It has been observed that there is an inverse relationship between dietary or serum lutein levels and risk for age-related macular degeneration and cataracts. There are also amounting evidences suggesting that dietary antioxidant vitamins are beneficial for cancers and positively associated with lung function and enhancing heart function.

Although the consumption of vegetables and fruits, the source of carotenoid antioxidants including lutein, have been related to the prevention of many types of cancer, research evidences are poor and uncompelling for breast cancer. Here is an excerpt of the study published in June 2001 [P. Toniolo, et al. July, 2001. Serum carotenoids and breast cancer. June 15, 2001. Am. J. Epidemiol. 153(12):1142-7.]. Blood concentration of carotenoids have been proposed as integrated biochemical markers of vegetables, fruit, and synthetic supplements consumed. In a case-control study with 270 cases and 270 controls nested within a cohort in New York during 1985-1994, the carotenoids lutein, zeaxanthin, beta-cryptoxanthin, lycopene, alpha-carotene, and beta-carotene were measured in archived serum samples using liquid chromatography. There was an evident increase in the risk of breast cancer approximately doubled among subjects with blood levels of beta-carotene at the lowest quartile, as compared with those at the highest quartile (odds ratio = 2.21; 95% confidence interval: 1.29, 3.79). The risk associated with the other carotenoids was similar, varying between 2.08 (95% confidence interval: 1.11, 3.90) for lutein and 1.68 for beta-cryptoxanthin. The odds ratio for the lower quartile of total carotenoids was 2.31 (95% confidence interval: 1.35, 3.96). These observations offer evidence that a low intake of carotenoids, through poor diet and/or lack of vitamin supplementation, may be associated with increased risk of breast cancer and may have public health relevance for people with markedly low intakes.