单选题


{{B}} Mind Your Calories or Your Waistline?{{/B}}
Cutting back the calories may do more than whittle your waistline; it could protect your brain from the effects of aging. A new study suggests that calorie restriction can help slow the normal process of cell death that happens with age.
Researchers say the body naturally goes through a process known as apoptosis, or cell death, to destroy old cells so new ones can be made, and many factors can alter this process. Age-related diseases, such as Alzheimer's and Parkinson's, cause a higher-than-normal loss of cells in the brain, which can lead to loss of function.
Previous studies have suggested that calorie restriction can boost life span and mental capacity. That prompted researchers to look at whether cutting calories might also play a role in protecting aging brain cells. They compared levels of proteins indicating brain cell death in two groups of rats. One group was given unrestricted access to food and water throughout their lives. The other was given 40% fewer calories (but still adequate nourishment) than the unrestricted group.
They found that the levels of these proteins increased with normal aging in the rats fed unrestricted diets. The rats given a restricted diet did not have an increase in the levels of these proteins.
Another protein thought to protect from cell death dropped by 60% in the well-fed rats, but it actually increased over time in the calorie-restricted rats.
Finally, DNA fragmentation, a third indicator of cell death, more than doubled in the unrestricted rats with age, but this increase was 36% less in the calorie-restricted rats.
Although the results are promising, researchers say more study is needed to completely understand the processes that lead to cell death and the role nutrition plays in that process.
Meanwhile, they say, their study provides yet another reason to watch what you eat. "We're not going to do it right away to improve our memories; we're going to do it probably in general for the first reasons, which would be to prevent cardiovascular disease and cancer," says Christian Leeuwenburgh at the University of Florida.

单选题 The main purpose of these researchers is ______

单选题 The rats fed unrestricted diets do NOT ______

单选题 The result of the researches so far may help, as asserted by one of the researchers, ______

单选题 Which of the following statements is true, according to the passage?

单选题 What kind of benefits has been or will be brought to us as a result of the researches?