Eye-Health Ingredient Research Update

ALA for AMD
Investigators from Shandong University (Shandong, China) recently evaluated the effect of alpha-lipoic acid in individuals with the dry form of AMD. Dry AMD is by far the most prevalent type of this condition and is characterized by the formation of yellow fatty deposits called drusen under the retina as well as the progressive breakdown of light-sensing cells in the macula of the eye. Since alpha-lipoic acid is well-known for its antioxidant benefits, the researchers believed it to be a good candidate for reducing oxidative stress in eye tissue.

In the study, 100 individuals aged 60-83 with dry AMD were randomly assigned to supplementation with alpha-lipoic acid (200 mg/day) or control (vitamin C; 1 g/day) for three months. (2) Serum superoxide dismutase (SOD) activity, a measure of antioxidant power, increased significantly with alpha-lipoic acid, as did measures of contrast sensitivity and vison-related quality of life. The alpha-lipoic acid group’s improvements in SOD activity and vision-related quality of life were significantly greater than those of the control group, further supporting the benefits of alpha-lipoic acid in AMD sufferers.

References:
2. Tao Y, et al. “α-lipoic acid treatment improves vision-related quality of life in patients with dry age-related macular degeneration.” The Tohoku Journal of Experimental Medicine, vol. 240, no. 3 (November 2016): 209-214


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Omega-3s for Dry Eyes
Omega-3 fatty acids have previously been studied for their benefits in individuals with dry eyes and their ability to support tear production. Numerous individuals experience decreased eye moisture on a regular basis as a result of immune system disorders, eye surgery, contact use, medications, and other causes. In a new multicenter, double-blind placebo-controlled study, Alice Epitropoulos from The Ohio State University (Columbus, OH) and colleagues randomized 105 individuals diagnosed with dry-eye disease into 1) a group receiving 1680 mg of EPA + 560 mg of DHA daily for 12 weeks, or 2) a control group receiving 3,136 mg of linoleic acid/day. (3)

Researchers found significant improvements in the omega-3 group at the end of the study, including a reduction in tear osmolarity (a sensitive marker for dry-eye disease), increased tear break-up time, decreased inflammation on the ocular surface (measured as matrix metalloproteinase-9 activity), as well as improvements in Ocular Surface Disease Index scores, a measure of chronic dry-eye symptoms. The results of this study indicate important benefits of omega-3 fatty acids for those suffering from dry-eye disease.

References:
3. Epitropoulos AT, et al. “Effect of oral re-esterified omega-3 nutritional supplementation on dry eyes.” Cornea, vol. 35, no. 9 (September 2016): 1185-1191


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Lutein and Zeaxanthin for Visual Protection in AMD
Evidence of the benefits of lutein and zeaxanthin for supporting macular health continues to expand. In a recent study led by Mei-Ling Peng from Chung Shan Medical University Hospital (Taichung, Taiwan), 56 healthy individuals with early-stage AMD aged 30-50 years were asked to consume a marigold and wolfberry beverage (providing 12 g lutein and 2 mg zeaxanthin) daily for five months. (4)

Consumption of the beverage led to significant decreases in total free radicals, while antioxidant capacity, glutathione content, and antioxidant enzyme levels increased. C-reactive protein (hs-CRP) levels, a measure of inflammation, also decreased. In addition, daily consumption of lutein plus zeaxanthin led to significant improvements in macular pigment optical density (MPOD), visual acuity, decreased intraocular pressure, and improved photostress recovery. Taken together, these results indicate eye-health protective effects of lutein and zeaxanthin consumption, as well as systemic effects related to improved antioxidant activity and anti-inflammatory benefits.

References:
4. Peng ML, et al. “Influence/impact of lutein complex (marigold flower and wolfberry) on visual function with early age-related macular degeneration subjects: a randomized clinical trial.” Journal of Functional Foods, vol. 24 (April 2016): 122-130


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Lutein Supports Visual Function in Diabetics
Diabetic retinopathy is a common cause of blindness and visual impairment. It is characterized by oxidative damage leading to lipid peroxidation in the retina and is a result of high blood sugar levels and high metabolic activity in retinal tissue. In a randomized study led by Ping-Chuan Zhang of Xi’an Jiaotong University Health Science Center (Xi’an, China), 31 individuals with diabetes aged 40-85 years suffering from diabetic retinopathy were given either 10 mg/day lutein or a placebo daily for 36 weeks. (5) Visual parameters including visual acuity, contrast sensitivity, and glare sensitivity were monitored from baseline to 36 weeks.

In the lutein group, visual acuity and glare sensitivity improved, but the magnitude of improvement was not statistically significant. Contrast sensitivity, however, significantly improved from baseline to 36 weeks in the lutein-supplemented group, indicating that lutein may improve parameters of visual function in individuals with diabetic retinopathy.

References:
5. Zhang PC, et al. “Effect of lutein supplementation on visual function in nonproliferative diabetic retinopathy.” Asia Pacific Journal of Clinical Nutrition, vol. 26, no. 3 (May 2016): 406-411


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