Low GI Diet to Preserve Our Eyes
A low glycemic index (GI) diet can help you maintain a good view.
More risk of AMD when eating high GI foods
Age-related macular degeneration (AMD) is the aging of the central retinal zone (macula), which allows for fine vision, ie, reading, face recognition, car driving. The leading cause of visual disability in people over 50, it affects the millions people in the world.
In 2007, a study showed that eating high glycemic index (GI) foods increased the risk of AMD by 50%. This study of Tufts University in Boston was conducted on 4099 people aged 55 to 80 years. The researchers screened 602 cases of AMD. Comparing this diagnosis with dietary habits of patients, they found that those whose eyes were most sensitive to aging were also those who consumed the most high GI foods. This diet increases the risk of developing AMD by 50%.
High GI foods include white bread, sweets, etc. They quickly increase blood sugar and produce inflammation, a condition that promotes AMD. In contrast, other more complex carbohydrates, such as whole grains, are digested more slowly, and allow lower blood sugar. And more the glycemia remains low in time, more the risk of AMD would be reduced.
In 2012, an Australian study linked the consumption of high GI carbohydrates to the condition of blood vessels around the retina for 2353 children aged 12 years on average. Children who consume the most sodas or more carbohydrates in their diet have retinal arterioles narrowed from normal.
Similarly a high GI diet is suspected of increasing the risk of myopia.
The beneficial effects of a diet change
Can we reverse the trend by deciding to adopt a low-GI diet? This is the question that scientists at Tufts University asked themselves. For this new research published in 2017 in PNAS, the researchers tested two diets in mice: one group consumed a high GI diet and the other low GI diet; a third group moved from a high GI diet to a low GI.
Mice on a low GI diet did not develop AMD, unlike those following the high GI diet. In the group of mice that changed diets, not only was there a preventive effect on AMD, but the damage to the retina was reversible! These results suggest that a change in diet can have an impact on vision.
To find out more, scientists have done blood and urine tests on rodents. They observed that mice following the high GI diet had high levels of AGEs (advanced glycation end products), toxic compounds derived from sugars. These AGEs damage proteins and lipids important for cell function. In the retina, proteins can accumulate in deposits that destroy retinal cells.
Researchers have also identified AMD markers in blood and urine, such as serotonin. As this molecule is related to intestinal flora, it can be assumed that intestinal bacteria can influence eye health. One hypothesis is that carbohydrates with high GI pass rapidly into the bloodstream without serving to nourish beneficial and neuroprotective intestinal bacteria.
In addition to improving eyesight, a low GI diet is good for cardiovascular health, diabetes and can also help you lose weight.
In practice, for a low GI diet
If you eat ultra-processed foods like breakfast cereals, a lot of refined grains and white bread, you will have to change some habits. The simplest is to reduce the proportion of refined products in the diet, by replacing them with complete foods, and consume vegetables in quantity.