Curcumin (Turmeric Root Extract)

Extract from Curcuma longa, standardized to 90 percent curcuminoids

Evidence: Moderate

Turmeric has been used to support digestion across South Asia for thousands of years, and modern science has zeroed in on why. Its golden colour comes from curcuminoids, a family of polyphenols led by curcumin. Whole turmeric root contains only about 2 to 5 percent curcuminoids, so to deliver a meaningful amount we use a concentrated extract standardised to 90 percent curcuminoids rather than the raw spice.

Curcumin is among the most heavily researched plant compounds in the world, and a growing share of that work focuses on the gut, where curcumin interacts with the microbiome and the cells lining the intestine. Because curcumin is poorly absorbed on its own, much of it reaches the colon, where research is examining its interplay with gut bacteria and microbial diversity. We pair it with black pepper for exactly this reason, as explained on the black pepper page.

PubMed indexes over 28,000 peer-reviewed papers on curcumin.

Selected study

Enayati A, Soghi A, Butler AE, Rizzo M, Sahebkar A. The Effect of Curcumin on the Gut-Brain Axis: Therapeutic Implications. Journal of Neurogastroenterology and Motility. 2023;29(4):409-418. doi:10.5056/jnm23065

Study summary

Study type: Narrative review collating pre-clinical and human studies on curcumin and the microbiota-gut-brain network.

Observed benefits:

• Across the literature, curcumin is associated with higher levels of beneficial genera such as Lactobacillus, Bifidobacterium and Akkermansia, and with short-chain fatty acid producers.
• Studies report support for tight-junction integrity in the gut lining.

Mechanisms: Poorly absorbed curcumin reaches the colon and behaves in a prebiotic-like way; it also engages cellular oxidative and signalling pathways (including Nrf2).

Safety: Generally well tolerated; high doses may cause transient digestive upset.

Evidence strength: Biologically plausible and supported by small human studies, with most trials short and varied in curcumin form and dose.