Antioxidants and Eye Health
What are Free Radicals?
First, it is important to understand what free radicals are. Free radicals are atoms that lack a particle called an electron, and, as a result, are very unstable. In the free radicals' attempt to become stable, they attack other cells as they try to "steal" an electron. This attack harms the cells' delicate membranes and makes them a target for disease.
When free radicals steal electrons from healthy cells it is called oxidation. Just like oxygen causes metal to rust, oxidation can also damage cells. In humans, the common signs of oxidative damage can be seen in the normal signs of aging: skin changes such as the appearance wrinkles, and ocular changes, including the development of cataracts and macular degeneration.
How do Antioxidants Help?
Antioxidants neutralize free radicals by donating an electron to these unstable atoms. After being neutralized, those free radicals will no longer attempt to damage cells, and therefore become less harmful to the body.
The body makes some of its own antioxidants including glutathione, super oxide dismutase, and coenzyme Q10. Nutrients such as selenium, riboflavin, zinc, and cysteine are needed to help the body produce these antioxidants.
Ultraviolet sun rays promote oxidation. If you stare at the midday sun, the UV rays can "oxidize" retinal cells at the back of the eyes, resulting in a short time in a loss of central vision. Similarly, the destruction of retinal cells can occur slowly over many years, from exposure to low levels of sunlight and/or from a gradual degradation of the antioxidant defense system.
Decreases in the level of antioxidants in the eyes as we age is believed to be a major factor in the decline of vision.
Dr. Grossman's Advanced Vision Support Formula contains therapeutic levels of these antioxidants and other nutrients for healthy vision.
Increasingly in both vision care and general health care practitioners are recognizing that oxidative stress is probably at the root of most health conditions. Antioxidants play a powerful role in reducing oxidative stress. When our bodies experience oxidative stress certain biomarkers increase warning of the problem. Biomarkers are biochemicals which increase when stressed conditions prevail, such as oxidative stress or inflammation.
Here's an example of how researchers evaluate whether certain nutrients can reduce oxidative stress:
The researchers wanted to evaluate whther bilberry extracts could help reduce levels of a biochemical marker for oxidative stress. In this case the researchers were looking at enzyme levels that increase as a defense of oxidative stress. The enzymes are called heme-oxygenase (HO)-1 and glutathione S-transferase-pi (GST-pi). They were measured in human retinal pigment cells which had been grown in the lab.
Before exposure to chemicals that would increase oxidative stress in the cells they were exposed to 25% enriched bilberry extractions. After the extracts were removed from the cell cultures they were exposed to H2O2 (hydrogen peroxide). Under a stressed situation like H2O2 exposure, the normal concentrations of glutathione (an antioxidant) are reduced and free radicals increase.
The scientists found that early exposure to the bilberry extract reduced the development of free radicals in the cell tissue, even though the toxicity of H2O2 was not affected. After 4 hours of exposure to H2O2 the defense enzymes levels had increased suggesting that such exposure to the extract had stimulate defense mechanisms against free radicals.1
Antioxidants may be divided into three groups:
- Enzymes: (glutathione, super oxide dismutase)
- Phytonutrients: (bioflavonoids, carotenoids, polyphenols, indoles)
- Vitamins/Vitamin-like: (Vitamins A, C, E, CoQ10, alpha lipoic acid)
For more information on specific antioxidants, see the section of this website on nutrient details.
1. P. Milbury, B. Graf, et al, Bilberry (Vaccinium myrtillus) anthocyanins modulate heme oxygenase-1 and glutathione S-transferase-pi expression in ARPE-19 cells, Investigations in Ophthalmology and Visual Science, May, 2007.