Study: Smokers’ Lung Cancer Risk Not Reduced By Vitamin E, C, Or B9

Pills spilling from bottleA scientific study has shown that three popular vitamins, vitamin C, vitamin E, and folic acid (vitamin B9) do not reduce lung cancer risk. Furthermore, researchers found a small but significant increase in lung cancer risk amongst smokers taking vitamin E supplements.

The research, which is reported in the March 2008 issue of the American Journal of Respiratory and Critical Care Medicine, followed 77,126 American men and women from the state of Washington aged between 50 and 76. The study participants were asked to fill out surveys asking about their past and present vitamin supplement use, smoking habits, medical history and family history of lung cancer.

During the four year study period 512 participants developed lung cancer. After adjusting for other factors the researchers found no reduction in lung cancer due to vitamin E, vitamin C, or folic acid supplementation.

The researchers did however find that the risk of developing lung cancer increased by 5 percent for each 100mg per day increase in vitamin E supplementation. The increase in lung cancer risk was largely confined to smokers, lung cancer risk for smokers increased by 11 percent for each 100mg per day increase in vitamin E. A smoker taking 400mg of vitamin E per day was as much as 44 percent more likely to develop lung cancer as a smoker not taking the supplement. Amongst non-smokers, vitamin E had no significant effect on lung cancer risk.

The increased lung cancer risk appears only in relatively high doses of Vitamin E in excess of 100mg per day. The recommended daily intake of Vitamin E is just 10-20mg per day and a person would be unlikely to exceed 100mg of Vitamin E from dietary sources alone. Sources rich in Vitamin E include peanuts and peanut butter, almonds, hazelnuts, leafy green vegetables such as spinach and broccoli, kiwifruit and mangoes.

Other studies have linked moderate Vitamin E use to a decrease in some forms of cancer such as prostate cancer. One Finnish study found a Vitamin E dosage of 50mg per day decreased the probability of developing prostate cancer by 32 percent and the probability of dying from the cancer by 41 percent.

The results of this study indicate that smokers are unlikely to be able to reduce their risk of developing lung cancer through vitamin supplementation alone. A smokers best chances of avoiding lung cancer quite simply come from quitting smoking. After ten years without smoking, the risk of developing lung cancer is about half what it would’ve been had the individual not quit smoking.

Smoking is overwhelmingly the most important risk factor for the development of lung cancer. Smoking is estimated to be responsible for between 85 and 90 percent of all lung cancers. Radon gas, asbestos exposure, and marijuana use are also risk factors for lung cancer, albeit less significant ones.