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Fructose is a simple sugar that belongs to the ketose group. In combination with glucose, it forms sucrose. It has strong reducing and hygroscopic properties – it binds water from the surrounding air at a relative humidity of 45–50 percent.
Fructose – occurrence
Free fructose occurs mainly in fruitsand also in honey and flower nectars. Its small amounts are also found in vegetables. The main source of fructose in the daily diet of humans is sugar (sucrose) and fructose syrups: corn and glucose-fructose.
Fructose – properties
Fructose is a source of easily digestible simple sugars that provide a lot of energy to living organisms at a very fast pace. Fructose metabolism occurs without insulin. There are two ways of its transformation: hepatic and muscle-fat. In muscle and adipose tissue, fructose is phosphorylated by hexokinase and turns into fructose-6-phosphate entering glycolysis.
In the liver, fructose is phosphorylated to fructose-1-phosphate by the enzyme fructokinase. The fructose-1-phosphate is then broken down by fructose-1-phosphate aldolase to glyceraldehyde and phosphodihydroxyacetone. Glyceraldehyde phosphorylates to glyceraldehyde-3-phosphate. Along with phosphodihydroxyacetone, it can be included in the glycolysis cycle
Fructose – negative effect
Fructose is absorbed much more slowly by the body than sucrose and glucoseTherefore, excessive consumption of it may cause gastrointestinal pain, lead to diarrhea and raise blood cholesterol levels. Excess fructose in the diet may contribute to the development of metabolic disorders conducive to the development of cardiovascular diseases and type 2 diabetes, may cause gout and pose a serious threat to the proper functioning of the brain.
Clinical studies have confirmed the relationship between fructose consumption and the development of arterial hypertension, which is caused by an increase in uric acid synthesis and increased sodium absorption. It is worth noting that the impact of glucose-fructose syrup on the human body is still being studied.
Researchers at the University of California found that fructose is carcinogenic. According to their research, cancer cells, after receiving fructose and glucose, began to metabolize them differently. It turned out that cancer cells began to grow faster. Scientists also found that fructose has a beneficial effect on the development of various types of malignant tumors.
Excessive consumption of fructose leads to cardiovascular disease. People who eat high fructose foods have elevated blood cholesterol levels. The consequence of this is a greater probability of a heart attack. Moreover, due to fructose, visceral fat is deposited in the abdominal cavity. Its excess also influences the development of arterial hypertension.
Fructose makes the nervous tissue less sensitive to insulin. This is one of the direct causes of memory impairment. Fructose also increases blood levels of uric acid, which can accelerate the onset of arthritis. Arthritis manifests itself as severe joint pain. In some cases, it may make it impossible to move – therefore the consumption of fructose should be limited by the elderly.
Fructose – application
In the food industry, fructose acts as a sweetener and preservative. Due to its hygroscopicity, it is useful for extending the shelf life of bakery products. It is thanks to her that the ice cream has a smooth texture. In addition, it replaces sugar for diabetics. It is used as a substrate in the pharmaceutical industry. In processing, it is used in the form of sugar syrups
In the processing of fructose, it is used in the form of, among others high-fructose corn syrup and glucose-fructose syrup. Their popularity is mainly due to the fact that they are cheaper than, for example, sugar. In addition, they have better sensory properties. Food producers add them, for example, to jams, carbonated and non-carbonated drinks. Foods containing fructose will give you energy quickly.
Glucose and fructose – similarities and differences
Glucose and fructose are simple sugars. Ripe fruits and vegetables have a high glucose content. In turn, fructose is found in fruit juices, honey and sweets. Both components have the same caloric content, but have different glycemic indexes and are metabolized differently in the body. Pure glucose is visually no different from fructose. However, the differences are already visible in the chemical structure.
Both compounds have a different effect on the human body, and in particular on the brain. Research by American scientists has shown that a drink with fructose activates the nucleus accumbens and thus increases the feeling of hunger. In turn, drinking a drink with glucose no longer causes this condition. Glucose and fructose are sources of energy, but glucose can be described as “the healthy fuel”.
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Reducing properties of sugars
Reducing sugars are carbohydrates that react positively with the Tollens, Benedict and Fehling reagents. They are, among others glucose and fructose. In addition to them, this group includes galactose, ribose and xylose. The reducing properties of sugars are the reduction of metal hydroxides or metal oxides. In addition, it is they who give flavor to food products.
Fructose and slimming
Eating too much fructose in fruit doesn’t help you lose weight as it builds up as body fat. Fruits such as dates, raisins, dried apricots and figs are especially caloric – most of them contain more than 50% sugar. Of course, eating them on a reducing diet is allowed, but you should be moderate.
It is not necessary to completely give up fruit on the diet. First of all, eat them in reasonable portions. The fruit is a source of minerals and vitamins that the body needs. The healthiest ones include, among others wild strawberries, strawberries, cranberries, grapefruits, blackberries and rhubarb. However, be aware that grapefruits can interact with some medications. Fructose is also available on Medonet Market.
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