Arteriosclerosis (hardening of the arteries) occurs in 70% of heart transplant patients within three years after transplantation. A process called oxidative stress is believed to contribute to this accelerated development of arteriosclerosis among heart transplant patients. Researchers know, however, that certain compounds in the body called antioxidants can protect cells from oxidative stress.
Researchers from Brigham and Women’s Hospital in Boston and the Linus Pauling Institute at Oregon State University tested the hypothesis that antioxidants could reduce oxidative stress, and subsequently inhibit the development of arteriosclerosis in heart transplant patients. Their results, recently published in
, suggest that taking the antioxidant vitamins C and E after heart transplant surgery may help prevent transplant-induced arteriosclerosis.
About the study
Between February 1996 and November 1998, the researchers enrolled 40 heart transplant patients from Brigham and Women’s Hospital into this study. The starting point of the study varied for each patient. Patients entered into the study either a few weeks after their transplant or at their one-year or two-year exams.
Patients were excluded from this study if they had kidney problems, a greater than 50% narrowing of a coronary artery, or were unable to temporarily stop cardiac medications. They were also excluded if they were: participating in another clinical trial, not able to take vitamin C and E supplements or certain transplant medications, currently using vitamin C and E supplements greater than the amount present in multivitamins, taking the anticoagulant drug warfarin, deemed medically in need of retransplantation, or pregnant.
At the start of the study, each patient underwent coronary angiography and intravascular ultrasonography (IVUS). These tests visualize the inside of a coronary artery and allow doctors to measure plaque (fatty deposits) in that artery. The researchers then calculated the intimal index—a measure of arteriosclerosis, which is calculated as the area of plaque divided by the area of the blood vessel.
Patients were assigned to take either supplements of vitamins C (500 mg each) and E (400 international units each) or a placebo (inactive) pill twice daily. At their regular doctor visits throughout the year, patients’ blood was tested to make sure they were taking their supplements. All patients took the lipid-lowering drug pravastatin (Pravachol) and their usual heart transplant medications.
After one year of taking the vitamin supplements, researchers again measured the plaque in the same coronary artery and calculated the intimal index. Finally, they compared the average intimal index among patients taking vitamin supplements with the average intimal index among those taking placebo.
During the one-year study, the intimal index increased by 8% in the placebo group, but increased by only 0.8% in the vitamin group. This means that the amount of plaque did not increase significantly in the people taking vitamin C and E supplements, but it did increase among those not taking the supplements.
Researchers also measured the amount of vitamins C and E in participants’ blood. As expected, the levels of these vitamins rose significantly in those who took vitamin supplements, but did not change appreciably in those taking placebo.
Although these results are interesting, there are some limitations to this study. The study sample was quite small, containing only 40 people. However, studies of heart transplant patients tend to be small due to the relatively small number of heart transplant patients. In addition, the study focused on treating patients zero to two years after transplantation. Though this is the time when intimal thickening happens most rapidly, more research is needed to determine whether the beneficial effects of vitamin C and E supplementation are sustained over many years. Finally, though participants did complete questionnaires about their dietary habits (which could affect plaque build-up), the accuracy of self-reporting can be limited. And, this study focused only on vitamins C and E in supplement form. Therefore it is not clear how vitamins C and E in the diet affect plaque build-up in the arteries of heart transplant patients.
How does this affect you?
Does this mean that heart transplant patients should be taking vitamin C and E supplements? Possibly. This study offers some promising evidence that these vitamins help reduce the amount of plaque build-up in the coronary arteries of heart transplant patients.
If you have had a heart transplant or will be having one, talk to your doctor about the possibility of taking vitamin C and E supplements as part of your post-transplant treatment. Although vitamin supplements are available without a prescription, you should speak with your doctor before taking any supplements or non-prescription medications. Heart transplant patients have many complex medical concerns that need to be assessed before starting any new therapies.
Fang JC, et al. Effect of vitamins C and E on progression of transplant-associated arteriosclerosis: a randomised trial.
. March 30, 2002;359:1108-1113.
Please be aware that this information is provided to supplement the care
provided by your physician. It is neither intended nor implied to be a
substitute for professional medical advice. CALL YOUR HEALTHCARE PROVIDER
IMMEDIATELY IF YOU THINK YOU MAY HAVE A MEDICAL EMERGENCY. Always seek the
advice of your physician or other qualified health provider prior to
starting any new treatment or with any questions you may have regarding a