Low GI foods, by virtue of their slow digestion and absorption, produce gradual rises in blood glucose and insulin levels and have proven health benefits. High GI foods are those that are rapidly digested and absorbed and result in marked fluctuations in blood glucose levels. The GI is a ranking of carbohydrates on a scale from 0 to 100 according to the extent to which they raise blood glucoselevels after eating. 5,6 Additionally, the carbohydrates present in hunter-gatherer diets were typically of a low glycemic index (GI) they are slowly absorbed and produce a gradual and minimal rise in plasma glucose and insulin levels when compared with the sugars and refined starches in western diets. The diets of hunter-gatherer civilizations are typically considered to have high protein, moderate levels of fat, and low levels of carbohydrates when compared with modern western diets. Moderate to high myopia (–3.00 to –9.00D) is either nonexistent or occurs in approximately 1in1000 individuals. 2-4 The few studies carried out in existing hunter-gatherer societies and in recently westernized hunter-gatherer groups indicate that the incidence of myopia normally occurs in less than 2% of the population, and most refractive errors are less than –1.00D. Studies of nonwesternized Eskimos indicate those who have engaged in long hours of near work (eg, sewing, tool making) in dimly lit houses did not develop myopia. Other environmental factors could have effects on myopia development and progression, most specifically a high availability of processed foods. 1 The quantity and intensity of education in these rural areas are less than in urban settings. In rural areas with little exposure to modern lifestyles, the near work of reading indicates the rate of myopia reaches much beyond the rates of that of hunter-gatherers-typically less than 4%. However, they also hypothesized that dietary changes, especially higher carbohydrate intake, might affect the structure of the growing eye. Studies by Morgan and Monroe 1 suggested that increased near work among younger individuals was the environmental factor that may have influenced the higher rates of myopia. Thus, any gene or genes that would producehigh myopia would be lethal and rapidly eliminated by natural selection. We can infer that significant myopia was not likely present in the population of the early Homosapiens, as these early humans required clear distance vision to escape predators, find food, and recognize members of other species and a host of environmental dangers. When considering the genetic influence on ocular growth and function, it must be considered to first analyze our ancestral genetic makeup. We will review the role of nutrition and how it interacts with the expression of genes to create the conditions thatmight lead to the development of myopia. There are several factors that have been explored as potential environmental contributors to myopia development, including the spectrum of exposed light, outdoor time, circadian rhythms, spatial frequency characteristics of written material, vitamin levels, dietary intake, physical activity, excessive near work, intraocular pressure, form deprivation, and binocular vision disorders. Numerous studies have demonstrated that near work is related to myopia however, all individuals in industrialized countries must do regular near work during childhood education, yet only a certain percentage of the population ultimately develops myopia. It is becoming more apparent that myopia is not only a benign refractive error but also has long-term medical and visual consequences, yet little attention has been paid to the possible role of nutrition in the development and advancement of myopia. However, the interaction of these 2 components to create refractive error remains speculative. The rise in the prevalence of myopia has been too rapid to be explained by genetic factors alone and thus suggests a substantial role of environmental influences. Within the eyecare community, there is a predominant consensus that the cause of juvenile onset myopia-a significant worldwide public health concern-involves both genetic and environmental elements.
0 Comments
Leave a Reply. |