The research team, led by Dr. Andrew Levy of the Faculty of Medicine, had earlier demonstrated that diabetics with a particular form of a blood protein called haptoglobin had as much as a 500% increased risk of developing heart disease. The new study shows that when these at-risk patients, who have the 2-2 form of haptoglobin, took 400 international units of vitamin E daily, they reduced their risk of heart attack by 43 percent, and their risk of dying of heart disease by 55 percent.
About 40% of diabetics have the 2-2 form of haptoglobin; the rest have the 1 -1 or 2-1 forms. When they took the same vitamin E supplements, they did not show any significant reduction of cardiovascular risk resulting from vitamin E therapy.
Dr. Levy's study analyzed serum samples that had been stored from the Heart Outcomes Prevention Evaluation (HOPE) trial of 2000, designed to study the effect of antioxidant therapy such as vitamin E on cardiovascular risk. The results of that study showed no benefit from vitamin E therapy on cardiovascular risk. However, Dr. Levy notes, the study did not segregate patients according to their haptoglobin type, analyzing instead the benefits of vitamin E in all patients. When he studied the serum samples from the HOPE study according to haptoglobin type, he found the greatly reduced risks noted above.
Now, a large-scale, five-year study of some 2,000 diabetics with haptoglobin 2-2, being conducted in northern Israel, is expected to corroborate Dr. Levy's findings.
"If this larger study confirms our findings, the public health implications will be huge. Vitamin E would represent an inexpensive and safe way to reduce the risk of cardiovascular death and heart attack in a significant proportion of diabetic patients," he said.
Dr. Levy had demonstrated in multiple previous studies that haptoglobin 2-2 is predictive of heart disease -- but only in people with diabetes. That's because diabetics tend to have more free radicals that destroy antioxidants. Furthermore, haptoglobin 2-2 is a very poor antioxidant when compared to the other haptoglobin types. This combination means that diabetics with haptoglobin 2-2 have an even greater deficiency of antioxidants than do diabetics with the other haptoglobin variants. Therefore, an increased supply of antioxidants, such as those found in vitamin E, would be expected to provide the greatest benefit for these patients.
The Technion-Israel Institute of Technology and the Kennedy-Leigh Charitable Trust is funding the new study. Dr. Levy is partial owner of a patent for a blood test that predicts susceptibility to diabetic vascular disease based on haptoglobin type.
The Technion-Israel Institute of Technology is Israel's leading science and technology university. Home to the country's only winners of the Nobel Prize in science, it commands a worldwide reputation for its pioneering work in computer science, biotechnology, water-resource management, materials engineering, aerospace and medicine. The majority of the founders and managers of Israel's high-tech companies are alumni. Based in New York City, the American Technion Society is the leading American organization supporting higher education in Israel, with more than 20,000 supporters and 17 offices around the country.