Vitamin E

Vitamin E was found to enhance aspirin’s ability to prevent blood clots. This study reports that vitamin E (50 and 100 μM) inhibited aggregation of platelets, one of many cell types present within blood. In addition, vitamin E was associated with an 80% reduction in platelet adhesion to collagen (a protein). Platelet adhesion to collagen is fundamental during blood clotting. (5)

Researchers conducted a study to determine if vitamin E supplementation affects vitamin K status or blood clotting time in patients not treated with warfarin. Their study involved 38 men and women with rheumatoid arthritis and 32 healthy men participating in two independent 12-week randomized clinical trials of vitamin E supplementation. All trial participants were given 1000 IU/day of natural vitamin-E. The researchers used plasma concentration of proteins induced by vitamin K absence-factor II, or PIVKA-II for short, as a sensitive measure of vitamin K status. A normal value for PIVKA-II is 2.4 ng/mL or less and values higher than this indicate poorer vitamin-K status. At the end of the 12-week supplementation period PIVKA-II had increased from 1.7 to 11.9 ng/mL in the rheumatoid arthritis group and from 1.8 to 5.3 ng/mL in the healthy men. Thus, it would appear that supplementation with a high dose of vitamin E does indeed reduce body stores of vitamin K. The researchers concluded that high-dose vitamin E supplementation does reduce vitamin K status, but are uncertain whether this interaction is immaterial, beneficial (reduced stroke risk) or harmful (loss of bone density). (6)