We have long known about the importance of proper nutrition in staying healthy and avoiding cancer.
But now it seems that some people who take extra supplements in the hopes of preventing cancer may actually be making their situation worse.
A new study has shown that smokers and former smokers who take supplements of beta-carotene, retinol and lutein in amounts greater than traditional multivitamin doses over the long term may actually increase their risk of lung cancer.
Surprisingly, when people at high risk for lung cancer due to smoking (either presently or formerly) get carotenoids from dietary sources, it helps.
It is only getting excessive amounts through supplementation that seems to cause the problem. Researchers are unclear why this happens.
There are two types of lung cancer: small cell, and non-small cell. The most common type is non-small-cell lung cancer; small-cell tends to be more aggressive and responds better to cancer chemotherapy and radiation rather than surgery.
Beta-carotene seemed to increase the risk of small-cell lung cancer in particular, while retinol and lutein seemed to have more of an impact on non-small-cell lung cancer.
Only people at high risk of lung cancer due to smoking were studied. It is unclear how supplementation of beta-carotene, retinol and lutein affect lung cancer risk in the general population.