In this revision a brief introduction is presented about the absorption of carbohydrates and a method of preclinical study with mice where it was demonstrated by means of organismal performance assays (OPAs) that to feed with table sugar (sucrose, SU) is not the same thing that take glucose plus fructose.
The processes of digestion of carbohydrates produce a variety of monosaccharides, among those that are glucose and fructose. They are absorbed from the blood torrent and this way they are distributed to cells. The SU is a disaccharide compound for glucose and fructose. So that cells can use the sugars, they should cross the cellular membrane. They make it by means of active transport and facilitated diffusion.
The current diet includes a great quantity of foods edulcorated with high-fructose syrup (glucose plus fructose 1:1). A diet that is similar to the one consumed by 20% of Americans and inside the recommended dietetic ingest (RDI) approved by the Food and Drug Administration (FDA). A controversy exists about the excessive consumption of sugar and even more polemic the not resolved doubt about the toxicity of the high-fructose syrup.
Toxicity studies to environmental exposition often are not carried out at outstanding levels of exposition, under relevant environmentally conditions, or with genetically diverse populations. By means of OPAs it is possible consider all these problems because the sensibility of this method is able to detect health consequences at relevant levels of exposition, due to that are determined in a natural context and use animals that are not genetically close related, which possess the functional behaviors found in nature.
It is relatively easy to evaluate the acute toxicity index of a substance causing the death (median dose lethal). More challenging is recognizing whether the dietary or environmental exposures compromise long-term health and fitness. Scientists at The Wayne Potts Laboratory have developed an animal model to probe such chronic risks, ones that might diminish lifespan or animal´s ability to win a mate.
In the experiment the Utah biologists began feeding during three months newly weaned, three-week old mice a diet of healthy chow to which they added sucrose or simple sugars. In a second experiment corn starch or simple sugars. They release animals, the equivalent one to five reproductive units integrated from 1 male and 2 female, with different exposures together within a semi-natural ecosystem. It´s a huge well-lit enclosure with a few mouse houses that offer dark seclusion. With this environment, the animals eat at will, mate at will, fight at will or do whatever coexisting communities of mice do. Electronic tags identify each rodent so that scientists can keep track of where mice eat or sleep. By means of the use of OPAs demonstrated dramatic fitness reductions due to a diet 25% calories coming from an equal ratio of fructose and glucose monosacharides. Animals feed on this diet compared to those raised on either a diet compose of SU (table sugar) or a sugar-free diet suffered increased mortality and decreased territorial ability. These data represent the lowest observed adverse effect level (LOAEL) recorded for dietary fructose and are the first experimental indication that diets containing fructose and glucose monosaccharide are more deleterious than those containing the disaccharide sucrose.
Female mice that have been reared on the unbound single sugars experienced high rates of mortality (to less than 50% of lifespan). Their death rate was about the triple that of table sugar treated females. The experiment was repeated five times, each time with the same result. What impaired female´s survival remains unidentified.
Reference
1. http://stormy.biology.utah.edu/PEOPLE/jimmy.htm(4/13/11)
2. http://www.sciencenews.org/view/generic/id/72741/title/Simple-sugar_effects_aren%E2%80%99t_necessarily_simple,_animal_study_suggests (4/13/11)
3. J.S. Ruff,… and W.K. Potts. Health consequences of a moderate fructose diet revealed by organismal performance assays. Abstract: 766.11. Experimental Biology 2011, April 11, Washington, D.C.
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