A recent review paper published in the Foods, titled “Curcumin: A Review of Its Effects on Human Health,” details the many health benefits of these compounds which are extracted from the spice turmeric. “It aids in the management of oxidative and inflammatory conditions, metabolic syndrome, arthritis, anxiety, and hyperlipidemia. It may also help in the management of exercise-induced inflammation and muscle soreness, thus enhancing recovery and performance in active people,” the authors wrote.
Effects at multiple levels
“Curcumin, a polyphenol, has been shown to target multiple signaling molecules while also demonstrating activity at the cellular level, which has helped to support its multiple health benefits. It has been shown to benefit inflammatory conditions, metabolic syndrome, pain, and to help in the management of inflammatory and degenerative eye conditions. In addition, it has been shown to benefit the kidneys. While there appear to be countless therapeutic benefits to curcumin supplementation, most of these benefits are due to its antioxidant and anti-inflammatory effects,” the authors wrote.
Douglas Kalman, PhD, of Florida Atlantic University, is one of the paper’s authors. As a contract researcher and journal paper author and editor, Kalman is familiar with the activity of many dietary ingredients and was aware of the growing claims for curcuminoids. But he said even with this foreknowledge, the breadth and depth of the scientific backing of curcumin was a revelation once he and his coauthor Susan Hewlings of Central Michigan University really got into the nitty gritty of looking at the studies themselves.
“We felt that the evidence for health support and benefits was growing stronger and that a strong signal is there. The evidence surprised us. We review a lot of science related to dietary supplements. Few have been as convincing as curcumin. But that being said, the science speaks for itself as growing and real,” he said.
Dr Kalman said they found wide ranging effects, both at the cellular and macro levels, where curcumin affects metabolic processes. Among the most interesting research is the results that show curcumin can ameliorate muscle soreness among subjects post exercise, which augurs well for a future positioning for the polyphenol in sports nutrition and in joint health products.
Curcumin is a molecule that is notoriously difficult to absorb. There is evidence that turmeric in its basal state, when used as a persistent part of the diet, can exert health benefits, including antimicrobial effects, even with its poor absorption profile. The curcumin content of turmeric samples tested in India recently varied widely, from a low of about 2.5% to a high of almost 9% by weight. The discussion among researchers then has been what dosages in a dietary supplement application are effective, given that so little of the active ingredients actually end up crossing the blood barrier.
“Despite its reported benefits via inflammatory and antioxidant mechanisms, one of the major problems with ingesting curcumin by itself is its poor bioavailability, which appears to be primarily due to poor absorption, rapid metabolism, and rapid elimination. Several agents have been tested to improve curcumin’s bioavailability by addressing these various mechanisms,” Drs Kalman and Hewlings wrote.
Among these approaches have been nano sizing of particles to increase surface area and encapsulation of curcuminoids with lipid carriers that both protect the polyphenols and speed absorption. The researchers said particular attention has been given to approaches that block the metabolism of curcumin. Among these approaches among the oldest and therefore best established is the use of piperine, via an extract of black pepper, that has been found to boost the bioavailability and activity of a host of drugs and nutritional compounds, including curcuminoids, by affecting liver metabolism.
Kalman said the nagging questions of absorption needed to be addressed in the review, and do complicate the assessment of the science surrounding the polyphenol. But he said many approaches to this issue are possible, and the use of piperine shows up most frequently partly because it’s been around the longest.
“The focus of the paper was not about bioavailability, but what did the finished published randomized and related studies actually indicate or state as related to the use of curcumin and human health. [T]here are many approaches to enhance bioavailability, in fact one could write a paper devoted just to that topic alone. Again, therefore we chose to just mention it and not to make it the focus of our review and provided Piperine as an example since it is well known but we did not intend for it to seem like it was the only option,” he said.
Curcumin: A Review of Its Effects on Human Health
2017 Oct 22;6(10). pii: E92. doi: 10.3390/foods6100092
Authors: Hewlings SJ, Kalman DS