Sounds pretty healthy at first blush, doesn't it?  How could anything having to do with fruit be anything but healthy?  After all, it is recommended that we consume five to eight servings of fruits and vegetables each day.  They contain many healthy nutrients such as antioxidants-the compounds that counteract the harmful effects of 'free radicals', those damaging compounds that age cells, injure the genetic material they depend on, and cause clumping of our functional proteins and lipids- those fatty compounds that enhance function in each cell in the body.  For example, grapes contain resveratrol, a unique ingredient that has been purported to lengthen the life span of various organisms.  I believe there are many healthy nutrients in fruits and veggies.  However, try to imagine in your mind's eye how these foodstuffs might have appeared in the distant past.  For example, take an apple.  It would clearly not have been the large, succulent type of fruit that appears on today's grocery shelves.  It would have been small, tough, and shriveled.  Nothing resembling what is eaten today.  The major difference is that the current varietals are aptly described as tasting sweet, for good reasons.  They are large and starchy; full of sugar. The typical apple contains approximately 1.5 grams of glucose, 6 grams of fructose (fruit sugar), and 3 grams of sucrose (read table sugar).  

 As our gene pool evolved over the past several million years, one of the major influences shaping genetic alterations is the diet.  Of note is the observation that, aside from the past 10,000-20,000 years, we have been exposed to food that included essentially no rapidly absorbed carbohydrates (other than for seasonal honey-like substances).  The rapid absorption of the glucose in starchy foods such as potatoes and bread has been studied along with the related rapid rise in blood insulin levels (associated with the Glycemic Index concept).  Books have been written discussing the Glycemic Index and what it implies.  However, in my opinion, equal emphasis has not been given to the impact that fruit sugar, or fructose, as it is otherwise called, has upon our health.  As an example, the GI (Glycemic Index) of white bread is 100.  That represents the exaggerated rate of rise in blood glucose, and with it the tightly correlated rise in blood insulin levels.  If you consume the same number of carbohydrates in the form of table sugar (or sucrose, which consists of a molecule of glucose and fructose linked together), the GI is only about 60, roughly two-thirds as high as the white bread.  This makes it seem like eating sugar is healthy because its GI is much lower than that of bread.  This couldn't be further from the truth.... for reasons other than those reflected by their glycemic index.

Sugars, such as glucose and fructose, have the uncanny ability to bind to functional proteins, fats and DNA particles.  When this occurs, they dramatically degrade the vital activity of these molecules.  This forms the basis for a commonly requested lab test called HBA1c that measures the average blood sugar level for the past couple of months.  This is a test that represents adequacy of blood sugar regulation over a long period of time and is important in diabetic control.  It reflects the innate ability of these sugars to bind to the hemoglobin protein that is naturally present in the bloodstream.

What is important to note is that the propensity of fructose to bind to these important biological molecules is ten-fold greater than that of glucose even though glucose has a much higher GI.  This is a shortcoming of the GI.  There are many reasons why this distinction is important, but the one I am most concerned about is the relationship between binding of these sugars to delicate proteins in the body and the correlation with brain atrophy.  Brain atrophy may be viewed as brain shrinkage, which is not a good thing to have going on in your brain.  Clinical investigations have documented the close correlation between brain atrophy and level of HbA1c in the blood-a proxy for the degree of binding of these sugars to functional compounds in the body.  One study even found it to be the most significant indicator of brain atrophy. 

The take home message is to avoid foods that contain high amounts of fructose, or fruit sugar.  In this context it is not necessarily the apple I am referring to, but HFCS (high-fructose corn syrup) and table sugar (sucrose).  Numerous foods contain 20 to 40 or more grams of these ingredients.  Be careful to read labels because they even sneak into ketchup and other condiments.