Live longer with fewer calories

By consuming fewer calories, ageing can be slowed down and the development of age-related diseases such as cancer and type 2 diabetes can be delayed. The earlier calorie intake is reduced, the greater the effect. Researchers at the University of Gothenburg have now identified one of the enzymes that hold the key to the ageing process. 

"We are able to show that caloric restriction slows down ageing by preventing an enzyme, peroxiredoxin, from being inactivated. This enzyme is also extremely important in counteracting damage to our genetic material," says Mikael Molin of the Department of Cell and Molecular Biology. 

By gradually reducing the intake of sugar and proteins, without reducing vitamins and minerals, researchers have previously shown that monkeys can live several years longer than expected. The method has also been tested on everything from fishes and rats to fungi, flies and yeasts with favourable results. Caloric restriction also has favourable effects on our health and delays the development of age-related diseases. Despite this, researchers in the field have found it difficult to explain exactly how caloric restriction produces these favourable effects. 

Using yeast cells as a model, the research team at the University of Gothenburg has successfully identified one of the enzymes required. They are able to show that active peroxiredoxin 1, Prx1, an enzyme that breaks down harmful hydrogen peroxide in the cells, is required for caloric restriction to work effectively.  

The results, which have been published in the scientific journal Molecular Cell, show that Prx1 is damaged during ageing and loses its activity. Caloric restriction counteracts this by increasing the production of another enzyme, Srx1, which repairs Prx1. Interestingly, the study also shows that ageing can be delayed without caloric restriction by only increasing the quantity of Srx1 in the cell. Repair of the peroxiredoxin Prx1 consequently emerges as a key process in ageing. 

"Impaired Prx1 function leads to various types of genetic defects and cancer. Conversely, we can now speculate whether increased repair of Prx1 during ageing can counteract, or at least delay, the development of cancer." 

Peroxiredoxins have also been shown to be capable of preventing proteins from being damaged and aggregating, a process that has been linked to several age-related disorders affecting the nervous system, such as Alzheimer's and Parkinson's. The researchers are accordingly also considering whether stimulation of Prx1 can reduce and delay such disease processes. 

Source: University of Gothenburg [October 31, 2011]

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The 'Freshman 15' is just a myth

Contrary to popular belief, most college students don’t gain anywhere near 15 pounds during their freshman year, according to a new nationwide study. 

Rather than adding “the freshman 15,” as it is commonly called, the average student gains between about 2.5 and 3.5 pounds during the first year of college. 

And college has little to do with the weight gain, the study revealed.  The typical freshman only gains about a half-pound more than a same-age person who didn’t go to college. 

“The ‘freshman 15’ is a media myth,” said Jay Zagorsky, co-author of the study and research scientist at Ohio State University’s Center for Human Resource Research. 

“Most students don’t gain large amounts of weight.  And it is not college that leads to weight gain – it is becoming a young adult.” 

The results suggest that media reporting of the freshman 15 myth may have serious implications. 

“Repeated use of the phrase ‘the freshman 15,’ even if it is being used just as a catchy, alliterative figure of speech, may contribute to the perception of being overweight, especially among young women,” Zagorsky said. 

“Weight gain should not be a primary concern for students going off to college.” 

Zagorsky conducted the study with Patricia Smith of the University of Michigan-Dearborn.  The study will appear in the December 2011 issue of the journal Social Science Quarterly. 

The study uses data from 7,418 young people from around the country who participated in the National Longitudinal Survey of Youth 1997.  The NLSY97 interviewed people between the ages of 13 and 17 in 1997 and then interviewed the same people each year since then.  The NLSY is conducted by Ohio State’s Center for Human Resource Research for the U.S. Bureau of Labor Statistics. 

Among many other questions, respondents were asked their weight and college status each year. 

Other studies have shown that college students tend to underestimate their weight by half a pound to 3 pounds.  But if people are consistent in underestimating their weight from year to year, it would not impact these results, Zagorsky said. 

