Supplements may have an effect, so for example taking beta carotene while being a smoker may be counterproductive: > Among current smokers, beta-carotene suppl

Supplements may have an effect, so for example taking beta carotene while being a smoker may be counterproductive: > Among current smokers, beta-carotene supplementation was found to be significantly associated with an increased risk of lung cancer (odds ratio [OR], 1.24; 95% confidence interval [95% CI], 1.10-1.39). [Beta-carotene in multivitamins and the possible risk of lung cancer among smokers versus former smokers: a meta-analysis and evaluation of national brands](https://pubmed.ncbi.nlm.nih.gov/18429004/ https://pubmed.ncbi.nlm.nih.gov/18429004/)