The controversy involving the use of antioxidant supplements like vitamin E, beta carotene, and vitamin A is still continuing even after research published in the early 1990s found an increased risk of lung cancer development in male smokers who had taken beta carotene and vitamin E supplements. In fact, several rather large studies have previously shown this relationship between the use of antioxidant supplements and lung cancer development in higher-risk individuals.
New research recently published may be able to indicate the reason for this interesting phenomenon. Researchers have postulated that the use of large doses of antioxidant supplements not found in foods can actually prevent the cell’s own natural defense mechanism from being activated.
The researchers discovered that two different antioxidants, vitamin E and N-acetylcysteine, could encourage lung cancer growth in mice that had early lung cancer. They discovered that the addition of these antioxidants resulted in an almost three-fold increase in the number of lung tumors and also that these tumors were more aggressive in nature contrasted to the mice who did not receive the antioxidants.
The same result was also found when human lung cancer cells were exposed to similar concentrations of antioxidants in vitro (lab dishes).
Antioxidants protect the cell’s DNA from damage which can cause abnormal cancer cell growth. Large doses of antioxidants do protect the cell’s DNA from the damaging effects of harmful chemicals, but in so doing, prevent the cell’s natural defense mechanism from working correctly. Under normal conditions, when the cell’s DNA is damaged, it produces a protein called p53.
This protein, when activated, causes this damaged cell to be destroyed before it can become cancerous. It is felt that large doses of antioxidants prevent this very important protein from controlling cancer cell growth. This would explain the excessive cancer cell growth seen in these types of experiments.
According to one of the study’s authors, “antioxidants allow cancer cells to escape cells’ own defense system.” Other groups have criticized this study suggesting that the dosages of the antioxidant vitamin E used in this experiment were between four to 50 times higher than the average daily intake of most Americans. Even though the intake of most antioxidant nutrients are lower than they should be, caution should be exercised when taking high dosages of antioxidant supplements in high risk groups like smokers. There are no current issues regarding the consumption of antioxidants in food and lung cancer growth.
In my opinion, if you want to reduce the risk of developing lung cancer, do not smoke or quit if you are a current smoker; eat a diet high in brightly colored fruits and vegetables; and avoid toxic chemical lung exposure.
Although the use of antioxidants may be helpful in certain circumstances, it does not seem to help prevent lung cancer cell growth in high-risk populations.
Source:
Begley, S., “New Clues To Why Antioxidants Seem To Promote Lung Cancer In Some People,” The Huffington Post web site; http://www.huffingtonpost.com/2014/01/29/antioxidants-lung-cancer-vitamin-e-beta-carotene_n_4689247.html, last accessed Feb 3, 2014.