KATHMANDU — Putting just a bit less on your dinner plate each day reducing caloric intake might be key to a longer life, a preliminary research has suggested.
According to a small clinical trial, people who reduced their caloric intake by just 15 percent over two years experienced a significant decrease in their metabolism.
These people also saw improvements in biomarkers associated with slower aging and longer life span, said lead researcher Leanne Redman, an associate professor of clinical sciences at Pennington Biomedical Research in Baton Rouge, La.
For the study published March 22 in the journal Cell Metabolism, Redman’s team recruited 34 healthy people with an average age of 40 to follow a calorie-restricted diet for two years.
The researchers found that the participants developed a lower core body temperature, lower blood sugar and insulin levels, and significant drops in hormones that moderate metabolism.
“We know these things are lower in people who live longer lives,” Redman said.
Researchers taught the study participants how to cut 25 percent of their daily caloric intake using three different models of a healthy diet, Redman said.
The participants then were free to follow their diet by any means they chose.
“On their own, they achieved a 15 percent reduction in calorie intake that was sustained for the two years, which is pretty remarkable,” Redman said.
On average, the group lost about 20 pounds, mostly in the first year, even though half entered the study at normal weight and the rest were only modestly overweight, Redman said.
Aging studies in animals have tied lower calorie intake to longer lives, but this is the first clinical trial to bridge the gap between animals and humans, said Rozalyn Anderson, an expert with the American Federation for Aging Research who reviewed the findings.
“So much of what they’re reporting is entirely consistent with what we’ve seen in our monkey studies,” said Anderson, an associate professor who studies aging and calorie restriction at the University of Wisconsin School of Medicine and Public Health.
“We’ve got a match between the monkeys and the humans, and that’s absolutely brilliant. This is a really neat gap to have closed in terms of aging biology,” she said.
The researchers said this offers support to controversial theories linking high metabolism and increased oxidative stress to faster aging.
“When we make energy, we have byproducts of metabolism, and these byproducts called oxygen radicals accumulate in the body and cause damage to cells and tissues,” Redman said. Such damage can cause cells to age faster and contribute to diseases like cancer.
Anderson isn’t so sure that’s the best explanation. She noted that lab studies in mice have shown that damage done by oxidative stress has no effect on overall life span.
Anderson thinks lower calorie intake prompts the body to use energy more efficiently, and that somehow results in benefits for aging.
“We know, for example, there’s a really tight connection that we don’t understand between fasting and resilience — the ability to stand up against distress,” Anderson said.
People who want to try to eat less in an attempt to live longer should focus on portion size while following a healthy and well-balanced diet, Redman said.
They should aim for lowering calorie intake by 25 percent, with the understanding that they will probably fall short of the goal, Redman said. They shouldn’t be discouraged if they don’t keep losing weight long-term.
“The goal is not to lose weight. The goal is to have this sustained lower intake,” Redman said.
Regular physical activity may reduce heart attack risk even in highly polluted areas
Regular physical activity may reduce the risk of heart attack, even in areas with moderate-to-high levels of traffic pollution, a study has claimed.
Higher levels of pollution were associated with more heart attacks, however, the risk was lower among those who were physically active, the researchers found in the study published in the Journal of the American Heart.
“While exercise is known to reduce cardiovascular disease risk; pollution can increase the risk of cardiovascular disease, including heart attacks, asthma and chronic obstructive lung disease,” said lead author Nadine Kubesch from the University of Copenhagen in Denmark.
“Currently there is little data on whether poor air quality cancels out the protective benefits of physical activity in preventing heart attacks,” Kubesch added.
Researchers in Denmark, Germany and Spain evaluated outdoor physical activity levels (sports, cycling, walking and gardening) and nitrogen dioxide (NO2 pollutant generated by traffic) exposure in 51,868 adults, aged 50-65.
Over a 17.7-year period, there were 2,936 first heart attacks and 324 recurrent heart attacks.
Moderate cycling for four or more hours per week cut risk for recurrent heart attack by 31 per cent; and there was a 58 per cent reduction when all four types of physical activity (together totalling four hours per week or more) were combined, regardless of air quality.
Those who participated in sports had a 15 per cent lower rate of initial heart attacks and there was a 9 per cent risk reduction associated with cycling, regardless of air quality, the researchers said.
Compared to participants with low residential NO2 exposure, those in higher risk areas had a 17 per cent increase risk in first heart attack and 39 per cent for recurrent heart attack, the researchers noted.
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