Читать книгу Alzheimer's Disease - Michelle Deetken - Страница 21

Let's have a short lesson on carbohydrates to understand the importance of glucose. Dietary carbohydrates are either simple carbohydrates (sugars) or complex carbohydrates (starches and fibers). The building blocks of all carbohydrates are three sugars: glucose, fructose, and galactose. Fructose is the sweetest of the sugars and is found naturally in fruit and honey. Galactose binds together with glucose to form lactose, or milk sugar. Fructose and galactose will be converted to glucose in the liver. Glucose is the most abundant sugar in nature, and it is found in all plants as starch. Starch is the way that plants store their glucose for energy, which is in long chains of hundreds or thousands of glucose molecules. Since all animals consume some plants, glucose is the main energy source for almost every living thing. When a body consumes plants, the complex carbohydrates (starch and fiber, along with their associated minerals and vitamins) are slowly digested, and the glucose is released at a modest, regulated rate so that the blood glucose levels rise only slightly. Starches like those found in white flour, white rice, and all the other processed and refined starch products behave more like simple carbohydrates because their long chains of glucose have been broken down and stripped of their fiber and nutrients. As a result, they digest quickly, causing a surge in blood glucose levels. When you consume a meal, all of these simple and complex carbohydrates will be broken down so that the glucose can be used for energy immediately—anywhere in the body—or stored in the liver and muscles, ready to release their supplies when blood glucose levels drop between meals or during physical exercise or work. Any excess glucose goes into longer-term storage. This storage happens after a few modifications are made to glucose to become fat and then placed into fat (adipose) cells for future energy needs.