Beta-carotene is a precursor of vitamin A (provitamin A), and is a conditionally essential nutrient. It is essential only when the dietary intake of vitamin A is inadequate. Beta-carotene is a natural fat-soluble pigment found principally in plants, algae, and photosynthetic bacteria. It is claimed to have immuno-mudulatory and anti-carcinogenic activities. Carotenoids are the principal pigments responsible for the red, orange, yellow and green colors of vegetables and fruits (beta-carotene is responsible for the color of carrots). Rich sources are carrots, cantaloupe, broccoli, spinach, collard greens, and palm oil. Supplemental intake of beta-carotene ranges from 3-15 milligrams/day. (For more detailed information, please visit ISM’s searchable database: Nutraceutical Search.)

Many epidemiologic studies have associated the consumption of diets rich in fruit and green and yellow vegetables with a decreased risk of cancer. Of the many components of such a diet, the content of carotenoids, particularly beta-carotene, has been most consistently linked to decreased risk…….These results strongly suggest that carotenoids have intrinsic cancer chemopreventive action in humans.

o        Bertram, JS & Bortkiewicz, H (1995). Dietary carotenoids inhibit neoplastic transformation and modulate gene expression in mouse and human cells. Am J Clin Nutr. 62, 1327S-1336S.

Consuming beta-carotene in vegetables (three or more servings a week) could reduce the risk of stomach cancer by between 35 and 57 per cent.

    o        L. Larsson, Cancer Epidemiology Biomarkers & Prevention Vol. 15, pp. 1998 -2001.

People with the highest intake of the carotenoids, lutein and zeaxanthin, were associated with a 46 per cent lower risk of non-Hodgkin lymphoma, compared to people in the lowest intake group, while zinc intake was also linked to a lower risk (42 per cent) (epidemiological study). The researchers propose that the mechanism is the antioxidant effects of the carotenoids. One of the risk factors for NHL is said to be DNA damage caused by oxidative stress from reactive oxygen species (ROS), and this is reduced by an antioxidant-rich diet. Non-Hodgkin Lymphoma is a cancer that starts in the lymphatic system and encompasses about 29 different forms of lymphoma. According to the American Cancer Society, over 50,000 new cases are diagnosed in the US every year.

    o        Kelemen, American Journal of Clinical Nutrition Vol. 83, pp. 1401-1410.

Various natural carotenoids were proven to have anticarcinogenic activity. Multi-carotenoids (mixture of natural carotenoids) seems to be of interest in human cancer prevention.

    o        Biofactors. 2000; 13(1-4): 89-94.

Population of 25,000 showed beta-carotene protected against cancers of lung, stomach, colon, prostate & cervix.

    o        Hughes, Nutr. Rep (1992) 10(1):1-8.

Major review found “carotenoids exert an important influence in modulating the actions of carcinogens”.

    o        Krinsky, Amer. J. of Clinical Nutr. (1991) vol 53, p 238s.

A diet rich in carotenoids, including beta-carotene can decrease the risk of ovarian cancer in postmenopausal women.

    o        Cramer, Int J Cancer 94:128-34.

Bladder cancer:

Studies have shown that carotenoid supplementation is associated with decreased DNA damage, but the role of dietary carotenoids in cancer risk remains controversial……..This study provides evidence of a preventive role for carotenoids in bladder cancer, and these data may have important implications for cancer prevention, especially for individuals susceptible to DNA damage.

     o       Schabath, MB et al (2004). Dietary Carotenoids and Genetic Instability Modify Bladder Cancer Risk. J Nutr. 134, 3362-3369.

Breast Cancer:

A low intake of carotenoids, through poor diet and/or lack of vitamin supplementation, may be associated with increased risk of breast cancer.

   o        Am J Epidemiol. 2001 Jun 15; 153(12): 1142-7.

Women with cancer of the breast or of other sites might have low intake of carotenoids such as beta-carotene and zeaxanthin & lutein.

  o        J Epidemiol. 1999 Nov; 9(5): 306-14.

Objective: The objective of this study was to evaluate associations between dietary α-carotene, ß-carotene, lycopene, lutein, zeaxanthin, and ß-cryptoxanthin and the risk of colon cancer……..Results: Lutein was inversely associated with colon cancer in both men and women…….Conclusion: The major dietary sources of lutein in subjects with colon cancer and in control subjects were spinach, broccoli, lettuce, tomatoes, oranges and orange juice, carrots, celery, and greens. These data suggest that incorporating these foods into the diet may help reduce the risk of developing colon cancer.

       o        Slattery, ML et al (2000). Carotenoids and colon cancer. Am J Clin Nutr. 71(2), 575-82.

