We talk a lot about nutrition here on Rebuild Your Vision. This discussion mostly centers around foods that we know are good for the eyes. Take leafy greens for instance. They’re generally healthy as they contain some specialized pigments that can reduce the amount of stress aging eyes experience, lowering your chances for a few serious vision disorders.
In this article, we’ll go off track a bit by talking about a food that might be best avoided for the sake of visual health. We’re talking about starch, a component of stolid, dietary anchors such as rice, potatoes, and wheat.
While there’s still plenty of debate on the subject, some research has shown that starchy foods may pose some unique dangers to the eyes. We’ll discuss what science there is, and then give you a quick summary of the evidence for and against starch.
What Is Starch?
Starch itself is a complex sugar, a network of connected glucose molecules that, in practice, looks like a rather dull white powder. It’s commonly produced by vegetables, which use it as an energy storage unit. Plants create it during the day, using sunlight to power the process, then consume it as fuel during the night.
As you might guess from the above description, starch is absolutely energy-packed. For humans, it’s an incredibly dense source of sugars, making it a valuable means of filling out a diet. More recently, it’s also seen use as an industrial base for the manufacture of sugars, as starch can be converted to glucose and from there into a variety of similar chemical structures that give rise to different sugars.
Foods that contain starch are relatively abundant. Many cultural diets rely on starchy foods to provide a staple source of energy. As mentioned above, potatoes and rice are both extremely starchy foods. But as useful as starch is, it plays an increasingly uncertain role in modern diets.
Problems with Starch
Starches, being as they are giant collections of sugar molecules, lie extremely high on the glycemic index (GI), a measurement of the extent to which a food increases blood sugar after a human munches it. It’s a useful tool for determining how the body deals with different carbohydrates. A high GI score generally means that the carbohydrate in question is quickly broken down into glucose, which then enters the blood; a low GI score indicates the opposite.
Starches lie on the high end of the scale. Ingest a starch and it will rapidly translate to an increase in blood sugar, not surprising given that they’re basically superstructures built from glucose.
That spike can pose some problems, however. Diabetics in particular can have difficulty controlling blood sugar levels after a starch-heavy meal. While non-diabetics don’t have to face those particular challenges, there’s some evidence high-starch diets can still deal damage to eyes, giving just about everyone some incentive to watch their intake.
Starches and AMD
Age-related macular degeneration (AMD) is a widespread threat to aging eyes. AMD occurs either when waxy deposits form on the back of the eye, or when tiny capillaries in the eye rupture, then begin to grow abnormally, putting stress on and eventually scarring the retina.
A leading cause of blindness, AMD progresses very slowly and often imperceptibly. By the time changes are noticed, sufferers will have often lost a significant amount of center-field visual acuity. While the exact causes of AMD are still being researched, at least one study published in the The American Journal of Clinical Nutrition has linked high starch intake to an increased risk of developing the condition.
Researchers from Tufts University recruited over 4,000 US adults aged 55-80, had them fill out surveys on dietary habits, then ran them through eye exams to test for the presence of AMD. Out of all the participants who had AMD, it was determined that those with diets that landed high on the glycemic index were much more likely to have advanced AMD in at least one eye.
High GI diets generally included foods high in starch, such as white rice and refined flour. While the connection between these foods and AMD isn’t entirely clear at the moment, the team responsible for the study did conclude their paper by stating that one-fifth of the AMD cases they saw could have been prevented through dietary control.
What You Can Do
First, understand that the correlation between high-starch diets and AMD hasn’t reached slam-dunk point. Research is still needed to fully understand how one affects the other. However, there are plenty of more no-nonsense reasons to ditch starch anyhow.
A diet extremely heavy in starchy foods does contribute to obesity and, by the same token, to the odds of contracting type II diabetes. Both of these conditions can prove dangerous to the eyes, as they put extreme stress on blood vessels in the eye, eventually causing symptoms similar to those of AMD. Not only that, but they crowd out much more eye-healthy foods.
To start de-starching your diet a little bit, don’t immediately conclude that you need to cut rice and bread out of your diet. You can still eat them, just aim for unrefined versions. Brown rice and whole-wheat bread are both further down the GI than their processed cousins, thanks to the additional nutrients they contain. Switching over to these friendlier foods means that you can still eat what you like, but also avoid some of the stresses that starch can put on your body and your eyes.