From the Guidelines
Beta-carotene supplements have been associated with an increased risk of lung cancer in people who smoke. This finding is based on the most recent and highest quality evidence from studies such as the Alpha-Tocopherol, Beta-Carotene Cancer Prevention (ATBC) Study and the Beta-Carotene and Retinol Efficacy Trial (CARET) 1. The ATBC study, which randomized 29,133 people to receive alpha-tocopherol, beta-carotene, both, or placebo, found that the incidence of lung cancer in the beta-carotene group was 18% higher than in the placebo group. Similarly, the CARET trial, which evaluated high-risk current and former smokers, found that the relative risk of lung cancer in the active treatment group (beta-carotene and vitamin A) was 1.28, with a higher risk observed in current smokers (RR 1.40) compared to former smokers (RR 0.80) 1.
Key Findings
- The ATBC study and CARET trial demonstrated a higher incidence of lung cancer in those who received beta-carotene supplements, particularly among active smokers 1.
- The mechanism behind this increased risk is thought to be related to the interaction between beta-carotene and cigarette smoke in the lungs, potentially promoting cellular damage in this population.
- Current health guidelines recommend that smokers avoid beta-carotene supplements and instead focus on obtaining nutrients through a balanced diet and smoking cessation to reduce lung cancer risk.
Recommendations for Smokers
- Avoid beta-carotene supplements due to the increased risk of lung cancer associated with their use 1.
- Focus on smoking cessation as the most effective way to reduce lung cancer risk.
- Obtain nutrients through a balanced diet rather than relying on isolated supplements.
From the Research
Supplements Associated with Increased Risk of Lung Cancer
- Beta-carotene supplements have been linked to an increased risk of lung cancer in people who smoke, as shown in studies 2, 3, 4, 5, 6.
Key Findings
- A study published in the American Journal of Epidemiology found that longer duration of use of individual beta-carotene supplements was associated with a statistically significantly elevated risk of total lung cancer and histologic cell types 2.
- Another study published in the Canadian Journal of Dietetic Practice and Research found that beta-carotene supplementation is contraindicated among smokers, as it may increase the risk of lung cancer 3.
- A systematic review with meta-analysis and meta-regression published in Nutrients found that beta-carotene supplementation was associated with an increased risk of lung cancer, particularly among smokers and asbestos workers 4.
- The Alpha-Tocopherol, Beta-Carotene Cancer Prevention Study found that beta-carotene supplementation increases lung cancer incidence in smokers, regardless of the tar or nicotine content of cigarettes smoked 5.
- A meta-analysis published in Cancer found that high-dose beta-carotene supplementation appears to increase the risk of lung cancer among current smokers, while beta-carotene was prevalent in multivitamins, but high-dose beta-carotene was observed among multivitamin formulas sold to promote visual health 6.