Study outlines how inadequate
vitamin E can cause brain damage

Field of sunflowersSunflower seeds and oil are a particularly good dietary source of vitamin E. Photo by Bruce Fritz, courtesy U.S. Department of Agriculture

Vitamin-E deficiency, it appears, may cause neurological damage by interrupting a supply line of specific nutrients, robbing the brain of the building blocks it needs to maintain the function and integrity of the neural membrane.

New findings on this role of this micronutrient, in National Institutes of Health-supported work done with zebrafish, were published in the Journal of Lipid Research by scientists from Oregon State University.

The research showed that zebrafish fed a diet deficient in vitamin E throughout their lives had about 30 percent lower levels of docosahexaenoic acid-containing phosphatidylcholines, or DHA-PC. This major membrane phospholipid species is part of the cellular membrane of every neuron.

In searching for a mechanism of action, scientists examined the level of lysophospholipids, or lyso PLs, that serve as substrates for phospholipid synthesis and as transporters for getting DHA from the plasma into the brain. Once inside, these lyso PLs become the building blocks for neural-membrane maintenance and repair. It was found that brain lyso PL levels are an average of 60 percent lower in fish maintained on the diet deficient in vitamin E.

Why is this important? Because the year-old zebrafish used in this study, and the deficient levels of vitamin E they were given, are equivalent to humans that have eaten a low vitamin E diet for a lifetime. And unfortunately, that’s pretty common.

In the United States, 96 percent of adult women and 90 percent of men do not receive adequate levels of vitamin E in their diets. And the new findings about the role of lyso PLs also come after other recent studies showed that low levels of DHA-PC in the blood plasma of humans are a biomarker than can predict a higher risk of developing Alzheimer’s disease.

“This research showed that vitamin E is needed to prevent a dramatic loss of a critically important molecule in the brain and helps explain why vitamin E is needed for brain health,” said Maret Traber in the College of Public Health and Human Sciences at OSU, and lead author on this research.

“Human brains are very enriched in DHA but they can’t make it — they get it from the liver,” said Traber, who also is a principal investigator in the Linus Pauling Institute at OSU. “The particular molecules that help carry it there are these lyso PLs, and the amount of those compounds is being greatly reduced when vitamin E intake is insufficient. This sets the stage for cellular membrane damage and neuron death.”

DHA, an omega-3 polyunsaturated fatty acid, has been increasingly recognized as one of the most important fatty acids for brain health. It’s found in certain omega-3 rich foods, primarily cold-water fish like salmon and mackerel.

DHA is the needed nutrient, Traber said, but it’s the lyso PLs that help get it into the brain and ultimately act as the building blocks for maintaining the neural membrane.

This membrane is highly dynamic and is in a constant state of turnover, so an adequate supply of lyso PLs is needed at all times to facilitate normal membrane — and, subsequently, neuron activity.

“You can’t build a house without the necessary materials,” Traber said. “In a sense, if vitamin E is inadequate, we’re cutting by more than half the amount of materials with which we can build and maintain the brain.”

Some other research, Traber said, has shown that the progression of Alzheimer’s disease can be slowed by increased intake of vitamin E, including one study published last year in the Journal of the American Medical Association. But that disease is probably a reflection of years of neurological damage that already has been done, she said. The zebrafish diet used in this study was deficient in vitamin E for the whole life of the fish – as is the diet of some humans.

Vitamin E most often is provided by oils, such as olive oil. But the highest levels are often found in foods that don’t make the highlight list of an average American diet — almonds, sunflower seeds or avocados.

“There’s increasingly clear evidence that vitamin E is associated with brain protection, and now we’re starting to better understand some of the underlying mechanisms,” Traber said.

David Stauth David Stauth is a science writer at Oregon State University.