection limit (Anand 2007). Each delivery system has its own pharmacokinetic study: piperine raised plasma curcumin about twentyfold in one small human study (Shoba 1998), Meriva's phosphatidylcholine complex about 29-fold (Cuomo 2011), BCM-95's turmeric oil base about sevenfold (Antony 2008), and Theracurmin's colloidal particles about 27-fold (Sasaki 2011). These studies used different comparators and measured different curcumin fractions, so the fold numbers cannot be ranked against each other. Piperine works by inhibiting the enzymes and transporters that clear many drugs, which is also its main risk.

Typical Dosing

Osteoarthritis trials used 1,000-1,500 mg of curcuminoid extract daily in divided doses, or smaller doses of enhanced-absorption formulations. EFSA's acceptable daily intake for curcumin as a food additive is 3 mg/kg body weight, about 210 mg for a 70 kg adult.

Food sources: turmeric spice, curry powder.

What to Look For

Read the curcuminoid milligrams, not the turmeric milligrams. A 500 mg turmeric root capsule holds about 15 mg of curcuminoids. For knee pain, the trial-supported approach is 1,000-1,500 mg daily of a 95% curcuminoid extract in divided doses with food, or an enhanced form at the dose used in its own trials. Give it four to eight weeks.

Skip piperine products if you take warfarin, other anticoagulants, or any drug with a narrow dosing margin. Avoid curcumin with gallstones or bile duct obstruction, and stop it if you notice jaundice, dark urine, or unusual fatigue. Turmeric is a crop that has been adulterated with lead-based colorants in some markets, so third-party testing for heavy metals matters more here than for most supplements.

Red flags: turmeric root powder capsules sold for inflammation, "up to 185 times better absorbed" marketing that compares across studies, and proprietary joint blends that hide the curcuminoid dose. Green flags: curcuminoid content per serving, a named delivery system with its own data, and heavy metal testing.

Products on Titrate

5,316 of the 214,745 labels in the NIH Dietary Supplement Label Database list turmeric and curcumin as an active ingredient (2,641 on market). 1,778 are sold as turmeric and curcumin products by name.

Top on-market labels, ranked by label completeness and simplicity:

1. Curcumin Bio-Tech Pharmacal · 450 mg as standardized extract
2. Curcumin C3 Complex Herbadiet · 200 mg as standardized extract
3. Curcumin Complete 95 Lidtke · 500 mg
4. Theracurmin & L-Glutamine Natural Factors CurcuminRich · 30 mg as extract
5. Turmeric MD +BioPerine Approved Science · 1.5 g as extract

Open supplement search

Turmeric and Curcumin does not have its own search category yet. Each product above links to its full label in the NIH database.

Related Tools

• Colloidal Curcumin vs 95% Curcumin Extract
• Colloidal Curcumin vs Curcumin Phytosome
• Colloidal Curcumin vs Curcumin with Piperine
• 95% Curcumin Extract vs Curcumin Phytosome
• 95% Curcumin Extract vs Curcumin with Piperine
• Curcumin Phytosome vs Curcumin with Piperine
• BCM-95 Curcumin vs Colloidal Curcumin
• BCM-95 Curcumin vs 95% Curcumin Extract
• All turmeric and curcumin form comparisons
• All supplement guides

References

National Center for Complementary and Integrative Health. Turmeric.

EFSA Panel on Food Additives and Nutrient Sources added to Food (ANS). Scientific Opinion on the re-evaluation of curcumin (E 100) as a food additive. EFSA J. 2010;8(9):1679.

Shoba G, Joy D, Joseph T, Majeed M, Rajendran R, Srinivas PS. Influence of piperine on the pharmacokinetics of curcumin in animals and human volunteers. Planta Med. 1998;64(4):353-356.

Anand P, Kunnumakkara AB, Newman RA, Aggarwal BB. Bioavailability of curcumin: problems and promises. Mol Pharm. 2007;4(6):807-818.

Antony B, Merina B, Iyer VS, Judy N, Lennertz K, Joyal S. A pilot cross-over study to evaluate human oral bioavailability of BCM-95CG (Biocurcumax), a novel bioenhanced preparation of curcumin. Indian J Pharm Sci. 2008;70(4):445-449.

Cuomo J, Appendino G, Dern AS, et al. Comparative absorption of a standardized curcuminoid mixture and its lecithin formulation. J Nat Prod. 2011;74(4):664-669.

Sasaki H, Sunagawa Y, Takahashi K, et al. Innovative preparation of curcumin for improved oral bioavailability. Biol Pharm Bull. 2011;34(5):660-665.

Kuptniratsaikul V, Dajpratham P, Taechaarpornkul W, et al. Efficacy and safety of Curcuma domestica extracts compared with ibuprofen in patients with knee osteoarthritis: a multicenter study. Clin Interv Aging. 2014;9:451-458.

Daily JW, Yang M, Park S. Efficacy of turmeric extracts and curcumin for alleviating the symptoms of joint arthritis: a systematic review and meta-analysis of randomized clinical trials. J Med Food. 2016;19(8):717-729.

Nelson KM, Dahlin JL, Bisson J, Graham J, Pauli GF, Walters MA. The essential medicinal chemistry of curcumin. J Med Chem. 2017;60(5):1620-1637.

Halegoua-DeMarzio D, Navarro V, Ahmad J, et al. Liver injury associated with turmeric: a growing problem. Ten cases from the Drug-Induced Liver Injury Network [DILIN]. Am J Med. 2023;136(2):200-206.