Fructose, also called fruit sugar, is a simple monosaccharide found in many different kinds of ripe fruit and some vegetables. Fructose is considered to be the sweetest of all naturally occurring carbohydrates and is the most water-soluble of all sugars. Fructose exists within fruit by itself, but more often it is combined with glucose to form sucrose, which is commonly refined and used as table sugar. Fructose is a favorite among commercial food manufacturers.
Rich Sources of Natural Fructose
Natural sources considered rich in free molecular fructose include honey, apples, pears, bananas, grapes, pineapple, berries, melons, red peppers, sugar cane, onions, parsnips and sweet potatoes, according to "American Dietetic Association Complete Food and Nutrition Guide." Apple and pear juices can be of concern if given excessively to children because fructose is not absorbed well in the intestine, which draws water in and leads to diarrhea. Glucose, another monosaccharide, is also found naturally within fruits, but is not referred to as fruit sugar.
Refined Sources of Fructose
The highest dietary sources of fructose are processed foods containing table sugar, high-fructose corn syrup, agave nectar, honey, molasses, maple syrup and concentrated fruit juices, according to the book "Biochemistry of Human Nutrition." Within these types of foods, fructose exists as free monosaccharides and binds to glucose in the form of sucrose. High-fructose corn syrup is used extensively in commercial baked goods and has been linked to pancreas debilitation and increased risks of developing Type II diabetes, according to "Human Biochemistry and Disease."
Commercial Benefits of Using Fructose
Fructose is a favorite among commercial food manufacturers for main two reasons. First, it is less expensive than refined sugar products, making it much more cost effective to use as a sweetener. Secondly, fructose is much sweeter than other refined sugar products, so smaller amounts are required to achieve a certain sweetness index, which is also a cost savings to manufacturers. Fructose is about 1.7 times sweeter than sucrose, although if fructose is heated it slightly changes its molecular structure and becomes on par with sucrose.
Digestibility
Although refined sources of fructose can have negative effects on the pancreas and gastrointestinal system, natural sources of free molecular fructose can provide some benefits over glucose and sucrose. According to "Advanced Nutrition and Human Metabolism," natural fructose from fruit and vegetables is almost entirely metabolized in the liver, so it takes longer to reach the bloodstream and produces a lower glycemic index. Consequently, medical consensus is that natural sources of fructose can be moderately tolerated by diabetics and produce less of a "sugar rush" in healthy individuals. However, processed forms of fructose will still cause blood sugar levels to peak and should be avoided by diabetics.
References
- "American Dietetic Association Complete Food and Nutrition Guide"; American Dietetic Association; 2006
- "Biochemistry of Human Nutrition"; George Gropper; 2000
- "Human Biochemistry and Disease"; Gerald Litwack; 2008
- "Advanced Nutrition and Human Metabolism: 5th Edition"; Sareen S. Gropper and Jack L. Smith; 2009
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