Fructose changes brain to cause overeating, scientists say
Fructose, a common sugar found in the U.S. diet, may cause changes in the brain that trigger a person to overeat, a new brain imaging study shows.
After drinking a fructose beverage, the brain doesn't register the same feeling of being full as it does when simple glucose is consumed, scientists found.
From fructose to fat
All sugars are not equal -- even though they contain the same amount of calories -- because they are metabolized differently in the body. Table sugar is sucrose, which consists of half fructose, half glucose. High-fructose corn syrup is 55 percent fructose and 45 percent glucose. Some nutrition experts say this sweetener may pose special risks, but others and the industry reject that claim. And doctors say we eat too much sugar in all forms.
For the small study, published Jan. 2 in the Journal of the American Medical Association (JAMA), scientists used magnetic resonance imaging, or MRI, scans to track blood flow in the brain in 20 young, normal-weight people before and after they had drinks containing glucose or fructose in two sessions spaced several weeks apart.
Is sugar toxic?
The brain scans showed that drinking glucose "turns off or suppresses the activity of areas of the brain that are critical for reward and desire for food," said one study leader, Dr. Robert Sherwin, chief of endocrinology at Yale University School of Medicine in New Haven, Conn.
With fructose, "we don't see those changes," he said. "As a result, the desire to eat continues -- it isn't turned off."
The researchers saw these changes in the hypothalamus, insula, and striatum, which are regions of the brain that regulate appetite, motivation, and reward processing, in addition to increasing connections in certain brain pathways linked to satiety.
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It's a small study and does not prove that fructose or its relative, high-fructose corn syrup, can cause obesity, but experts say it adds evidence they may play a role. These sugars often are added to processed foods and beverages, and consumption has risen dramatically since the 1970s along with obesity. A third of U.S. children and teens and more than two-thirds of adults are obese or overweight.
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What's convincing, said Dr. Jonathan Purnell, an endocrinologist at Oregon Health & Science University, is that the imaging results mirrored how hungry the people said they felt, as well as what earlier studies found in animals.
"It implies that fructose, at least with regards to promoting food intake and weight gain, is a bad actor compared to glucose," said Purnell. He wrote an accompanying commentary to the study that also appears in JAMA.
Researchers now are testing obese people to see if they react the same way to fructose and glucose as the normal-weight people in this study did.
Purnell said that people should cook more at home and limit processed foods containing fructose and high-fructose corn syrup. "Try to avoid the sugar-sweetened beverages," he said. "It doesn't mean you can't ever have them," but control their size and how often they are consumed, he added.
Industry trade groups contacted by CBSNews.com downplayed the study's significance.
"These findings should be kept in perspective: The researchers gave 20 adults a beverage sweetened with either fructose or glucose - neithe
r of which are found alone in any sweetened beverage," the American Beverage Association said in an emailed statement to CBS News. "In fact, the authors themselves note that the study is exploratory and has limitations."
"What we really need are real world studies where fructose and glucose are consumed together rather than artificial ones where fructose and glucose are consumed separately," added Dr. James Rippe, a professor of biomedical sciences at the University of Central Florida, who is a consultant to the Corn Refiners Association, in an emailed statement. "Any suggestion that this artificial experiment has implications for human nutrition or obesity is unwarranted speculation."
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Considering that HFCS and sucrose actually contain (almost) equal amounts of glucose and fructose - it is a little hard to extrapolate this study, even if there was differences in the actual physical outcomes. Also consider the serving sizes used, 75g of glucose would require drinking 150g of sucrose or slightly less HFCS (we also don't know if there would be any effect in solid vs liquid food)
A little early to take anything from a study that really only showed changes in blood flow but NOT in actual measures of hunger, fullness and satiety!
How much longer are they going to allow Aspartame in our food and drinks? The proof has been in on that wonderful little "additive" for a long time and yet the FDA still allows that to be used. This is another example why less regulation isn't always good. We as a country used to regulate things that affected our food supply and our air/water quality for a reason. It's a shame that we value Wall St's profitability more than we do the food we eat and the air we breathe.
This small experiment suggests that fructose does not reduce hunger like glucose does, but high-fructose corn syrup has almost the samepercentage of fructose as regular sugar. So is there a noticeable difference? Probably best to avoid both.
1. Food is digested down to molecules before entering our blood. This means your cells don't distinguish between fructose derived from sucrose, high fructose corn syrup, agave or an apple.
2. It is fructose molecules that make high fructose corn syrup unhealthy.
3. It is fructose molecules that make sucrose (cane & beet sugar) unhealthy
4. It is fructose molecules in fruit (about 25-50% by dry weight of part we eat) that make whole fruit at best a special treat to eat sparingly.
5. All the essential nutrients in fruits (such as potassium, vitamin-C etc.) and most phytochemicals that can have therapeutic effects can also be obtained in safer and less expensive foods.
6. Why worry about a little fructose in a meal? A little fructose changes liver enzymes to turn more of any carbohydrate, not just fructose into fatty acids (triglycerides). As a result, even after eating sufficient calories, you are still hungry.
7. We don't need to eat any fructose. Cells do need fructose for making genetic material when they replicate. Gut lining cells replicate every three days cells that line blood vessels replicate every 5 years so not much fructose is needed. So where do cells get fructose if we don't eat it?
8. When cells need fructose to replicate they make only what is needed from glucose. This is nice example of a "just in time supply system" which is ideal when you don't want a reactive chemical which is 7 times more reactive than glucose sitting around. Even glucose is reactive but the body has safe storage (glycogen) and elaborate control system to keep blood glucose as low as possible without creating problems.
9. High blood glucose as seen in diabetes is unhealthy because it creates an excess of fructose in cells. High blood glucose pushes the sorbitol pathway to form excess fructose in all cells. So the bad effects of diabetes are really caused by elevated fructose in cells.
10. So why is excess fructose in a cell a problem? It forms glyceraldehyde. Glyceraldehyde is the most reactive sugar in the body. Glyceraldehyde can react directly with cell messengers and nuclear material. Glyceraldehyde is a small molecule and can leave the cell and reacts with lysine in blood to form a toxic advanced glycation end product or TAGE. TAGE is recognized by our innate immune system as a foreign molecule that via RAGE receptors causes cell INFLAMMATION. TAGE also increases VegF. VegF is involved in over 60 chronic diseases. The bottom line... Fructose (from diet or elevated blood glucose) via effects of glyceraldehyde, TAGE, RAGE and VegF increases by 10 to 20 fold the expression of many noninfectious diseases.
John E Weaver MD
Sugar is Sugar.... (LOL)
Basically companies not meeting industry requirements can be denied the money. This has the effect of removing any competing industry that does things a little differently, such as not using high fructose. Those industries often are unable to compete and their products promptly removed from store shelves. And oh.... most if not all of the studies into fructose were funded by the very industries promoting it's use. Kinda hard to take anything publish by Coca-Cola seriously when they stand so much to gain by promoting fructose addiction. Its not like these industries have to pay the tab when their customers require medical care later on in life.