Curcumin

Curcuma longa, a flowering plant of the ginger family best known as a spice used in curry. It is a polyphenol with anti-inflammatory properties and the ability to increase the amount of antioxidants that the body produces.^[1]

Curcumin and the curcuminoids found in turmeric can be extracted to produce supplements that have a much higher potency than turmeric. However, orally ingested curcumin is poorly absorbed during digestion,^[2][3] so a variety of different formulations have been created to improve its bioavailability.^[4][5][6][7]

Supplementation with curcumin reliably reduces some markers of inflammation^[8][9][10] and increases the levels of endogenous antioxidants in the body.^[11][12][9] However, curcumin has a poor effect on markers of inflammation in people with chronic inflammatory diseases.^[13]

More research is needed on curcumin in many areas of health, but the current evidence shows small to moderate improvements in the symptoms of depression^[14][15][16] and moderate to large improvements in pain and function in osteoarthritis.^{[17][18][19][20][21]}. Curcumin also shows promise for treating a type of inflammatory bowel disease called ulcerative colitis,^[22][23][24] but further research is needed to clarify the optimal dose and route of administration.

Improvements in blood lipids,^{[25][26][27][28][29][30][31][32]} markers of glycemic control,^{[33][26][28][29][30]} blood pressure,^[26][34] liver enzymes,^{[35][36][37][38]} and weight loss^{[39][40][41][42][43][44]} have also been observed following supplementation with curcumin. However, the research on these outcomes is sometimes inconsistent and further high-quality randomized controlled trials are needed to draw firm conclusions.

One of curcumin’s greatest drawbacks is that it is poorly absorbed when orally ingested by itself.^[3]

In terms of potential adverse effects, doses of up to 8 grams of curcuminoids have not been associated with serious adverse effects in humans.^[45] However, long-term studies that are more comprehensive in their assessments are needed to confirm this lack of adverse effects. Studies using high doses of curcumin have reported some mild adverse effects, including nausea, diarrhea, headache, skin rash, and yellow stool.^[46][47][48] Use of curcumin with piperine (a black pepper extract) may cause adverse drug reactions because piperine greatly increases intestinal permeability.^[49] Not all formulations of curcumin have been safety tested to the same degree.

The potential beneficial effects of curcumin seem to be largely the result of its anti-inflammatory and antioxidant properties.^[1][50] These properties are mediated by curcumin’s direct or indirect interaction with, and modulation of, various molecular targets, including transcription factors, enzymes, cell cycle proteins, receptors, cell surface adhesion molecules, growth factors, and protein kinases.^[51][52]