High carb diet increases risk of cataract development in elder women

Scientists working for the Agricultural Research Service, the US government's scientific agency, tracked 471 women aged between 53 to 73 years during a 14 year period.

They found that women in the study whose average carbohydrate intake was between 200 and 268 grammes per day were 2.5 times more likely to get cortical cataracts than the women whose intake was between 101 and 185 grams per day.

The recommended dietary allowance for daily carbohydrate intake for adults and children is 130 grams, which is based on how much glucose the brain needs.

The UN's World Health Organisation estimating between 16 to 20 million people worldwide are currently blind as a result of cataracts, the leading cause of blindness in the world.

Proteins in the eye's lens unravel, tangle and accumulate pigments that cloud the lens and eventually lead to blindness. Cataracts appear to different degrees in most individuals as they age.

Cortical cataract is one of three distinguishable types of cataracts. Carbohydrates are mainly sugars and starches that the body breaks down into glucose, a simple sugar that feeds the body's cells.

"The potentially harmful effect of high-carbohydrate diets on the lens could be a result of increased exposure of normal lens proteins to glucose,"​ suggest the scientists.

The researchers conducted eye exams and studied dietary data taken from questionnaires to assess the relationship between volunteers' newly diagnosed cataracts and their average carbohydrate intake over a 14 year period.

The scientists are currently unaware if these findings could be generalised to men and other age groups. "But the mechanisms underlying cataract development have not been known to vary by sex or socioeconomic status,"​ they add.

Full findings of the study, led by Chung-Jung Chiu and Allen Taylor at the Jean Mayer USDA Human Nutrition Research Center on Aging in Boston, are published in the June issue of the American Journal of Clinical Nutrition.​

Carbohydrates come in two forms: simple and complex. Simple carbohydrates contain naturally occurring sugars, such as those found in fruit (fructose) for example. The sugars that make up simple carbohydrates also include table sugar (sucrose) and a variety of syrups.

Because simple carbohydrates are already simple sugars they can rapidly be converted into glucose and enter the bloodstream very soon after consumption.

Complex carbohydrates are present in most grain products, vegetables and potatoes. Unlike simple carbohydrates, complex carbs are digested at a much slower rate. As a result of this, the conversion to glucose also happens at a slower rate and blood sugar levels will not fluctuate as rapidly as they do when digesting simple carbohydrates.