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Research has shown that eating fewer calories decreases the risk of heart disease. While there are also theories that calorie restriction can slow the effects of aging, none have yet been proven. Dr. Timothy Meyer and his colleagues (JACC. 2006; 47:398-401) looked at the question of what effect reducing calories might have on the heart by evaluating a group of 25 people who had been following a calorie restricted diet.
To test their theory the researchers matched the 25 study participants with 25 people who ate a traditional western diet. All of the study subjects were matched for age and gender. None had evidence of any chronic disease, took cholesterol or high blood pressure medication, or smoked. Ultrasound pictures were taken of their hearts to evaluate heart function and blood was drawn to look at specific inflammatory markers that are felt to be associated with heart disease.
The subjects recorded their food consumption for 7 days and the analysis showed that the calorie restricted group averaged 1,671 calories per day while those eating a western diet ate 2,445 calories per day. The nutritional breakdown of their diets is in the table below.
The scientists specifically looked at how well heart muscle is able to relax after each heart beat. Systole (sis toe lee) is the term used to describe when the heart squeezes to pump blood and diastole (die ass toe lee) is the relaxation of the heart when the chambers fill with blood. As we age, the ability of the heart to relax declines.
When the researchers evaluated the participant’s heart function they found no differences between the two groups in systolic function (how well the heart squeezes). There was, however, a greater decline in the group eating a western diet in the diastolic function (how well the heart muscle relaxes). Decline in diastolic function is associated with aging and the participants eating a calorie restricted diet had heart function similar to that of younger individuals.
In addition, the serum markers of inflammation were found to be significantly lower in the calorie restricted group. The researchers looked at three blood tests that they feel may contribute to the stiffness of the heart muscle. They theorize that the elevation of these in those eating a western diet group may be an explanation for the worsening diastolic function in that group.
One of the most interesting tables shows the vital statistics of 18 participants in the calorie restricted group before they began eating less food. Their weights, body mass index and blood pressure were significantly lower after following a reduced calorie diet. The researchers do consider that these factors may contribute to the slower decline in diastolic function and improvement in the levels of the inflammatory markers.
This is a small study and we do need a much larger one to reinforce these findings. There is a great deal of research to show that eating fewer calories leads to a longer and healthier life and this information may be a clue to some of the mechanisms of how a reduced calorie diet helps the body age slower.
February 13, 2006