Research Review Confirms Benefits of Antioxidants for Eye Health

by | Oct 8, 2013 | 2013, Antioxidants, Eye Health, Lutein, SOD (superoxide dismutase), Vitamin E, Zeaxanthin

Written by Greg Arnold, DC, CSCS. 13 studies of 18,999 participants found that the following supplements decreased  age-related cataracts by the following percentages:  Vitamin E by 25%; alpha carotene by 28%; lutein by 25%; zeaxanthin by 30%; vitamin A by 31% and Vitamin C by 33%.

Cataracts are defined as “a clouding of the lens in the eye that affects vision” and is the most common cause of blindness worldwide (1), affecting more than half of all Americans over the age of 80 (2). More than 1.5 million cataract operations are performed each year in the U.S. alone (3), which cost our healthcare system over $3.4 billion each year (4).

Fortunately, a number of studies have identified natural ways to help maintain eye health, including SOD (superoxide dismutase) (5), a diet low on the glycemic index (6), and antioxidant supplementation (7). Now a new study (8) has reviewed all of the research and further confirmed the benefits of antioxidant supplementation for eye health.

In the study, researchers reviewed 13 studies comprising 18,999 participants.  They found the  antioxidants most beneficial for eye health were vitamin E (25% reduced risk of age-related cataract), alpha-carotene (28% reduced risk), lutein (25% reduced risk), and zeaxanthin (30% reduced risk). While vitamin A showed a 31% reduced risk and vitamin C showed a 33% reduced risk, this was only seen in Asian populations, not Western populations. No decreased risks of age-related cataracts were seen with beta-carotene, lycopene, or beta-cryptoxanthin.

Regarding dosages, beta-carotene dosages ranged from 7.5 to 25 mg per day, vitamin C ranged from 250 to 750 mg per day, and vitamin E ranged from 75 to 900 International Units per day. Blood levels of these antioxidants increased with dosages starting at 15 mg of beta-carotene per day, 500 mg of vitamin C per day, and 400 IU of vitamin E per day. The researchers did not give recommendations for specific dosages that may produce the best results “because of the great difference in blood antioxidant levels in different populations.”

The researchers admitted that deciding “whether it is a combination of antioxidants or one specific antioxidant that exerts a protective effect is likely to be difficult” but did cite research showing certain antioxidants to be more effective when taken together and which “act synergistically”, like lutein with zeaxanthin (9, 10) and vitamin C with vitamin E (11).

For the researchers, “This meta-analysis provides additional evidence supporting the view that blood levels of certain antioxidants are inversely associated with risk of age-related cataract” but that “the role of antioxidant or vitamin supplement intake in preventing cataract should be further investigated in interventional studies.”

Source: Cui, Yu-Hong, Chun-Xia Jing, and Hong-Wei Pan. “Association of blood antioxidants and vitamins with risk of age-related cataract: a meta-analysis of observational studies.” The American journal of clinical nutrition 98, no. 3 (2013): 778-786.

© 2013 American Society for Nutrition

Posted September 30, 2013. 

Greg Arnold is a Chiropractic Physician practicing in Hauppauge, NY.  You can contact Dr. Arnold directly by emailing him at PitchingDoc@msn.com or visiting his web site at www.PitchingDoc.com

References:

  1. Foster A, Johnson GJ. Magnitude and causes of blindness in the developing world. Int  Ophthalmol 1990;14:135-40.
  2. “Facts About Cataract” posted on the National Institutes of Health website.
  3. Schein OD, Katz J, Bass EB, et al. The value of routine preoperative medical testing before cataract surgery. N Engl J Med3.    2000; 342: 168–75.
  4. Steinberg EP, Javitt JC, Sharkey PD, et al. The content and cost of cataract surgery. Arch Ophthalmol 1993; 111: 1041–9.
  5. Reddy VN. SOD2 Protects against Oxidation-Induced Apoptosis in Mouse Retinal Pigment Epithelium: Implications for Age-Related Macular Degeneration. Invest. Ophthalmol. Vis. Sci. 2005 46: 3426-3434.
  6. Chiu CJ. Dietary carbohydrate intake and glycemic index in relation to cortical and nuclear lens opacities in the Age-Related Eye Disease Study. Am. J. Clinical Nutrition, May 2006; 83: 1177 – 1184.
  7. Chylack, L.T., Jr., et al., The Roche European American Cataract Trial (REACT): a randomized clinical trial to investigate the efficacy of an oral antioxidant micronutrients mixture to slow progression of age-related cataract. Ophthalmic Epidemiol, 2002. 9(1): p. 49-80.
  8. Cui YH.  Association of blood antioxidants and vitamins with risk of age-related cataract: a meta-analysis of observational studies.  Amer Jou Clin Nutr 2013; 98:778–86.
  9. Delcourt C, Carriere I, Delage M, Barberger-Gateau P, Schalch W, Group PS. Plasma lutein and zeaxanthin and other carotenoids as modifiable risk factors for age-related maculopathy and cataract: the POLA Study. Invest Ophthalmol Vis Sci 2006;47:2329–35.
  10. Karppi J, Laukkanen JA, Kurl S. Plasma lutein and zeaxanthin and the risk of age-related nuclear cataract among the elderly Finnish population.  Br J Nutr 2012;108:148–54.
  11. Shang F, Lu M, Dudek E, Reddan J, Taylor A. Vitamin C and vitamin E restore the resistance of GSH-depleted lens cells to H2O2. Free Radic Biol Med 2003;34:521–30.