CHAPEL HILL - A component of vitamin E known as gamma tocopherol may somehow contribute to arthritis, a unique new study of vitamin E and the painful degenerative illness suggests.
The study, described at an American College of Rheumatology news conference in Boston Monday, also suggests that having a high proportion of alpha tocopherol - the most common ingredient in vitamin E - relative to gamma tocopherol may help prevent arthritis, at least in knees.
Dr. Joanne Jordan, research associate professor of medicine at the University of North Carolina at Chapel Hill, presented the findings. A member of the Thurston Arthritis Research Center at UNC-CH's School of Medicine, Jordan is principal investigator of the Johnston County Osteoarthritis Project, a large, government-sponsored study of the illness that for the first time includes many black subjects.
The latest research involved comparing results of X rays of subjects' knees with their blood levels of the various substances that make up vitamin E. Scientists limited the investigation to 400 of the 3,200 participants. Half the study group was white and the other half black.
"The Framingham study earlier suggested that higher vitamin E intake in the diet might help prevent progression of knee osteoarthritis, but that study did not include African- Americans," Jordan said. "Also, no previous studies have looked at actual blood levels of these tocopherols but relied instead on what people reported eating, which is much less reliable."
Tocopherols are fat-soluble substances in the blood collectively known as vitamin E, she said. Gamma forms are found in palm, soybean, corn and cottonseed oils. "We didn't find any protective effect for alpha tocopherol, but we did find gamma tocopherol was clearly associated with more arthritis," Jordan said. "This was very marked in African-Americans and less so in Caucasians. We don't know why." The new results suggest that people who want to take vitamin E supplements should stick to the straight form, which is alpha tocopherol, and not buy supplements with mixed tocopherols, Jordan said.
"We're going to go back and look at this in more detail including through longitudinal studies," she said. "When we have data from different time points, we'll be able to see what happened with our participants who already had arthritis and with those who did not. Did their knee osteoarthritis get worse or get better and how did their conditions compare with biomarkers of vitamin E and other substances in their blood? We also plan to look at osteoarthritis in other joints such as hips."
More research needs to be done on the various tocopherols and their effects, the physician said.
Others involved in the study were Drs. Jordan Renner, associate professor of radiology; Lenore Arab, professor of epidemiology and nutrition at the School of Public Health; Anneclaire DeRoos, graduate student in epidemiology; and Gheorghe Luta, graduate student in biostatistics, all at UNC-CH. Others were Drs. Marc Hochberg of the University of Maryland and Charles Helmick of the U.S. Centers for Disease Control and Prevention.
Alpha tocopherol is believed to have anti-inflammatory and anti-oxidant properties. Anti-oxidants have received considerable attention in the past few years because many people believe they can reduce health problems associated with aging.
No previous study of arthritis pain and disability has included large numbers of black volunteers, Jordan said. Including blacks is important because no one has looked before to see if they differ from whites in their experiences with osteoarthritis.
The Centers for Disease Control and Prevention and the National Institute of Arthritis, Musculoskeletal and Skin Diseases support the continuing research. The UNC-CH Institute of Aging also contributed to the latest study.
Note: Jordan can be reached at the American College of Rheumatology meeting at the
Heinz Convention Center on Monday and Tuesday (Nov. 15-16). The meeting's media
room number is (617) 954-2415. The news conference is being held from 8:30 to 9:30
a.m. Monday, and Jordan will respond to voice mail messages left for her at the hotel 1-
800-713-0775 and (617) 236-2000 (Sheraton Boston). Beginning Wednesday (Nov. 17),
she can be reached at (919) 966-0559.