Zinc, Copper, and Lung Cancer
Whether your risk for developing lung cancer is high or low, you may be able to meaningfully reduce your odds by adding more zinc- and copper-rich foods to your diet.
A first-of-its-kind study* looked at the possible connections between lung cancer and dietary intake of the trace metals zinc, copper, and selenium. While the results didn’t indicate a significant selenium link one way or the other, they did suggest that people who eat foods high in zinc and copper can lower their likelihood of getting the disease.
Comprised of 1,676 lung cancer patients and 1,676 healthy controls from a larger ongoing study led by Margaret Spitz, MD, of MD Anderson Cancer Center, the study considered a number of factors, including smoking status, diet, ethnicity, alcohol use, nutrient intake, family history of cancer, and body mass index.
“Dietary zinc and copper are essential for several biological functions throughout life, such as repairing cells and protecting them from damage,” says lead author Somdat Mahabir, PhD, of the MD Anderson Cancer Center. “We found a consistent and significant association between increased dietary zinc and copper intakes and lung cancer risk.”
Zinc and Risk of Lung Cancer
Overall, an increased dietary intake of zinc revealed a 20-43 percent reduction in lung cancer risk. Although the data showed that the current smokers received the most protection from a higher-zinc diet, Mahabir says, when they combined current and former smokers, they found that people who smoked less benefited more. And, he says, light drinkers benefited more than heavy drinkers.
The top dietary sources of zinc among study participants were beef and other meats, whole wheat bread, and cereals. Shellfish, poultry, beans, nuts, and whole grains are also good sources of zinc.
Copper and Risk of Lung Cancer
As for copper, a higher intake indicated a 41-66 percent risk reduction in study participants – and appears to offer the best protection to lifelong non-smokers and those under 60.
“Our results for dietary copper were very consistent across the board,” Mahabir says. “People who had never smoked benefited more than current or former smokers, and those 60 or younger benefited more and those older than 60.”
The primary sources of copper in participants’ diets were dark bread, nuts, seeds, and potatoes. Legumes and other plant foods, shellfish, and organ meats are also rich in copper.
Trace Metals in the Ground
“Because most trace metals are a function of what’s in the ground soil, they’re ubiquitous in our diets,” says senior author Michele Forman, PhD. “Even so, the relationship between cancer and dietary trace metals has been understudied, and various surveys have shown that people don’t consume enough of them – primarily because we consume them in such small amounts.”
Mahabir and Forman agree that more studies need to be done, and warn against self-medicating with dietary supplements. They instead recommend that people speak with their doctors to ensure they’re eating a healthful, well-rounded diet.
“It’s so important for people to understand that a balanced diet garners the greatest benefit for cancer protection,” they say.
* Mahabir S. et al., Dietary Zinc, Copper and Selenium, and Risk of Lung Cancer. Int J Cancer, 2007 Mar 1; 120(5):1108-15.