Curcumin is the hydrophobic polyphenol evolved from the plant source Curcuma longa constituting broader aspects of biological and pharmacological activities. The commercial curcumin consists of approximately 77% diferuloylmethane, 17% demethoxycurcumin, and 6% bisdemethoxycurcumin. The crude extract curcuminoid makes up upto 1-6% of turmeric by weight with distribution of 60%-70% curcumin, 20%-27% demethoxycurcumin,and 10%-15% bis-demethoxycurcumin (Nelson et al., 2017). Curcumin has shown potential effects towards treatment of several cancers such as gastrointestinal diseases, metabolic diseases, dermatologic conditions, cardiovascular diseases, neurodegenerative diseases, autoimmune conditions, and psychiatric disorders. Some of the evidence reveals the therapeutic efficacy of curcumin. Not only in cancer treatment, but curcumin has shown beneficial effects on other diseases as well. Although there are several positive outcomes on the use of curcumin, still a major criticism of curcumin regarding its poor bioavailability is reported. The researchers have revealed its negative outcome after the clinical trials as a result of its instability, reactivity, and non bioavailable nature.
Hence, the features of poor availability of curcumin is confirmed while many studies representing very low, or even undetectable, concentrations in blood and extraintestinal tissue. Its poor absorption, rapid metabolism, chemical instability, and rapid systemic elimination have resulted in poor availability of curcumin. Most oral curcumin is excreted in the faeces (≤90%). Hence, several methods are undertaken for increasing the bioavailability of curcumin.
Oral Curcumin Bioavailability
The bioavailability of polyphenols in the dietary sources are affected by theorigin, food processing, and macronutrients. The dietary lipids affect the solubility and absorption of curcumin. Turmeric is recommended to be consumed as cuisine which is linked with lecithin-rich ingredients such as eggs or vegetable oils for increasing the dietary intake of curcuminoids (Esatbeyoglu et al., 2012). Also the powdered curcuminoids when mixed in buttermilk before yoghourt manufacturing resulted in 15 times increase in the bioaccessibility of curcuminoids when compared with neat curcuminoids. Hence, the form of curcuminoids with enhanced bioaccessibility is still estimated to be low. Digestive steps of curcumin contribute towards lower bioavailability of polyphenols affecting solubility, degradation in the intestinal environment, and the permeation rate in the small intestine.
Overcoming bioavailability issues of curcumin
In order to increase the bioavailability of curcumin, different methods have been adopted. The use of adjuvants including piperine, formulating liposomal curcumin, curcumin nanoparticles, curcumin phospholipid complexes, and the use of structural analogs of curcumin including turmeric oil have been effective in increasing the bioavailability of curcumin. These methods have shown successful integration with increased blood concentrations. But still, therapeutic potencies and pharmacodynamic response of other bioavailable forms of curcumin have not been depicted due to lack of human trials on the same.
Association of bioavailability of curcumin with human health
The oral bioavailability of curcumin is determined to be low. Various strategies have been implemented for increasing the uptake and availability of curcumin while determining its biological activities. One of the most important strategies is the inhibition of curcumin metabolism with adjuvants which interfere with metabolising enzymes. The other phytochemicals are also capable of altering the curcuminoid metabolism and further its bioavailability. The administration of curcumin as a delivery system in the form of nanoparticles, and liposomes which is designed for enhancing the solubility and stability in the gastrointestinal tract. The combination of curcumin with other compounds have increased the solubility, extended the residence in plasma, and improved the pharmacokinetic profile and the cellular uptake. These strategies of increasing the bioavailability of curcumin helps in enhancing the health-beneficial potential of curcuminoids and thus stimulate their use as ingredients in dietary supplements and functional foods.
This way, curcumin has gained more attention towards its use providing multiple health benefits. It possesses anti-oxidant and anti-inflammatory properties which helps in treatment of several cancers along with other treatment of several other diseases. These advantages of curcumin can be achieved significantly when combined with agents such as piperine that eventually increases its bioavailability. Curcumin helps in the management of oxidative and inflammatory conditions, metabolic syndrome, arthritis, anxiety, and hyperlipidemia. It is effective in the management of exercise-induced inflammation and muscle soreness, thus enhancing recovery and subsequent performance in active individuals. Low dose of curcumin intake tends to provide health benefits for the individuals who are not diagnosed with any health condition.
- Nelson, K. M., Dahlin, J. L., Bisson, J., Graham, J., Pauli, G. F., & Walters, M. A. (2017). The essential medicinal chemistry of curcumin: miniperspective. Journal of medicinal chemistry, 60(5), 1620-1637. https://doi.org/10.1021/acs.jmedchem.6b00975
Esatbeyoglu, T., Huebbe, P., Ernst, I. M., Chin, D., Wagner, A. E., & Rimbach, G. (2012). Curcumin—from molecule to biological function. Angewandte Chemie International Edition, 51(22), 5308-5332. https://doi.org/10.1002/anie.201107724