A dietary strategy to increase daily vitamin K (phylloquinone) intake
Crystele Hogue, Applied Physiology, Nutrition, and Metabolism, Vol. 46, No. 4 (Suppl. 1): S17
Despite the arrival of new oral anticoagulants, warfarin remains a
commonly prescribed drug to treat and prevent thromboembolic diseases. Warfarin has a narrow therapeutic range and a considerable
proportion of patients fail to stay in the therapeutic range despite
close monitoring, exposing them to life-threatening complications
such as bleeding and thromboembolic events. Vitamin K (VK) is a key
element of anticoagulation stability as warfarin interferes with its metabolism. Observational studies have provided evidence that warfarin treated patients with higher usual VK intakes have more stable anticoagulation. A dietary intervention was developed as part of a clinical
trial that aimed to compare the clinical impact of a VK enriched (experimental group) versus a standard diet (control group) on anticoagulation stability, over a 24-week period. Specifically, patients allocated
to the experimental group were guided to increase their intakes of
phylloquinone, the main dietary source of VK, by 150 lg per day. Phylloquinone is found in highest concentrations in green leafy vegetables, soybean and canola oils. Significant amounts are also found in olive oil, mung beans, pistachio nuts, avocado and fresh or dried
herbs. The dietary intervention focused on three groups of phylloquinone-rich foods namely green vegetables, fats and herbs. The intervention consisted in five 1.5-hours dietary counselling sessions (weeks 0,4, 8, 12 and 18) conducted in groups of 6-8 participants. Sessions were
provided by nutrition specialists previously trained to deliver harmonized presentations. Educational material and tools were developed to
help participants implement recommendations and monitor their VK
intakes. When assessed between weeks 6 and 24 of the trial mean VK
intakes (mcg/d, [95% CI]) was statistically higher in the experimental
(n=23) than in the control group (n=22) (154.8 [115.5-207.5] vs 67.5 [50.0-
91.3]; P<0.001).
Higher daily VK intakes can help improve anticoagulation stability. Here we describe a dietary intervention focusing on strategic VK food groups that enabled to more than double daily VK
intakes in warfarin-treated patients. Although pertinent to this context, increasing daily VK intakes could prove beneficial for general
health, in light of the emerging protective role of this vitamin in
inflammation and cognitive function.