The Bioavailability of Curcumin: Problems and Progress

Article Summary:

• Curcumin’s natural unstable chemical structure results in poor solubility, rapid metabolism, and low absorption in the gut.
• Tetrahydrocurcumin, a primary active metabolite of curcumin, is more bioavailable than curcumin.
• Various advanced nanodelivery systems are being used to enhance curcumin’s bioavailability.
• Tesseract’s proprietary CyLoc® – DexKey® nutrient delivery system optimizes the absorption and bioavailability of curcumin to help achieve its health benefits.

The bioavailability of a nutrient is its ability to enter the circulation when introduced into the body and exert its active effect. Curcumin, the yellow pigment found in turmeric, is well-known for its antioxidant properties and its ability to help maintain the body’s normal inflammatory responses. However, curcumin’s poor natural bioavailability negatively impacts its efficacy in supplement formulations. This post explains the factors that influence the bioavailability of curcumin, as well as the various pharmacological approaches being taken to enhance its absorption and bioavailability. 

Factors That Influence The Bioavailability of Curcumin

The bioavailability of a nutritional supplement relies on several key factors: its transformation in the gastrointestinal (GI) tract, its bioaccessibility, and its subsequent metabolism, particularly in the liver. A 2015 human study tracked the degradation of orally ingested curcumin.¹ The low bioavailability of curcumin revealed in this study is attributable to its chemical instability, which leads to: 

• Poor solubility in water 
• Rapid metabolism
• Low absorption from the gut
• Rapid systemic elimination

These factors result in very low—or even undetectable—concentrations of curcumin in the blood and extra-intestinal tissues after supplementation. 

How Does Curcumin Break Down in The Body? 

• In the GI tract, curcumin tightly binds to mucus, which delays its uptake by epithelial cells and begins to cause oxidative degradation. 
• After being transported into epithelial cells, curcumin undergoes extensive Phase I and Phase II metabolism in the liver.
• Phase I metabolism reduces curcuminoids into dihydrocurcumin, tetrahydrocurcumin, hexahydrocurcumin, and octahydrocurcumin. Phase I metabolism is followed by Phase II conjugation with sulfate, glucuronide, and glutathione.
• Curcumin and its metabolites then proceed to the intestinal lumen for elimination, where they are further metabolized by the gut microbiome in the colon, leaving little opportunity for reabsorption. 
• What few curcumin compounds are reabsorbed are again metabolized by hepatocytes in the liver, transforming them into reduced and conjugated forms — the majority of which enter the bile with only minor amounts entering circulation. 
• After entering circulation, curcumin and its metabolites adhere strongly to proteins, particularly albumin. 

A Study Highlighting The Poor Absorption of Curcumin

Several human studies have investigated the poor absorption of curcumin. A dose escalation study in 2006 was performed on 24 healthy participants to determine the maximum tolerated dose and the safety of a single dose of curcumin powder extract.² With doses ranging from 0.5 g to 12 g, although the study revealed excellent tolerance of curcumin, no curcumin was detected in the serum of the subjects given amounts between 0.5 g and 8 g. Low levels of curcumin were detected in the participants who were administered 10 g or 12 g.

Approaches Undertaken to Increase The Bioavailability of Curcumin

Various novel approaches are being explored to increase curcumin’s bioavailability. Today, the most promising of these approaches involves using tetrahydrocurcumin.   

Tetrahydrocurcumin: The Most Bioavailable Form of Curcumin

Tetrahydrocurcumin—one of the primary active metabolites of curcumin, exhibits bioactivities similar to those of curcumin, but it is more easily absorbed in the GI tract. A 2013 animal study involving the administration of Curcuma-P® for four weeks found the presence of tetrahydrocurcumin—but not curcumin—inside subcutaneous adipose tissue.³ Several other studies have also shown that tetrahydrocurcumin is more bioactive than curcumin and appears to be a superior antioxidant with enhanced bioavailability.*

Enhancing the Bioavailability of Curcumin

Several nutritional supplement formulations have been designed to enhance curcumin’s bioavailability:

• A combination of curcumin and piperine: Piperine is the natural alkaloid of black pepper. A combination of curcumin and piperine produces significantly higher serum concentrations of curcumin than does curcumin alone. 

• A curcuminoid mixture with lecithin: It has better bioavailability than a non-lecithin curcuminoid mixture.   

Curcumin formulated as hydrophilic nanoparticles exhibits enhanced gastrointestinal absorption. A 2014 study on comparative absorption of various curcumin formulations revealed a 46-fold increase in oral absorption of a water-soluble curcumin formulation compared to unformulated curcumin.⁴

Curcumin delivery systems like liposomes, micelles, microemulsions, nano-emulsions, phospholipid complexes, nanostructured lipid carriers, solid lipid nanoparticles, and microgels all hold great potential in enhancing the bioavailability of curcumin.

Advanced tetrahydrocurcumin formulations, such as Tesseract Medical Research’s TetraCumin®, enhance the bioavailability of curcumin even further with a revolutionary delivery technology designed to ensure maximum absorption. The resulting enhanced curcumin absorption, in turn, unlocks the immense therapeutic potential of curcumin for supporting musculoskeletal health and immune function in the body.*

References

¹Schneider C, et al. Degradation of curcumin: From mechanism to biological implications. Journal of Agricultural and Food Chemistry 2015;63,357606-7614. doi:10.1021/acs.jafc.5b00244

²Lao CD, et al. Dose escalation of a curcuminoid formulation. BMC Complementary and Alternative Nedicine 2006;6:10. doi:10.1186/1472-6882-6-10

³Neyrinck AM, et al. Curcuma longa extract associated with white pepper lessens high fat diet-induced inflammation in subcutaneous adipose tissue. PloS One 2013;8:11 e81252. doi:10.1371/journal.pone.0081252

⁴Jäger R, et al. Comparative absorption of curcumin formulations. Nutrition Journal 2014;13:11. doi:10.1186/1475-2891-13-11