Research Unveils Food Link to Age-related Macular Degeneration (AMD)
Posted: Friday, October 17, 2008
by Paul Krawitz
Vitamin Science Inc
Nutrition plays an important role in the occurrence, prevention and treatment of Age-related Macular Degeneration (AMD). Nutrients--which are found in various foods--are commonly advocated for prevention as well as treatment of AMD. However, recent research has shown that some foods can substantially increase a person's risk for the disease.
The glycemic index (GI) is an index expressed according to a scale of 0-100. This index suggests how much the blood sugar level would increase when you eat certain foods. Glucose has the highest glycemic index, 100, whereas this index may vary according to the type of foods. A high glycemic index diet can cause an instant increase in your blood sugar level; however, a low glycemic index diet causes a slow rise of blood sugar and has little effect on the body's sugar level.
What the study says…
In order to find out a valid association between dietary factors and the risk of AMD, University of Sydney (Sydney, Australia) researchers Shweta Kaushik and colleagues conducted a population-based study, examining the link between dietary glycemic index and the 10-year incidence of AMD, in a group of participants aged 49 years and more. The researchers found that in the study population, the cumulative 10-year incidence for early AMD was 14.1%.
"After age, smoking, other risk factors, and dietary constituents were adjusted for, a higher mean dietary glycemic index was associated with an increased 10-year risk of early AMD," the researchers noted in the research paper. They also found that greater consumption of lower glycemic index foods could substantially reduce the risk of early AMD in the participants.
What's important in this study…
Like many other health conditions, AMD too, is connected with the foods you consume in your regular life, indicates the study by Kaushik and co-workers. According to the study, foods that instantly increase the blood sugar level (high glycemic index foods) may make you prone to early or dry AMD, whereas foods that cause a slow increase in your blood sugar level (low glycemic index foods) may cut the risk for the disease. The study also suggests that as early or dry AMD is a precursor for late or wet AMD (a condition that is strongly related to loss of vision), eating high glycemic index foods may also indirectly increase the risk for late or wet AMD.
The study by Kaushik and co-workers indicates that people are protected against AMD when they eat low glycemic index foods. Foods with a glycemic index of 70 and more are considered high glycemic index foods (e.g. steamed white rice; GI=98), and foods which have a glycemic index of 55 and less are called low glycemic index foods (e.g. spinach; GI=15).
Nutritional Supplements for AMD and Glycemic Index…
The findings of this study by Kaushik and co-workers emphasizes the importance of healthy eating habits and the use of nutritional supplements in the prevention and treatment of AMD. Nutritional supplements include various nutrients, such as lutein, zeaxanthin, beta-carotene, vitamin E, Glutathione, zinc and selenium. These nutrients work as antioxidants in retina and play an important role in protecting the macula against oxidative damages. Amid these nutrients, three major nutrients-lutein, zeaxanthin and beta-carotene are found in carrots (GI=49), squash (GI=15), peaches (GI=42), papaya (GI=58), broccoli (GI=15), spinach (GI=15) and peas (GI=48). Now, the glycemic index for most of these foods is less than 55. Glutathione can be found in foods such as broccoli (GI=15), spinach (GI=15), asparagus (GI =15), avocadoes (GI=15), squash (GI=15), cauliflower (GI=15), and walnuts (GI=15). All these foods are low glycemic index foods. Vitamin E can be obtained from tomato (GI=38), peanuts (GI=15), hazelnuts (GI=25), almonds (GI=15), avocadoes (GI=15), and carrot juice (GI=49). These foods also have a substantially low glycemic index. Zinc may be obtained from various foods, such as plain low-fat yogurt (GI=14), cashews (GI=15), baked beans (GI=48), milk (GI=27), walnuts (GI=15) and almonds (GI=15). Selenium can be found in oatmeal (GI=15), walnut (GI=15), spaghetti (GI=37), noodles (GI=40), eggs (GI=nearly 0) and so on. All these food sources have a substantially low glycemic index.
Conclusion…
When high glycemic index increase the risk of AMD, various nutrients can reduce the risk and slow the progression of AMD. There are 3 key mechanisms by which various nutritional supplements act against AMD-(1) working as scavengers for free radicals, (2)inhibiting oxidative damage to the retina, and (3) filtering the harmful blue light from the retina.
However, the recent research by Kaushik and co-workers indicates that apart from these 3 mechanisms of action, nutritional supplements may also have a fourth mechanism for providing protection against AMD, thanks to a substantially low glycemic index of their natural food sources.
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Top-level comments on this article: (1 total)Hi Paul.Very informative and somewhat alarming. I'm not sure that I can give up my little bit of sweet in the evening. Better beef up my supplements, I guess.This is well written and the information is well presented.Dianne
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