Very exciting research from Princeton University explains how taking in sugared drinks and any sugar added to foods (not in whole fruits and vegetables) can cause diabetes (Cell Metabolism, Feb 6, 2018;27(2):351–361).
The most common sugar source in foods contains two sugars, glucose and fructose. Glucose is the only sugar that your body allows to circulate in your bloodstream. The authors of this study show that fructose is converted to glucose primarily in the intestines, and not in the liver as scientists thought previously. However, if you overload your intestines with fructose, the unchanged fructose can pass through your intestines into your bloodstream and into your liver where it causes fat to accumulate in your liver to cause high blood sugar levels that are characteristic of diabetes.
This exciting new study also shows that fructose that is not converted to glucose in the small intestine can pass to the colon where it fosters the growth of harmful bacteria. These harmful types of bacteria try to invade the cells in your colon, which turns on your immunity to cause inflammation that increases risk for obesity, heart attacks and some cancers. On the other hand, adding high-fiber foods to a person's diet helps to prevent diabetes by fostering the growth of the good colon bacteria that do not invade the colon cells and help to reduce inflammation (Cell, January 2014). See Gut Bacteria Linked to Diabetes
Why Sugar in Fruits and Vegetables Is Safer
Virtually all studies on the subject show that eating fruits and vegetables is associated with the prevention and control of diabetes (PLoS Medicine, April 11, 2017), even though they contain sugar. The most likely explanation is that:
• Sugar added to foods and in all sugared drinks (including fruit juices) causes an immediate overload of fructose that allows some fructose to pass unchanged from the intestines into the bloodstream and then directly into the liver, where fructose is converted to fatty triglycerides, which fill up the liver cells with fat. Fat in the liver prevents the liver from lowering high blood sugar levels the way it is supposed to do.
• The sugar in fruits and vegetables is prevented from causing a high rise in blood fructose by the soluble fiber and anti-oxidants in them (Cell. January 9, 2014). The added sugars used in beverages and foods are the same as the sugars in fruits and vegetables, but when the sugars are extracted from their plant sources (sugar beets, sugar cane, maple trees, corn, flowers, grapes, apples and so forth), the beneficial soluble fiber and numerous antioxidants are removed.
Why Sugar in Drinks is Absorbed Most Quickly
Solid food is not allowed to pass directly into your intestines because it could block the intestines and kill you. When you eat food, your pyloric sphincter at the end of your stomach closes to prevent solid food from entering your intestines. Then your stomach muscles contract and push only a liquid soup through the closed sphincter muscle into your intestines. However, when you take sugar in a liquid, it is not stopped by the pyloric sphincter and enters the intestines immediately to allow the fructose to enter the liver and turn into fat.
How a Fatty Liver Can Cause Diabetes
A high rise in blood sugar can damage cells throughout your body. To prevent blood sugar levels from rising too high after eating, your pancreas releases insulin that is supposed to lower blood sugar by driving sugar from the bloodstream into the liver. However, if your liver is full of fat, your liver cannot accept the sugar and blood sugar levels rise even higher. High blood sugar levels cause sugar to stick to the outer membranes of every type of cell in your body. Once attached, sugar can never get off and eventually destroys cells to cause all the harmful side effects of diabetes.
Almost 50 percent of North Americans will develop diabetes. To reduce your risk for becoming diabetic:
• Avoid being overweight.
• Prevent fat from accumulating in your liver by losing excess weight until you cannot pinch more than three inches of fat under the skin near your belly button. I recommend intermittent fasting for weight loss.
• Restrict or avoid drinks with sugar (including fruit juices) and foods with added sugars.
• If you are overweight or have high blood sugar levels after eating (>140 mg/dl one hour after a meal) you should also restrict all refined carbohydrates (bakery products, pastas, most dry breakfast cereals and so forth), processed meats and red meat (which increase risk for not being able to respond to insulin), and fried foods.
• Try to exercise every day. Contracting muscles draw sugar from your bloodstream without needing insulin.
• Avoid vitamin D deficiency as it can prevent your cells from responding to insulin. Hydroxy vitamin D levels should be >20 ng/ml.