Does Turmeric Increase Risk of Cancer in Smokers or Ex-Smokers?

Antioxidant compounds, including turmeric and its compounds, can also promote oxidation in certain circumstances. This raises concern about turmeric's possible negative effects on health. ^(i.75, 76)

Decades of safety and other medical research have led food safety experts to declare that turmeric and curcumin do not cause cancer. However, results of one animal study published in 2009 suggest using the turmeric compound curcumin could increase your risk of cancer if you smoke tobacco. ^(i.75, 76)

Using an animal model of lung cancer, the study mimicked lung conditions that occur in smokers and ex-smokers. Mice were given doses of curcumin equivalent to approximately 2500 mg/day. At this dosage, curcumin seemed to promote the progression of lung lesions to lung tumors at higher rates than those found in the mice not given curcumin. ^(i.75)

The changes in the mice were associated with increased inflammation and oxidative injury in the already damaged lung lining. The researchers in this study proposed that this might indicate a need to exclude any smokers and ex-smokers from clinical trials with curcumin. This is because smokers and ex-smokers also have damaged lung lining. ^(i.75)

Conflicting Evidence?

However, results from a clinical trial involving 16 chronic smokers suggest turmeric could actually help prevent lung cancer. Daily doses of turmeric significantly reduced the amount of cancer-causing substances in their urine (compared to the untreated, non-smoker control group). This suggests that turmeric may actually protect against the kinds of DNA damage caused by known carcinogens that could lead to lung cancer. ^(i.5)