Beta-carotene and cancer
Beta-carotene is a carotenoid, a type of nutrient found in various colorful fruits and vegetables, such as carrots, sweet potatoes, and spinach. The body converts beta-carotene into vitamin A, which is essential for functions like vision, bone development, and cell growth. Research suggests that a diet rich in beta-carotene may lower the risk of certain cancers, including prostate and lung cancer, due to its antioxidant properties that protect cells from damage by free radicals. However, the effectiveness of beta-carotene supplements is debated; studies have indicated that taking these supplements alone does not prevent cancer and may actually increase the risk of lung cancer in smokers or those exposed to asbestos. Additionally, findings regarding prostate cancer risk associated with beta-carotene are mixed, with some studies indicating potential harm while others show no significant effects. It is recommended to obtain beta-carotene through a balanced diet rather than supplements, as this has not been linked to the same risks. Therefore, while beta-carotene plays a role in cancer prevention, its supplementation may require caution and further research.
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Beta-carotene and cancer
ATC CODE: A11CA02
ALSO KNOWN AS: A-Caro-25, betacarotene, carotene, carotenoid, Lumitene, retinal, retinol
DEFINITION: Beta-carotene is a member of a family of nutrients called "carotenoids," which are found in many red, orange, yellow, and green fruits and vegetables (such as carrots, sweet potatoes, squash, spinach, apricots, and broccoli). The body converts beta-carotene into vitamin A, which plays a role in vision, bone development, cell division, and cell differentiation.
Cancers treated or prevented: Studies have found that a diet high in fruits and vegetables containing beta-carotene reduces the risk of certain types of cancer, including prostate and lung cancer. Researchers believe that beta-carotene and other antioxidants in fruits and vegetables work together to lower cancer risk.
According to popular belief, beta-carotene supplements can reduce the risk of certain cancers, particularly lung cancer. According to a 2017 study by the National Cancer Institute, however, there is no evidence of any cancer preventive benefit when beta-carotene is taken alone in supplement form. Studies have found that smokers and people who have been exposed to asbestos who take beta-carotene supplements have a significantly higher risk of developing lung cancer and dying from their cancer than those who do not take the supplements. In 2024, Stanford University concurred that high intakes of beta-carotene supplements increase cancer risks.
Scientific evidence for beta-carotene elevating the risk of prostate cancer in men has been inconclusive. For instance, the National Cancer Institute's Prostate, Lung, Colorectal, and Ovarian Cancer Screening Trial (1992–2001) found that men with the highest levels of beta-carotene in their blood were at increased risk for developing more aggressive and deadly prostate cancer. However, 2009 follow-up results from the long-term Carotene and Retinol Efficacy Trial (1983–95) reported neither positive nor negative effects of beta-carotene supplementation on the rate of new prostate cancer cases. Similar results were published in the medical publication PlosOne in 2015.
Delivery routes: Oral in capsule and tablet forms. The US National Library of Medicine reports that eating five servings of fruits and vegetables daily provides six to eight milligrams of beta-carotene.
How this substance works: Beta-carotene is an antioxidant. It protects cells and deoxyribonucleic acid (DNA) from damage caused by unstable molecules called "free radicals," which are produced during metabolic processes as cells burn oxygen for energy. Free radicals are believed to contribute to cancer and other diseases. Vitamin A, which the body makes from beta-carotene, helps prevent cancer's uncontrolled cell growth.
Side effects: Beta-carotene may increase the risk of lung cancer or prostate cancer in people who smoke or drink alcohol heavily or who have been exposed to asbestos. It also may increase the risk of more aggressive prostate cancers. In high doses, beta-carotene may interact with some types of chemotherapy drugs or radiation—especially in lung cancer. According to the American Cancer Society, there is no evidence of any cancer preventive benefit when beta-carotene is taken alone in supplement form. Studies have found that smokers and people who have been exposed to asbestos who take beta-carotene supplements have a significantly higher risk of developing lung cancer and dying from their cancer than those who do not take the supplements.
Scientific evidence for beta-carotene elevating the risk of prostate cancer in men has been inconclusive. For instance, the National Cancer Institute's Prostate, Lung, Colorectal, and Ovarian Cancer Screening Trial (1992–2001) found that men with the highest levels of beta-carotene in their blood were at increased risk for developing more aggressive and deadly prostate cancer. However, 2009 follow-up results from the long-term Carotene and Retinol Efficacy Trial (1983–95) reported neither positive nor negative effects of beta-carotene supplementation on the rate of new prostate cancer cases. In 2024, the National Cancer Institute published what had become a consensus viewpoint that supplementation and other alternative treatments were either ineffective or potentially harmful.
Delivery routes: Oral in capsule and tablet forms. The US National Library of Medicine reports that eating five servings of fruits and vegetables daily provides six to eight milligrams of beta-carotene.
How this substance works: Beta-carotene is an antioxidant. It protects cells and deoxyribonucleic acid (DNA) from damage caused by unstable molecules called "free radicals," which are produced during metabolic processes as cells burn oxygen for energy. Free radicals are believed to contribute to cancer and other diseases. Vitamin A, which the body produces from beta-carotene, helps prevent cancer's uncontrolled cell growth.
Side effects: Beta-carotene may increase the risk of lung cancer or prostate cancer in people who smoke or drink alcohol heavily or who have been exposed to asbestos. It also may increase the risk of more aggressive prostate cancers. In high doses, beta-carotene may interact with some types of chemotherapy drugs or radiation.
Bibliography
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"Beta Carotene (Oral Route)." Mayo Clinic, www.mayoclinic.org/drugs-supplements/beta-carotene-oral-route/precautions/drg-20066795. Accessed 6 July 2024.
"11 Foods Full of Beta-Carotene and Their Health Benefits." Cleveland Clinic, 18 Oct. 2023, health.clevelandclinic.org/beta-carotene. Accessed 6 July 2024.
"Nutrition Services for Cancer Patients." Stanford Medicine, 2024, stanfordhealthcare.org/medical-clinics/cancer-nutrition-services/reducing-cancer-risk/antioxidants.html. Accessed 6 July 2024.
"Prostate Cancer, Nutrition, and Dietary Supplements (PDQ®)–Patient Version." National Cancer Institute, 8 May 2024, www.cancer.gov/about-cancer/treatment/cam/patient/prostate-supplements-pdq. Accessed 6 July 2024,
"The Effect of Vitamin E and Beta Carotene on the Incidence of Lung Cancer and Other Changes in Male Smokers." New England Journal of Medicine, vol. 330, no. 15, 1994, pp. 1029–35.
"Beta-Carotene." MedlinePlus, 30 Apr. 2024, medlineplus.gov/druginfo/natural/999.html. Accessed 6 July 2024.
"Vitamin A and Carotenoids." National Institutes of Health, 15 Dec. 2023, ods.od.nih.gov/factsheets/VitaminA-HealthProfessional. Accessed 6 July 2024.
Wang, Yulan. "Effect of Carotene and Lycopene on the Risk of Prostate Cancer: A Systematic Review and Dose-Response Meta-Analysis of Observational Studies." PlosOne, 15 Sept. 2015, journals.plos.org/plosone/article?id=10.1371/journal.pone.0137427. Accessed 6 July 2024.