Effect of vitamin E supplementation on vitamin K status in adults with normal coagulation status.
BACKGROUND
Cases of enhanced anticoagulant effect in response to high-dose vitamin E supplementation have been reported among patients taking oral anticoagulants. Although a vitamin E-vitamin K interaction was proposed to underlie this effect, it has not been systematically investigated in adults with normal baseline coagulation status.


OBJECTIVE
The objective was to study the effect of 12 wk of supplementation with 1000 IU RRR-alpha-tocopherol/d on biochemical measures of vitamin K status in men and women not taking oral anticoagulants.


METHODS
Vitamin K status, which was assessed with the use of plasma phylloquinone concentrations, the degree of under-gamma-carboxylation of prothrombin (proteins induced by vitamin K absence-factor II, PIVKA-II), and the percentage of undercarboxylated osteocalcin (ucOC), was determined in 38 men and women with rheumatoid arthritis (study A) and in 32 healthy men (study B) participating in 2 independent, 12-wk randomized clinical trials of vitamin E supplementation (1000 IU/d).


RESULTS
Mean (+/- SD) PIVKA-II increased from 1.7 +/- 1.7 to 11.9 +/- 16.1 ng/mL (P < 0.001) in study A and from 1.8 +/- 0.6 to 5.3 +/- 3.9 ng/mL (P < 0.001) in study B in response to 12 wk of vitamin E supplementation. An increase in PIVKA-II is indicative of poor vitamin K status. In contrast, the other measures of vitamin K status (ie, plasma phylloquinone concentration and percentage of ucOC) did not change significantly in response to the supplementation.


CONCLUSIONS
High-dose vitamin E supplementation increased PIVKA-II in adults not receiving oral anticoagulant therapy. The clinical significance of these changes warrants further investigation, but high doses of vitamin E may antagonize vitamin K. Whether such an interaction is potentially beneficial or harmful remains to be determined.
Booth
Sarah L
SL
Jean Mayer US Department of Agriculture Human Nutrition Research Center on Aging, Tufts University, Boston, MA 02111, USA. sarah.booth@tufts.edu
Golly
Ines
I
Sacheck
Jennifer M
JM
Roubenoff
Ronenn
R
Dallal
Gerard E
GE
Hamada
Koichiro
K
Blumberg
Jeffrey B
JB
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000975:Antioxidants / Q000008:administration & dosage / Q000494:pharmacology*; D001172:Arthritis, Rheumatoid; D001777:Blood Coagulation / Q000187:drug effects; D019587:Dietary Supplements; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009752:Nutritional Status; D014810:Vitamin E / Q000008:administration & dosage / Q000494:pharmacology*; D014812:Vitamin K / Q000097:blood*; D024502:alpha-Tocopherol / Q000097:blood
D000975:Antioxidants; D014812:Vitamin K; D014810:Vitamin E; D024502:alpha-Tocopherol