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Curcumin is the principal bioactive compound present in the yellow spice, turmerice. An abundance of scientific evidence indicates that curcumin exerts antioxidant, anti-inflammatory, anticancer, and neuroprotective properties in humans. Findings from a 2019 study suggest that curcumin improves exercise tolerance in mice with heart failure via its activation of Nrf2.
Heart failure, commonly referred to as the end stage of heart disease, affects more than 26 million people worldwide. Exercise intolerance is a common feature of heart failure and is typically attributed to low ejection fraction – a measure of ventricular efficiency. A critical driver of low ejection fraction is oxidative stress.
Nrf2 is a cellular protein that regulates the expression of antioxidant and stress response proteins via participation in the Keap1-Nrf2-ARE biological pathway. Nrf2 activates the transcription of cytoprotective proteins that protect against oxidative stress due to injury and inflammation.
The study investigators gauged the effects of curcumin in mice that had heart failure with reduced ejection fraction and in mice with healthy hearts. A subset of the mice received daily curcumin supplementation, while the others did not. The investigators measured the animals' heart function via echocardiogram, assessed their exercise performance on a treadmill, and measured the expression of Nrf2 and its target proteins in their muscles.
They found that both groups of mice that received curcumin (including those with healthy hearts) had improved exercise capacity compared to those that did not receive curcumin. They also found that Nrf2 expression and antioxidant proteins increased in the mice with heart failure that received curcumin.
These findings suggest that impaired Nrf2 drives oxidative stress in skeletal muscle in mice that have heart failure with low ejection fraction. Curcumin counters these effects by upregulating antioxidant defenses in skeletal muscle, likely mediated by Nrf2 activation. Many plant-based dietary compounds induce Nrf2 activity, including sulforaphane, a compound derived from broccoli and broccoli sprouts. Learn more about Nrf2 and sulforaphane in this episode featuring Dr. Jed Fahey.