Association between Dietary and Supplemental Antioxidants Intake and Lung Cancer Risk: Evidence from a Cancer Screening Trial.

Previous studies provided inconsistent results on the effects of antioxidant nutrient intake on lung cancer prevention. We aimed to evaluate the association between antioxidant consumption from food and supplemental sources and lung cancer incidence. Data were obtained from the Prostate, Lung, Colorectal, and Ovarian (PLCO) cancer screening trial. A total of 98,451 participants were included in the data analysis. We used a multivariable Cox proportional hazards regression model to calculate hazard ratios (HRs) and 95% confidence intervals (CIs) for the association between antioxidant intake and lung cancer risk. Dose-response assessments for individual nutrients were conducted. We also selected the model for the best combination of antioxidants for reducing lung cancer risk using machine learning methods. After the median follow-up of 12.2 years, 1642 new cases were identified. Intake of the calculated HRs indicated a trend for a higher quartile of food-based Composite Dietary Antioxidant Index (fCDAI) associated with a lower lung cancer risk after adjusting for covariates (HRQ4vs.Q1 = 0.64, 95% CI: 0.52, 0.79; P for trend < 0.001). Protective effects of dietary antioxidant intake were observed across all individual antioxidant micronutrients except magnesium. Random forests model suggested the dietary intake group of α-carotene, magnesium, vitamin C, vitamin E, lycopene, selenium, lutein, and zeaxanthin, and ß-carotene had the most favorable effects on lung cancer prevention. Higher consumption of antioxidants from food sources has a protective effect against lung cancer, while no effects were shown in the supplemental group. It is recommended to consume a combination of various antioxidants due to the potential benefits from the interaction, while more research should be performed to investigate the underlying mechanisms of antioxidant synergic effects on lung cancer risk reduction.

Association between ß-carotene supplementation and risk of cancer: a meta-analysis of randomized controlled trials.

CONTEXT: ß-Carotene, which is derived from most fruits and vegetables, is the most common type of carotenes. Existing studies have demonstrated that ß-carotene is associated with some positive health outcomes. However, results about the effects of supplemental ß-carotene on cancer are inconsistent. OBJECTIVE: To determine the association between supplemental ß-carotene intake and the risk of cancers. DATA SOURCES: Eight databases (PubMed, Web of Science, Embase, Cochrane, China National Knowledge Infrastructure, Wangfang, China Science and Technology Journal Database, and Chinese Biomedical Literature Database) were systematically searched until September 2022. DATA EXTRACTION: Only reports from randomized controlled trials in which an association between supplemental ß-carotene intake and the risk of cancer was found were included in the meta-analysis. DATA ANALYSIS: A total of 18 eligible studies based on 8 different randomized controlled trials were included in the meta-analysis, with varying sample sizes from 391 to 39 876 participants. There was no significant association between supplemental ß-carotene intake and overall cancer incidence rate after synthesizing all the results (risk ratio [RR]: 1.02; 95% confidence interval [CI], 0.99-1.05). Results from subgroup analysis indicated that intake of supplemental ß-carotene significantly increased the risk of lung cancer (RR: 1.19; 95%CI: 1.08-1.32), whereas no significant associations were observed for other site-specific cancers. In addition, smokers and the subgroup of participants with only low-dose ß-carotene intake had a risk increment of cancer if they took supplemental ß-carotene (RR: 1.16; 95%CI: 1.05-1.29). CONCLUSION: ß-Carotene supplementation has no beneficial or harmful effect on cancer incidence; moreover, it might have potentially harmful effects on lung cancer, especially for people who smoke. On the basis of the evidence from this study, supplemental intake of ß-carotene is not recommended for preventing cancer, and the establishment of a tolerable upper intake level of ß-carotene should be considered.

ß-Carotene Supplementation and Risk of Cardiovascular Disease: A Systematic Review and Meta-Analysis of Randomized Controlled Trials.

ß-carotene is widely available in plant-based foods, while the efficacy of ß-carotene supplementation on cardiovascular disease (CVD) risk remains controversial. Hence, we performed a systematic review and meta-analysis on randomized controlled trials to investigate the associations between ß-carotene supplementation and CVD risk as well as mortality. We conducted literature searches across eight databases and screened the publications from January 1900 to March 2022 on the topic of ß-carotene treatments and cardiovascular outcomes. There were 10 trials and 16 reports included in the meta-analysis with a total of 182,788 individuals enrolled in the study. Results from the random-effects models indicated that ß-carotene supplementation slightly increased overall cardiovascular incidence (RR: 1.04; 95% CI: 1.00, 1.08) and was constantly associated with increased cardiovascular mortality (RR: 1.12; 95% CI: 1.04, 1.19). Subgroup analyses suggested that, when ß-carotene treatments were given singly, a higher risk of cardiovascular outcomes was observed (RR: 1.06; 95% CI: 1.01, 1.12). In addition, cigarettes smoking was shown to be a risk behavior associated with increased cardiovascular incidence and mortality in the ß-carotene intervention group. In sum, the evidence of this study demonstrated that ß-carotene supplementation had no beneficial effects on CVD incidence and potential harmful effects on CVD mortality. Further studies on understanding the efficacy of multivitamin supplementation in nutrient-deficient or sub-optimal populations are important for developing the tolerable upper intake level for ß-carotene of different age and sex groups.