I asked him to close his eyes and imagine hearing some terrible news about being diagnosed with lung cancer. We discussed how it made him feel and if it would affect his continued smoking. We began a dialogue that I hope will lead to his reconsidering his smoking and his taking action to quit.
As part of the discussion, I cautioned him about taking beta-carotene supplements which are associated with increasing the risk for lung cancer among smokers. Beta carotene is an anti-oxidant that when taken in supplement form becomes an oxidant and does its own free radical damage. This effect is apparently not seen with natural sources of beta-carotene such as sweet potatoes and carrots.
In the 1990s, beta carotene was all the rage as supplements useful for preventing lung and other cancers . But since then, numerous studies have shown the opposite effect. It has been reported that Vitamin E and C can neutralize the oxidant effects of beta-carotene supplements, but we also now know that Vitamin E supplements can increase the risk of cancer and Vitamin C protects cancer cells as well as it does normal cells.
It should be increasingly clear that the best source of vitamins, minerals, and anti-oxidants continues to be the natural sources of these parts of our diet. In their natural environment, they work synergistically to be helpful to our bodies.
As with most supplements, beta-carotene seems to cause more harm than good. As for sweet potatos and carrots, I would keep eating them, even if you smoke. If you smoke--stop! It's a death wish and I'm sure someone in your life would like you around for many more years to come.