Scientists at Washington University School of Medicine in the US studied 42 people with an average age of just over 51 years. Twenty-two of the participants had eaten a healthy but calorie-restricted diet for an average of seven years, providing 30 per cent fewer calories than normal. The remaining 20 participants followed a standard western diet.
The researchers used portable heart monitors to measure patients' heart rate variability - a key measure of the organ's ability to adapt to exercise, stress, sleep and other factors. They found that people on the calorie-restricted diet had much greater heart rate variability than those on the standard diet. In addition, they tended to have significantly lower heart rates, which is an indicator of a healthy cardiovascular system. Overall, these individuals had hearts that functioned more like those found in healthy people who are 20 years younger.
Lead study author Dr Phyllis Stein, a research associate professor of medicine in the university's cardiology division, said: "Higher heart rate variability means the heart can adjust to changing needs more readily. Heart rate variability declines with age as our cardiovascular systems become less flexible, and poor heart rate variability is associated with a higher risk of cardiovascular death."
However the researcher, whose findings are published in the journal Aging Cell, conceded that the improvements seen in participants' cardiovascular health may not solely be down to their calorie-restricted diets. She observed that people who follow this type of diet plan "tend to be very healthy in other areas of life too ... [and] tend to engage in a large number of very healthy behaviours".
These might include avoiding too much saturated fat, taking part in physical activity on a regular basis and not smoking.