2011年7月25日星期一

Diet soda may contribute to weight gain and diabetes

Diet sodas and artificial sweeteners may not be the healthy alternatives to their regular counterparts that many people believe them to be. Two new studies out of the University of Texas Health Science Center in San Antonio suggest quite the contrary: artificial sweeteners may promote increased waistlines and insulin resistance.
One study focused on a population of elderly people, while a related study focused on the long-term impact of aspartame in mice.
The team first assessed data from 474 elderly Mexican Americans and European Americans. Diet soft drink users, as a group, experienced 70 per cent greater increases in waist circumference compared with non-users. Frequent users, who said they consumed two or more diet sodas a day, experienced waist circumference increases that were 500 per cent greater than those of non-users.
In the related project, researchers studied the relationship between oral exposure to aspartame and fasting glucose and insulin levels in 40 diabetes-prone mice. The mice in the aspartame group showed elevated fasting glucose levels but equal or diminished insulin levels, consistent with early declines in pancreatic beta-cell function.
Study researcher Gabriel Fernandes, professor of rheumatology and clinical immunology at the university, said that aspartame use might directly contribute to elevated glucose levels and thus the risk for Type 2 diabetes.
The two studies contribute to an interesting and on-going debate about the advisability of quaffing diet soda. Many individuals who are attempting to limit their calorie consumption opt for diet soft drinks because they provide zero calories. On paper, at least, diet soda appears to be as harmless as drinking water. Healthy-eating advocates have long maintained that diet sodas are not harmless, however, because they contain synthetic sweeteners with dubious biochemical properties.
No one has definitively proven that artificial sweeteners directly damage human tissue, but these studies may point out an altogether different harm vector. Unlike water, diet soda tastes quite sweet. When we consume a diet soft drink, our taste buds are sending a message to the brain which essentially says, “I am now ingesting sugary food.” The brain then signals the pancreas to release insulin in anticipation of the sugar being introduced into the body. However, the sugar never materializes, leading to an overproduction of insulin. Over time, chronic use of diet soda may thus lead to an exhausted pancreas and body cells which have been conditioned to be insulin-resistant – two hallmarks of Type 2 diabetes.
The studies were presented Saturday, June 25, at the meeting of the American Diabetes Association.
http://www.emaxhealth.com/6705/diet-soda-may-contribute-weight-gain-and-diabetes

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