Inhibit the growth of colon cancer cells and reduces colon cell proliferation of adenomatous polyps. The suppression of COX-2 may represent a molecular mechanism by which beta-carotene acts as an anti-tumor agent in colon carcinogenesis.

  o        J Nutr. 2005 Jan; 135(1): 129-36.

Increasing dietary beta-carotene can decrease the incidence of colorectal cancer.

  o        Levi, Eur J Cancer 2000;36:2115-9.

Intervention trials with large doses of beta-carotene found an adverse effect on the incidence of lung cancer in smokers and workers exposed to asbestos. Until the efficacy and safety of taking supplements containing these nutrients can be determined, current dietary recommendations of diets high in fruits and vegetables are advised.

       o         Johnson, EJ (2002). The role of carotenoids in human health. Nutr Clin Care. 5(2), 56-65

Observational studies indicate a lower incidence of chronic diseases, including various cancers and cardiovascular disease, related to higher intakes of carotenoid containing foods (fruits and vegetables). Beta-carotene, one of the large number of naturally occurring carotenoids, thus appears to actively participate in health. However, recent intervention trials indicate that beta-carotene supplements are not efficacious in the prevention of cardiovascular disease and major cancers occurring in well-nourished populations. In fact, supplemental beta-carotene appears to increase, rather than to reduce, lung cancer incidence and deaths from cardiovascular disease in current smokers and in asbestos exposed workers.

       o      Vainio, H (2000). Chemoprevention of cancer: lessons to be learned from beta-carotene trials. Toxicol Lett. 15(112-113), 513-7

More than 30 case-control and cohort studies were conducted over many years in various populations and indicated that people who eat more vegetables and fruit, foods rich in carotenoids, and carotenoids (beta-carotene in particular), as well as those with higher blood beta-carotene concentrations, have a lower risk of lung cancer than those who eat fewer such foods or have lower beta-carotene concentrations. In contrast, the intervention results from large, controlled trials of beta-carotene supplementation do not support the observed beneficial associations or a role for supplemental beta-carotene in lung cancer prevention; instead, they provide striking evidence for adverse effects (ie, excess lung cancer incidence and overall mortality) in smokers. The findings require that caution be exercised in recommending supplemental beta-carotene, particularly for smokers……

o              o      Albanes, D (1999). Beta-carotene and lung cancer: a case study. Am J Clin Nutr. 69(6),1345S-50S.

A number of epidemiological studies have reported associations of beta-carotene plasma levels or intake with decreased lung cancer risk. However, intervention studies in smokers have unexpectedly reported increased lung tumor rates after high, long-term, beta-carotene supplementation.

o              o      Goralczyk, R (2009). Beta-carotene and lung cancer in smokers: review of hypotheses and status of research. Nutr Cancer. 61(6), 767-74.

Carotenoids exert antioxidant functions and inhibit carcinogen-induced neoplastic transformation………carotenoids have intrinsic cancer chemopreventive action in humans. Many cohort and case-control study data have shown an inverse relationship between fruit and vegetable consumption and lung cancer……Several prospective intervention trials were undertaken to examine the effect of supplementation on the risk of lung cancer. Some of these studies demonstrated an increased incidence and mortality from lung cancer in those receiving supplementation.

o              o       Epstein, KR (2003). The role of carotenoids on the risk of lung cancer. Semin Oncol. 30(1), 86-93.

We investigated whether various carotenoids present in foodstuffs were potentially involved in cancer-preventing action on human prostate cancer. The effects of 15 kinds of carotenoids on the viability of three lines of human prostate cancer cells, PC-3, DU 145 and LNCaP, were evaluated……..These results suggest that ingestion of leafy green vegetables and edible brown algae rich in neoxanthin and fucoxanthin might have the potential to reduce the risk of prostate cancer.

    o        Kotake-Nara, E et al (2001). Carotenoids Affect Proliferation of Human Prostate Cancer Cells. J Nutr. 131,3303-06.

Background: Epidemiologic evidence suggests that serum carotenoids are potent antioxidants and may play a protective role in the development of chronic diseases including cancers, cardiovascular disease, and inflammatory diseases…………

Objective: This study examined data from a cross-sectional survey to investigate the association between serum carotenoids and type 2 diabetes……..

Conclusions: Serum carotenoids are inversely associated with type 2 diabetes and impaired glucose metabolism.