Antioxidant Supplements Don't Protect the Heart
Vitamin E and beta carotene fail to fight cardiovascular disease, study finds
(HealthDay is the new name for HealthScoutNews.)
THURSDAY, June 12, 2003 (HealthDayNews) -- If you've been buying antioxidant supplements to protect your heart, you can look forward to more money in your pocket.
A new study in the June 14 issue of The Lancet offers the best evidence yet that supplements containing vitamin E or beta-carotene -- a form of vitamin A -- don't protect the heart, as once believed.
The new research analyzed 15 major studies of nearly 220,000 people before coming to these conclusions about supplement safety and efficacy.
"From high doses to low doses, in men and women of all ages, we found these supplements did not offer any benefits in relation to all-cause mortality, or even decrease the risk of death from stroke or heart disease," says study author Dr. Marc Penn, a cardiologist at the Cleveland Clinic Foundation.
In the case of beta-carotene, Penn says the risk of death was slightly higher for those using the supplements.
The finding does not surprise New York University cardiologist Dr. Dan Fisher.
"What we believed to be true in the 1980s concerning the protective effects of antioxidant supplements simply did not hold up to scientific scrutiny. And it's good to have this solid scientific validation of the conclusion that I and many doctors have come to realize," Fisher says.
While Fisher doesn't believe the book is completely closed on antioxidant protection, he adds, "Clearly, supplements of vitamin E and beta-carotene are not part of the solution."
Penn agrees: "I think antioxidants will play some future role in protection from cardiovascular disease, but I don't think we know what that role is just yet. And more importantly, we don't know what kind of supplementation, if any, is going to provide that protection."
The study drew immediate criticism from the Council for Responsible Nutrition, a Washington, D.C.-based trade association representing dietary supplement suppliers and manufacturers. The group called the study's conclusions "irresponsible, overinterpreted and old news disguised as something new for publicity purposes."
John Hathcock, the council's vice president for scientific and international affairs, says in a statement the researchers were guilty of "making sweeping statements that are not justifiable based on the studies they reviewed."
"For example, they discount the potential benefit of vitamin E for heart disease based largely on their review of secondary intervention trials on subjects with established heart disease." Hathcock says. "But what many researchers refer to as the 'antioxidant hypothesis' is the belief that antioxidants may be effective in decreasing the risk of heart disease if consumed before the atherosclerosis develops."
How did all the attention to the power of antioxidant supplements get started in the first place? Penn believes it can be traced to several key developments.
The first, he says, occurred in the 1970s when scientists uncovered the power of oxidation, a physiologic process that works in tandem with blood fats like cholesterol to cause damage to the heart.
Then researchers set out to prove that taking antioxidants, vitamins such as E and beta-carotene, could stop or even reverse that damage. The concept was proven -- but only in animal studies. And that, says Penn, is when things started to go astray.
"In translating those [animal] findings to clinical human practice, we didn't take into account that the animals had no lesions. And the findings could not be equated with giving vitamin E to people who had already experienced 20, 30, 40 or more years of oxidative damage to their body," Penn says.
The third problem, he says, was the clinical studies showing the vitamins worked in people were not randomized.
"What those patient questionnaires really told us was that vitamin E was a marker for people who took better care of their bodies. Overall, they exercised more, they ate better, they reduced stress. And those were the real reasons their risk of cardiovascular disease was lower, not the use of the supplements," Penn says.
The new research analyzed seven major randomized trials on vitamin E and eight on beta-carotene. Each study included at least 1,000 people, with a total of nearly 220,000 participants. The dose range for vitamin E was between 50 and 800 international units (IUs) daily, and beta-carotene dosing ranged from 15 milligrams to 50 milligrams daily. The follow-up on each study ranged from 1.4 years to 12 years.
The result: The overall rate of death for those taking vitamin E was statistically no better than for those who didn't use the supplements -- 11.1 percent versus 11.3 percent. The death rate specifically related to cardiovascular disease was equal in both groups -- 6 percent. And the death rate due to stroke was also nearly identical -- 3.6 percent for the supplement users versus 3.5 percent for non-users.
For those taking beta-carotene, the results were slightly worse. There was a small but significant increase in deaths from all causes in the group taking the supplement -- 7.4 versus 7 percent. There was also a small increase in the number of deaths from cardiovascular disease compared to the control group -- 3.4 percent versus 3.1 percent.
Based on the findings, Penn strongly suggests all trials on beta-carotene stop immediately. Further, he suggests the use of vitamin E for cardiovascular protection be discontinued and that patients at high risk for cardiovascular disease or death not be included in any future trials involving vitamin E. Fisher says he agrees with these recommendations.