Some might think that all sugars are the same. They certainly have many confusing names and aliases such as dextrose, fructose, glucose, lactose, maltose, mannitol, sorbitol, sucrose, xylitol and many more. Even though all of these taste sweet, not all are made equal.
In contrast to glucose (what all sugars get converted to in the blood) and sucrose (known as table sugar or white sugar), some nutritionists regard fructose as a relatively safe form of sugar. Fructose does not require insulin for uptake into cells, so it does not affect blood-glucose levels, at least in the short term. Compared with sucrose, fructose consumption appears less likely to cause symptoms of reactive hypoglycemia or to trigger overeating. For these reasons, fructose is often recommended for people with diabetes and is included in many weight loss products and energy bars.
However, while fructose consumption may not adversely affect glycemic control in most studies, it does have deleterious effects on other aspects of metabolism. Fructose reacts with protein molecules to form something called, toxic “advanced glycation end-products (AGE)”. Say what?!! What that means is that fructose reacts with proteins and amino acids to form substituted amino sugars. This reaction undergoes further reactions and rearrangements to form AGEs, that accumulate indefinitely on molecules such as collagen and DNA. There is evidence that AGEs play a role in the aging process in the progression of vascular, renal and ocular (eye) complications of diabetes. It also contributes to the development of atherosclerosis.
The consumption of fructose, primarily from high-fructose corn syrup (HFCS), has increased dramatically in the United States during the past several decades. HFCS is used extensively in carbonated beverages and other sweetened drinks, baked goods, candies, canned fruits, jams, jellies and baked goods. Processed-food manufacturers prefer to use HFCS to sucrose because it is inexpensive to use and mixes well in many foods. The annual per capita use of HFCS has increased from 1970 to 1997 from 0.5 pounds to 62.4 pounds, while sucrose consumption decreased from 102 pounds to 67 pounds.1
To recap, the potential adverse health effects of dietary fructose includes obesity, accelerated aging, insulin resistance, Diabetes mellitus and its complications, non-alcoholic fatty liver disease, high triglycerides, chronic diarrhea, irritable bowel syndrome and hives. Although the long-term effects of consuming fructose have not been adequately studied in humans, the available evidence suggests it may be more harmful than was once recognized. The extent that someone might be adversely effected by dietary fructose depends both on the amount consumed and the persons tolerance level. Also, the small amounts of fructose that occur naturally in fruits and vegetables are unlikely to have the deleterious effects that I have discussed. I encourage the consumption of fruits and vegetables, but recommend reading labels closely and reducing the overall intake of HFCS in your diet.
1 Gaby, A. Adverse effects of dietary fructose. Alternative Medicine Journal 2005; 10: 294-305.