The Nutrition Debate #28: Sugar in the Diet: What does it mean?

I ran into a friend at the supermarket the other day and asked her how she was. She replied, “Fine,” but “tired a lot.” Not wanting to miss an opportunity to proselytize, I suggested, “sugar crash.” She protested, “I don’t eat sugar!” So, I asked her what she ate for breakfast. Therein lies a tale of folly that deserves to be more widely known and understood.

Sugar, as she and virtually the “whole world” thinks of it, is table sugar, as in “added sugar” such as that sprinkled on cereal. It is also an ingredient in candy and ice cream. Soft drinks usually are sweetened with high fructose corn syrup.

Table sugar, the “added” sugar, is cane sugar and chemically is known as sucrose. It is a disaccharide, meaning it is composed of two simple sugar molecules. One of those molecules is fructose and the other is glucose. All chemical compounds ending in “ose” are sugars. Most break down in the digestion process to glucose, some to fructose, and a few to galactose, the third monosaccharide, before entering the blood stream through the wall of the small intestine.

Sugars in this “whole-world” sense do not include those found in fruits, which are a combination of free fructose, free glucose and sucrose. Fruit sugars are regarded in this “whole-world” view as good for you, because they are an inherent component of this “real” or whole food. Forget that for centuries hybridizers have been making fruits sweeter than those found in nature to appeal to our sweet tooth.

Carbohydrates, one of the three basic elements of nutrition (the other two being protein and fat), are all saccharides. Carbohydrates, including fruits, cereals, bread, potatoes, rice and pasta, are somewhat more complex compounds, meaning composed of many molecules. Nevertheless, they virtually all break down in the digestion process to the simple sugars glucose and fructose. Glucose goes to the cells for quick energy. Fructose goes directly to the liver and is stored.

Back to the question I asked of my friend: “What did you eat for breakfast?” Her answer: “A glass of orange juice, a whole grain cereal ‘with 3 grams of protein’ [in reduced-fat milk, I assumed], toast and jelly.” “All sugar,” I exclaimed! Obnoxiously, I said, “if you eat a lot of ‘sugar’ – read any food except fat and protein -- all at once, your blood stream will be flooded with sugar (glucose) sooner or later (up to a few hours, depending on the food and the condition of your metabolism), and insulin pumped from the pancreas (if it is still working well). And then, after the ‘sugar’ gets delivered to the muscles and organs by the insulin, your blood sugar level will crash and you will ‘feel tired’ (and hungry) again.”

You will feel hungry again because another hormone, ghrelin (first reported in Nature in 1999!), will send a signal from cells lining the fundus of the stomach to the hypothalamus in the center of your brain, that the “quick energy” in your blood (glucose) is low again. So, when your “all sugar” breakfast is digested, in mid-morning your body will again crave “sugar” (anything that will break down to glucose) to “feed the beast.” “Sugary snack” doesn’t mean a candy bar. It means any carbohydrate, including fruit, or a glass of milk (lactose), all of which will break down to glucose and again raise the level of sugar in the blood. It will also overwork the pancreas again to produce more insulin. A vicious cycle.

Over a course of years the cell wall of the destination cells in many people will develop insulin resistance, requiring more insulin to get the job of delivering glucose energy to our muscles done. Eventually, in many of these people, the pancreas will slowly burn out. The islets of langerhans that produce the beta cells in the pancreas will stop working. They will die. By the time your doctor discovers this, up to 80% of your pancreatic function will probably already have been lost. That was the stunning conjecture made by Dr. Ralph DeFronzo, American Diabetes Association keynote speaker at their annual meeting in San Francisco in 2008. You will be diagnosed with full-blown Type 2 Diabetes. You will be drug dependent for the rest of your life. You will then be watchful for, or worse, diagnosed with the “dreaded complications.”

As a result, in recent years the standards and methodology for diagnosing Metabolic Syndrome and Type 2 diabetes has evolved. The old standard was two consecutive elevated plasma blood glucose tests above 140mg/dl, lowered to 126 in 1997, where it remains today. Fasting blood glucose between 100 and 125mg/dl is now regarded as pre-diabetes.

The new diagnostic standard for T2 diabetes is the Hemoglobin (Hb) A1c test. The diagnostic standard was formerly 7.0%. A few years ago it was lowered to 6.5%, and a 6.0% level added for pre-diabetes. Some activist endocrinologists, such as Dr. Richard K. Bernstein, use a much lower standard, regarding an A1c of 5.8% as indicating full-blown Type 2.

So, to stay healthy, watch your total sugars and remember: All carbohydrates are sugars. Your body breaks sugars down into glucose, the simplest sugar. Glucose induces insulin secretion. If you still think you don’t eat sugar, read this again!
© Dan Brown 10/23/11