January 13, 2006 - 5:20pm
People who follow a low-calorie, high-nutrition diet are among the young at heart, a new study from Washington University shows.
Caloric restriction, as the diet is known, has been shown to increase the life span of a variety of animals, including dogs, mice, rats and even creatures such as yeast. But no one knew whether severely cutting back on calories would have the same effect on humans.
This new study, which compared people who voluntarily followed calorie-restricted diets with healthy people who ate average diets, showed that the low-cal group had hearts that worked as well as those of people 10 to 15 years younger. It is the first clear evidence that calorie restriction is associated with delayed aging in humans, the study's authors say.
The study, led by Dr. Luigi Fontana of Washington University and the Instituto Superiore di Santi in Rome, Italy, will appear Tuesday in the Journal of American College of Cardiology.
Fontana and his colleagues measured heart function in 25 people on the calorie-restricted diet and 25 healthy people of average weight who ate a standard diet. None of the study participants exercised more than 20 minutes twice a week. The restrictive dieters ate fruits, vegetables, whole grains, beans, lean proteins, nuts and other foods for optimum nutritional value. They consumed 1,400 to 2,000 calories per day - about 25 percent fewer calories than an average American.
"It's not that draconian," said Joseph Cordell, 47, a divorce lawyer who started calorie restriction four years ago. Cordell eats about 1,850 calories a day.
He started the regimen after becoming dissatisfied with the "mediocre success" he had in improving his health with exercise. Since he started following the lower-calorie diet, Cordell says, his blood pressure, cholesterol and pulse rate have all dropped substantially. And the new study shows that he has "the heart of a 10-year-old," he said.
The researchers saw a marked change in the diastolic heart function of the calorie-restricted group over their peers.
During the diastolic phase, the left ventricle fills up with blood in a two-step process. During the first step, the ventricle relaxes and blood flows in, filling the chamber about 80 percent full in young people. In the second phase, the atrium contracts to top off the ventricle. Once full, the ventricle pumps the blood into the body.
As people age, their hearts become less elastic. That means that less blood gets in during the passive filling phase and the atrium must work harder and pump in more blood as it contracts. The decline in diastolic heart function is a good measure of aging, Fontana said.
People on the restrictive, nutritious diets filled their ventricles with more blood during the passive filling phase than the average eaters did. The low-cal dieters have been on the diet for an average of only six years, but their hearts appeared as much as 15 years younger. That could mean the diet reverses aging, Fontana said.
The CRONies, as the people on Calorie Restriction-Optimal Nutrition diets call themselves, also had lower levels of two proteins involved in inflammation, as well as lower levels of a protein involved in depositing collagen and scar tissue in wounded or inflamed tissue. That is important because it could indicate that restricted-calorie diets help prevent the heart from losing elasticity as people age and protect them from damaging inflammation.
The difference between the two groups was not attributable to genetics, Fontana said. People in both groups had family histories of heart disease, and some of the people in the calorie-restriction group had previously taken medications to lower blood pressure or cholesterol. Those problems improved once the people started calorie restriction.
"These people are not genetically lucky," Fontana said.
He also cautioned that simply cutting calories is not enough to improve health. Low-calorie diets that don't provide optimal nutrition may actually speed up aging and be dangerous, he said. But avoiding weight gain and improving the diet by eating fresh fruits and vegetables, whole grains, fish, nuts and beans also could improve overall health for average people, Fontana said.
(c) 2006, St. Louis Post-Dispatch. Distributed by Knight Ridder/Tribune News Service.