Two recent studies offer new evidence suggesting an alternative form of natural vitamin E can be taken by mouth and will reach the blood in humans at levels determined to protect against stroke and other diseases.
Vitamin E occurs naturally in eight different forms. The primary vitamin E on drugstore shelves is called tocopherol, or TCP. But another natural form of vitamin E surfacing as a potent neuroprotective agent in repeated Ohio State University Medical Center studies is tocotrienol, or TCT.
This form, while not abundant in the American diet, occurs naturally in palm oil; this vegetable oil is increasingly used in prepared foods because it has no trans fat.
In the first study of this form of the nutritional supplement in humans, Ohio State researchers determined that a moderate dose of tocotrienol reached concentrations in human blood plasma that would be more than adequate to protect against neurological damage that follows stroke. These findings were published in the May issue of the journal Antioxidants & Redox Signaling.
In a separate study, the scientists determined that TCT is effective at two concentrations, one at which it functions as an antioxidant, and another, lower concentration at which the supplement offers non-antioxidant protection. Both functions of TCT are directed against neurodegeneration. These findings were published June 26 in an online edition of the Journal of Neurochemistry.
"We have determined that when administered orally, tocotrienol can reach concentrations needed to serve these dual protective functions," said Chandan Sen, professor and vice chair of surgery, deputy director of the Davis Heart and Lung Research Institute at OSU, and senior author of both studies. "It is a regular dietary ingredient in Asia, so it can safely be a part of a daily diet within prepared foods or as a supplement in the United States . Can it be therapeutically used to prevent stroke? Results from animal studies are encouraging, but it is still too soon to tell for humans. More mechanistic and outcomes studies are warranted."
In the first study, collaborating scientists at Wayne State University fed participants 400 milligrams of a time-release formulation of a supplement containing primarily TCT. Researchers collected blood samples from the participants two, four, six and eight hours after supplementation.
Sen said the maximum TCT concentrations in the bloodstream of supplemented patients averaged concentrations between 12 and 30 times higher than that needed to completely prevent stroke-related neurodegeneration as determined by earlier research.
Conventional wisdom has suggested that TCT, if eaten, cannot be carried to organs because the protein known as tocopherol transfer protein (TTP), which delivers TCP throughout the body, doesn't transport TCT very well.
"Our results demonstrate that TCT is efficiently delivered to the bloodstream despite the fact that the transfer protein has a lower affinity for TCT than it has for TCP," Sen said. Absorption of TCT is increased when the supplement is taken with fat-containing food, so the research participants took the study supplement with a high-fat (60 grams) meal to increase the efficiency of absorption.