Alpha-lipoic acid, sometimes called LA or ALA, should not be confused with the omega-3 fatty acid alpha linolenic acid, also called ALA. Alpha-lipoic acid, also called thioctic acid, is both synthesized in small amounts in the body and obtained from foods. This compound has antioxidant properties that may help reduce damage to the eye that occurs as part of the aging process or from diseases such as diabetes. Cellular damage that leads to cataracts, macular degeneration and glaucoma may be caused by harmful substances known as free radicals that accumulate as part of aging.
Antioxidant Properties
Alpha-lipoic acid is both fat- and water-soluble, giving it a unique benefit as an antioxidant. Antioxidants are substances that scavenge and destroy harmful compounds such as reactive oxidative species, or ROS, and reactive nitrogen species, or RNS. Most antioxidants are either water-soluble, such as vitamin C, or fat-soluble, such as vitamin E, but not both. Alpha-lipoic acid reduces to dihydrolipoic acid, or DHLA, which in turn can reduce other antioxidants. Antioxidants become oxidized themselves after destroying free radicals. Reducing them restores their ability to act as antioxidants. In cells, LA also increases glutathione synthesis; glutathione acts as an antioxidant within cells.
Eye Benefits
Free radicals are a major cause of cataract formation, according to Marc Grossman, O.D. Because high glucose levels also increase cataract formation, diabetics have three to four times the risk of developing cataracts over people without diabetes, Grossman states. Alpha-lipoic acid may help lower glucose levels by increasing insulin sensitivity. A Russian study published in the October-December 1995 issue of "Vestnik Oftamologii" reported that 45 percent to 47 percent of people in groups treated with lipoic acid showed improvement. Researchers attributed the improvement to antioxidant properties of LA and its influence on ocular metabolism.
Disadvantages
Alpha-lipoic acid is eliminated rapidly from cells, according to the Linus Pauling Institute, so its benefits may not be sustained. Since LA may lower glucose levels, people with diabetes who take anti-diabetic drugs could experience hypoglycemia, or low blood sugar, when taking LA. Allergic reactions such as rash, hives and itching may also occur when taking supplements. Do not take LA without discussing its use with your doctor. Safe use in pregnancy has not been established.
Considerations
Some of the leading causes of blindness, such as cataracts and macular degeneration, are associated with cellular damage from free radicals, researchers from the London School of Hygiene and Tropical Medicine reported in the September 2010 issue of "Ophthalmic Research." For diabetics, reducing blood glucose levels helps prevent diabetic retinopathy, another leading cause of blindness. Supplemental LA may not only reduce damage to DNA in cells from free radicals, but may also improve blood glucose levels.
References
- Natural Eye Care; Cataracts; Marc Goodman, O.D., et al.; 2002
- Epic4health; Alpha Lipoic Acid: Its Role in Human Health; Hemmi N. Bhagavan, Ph.D.
- "Vetnik Oftalmologii;" Lipoic Acid As a Means of Metabolic Therapy of Open-Angle Glaucoma; A. Filina; October-December 1995
- Linus Pauling Institute; Alpha-Lipoic Acid; Jane Higdon, Ph.D.
- University of California San Diego Math Department: Antioxidants and Phytochemicals
- "Ophthalmic Research;" Free Radicals, Antioxidants and Eye Diseases: Evidence From Epidemiological Studies on Cataract and Age-Related Macular Degeneration; A. Fletcher; September 2010
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