Curbing calories might help your heart stay young longer, new research shows.

Scientists recently compared the hearts and calories of two groups of people. People in one group ate typical Western diets, totaling about 2,445 daily calories.

The other group included people who willingly ate low-calorie diets and had done so for three to 15 years. They consumed about 1,671 calories per day.

As people age, the heart muscle can get stiffer, which can affect the heart chambers’ ability to fill with blood, called diastolic function.

The low-calorie group showed several heart advantages: lower blood pressure, less inflammation, and better diastolic function.

Calorie restriction may slow the heart’s aging, write the researchers. They included Timothy Meyer, PhD, and Luigi Fontana, MD, PhD, of Washington University School of Medicine’s geriatrics and human nutrition division.

The study appears in the Journal of the American College of Cardiology.

Cut Calories, Live Longer?

“This is the first report ever to show that calorie restriction with optimal nutrition may delay primary aging in humans,” Fontana says in a news release.

“Eating less, if it is a high-quality diet, will improve your health, delay aging, and increase your chance of living a long, healthy, and happy life,” he says.

Calorie restriction has been tied to longevity in animals including mice. People have been harder to study, since many people won’t curb calories for a long time.

Not all scientists agree that calorie restriction boosts longevity in humans. In August 2005, a team of researchers concluded that the payoff, in terms of human longevity, wasn’t worth it.

Fontanaand colleagues aren’t recommending calorie restriction.

“If you change the quality of your diet by increasing the servings of nutrient-dense food and reducing -- actually, it would be better to slowly eliminate -- all of the servings of ‘empty’ calorie foods, you improve your chances of living a healthier and longer life,” Fontana says.

Heart Check

Meyer and Fontana didn’t ask anyone to change their eating habits. Instead, they studied 25 people who had chosen to practice calorie restriction and 25 people who ate typical Western fare.

All participants were nonsmokers with no chronic medical diseases. Their weight hadn’t changed in at least six months. None exercised vigorously more than twice weekly.

Participants wrote down what they ate and drank. They also gave blood samples, got their blood pressure checked, and got echocardiograms of their hearts. The echocardiogram gives information about heart chamber size, heart valves, and the heart’s filling and pumping ability.

Those practicing calorie restriction consumed less salt and fat and were leaner than those who ate typical Western foods. Here are the two groups’ average BMIs (body mass index):

--Calorie-restriction group: 19.7 (lower end of normal)

--Comparison group: 27 (overweight but not obese)

Key Findings

The calorie-restriction group had lower blood levels of chemicals tied to inflammation. Blood pressure and heart flexibility might benefit as a result, the researchers write.

That finding might be the most important part of the study, states a journal editorial.

The researchers should be “congratulated” for their study, writes editorialist Gary Gerstenblith, MD, FACC. He adds that it’s not likely that many people would restrict calories for a long time.

Gerstenblith works in Baltimore at Johns Hopkins Hospital. He wasn’t involved in Fontana’s study.

Like other muscles, the heart works better when it’s flexible. That flexibility fades with age, making it harder to pump blood through the heart.

Flexible Heart, Youthful Heart

Picture yourself in the heart’s upper left chamber, the left atrium. You’ve got oxygen-rich blood pouring in from the lungs, and the entire body demanding that blood. “We’ve gotta have it,” cry the brain, muscles, stomach, skin, and the rest of the body.

Not so fast. First, you’ve got to push that blood through a valve down into the heart’s lower left chamber, the left ventricle. Then the blood has to be pumped by the left ventricle to reach the rest of the body.

Now, imagine that the heart isn’t what it used to be. If the heart chamber’s walls are stiffer, then doing its job will be a lot harder.

Preserving that elasticity would have been a hedge against aging for the heart. In short, less stiff hearts act younger, no matter how old the calendar says they are.

Nutrition Counts, Too

Participants practicing calorie restriction didn’t ditch good nutrition. They got at least 100 percent of recommended vitamins and minerals, the researchers note.

The calorie-restriction group essentially followed a traditional Mediterranean diet, with whole grains, beans, fish, fruit, olive oil, and many kinds of veggies, according to Fontana.

“Calorie restriction is associated with longevity only when it is coupled with optimal nutrition,” Fontana says in the news release.

He continues, “Calorie restriction coupled with malnutrition accelerates aging and causes severe diseases. Therefore, eating half a hamburger, half a bag of French fries, and half a can of soft drink is not healthy caloric restriction and is harmful.”

By Miranda Hitti, reviewed by Louise Chang, MD

SOURCES: Meyer, T. Journal of the American College of Cardiology, Jan. 17, 2006; vol 47: pp 398-402. News release, American College of Cardiology. WebMD Medical News: “Extremely Low-Calorie Diet Won’t Extend Life.” WebMD Medical Reference from Healthwise: “How the Heart Works.” News release, Washington University School of Medicine. Gerstenblith, Journal of the American College of Cardiology, Jan. 17, 2006; vol 47: pp 403-404. Associated Press.