Is curcumin bioavailability a problem in humans: lessons from clinical trials

ABSTRACT

Introduction: Since ancient times, turmeric has been used in several folklore remedies against various ailments. The principal component of turmeric is curcumin and its efficacy has been advocated in various in vitro, in vivo and clinical studies for different chronic diseases. However, some studies suggest that curcumin bioavailability is a major problem.

Areas covered: This article discusses over 200 clinical studies with curcumin that have demonstrated the pronounced protective role of this compound against cardiovascular diseases, inflammatory diseases, metabolic diseases, neurological diseases, skin diseases, liver diseases, various types of cancer, etc. The review also describes the combination of curcumin with many natural and synthetic compounds as well as various formulations of curcumin that have shown efficacy in multiple clinical studies.

Expert opinion: The therapeutic potential of curcumin, as demonstrated by clinical trials has overpowered the myth that poor bioavailability of curcumin poses a problem. Low curcumin bioavailability in certain studies has been addressed by using higher concentrations of curcumin within nontoxic limits. Moreover, curcumin, in combination with other compounds or as formulations, has shown enhanced bioavailability. Hence, bioavailability is not a problem in the curcumin-mediated treatment of chronic diseases. Therefore, this golden nutraceutical presents a safe, low-cost and effective treatment modality for different chronic diseases.

KEYWORDS:

• Turmeric
• curcumin
• bioavailability
• chronic diseases
• antioxidant
• anti-inflammatory

Article highlights

• Curcumin is one of the most extensively studied nutraceuticals, which has been approved by the FDA as ‘Generally Recognized As Safe’ (GRAS).

• Several in vitro and in vivo studies have documented the beneficial effect of curcumin in the management of various chronic diseases.

• A number of clinical trials with curcumin have been conducted and several new trials have been registered. Majority of these trials have reported positive outcome in the treatment of chronic diseases.

• The therapeutic action of curcumin involves modulation of several molecular targets and signaling pathways.

• Bioavailability of curcumin is not an issue. The therapeutic efficacy of curcumin as evident from numerous clinical trials overpowers the hindrance of low bioavailability.

• New formulations of curcumin in the form of micelles, liposomes, phospholipids, exosomes have been synthesized. These formulations have reported enhanced bioavailability.

This box summarizes key points contained in the article.

Declaration of interest

The authors have no relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript. This includes employment, consultancies, honoraria, stock ownership or options, expert testimony, grants or patents received or pending, or royalties.

Reviewer disclosures

Peer reviewers on this manuscript have no relevant financial or other relationships to disclose.

Additional information

Funding

The work was supported by the Department of Biotechnology, Government of India—BT/556/NE/U-EXCEL/2016 dated 31.03.2017 awarded to Dr. Ajaikumar B. Kunnumakkara. The author Kishore Banik acknowledges UGC New Delhi, India and the author Bethsebie Laduhsaki Sailo acknowledges DST-INSPIRE for providing their fellowship.