Health benefits of another vitamin E.

References to antioxidants often use vitamin E and alpha-tocopherol interchangeably. Yet Nature makes a host of structurally similar tocopherols and generally packages them together. In these mixtures, gamma-tocopherol usually dominates.

Now, Stephan Christen of the University of California, Berkeley and his colleagues report that gamma-tocopherol provides valuable protection from nitrogen oxides, a broad class of reactive compounds that alpha-tocopherol largely ignores. That's important, Christen argues, because the vitamin E sold as a dietary supplement contains primarily alpha-tocopherol.

Christen's team focused on the ability of tocopherols to defuse nitrogen oxides. Outdoors, these compounds play a role in producing acid rain. In the body, many serve as destructive oxidants that can alter DNA and trigger some of the damage caused by inflammation.

Working with simulated cell membranes and low-density lipoproteins from people who had taken different vitamin E supplements, the scientists tested the tocopherols' ability to detoxify peroxynitrite, a nitrogen oxide that appears to be associated with inflammation. Though alpha-tocopherol "eliminates the oxidant character of the molecule," Christen says, it leaves behind a reactive nitrogen component. "And that's where gamma-tocopherol comes in."

During a follow-up reaction, he observes, "it permanently traps what's left over and still reactive." This tocopherol exhibits a special affinity for reacting with and inactivating nitrogen oxides, he says.

In an as-yet-unpublished study, Christen's team induced inflammation in animals and then watched what happened to tocopherols in the blood. Concentrations of the gamma form dropped quickly, they found. At the same time, certain nitrogenous compounds increased, suggesting that the gamma-tocopherol was trapping nitrogen oxides.

Because consumption of large amounts of alpha-tocopherol appears to push gamma-tocopherol out of the system, both forms should be consumed together, Christen's team argues in the April 1 Proceedings of the National Academy of Sciences.

Anders G. Olsson, a physician who studies lipids and atherosclerosis at University Hospital in Linkoping, Sweden, agrees. In the March 1 British Medical Journal, he and a team of European colleagues described their investigation into risk factors that might explain why Lithuanian men face four times the heart disease mortality of Swedish men the same age.

Neither conventional risk factors-such as blood pressure or cholesterol-nor alpha-tocopherol concentrations differed substantially between the groups. The Lithuanian men, however, did possess significantly lower gamma-tocopherol concentrations in their blood than the Swedes did.

"The new paper [by Christen's group] could explain our findings," Olsson concludes.

Heart disease isn't the only degenerative condition linked to low gamma-tocopherol. Robert V. Cooney's team at the Cancer Research Center of Hawaii in Honolulu has shown in test-tube studies that "gamma-tocopherol pretty well blocks the formation of tumor cells at high doses. It's much more effective than alpha-tocopherol."

On the basis of such findings, Christen's group now suspects that "gamma-tocopherol may be as important as alpha-tocopherol in the prevention of degenerative diseases."

Adds Cooney, "the fact that 75 years after its discovery we still don't understand what vitamin E really does says a lot about the state of this research." Moreover, it "argues that we need to get our vitamin E from natural sources," not synthetic supplements.