Dietary supplements have long been believed by some to provide your body needed vitamins and guard against disease. There was a time when it was thought that antioxidant supplementation could be a major breakthrough for disease treatment and prevention. But recently, two studies have found evidence that antioxidants may cause lung cancer cells to spread.

To understand the role of antioxidants in the body, you must start with understanding free radicals. Free radicals are unstable molecules that form in one of two ways. They can form naturally in the body when it converts food to energy or they form when you are exposed to certain environmental sources like tobacco smoke, air pollution and sunlight. Free radicals are dangerous because they can cause a process called "oxidative stress," which is an imbalance between the antioxidants and free radicals in the body and is thought to play a role in certain diseases, like cancer.

Research in the 1990s was on the forefront of understanding the way supplements affect cancer cells and our body. These studies, which focused on beta-carotene and vitamin A, were stopped early when it was discovered that not only were the supplements not preventing lung cancer, but they were causing increased risk of developing lung cancer in people who were already at high risk. Following several other studies, there is enough evidence that physicians recommend smokers avoid taking beta-carotene supplements.

Researchers continue to examine antioxidants, and two recent studies found that antioxidants can actually make lung cancer spread or metastasize in certain types of lung cancer. A study from  New York University School of Medicine showed how two tumor mutations, common in about 30% of non-small cell lung cancer, can help the lung cancer cells make their own antioxidants which causes the cancer to metastasize through a sophisticated cellular pathway. A study from the Karolinska Institute in Stockholm also showed that when given long term, the supplements N-acetylcysteine and vitamin E help lung cancer spread in tissue with the KRAS mutation. Both studies examine the role of a protein called Bach1. When antioxidants eliminated oxidative stress, they unknowingly protected tumors and prompted the buildup of Bach1 which increases the uptake and use of glucose, or sugar, giving cancer the energy needed to spread.

So, what does all this mean for patients? We asked Anthony Alberg, Ph.D., MPH, an epidemiologist who has studied lung cancer and nutrition. "As we learn more and more about how complex cancer cells are and how they figure out ways to survive and grow, working against the normal cellular constrictions, it makes us understand why they are so hard to fight." Dr. Alberg continued. "The hope is that the more we can understand these pathways, maybe we can better understand ways to control cancer and new treatments can be developed."

It is this hope that has scientists excited about the findings of these studies. Identifying this powerful "promoter of metastasis" could help doctors better advise patients about what, if any, role supplements may have and understand that certain cancers may act differently in the presence of supplemental antioxidants.

For now, experts agree that patients should aim to get all of their nutrients from a natural, balanced diet rich in fresh fruits and vegetables; not supplements, unless otherwise directed by a doctor. But each person's dietary needs are unique, which is why it is also recommended that people being treated for lung cancer consult a doctor or a registered dietitian nutritionist.

Learn more about nutrition for lung cancer prevention, treatment and to combat treatment side effects.

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