Because it takes our our bodies a long time to digest that fiber, the apple's sugar is slowly released into our blood stream, giving us a sustained supply of power. Those who've retained the flexibility to digest dairy products efficiently in adulthood are primarily of northern European ancestry. In much of the world’s inhabitants, lactase activity declines throughout childhood and adolescence, which leads to an inability to digest lactose adequately. Monosaccharides of nutritional significance are glucose, fructose, and galactose