From the Guidelines
Beta-carotene supplements are associated with an increased risk of lung cancer in smokers and should be avoided by current smokers and those with a history of smoking. The evidence from studies such as the ATBC study and CARET trial, as reported in the 2013 American College of Chest Physicians evidence-based clinical practice guidelines 1, demonstrates a higher incidence of lung cancer in those who received beta-carotene supplements, particularly among active smokers. The relative risk of lung cancer in current smokers was found to be 1.40 (95% CI, 1.07-1.87) in the CARET trial.
Key Findings
- The ATBC study and CARET trial showed an increased risk for lung cancer incidence and mortality in participants with a high baseline risk for lung cancer who received beta-carotene supplements 1.
- A meta-analysis of β-carotene trials reported an increased risk for lung cancer (pooled odds ratio, 1.24 [CI, 1.10 to 1.39]) in current smokers 2.
- The USPSTF recommends against the use of beta-carotene supplements, either alone or in combination, for the prevention of cancer or cardiovascular disease, citing good evidence that β-carotene supplementation provides no benefit and might cause harm in some groups 3.
Recommendations
- Smokers should avoid high-dose beta-carotene supplementation and instead obtain their carotenoids through a varied diet rich in fruits and vegetables.
- If you smoke or have recently quit, it's best to discuss any supplement regimen with your healthcare provider before starting.
- Beta-carotene from food sources is considered safe, but supplements should be used with caution, especially in smokers, due to the potential for increased risk of lung cancer.
From the Research
Supplement Associated with Increased Risk of Lung Cancer in Smokers
- Beta-carotene, a precursor to Vitamin A, has been linked to an increased risk of lung cancer in smokers, as evidenced by multiple studies 4, 5, 6, 7.
- The Alpha-Tocopherol, Beta-Carotene Cancer Prevention Study found that beta-carotene supplementation was associated with increased lung cancer risk, particularly among those who smoked at least 20 cigarettes daily 4.
- The VITamins And Lifestyle (VITAL) study also found that long-term use of individual beta-carotene supplements was associated with an elevated risk of total lung cancer and histologic cell types 5.
- A review of randomized clinical trials found that beta-carotene supplementation is contraindicated among smokers due to the increased lung cancer risk 6.
- A meta-analysis of large randomized trials found that beta-carotene supplementation was significantly associated with an increased risk of lung cancer among current smokers, but not among former smokers 7.
Key Findings
- The increased risk of lung cancer associated with beta-carotene supplementation appears to be stronger among heavier smokers and those with higher alcohol intake 4.
- Long-term use of individual beta-carotene supplements, rather than total dose, was associated with an elevated risk of lung cancer 5.
- Dietary intakes of carotenoids and vitamin A were not associated with overall lung cancer risk, but a significant positive association of dietary vitamin A intake with lung cancer risk was observed among current smokers 8.
- Beta-carotene was present in 70% of common multivitamins, but high-dose beta-carotene was observed among multivitamin formulas sold to promote visual health 7.