What is fructose ?
Fructose, also levulose or fruit sugar, is a monosaccharide (a simple sugar) with the formula C6H12O6 (a ketohexose). Fructose is among others in sweet fruits. In sucrose (cane and beet sugar), fructose is bound to glucose (dextrose). Two molecules of fructose crystallization with a molecule of water. Fructose is left-handed.
Sweetness
Fructose is widely used as a sweetener. It is 2.5 times as sweet as glucose and about 1.7 times as sweet as sucrose. It can not as a substitute for regular sugar used in products for diabetics because fructose does not fit in the diet of diabetics. Furthermore, in most low-calorie (light) sweet products not used because modern fructose sweeteners like aspartame and acesulfame K are hundreds of times as sweet as sucrose and therefore for the same sweetening power supply far fewer calories.
Fructose is absorbed faster by the body than sucrose or glucose and the taste sensation is stronger and disappears faster than sucrose. Fructose may also enhance other flavors.
Fructose has been for many years considered a safe sugar for diabetics, because it does not lead to a rapid increase in the blood sugar level. Although fructose is indeed more slowly absorbed into the blood, it starts from that point of view to come back, because there is evidence that frequent use of fructose may actually contribute to diabetes and related disorders.
Fructose in food
Although the name suggests otherwise fructose, most fruits contain unprocessed only relatively small quantities of pure fructose, usually no more than 5 grams per 100 grams. Apricots, plums, berries and grapefruit contain no more than 1.5 grams per serving of 100 grams. In most vegetables is barely fructose for.
The vast majority of fructose in the diet is derived from sucrose, which is broken down in the digestive system to equal parts glucose and fructose, and glucose-fructose syrup. Many foods and drinks are now sweetened with HFCS. HFCS is a popular sweetener because it is much sweeter than sucrose or glucose, is considerably cheaper and can also be kept longer. It is sometimes referred to as "natural sugars" promoted. In the US (but hardly beyond) in place of sugar beet used mostly High Fructose Corn Syrup (HFCS). However, the fructose content thereof does not differ or hardly to that of sugar beet.
A rich natural source of fructose is honey, which contains approximately 40% fructose.
Securities
The consumption of fruit juices with a high percentage of fructose compared to glucose (such as apple and pear juice concentrate) results in babies and children under five regularly to fructose malabsorption. The cells (enterocytes) which in small children lining the small intestine from the inside, are less able to include fructose than on glucose. Fructose malabsorption can lead to restlessness, colic, flatulence and abdominal pain, as well as to (osmotic) diarrhea.
There are suspicions that prolonged high intake of fructose, mostly due to consumption or not "hidden" sugars, leading to metabolic syndrome, insulin resistance, obesity, fatty liver, diabetes and cardiovascular disease (including hypertension, myocardial infarction, dyslipidemia. In normal use sucrose and fructose, however, according to a research review from 2013, partly sponsored by the ASN (American Society of Nutrition), expect no adverse effects.
Hereditary fructose intolerance
People with hereditary fructose intolerance may have to either defect
- The enzyme fructose-1-phosphate. Due to the inactivity of this enzyme hopes to fructose-1-phosphate accumulates in the liver. In addition to accumulation of fructose in the blood (fructosemie), this also leads to a degradation of ATP to uric acid. Even in the ingestion of very small amounts of fructose, this can lead to an increase in the serum urate. This may indicate familial fructose intolerance as a cause of (hereditary) gout.
- Liver enzyme fructokinase, making fructose unchanged in the urine excreted (fructosurie). This is a relatively harmless condition that usually proceeds without many complaints.