Who Should Not Take Curcumin

Curcumin, the main active compound in turmeric, is popular among athletes for joints and recovery. As a spice it is very safe, but concentrated supplements, especially enhanced-absorption formulas, behave differently. Our editorial team outlines who should avoid them or use them only with medical guidance.

Curcumin Supplements in Brief

Turmeric root contains only about 3 percent curcuminoids by weight. Supplements are typically concentrated to 95 percent curcuminoids and delivered at doses of 500 to 2,000 milligrams a day, far more than a curry provides.

Plain curcumin is poorly absorbed. Manufacturers boost bioavailability with piperine from black pepper, phospholipid complexes, nanoparticles or other technologies. Shoba and colleagues showed that piperine markedly increased curcumin blood levels in humans.

Higher absorption may improve effectiveness, but it also changes the safety profile and increases the potential for drug interactions, since piperine itself inhibits drug-metabolizing enzymes.

Hewlings and Kalman's review summarizes potential benefits for inflammation, joint pain and exercise-induced soreness. These benefits are modest and do not apply equally to everyone.

Liver Concerns

Turmeric-associated liver injury has emerged as a real, if uncommon, problem. The US Drug-Induced Liver Injury Network (DILIN) reported a series of cases in which turmeric supplements were the likely cause, and Lombardi and colleagues described a cluster of cases in Italy.

Many affected individuals carried the HLA-B*35:01 genetic variant, suggesting an immune-mediated, idiosyncratic reaction. Many cases involved enhanced-absorption products.

Warning signs include fatigue, nausea, dark urine, pale stools, itching and yellowing of the skin or eyes. Anyone experiencing these while taking curcumin should stop and see a physician promptly.

People with existing liver disease, and those taking other potentially hepatotoxic substances, should avoid concentrated curcumin unless their doctor approves it.

Gallbladder, Bleeding and Iron

Rasyid and Lelo showed that curcumin stimulates gallbladder contraction. That can be harmful in people with gallstones or bile duct obstruction, as it may provoke pain or complications.

Curcumin has mild antiplatelet effects in laboratory studies. Combined with anticoagulants such as warfarin or apixaban, antiplatelet drugs, or high-dose fish oil, it could increase bleeding risk. Stopping curcumin about two weeks before surgery is a common precaution.

Curcumin binds iron and may reduce its absorption. A case report by Smith and Ashar described iron deficiency anemia associated with high-dose turmeric. Athletes with low ferritin, particularly menstruating women and endurance runners, should be cautious.

Drug Interactions and Other Groups

Curcumin and piperine can affect cytochrome P450 enzymes and drug transporters. This may change blood levels of medications such as certain chemotherapies, immunosuppressants like tacrolimus and some antidepressants.

In people with diabetes, curcumin may modestly lower blood sugar. Combined with insulin or sulfonylureas, it could contribute to hypoglycemia, so glucose monitoring is advisable.

Those with a history of calcium oxalate kidney stones should be aware that turmeric contains oxalate. Purified curcumin extracts contain less, but whole turmeric powder supplements may add to oxalate load.

Cancer patients should discuss curcumin with their oncologist. Although it is studied as an adjunct, it may interfere with some treatments.

• Blood thinners and antiplatelet drugs
• Diabetes medications
• Chemotherapy agents
• Immunosuppressants
• Drugs with narrow therapeutic windows

Using Curcumin Safely

For healthy adults, EFSA has set an acceptable daily intake for curcumin as a food additive of 3 milligrams per kilogram of body weight, roughly 210 milligrams for a 70-kilogram person. Supplement doses often exceed this, which is one reason to use them deliberately.

Typical studied doses for joint pain range from 500 to 1,500 milligrams a day of curcuminoids, often split. Take them with meals to reduce stomach upset.

Choose products tested by a third party for purity. Lead contamination of turmeric has been documented in some international supply chains.

Reassess after 8 to 12 weeks. If there is no meaningful improvement, there is little reason to continue.

Editorial Team Conclusions

Curcumin is safe for most healthy adults at studied doses, but it is not risk-free.

Gallstones, liver disease, anticoagulant use, iron deficiency, pregnancy and upcoming surgery are the main reasons to avoid it or seek medical advice.

Enhanced-absorption formulas may increase both benefits and risks, including rare liver injury.

You may also want to read our articles on omega-3 for joint health, iron deficiency in endurance athletes and how to recognize supplement-induced liver injury.

References

1. Hewlings SJ, Kalman DS. Curcumin: a review of its effects on human health. Foods. 2017;6(10):92.
2. Lombardi N, Crescioli G, Maggini V, et al. Acute liver injury following turmeric use in Tuscany: an analysis of the Italian Phytovigilance database and systematic review of case reports. Br J Clin Pharmacol. 2021;87(3):741–753.
3. 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.
4. Rasyid A, Lelo A. The effect of curcumin and placebo on human gall-bladder function: an ultrasound study. Aliment Pharmacol Ther. 1999;13(2):245–249.
5. Shoba G, Joy D, Joseph T, et al. Influence of piperine on the pharmacokinetics of curcumin in animals and human volunteers. Planta Med. 1998;64(4):353–356.
6. Smith TJ, Ashar BH. Iron deficiency anemia due to high-dose turmeric. Cureus. 2019;11(1):e3858.
7. 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.