The International Journal of Cardiology published results from a trial showing improved recovery after a heart attack using Vitamin C, or ascorbic acid. Patients who suffer a serious myocardial infarction (MI) often do not recover to pre-heart attack state. Their heart often underfunctions and does not respond well to stress or increased demand, such as that from exercise.
Most doctors and scientists believe the heart functions sub-optimally because of a weakness of the sympathetic nervous system, which controls both heart rate and blood pressure. The heart responds to adrenalin, or epinephrine, the main hormone of the sympathetic nervous system by increasing the rate at which it beats. And the blood vessels respond by constriction and therefore cause an increase in blood pressure.
After an MI patients' hearts tend to respond less to epinephrine, and heart rate does not increase adequately, even though it is needed. This is often evident during exercise, when an elevated heart rate is expected to provide increased oxygen to muscles. After a heart attack many patients will state they fatigue or tire earlier than before, and often cannot participate in an exercise program because of poor heart function.
There had been evidence that antioxidants could help reverse this effect post-MI. So researchers at Nippon Medical School in Tokyo Japan enrolled 21 men who had an MI one month prior into a study that measured the effects of daily Vitamin C intake on heart muscle response to exercise. Special exercise testing was conducted in each man, once after taking 2000 mg of Vitamin C and once without. The primary outcomes were heart rate, change in heart rate from resting to peak exercise performance, blood pressure, and oxygen consumption.
They found that the hearts of men who took Vitamin C responded more adequately to exercise than those who did not take Vitamin C. This was observed by an greater increase in heart rate after Vitamin C compared to after nothing. As well the change from resting to peak was greater in Vitamin C group. Blood pressure did not differ between the two groups. Oxygen consumption was improved in the Vitamin C group.
The researchers felt positive about the results and believe that Vitamin C improves recovery and increases sympathetic response to exercise in heart muscle. This effect could be due to antioxidant scavenging of free radicals and lack of oxidative stress on the heart muscle, but the authors did not elaborate on the possible mechanism.
They called for more studies to determine long term benefit and also to test the effect of other antioxidants on the same dysfunction.
Posted by Dr. Christina Gutierrez on September 14, 2006 02:12 PM
