Lung cancer is the leading cause of cancer deaths in the United States. Smoking is the major factor that increases the risk for developing lung cancer; dietary factors also have an influence.
The present study was done to test the influence of dietary trace mineral intake on the risk for lung cancer with 1,676 lung cancer patients and 1,676 controls were studied. Their diets were carefully studied for intakes of zinc, copper and selenium. Men were a higher percentage of patients as compared to controls.
Zinc, copper and selenium are trace minerals which act as cofactors for enzymes that maintain the health of DNA. All three minerals are important components of fruits and vegetables. Copper and zinc are an important part of the antioxidant enzyme superoxide dysmutase (SOD). Selenium is an important part of the antioxidant enzyme glutathione peroxidase. These enzymes protect DNA from oxidative damage.
Meat and shellfish are good sources of zinc, whereas plants contain little zinc. Beef, other meats, whole wheat bread and cereals are the main dietary sources of zinc. Phytates, which are found in whole grains and legumes, can reduce the absorption of zinc.
Plants are a good source of selenium; but little selenium is found in meat and shellfish. The selenium content of plants and meats depends on the selenium content of the local soil. The major sources of dietary selenium are dark bread, eggs, seafood, meat and cereals.
Copper is found in plants, shellfish and organ meats. The major dietary sources of copper are dark bread, potatoes, nuts and seeds.
The authors found that higher dietary zinc and copper intakes were associated with correspondingly reduced risk of developing lung cancer. This was not found to be true of dietary selenium intake, except at the highest intake levels of dietary selenium. The protective effect of zinc was especially for current smokers and mild zinc deficiency reduces immunity.
A study called the National Prevention of Cancer study found that 200 mg./day of selenium for an average of 4.5 years reduced non-melanoma skin cancers, reduced cancer deaths, reduced all cancer incidence and reduced lung cancer incidence.
CONCLUSION: With increasing dietary intakes of zinc and copper, decreasing risk of lung cancer was found by the authors. Dietary intake of selenium was not found to be associated with altered risk of lung cancer in this study except for the highest dietary intakes for selenium.
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