考博英語經典閱讀文章3

Blinded by Bread

　　Don't hold the book too close to your eyes or you'll need glasses, parents often warn their children. But the food kids eat might play just as big a role as books and computer screens when it comes to??? shortsightedness.

　　Diets high in refined starches such as breads and cereals in- creased insulin levels. This affects the development of the eyeball, making it abnormally long and causing shortsightedness, suggests a team led by Loren Cordain, an evolutionary biologist at Colorado State University in Fort Collins, and Jennie Brand Miller, a nutrition scientist at the University of Sydney. The theory could help explain the dramatic increase in myopia in de- veloped countries over the past 200 years, it now affects 30 per cent of people of European descent, for example.

　　“The rate of starch digestion is faster with modem processed breads and cereals,” says Brand Miller. In response to this rapid digestion, the pancreas pumps out more insulin. High insulin is known to lead to a fall in levels of insulin-like binding protein-3, the team points out. That could disturb the delicate choreography that normally coordinates eyeball lengthening and lens growth. And if the eyeball grows too long, the lens can no longer flatten itself enough to focus a sharp image on the retina, they suggest.