Vitamin C (1986, 1995, 1997, 2002, 2005-06, '11) & Cataracts
Learn more about natural treament of cataracts.
2011 A study of more than 31,000 Swedish men found that high-dose vitamin C (sometimes used in cancer therapy) can actually increase the risk of cataract, especially in older men.
Selin J. Zhen, et al.,
Published: High-dose supplements of vitamins C and E, low-dose multivitamins, and the risk of age-related cataract: a population-based prospective cohort study of men, American Journal of Epidemiology, March, 2013.
2011 A study of an Indian population evaluated the vitamin C levels in blood in over 5000 people who were 60 years old or greater. Like previous studies elsewhere in the world, the results demonstrated that vitamin C levels are associated with lower risk of cataract.
Furthermore, while low levels of the carotenoids lutein and zeaxanthin and the nutrient retinol were also tied to cataract risk, the importance of low vitamin C levels were shown to be the greatest risk factor.
The importance of vitamin C to eye health cannot be understated; concentrations of vitamin C in the lens are 20–30 times higher than those in the plasma. Vitamin C doesn’t work alone: it needs glutathione to improve the use of ascorbic acid (the purist form of vitamin C) in the body. Glutathione and vitamin C are thought to work together to promote proper water balance within the lens and prevent the protein clumping that can lead to cataracts.
Ravindran, R.D., Vashist, P., Gupta S.K., Young, I.S., Maraini, G., et al. (2011). Inverse Association of Vitamin C with Cataract in Older People in India. Ophthalmology, Oct;118(10):1958-1965.
Two studies show significant reductions in cataracts for those in the highest percentage of vitamin C intake.
In the first study, Japanese researchers followed 35,000 people. They evaluated the participants for their vitamin C intake and cataract formation. They found that those in the highest 20% of vitamin C intake had a 40% reduced risk of getting cataracts.
The second study followed 177 (116 women, 61 men) participants over the age of 60. In this study, the researchers found that if you are in the top 5% of vitamin C intake, your risk is reduced some 20% compared to the lowest 5%.
But that's not all this study found. If you ingest more than 3,290 mcg daily of lutein, your risk drops 14% compared to ingesting less than 256 mcg daily. Zeaxanthin had a smaller risk reduction, but mostly in men.
Interestingly, the study also found that sunlight exposure is also a major risk factor. If you were out in the sun a lot in your early years, your risk triples compared to being closeted indoors.
Ref: International Journal for Vitamin and Nutrition Research, 2006; 76(6); Nutr, 2007 January 30.
2005 In Italy, research substantiated earlier research supporting the understanding that high levels of vitamin C in the diet which are reflected in blood plasma are associated with lower risk and incidence of both nuclear (center) and posterior subcapsular cataract.
Researchers: L. Ferrigno, et al
Published: Associations between plasma levels of vitamins and cataract in the Italian-American Clinical Trial of Nutritional Supplements and Age-Related Cataract, Ophthalmic Epidemiology, April, 2005
2002 Researchers reported that females who take supplemental vitamin C while they are younger and middle-aged have a lower risk of cataract development later in life. This was another analysis from the extensive data gathered in the Nurses Health Study, which, as of 2002 had been ongoing for 26 years. They reviewed the information for nearly 500 middled aged (53-72) nurses, with especial attention to their long-term vitamin intake which had been taken from questionnaires about their diet for a 15 year period.
All of the women evaluated had had eye exams; 34% of them had a type of cataract in which the fiberous cells of the cortex break down. The data revealed that those women (younger than 60) who'd had a minimum of 362mg vitamin C daily over 13 to 15 years prior had a 57% lower risk of cataract. Daily use of vitamin C for 10 years was tied to a 60% lower risk compared to women who'd had no supplemental vitamin C.
Furthermore, women who had never smoked and who had included high levels of folate and antioxidant carotenoids also had a much lower risk of cataract.
Taylor, A., Jacques, P.F., Chylack, L.T., Hankinson, S.E., Khu, P.M., et al. (2002). Long-term intake of vitamins and carotenoids and odds of early age-related cortical and posterior subcapsular lens opacities, American Journal of Clinical Nutrition, Mar;75(3):540-9
The Nurses Health Study indicated that long-term consumption of vitamin C supplements can reduce the development of cataracts. This study was another long term study evaluating the diet and health of over 50,000 registered nurses. Researchers considered the connection between development of cataracts and vitamin C supplementation over 10 to 12 years in 247 56 to 71 year old nurses from the Boston area. The researchers did detailed eye exams to determine how much the eyes' lens were clouded and found that those women how had taken vitamin C supplements for over ten years had 77% fewer early lens opacities and 83% fewer moderate lens opacities.
Jacques, P.F., Taylor, A., Hankinson, S.E., Willett, W.C., Mahnken, B., et al. (1997). Long-term vitamin C supplement use and prevalence of early age-related lens opacities. American Journal of Clinical Nutrition, Oct;66(4):911-6.
1995 An analysis of some of the results from the Beaver Dam Eye Study (a long-term, large sample study of eye health and nutrition) evaluated the link between vitamin C and cataract. The researchers pointed out that the eye contains 20 times as much vitamin C as does the blood. Subjects with a high vitamin C intake were much less likely to develop cataracts than those who with low vitamin C intakes.
Researchers: C. Mares, J.A. Perlman, W.E. Brady, B.E. Klein, and others
Published: Diet and nuclear lens opacities, American Journal of Epidemiology, February, 1995
1986 There have been many studies on the role of vitamin C in preventing or reversing developing lens opacities of cataracts. Going back to 1935 this has been found to be the case.
Researchers: J. Blondin, et al.
Published: Prevention of eye lens protein damage by dietary vitamin C. Federal Proceedings 45, 1986