The study found that women gained an average of 2.4 pounds during their freshman year, while men gained an average of 3.4 pounds. No more than 10 percent of college freshman gained 15 pounds or more -- and a quarter of freshman reported actually losing weight during their first year. 

“It’s worth noting that while there’s this focus on weight gain among freshman, we found that one in four actually lost weight,” Zagorsky said. 

The researchers examined a variety of factors that may be associated with freshman weight gain, including whether they lived in a dormitory, went to school full or part time, pursued a two-year or four-year degree, went to a private or public institution, or was a heavy drinker of alcohol (consuming six or more drinks on at least four days per month.) 

None of these factors made a significant difference on weight gain, except for heavy drinking.  Even then, those who were heavy drinkers gained less than a pound more than students who did not drink at that level. 

Zagorsky said it was particularly significant that dorm living did not add to weight gain, since one hypothesis has been that the dorm environment encourages weight gain during the freshman year. 

“There has been concern that access to all-you-can-eat cafeterias and abundant fast food choices, with no parental oversight, may lead to weight gain, but that doesn’t seem to hold true for most students,” he said. 

The results do show, however, that college students do gain weight steadily over their college years. 

The typical woman gains between seven and nine pounds, while men gain between 12 and 13 pounds. 

“Not only is there not a ‘freshman 15,’ there doesn’t appear to be even a ‘college 15’ for most students,” Zagorsky said. 

Over the course of the entire college career, students who both worked and attended college gained an extra one-fifth of a pound for each month they worked. 

The researchers also examined what happened to college students’ weight after they graduated.  They found that in the first four years after college, the typical respondent gained another 1.5 pounds per year. 

“College students don’t face an elevated risk of obesity because they gain a large amount of weight during their freshman year,” Zagorsky said. 

“Instead, they have moderate but steady weight gain throughout early adulthood.  Anyone who gains 1.5 pounds every year will become obese over time, no matter their initial weight.” 

Although most students don’t need to worry about large weight gains their freshman year, Zagorsky said they still should focus on a healthy lifestyle. 

“Students should begin developing the habit of eating healthy foods and exercising regularly.  Those habits will help them throughout their lives.” 

Author: Jeff Grabmeier | Source: Ohio State University [October 31, 2011]

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Do deficits in brain cannabinoids contribute to eating disorders?

A new report in Biological Psychiatry suggests that deficits in endocannabinoid function may contribute to anorexia nervosa and bulimia. Endocannabinoids are substances made by the brain that affect brain function and chemistry in ways that resemble the effects of cannabis derivatives, including marijuana and hashish. These commonly abused drugs are well known to increase appetite, i.e. to cause the “munchies”. Thus, it makes sense that deficits in this brain system would be associated with reduced appetite. 

Researchers measured the status of the endocannabinoid system indirectly by determining whether there was an increase or decrease in the density of endocannabinoid receptors, called the CB1 receptor, in several brain regions using positron emission tomography, or PET, imaging. They compared these densities in women with anorexia or bulimia with those of healthy women. 

They found global increases in ligand binding to CB1 receptors in the brains of women with anorexia nervosa. This finding is consistent with a compensatory process engaged by deficits in endocannabinoid levels or reduced CB1 receptor function. 

CB1R availability was also increased in the insula in both anorexia and bulimia patients. The insula “is a region that integrates body perception, gustatory information, reward and emotion, functions known to be disturbed in these patients,” explained Dr. Koen Van Laere, the study’s lead author. 

“The role of endocannabinoids in appetite control is clearly important. These new data point to important connections between this system and eating disorders,” added Dr. John Krystal, Editor of Biological Psychiatry. 

Additional research is now needed to establish whether the observed changes are caused by the disease or whether these are neurochemical alterations that serve as risk factors for developing an eating disorder. 

Furthermore, since very few effective treatments exist for these disorders, these data indicate that the endocannabinoid system may be a potential new target for developing drugs to treat eating disorders. Such new therapies are currently being investigated in animal models. 

Source: Elsevier [October 31, 2011]

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