Japanese researchers compared the effects of tocotrienols from palm oil with alpha-tocopherol on adhesion molecules in endothelial cells.
The endothelium, or the inner lining of the vascular system, reacts to cholesterol by increasing expression of these adhesion molecules, which attract a kind of white blood cell - monocytes - into the subendothelial space to protect it.
These monocytes develop into macrophages that take up large amounts of LDL cholesterol.
As the process continues however, macrophages eventually become foam cells, which can then become fibrous and tough, forming plaques that block arteries and create a significant risk of heart attack.
Patients with atherosclerosis have been found to have high circulating levels of soluble adhesion molecules, leading researchers to investigate ways of lowering the production of these molecules to reduce the risk of developing heart disease.
The researchers from Kyoto Prefectural University of Medicine found that tocotrienols had a "profound inhibitory effect" on the adherence of monocytes to human endothelial cells studied in the lab.
The tocotrienols accumulated in endothelial cells taken from human aortas up to 95 times more than the alpha-tocopherol studied.
The scientists write in the May issue of Atherosclerosis (2005, 180(1), pp19-25) that the tocotrienol form of vitamin E has already been shown to effectively reduce adhesion of molecule expression and adherence of monocyte cells to the endothelium.
The new findings confirm this effect and also suggest that tocotrienols have a very different protective action on the heart than alpha-tocopherol.
"Although the exact molecular mechanism of the inhibition of endothelial inflammatory response by tocotrienols has not been elucidated, recent reports suggest that tocotrienols affect the mRNA expression of several genes and activate or regulate the targeted protein," write the authors.
"Recent advances in genomics and proteomics will provide the novel mechanism, probably beyond the antioxidant, of the inhibition of atherosclerosis by tocotrienols," they conclude.