It is a common belief that taking a beta-carotene supplement will have the same effect as eating fruits and vegetables that contain it.
However, this is not the case. Studies found an increased lung cancer risk among study participants. It is important to note that these participants were categorized as high risk for developing lung cancer prior to the study. They were smokers, ex-smokers, or had been exposed to asbestos.
The bottom line is that cigarette smokers should avoid beta-carotene supplements completely. Researchers found smokers had a significant increased risk of lung cancer due to the intake of a beta-carotene supplement, even years after the sudy had ended.
This study, reported in the Journal of the National Cancer Institute, December 1, 2004 stated that "not only do beta-carotene supplements not prevent lung cancer in people at high risk for the disease, they appear to increase rates of the disease, particularly among smokers."
The study also states that there is no evidence of harm to non smokers. Another study, the Physicians’ Health Study, found beta carotene presented no benefit or harm in healthy men.
So, your best bet is to take Mom's advice and eat your veggies.
Please refer to the abstract of the study cited in this article for more information.