News Release 

Eating more vitamin K found to help, not harm, patients on warfarin

Contrary to common wisdom, increasing vitamin K intake helps stabilize anticoagulation

American Society for Nutrition

Baltimore (June 11, 2019) - When prescribed the anticoagulant drug warfarin, many patients are told to limit foods rich in vitamin K, such as green vegetables. The results of a new clinical trial call that advice into question and suggest patients on warfarin actually benefit from increasing their vitamin K intake--as long as they keep their intake levels consistent.

Warfarin is widely used to prevent the dangerous blood clots that cause heart attacks and strokes. The drug's dosage must be carefully calibrated to balance the risk of clots against the risk of uncontrolled bleeding. Because warfarin counteracts the activity of vitamin K in the blood, large swings in vitamin K intake can disrupt this balance.

The current recommendation to keep daily vitamin K intakes consistent often translates into patients limiting vitamin K intake. According to the new trial, patients would be better advised to increase the amount of vitamin K in their diet.

"I think all warfarin-treated patients would benefit from increasing their daily vitamin K intake, said lead study author Guylaine Ferland, professor of nutrition at Université de Montréal and scientist at the Montreal Heart Institute Research Centre. "That said, given the direct interaction between dietary vitamin K and the action of the drug, it is important that (higher) daily vitamin K intakes be as consistent as possible."

Ferland will present the research at Nutrition 2019, the American Society for Nutrition annual meeting, held June 8-11, 2019 in Baltimore.

"Our hope is that healthcare professionals will stop advising warfarin-treated patients to avoid green vegetables," said Ferland. She explained that eating plenty of green vegetables and other nutritious vitamin-K rich foods can help stabilize anticoagulation therapy and offers many other health benefits.

The study is the first randomized controlled trial to test how patients on warfarin respond to a dietary intervention aimed at systematically increasing vitamin K intake. Researchers enrolled 46 patients with a history of anticoagulation instability. Half attended dietary counseling sessions and cooking lessons that provided general nutrition information, while half attended counseling sessions and cooking lessons focused on increasing intake of green vegetables and vitamin-K rich oils and herbs.

After six months, 50 percent of those counseled to increase their vitamin K intake were maintaining stable anticoagulation levels, compared with just 20 percent of those who received the general nutritional counseling, a significant improvement. The results suggest patients taking warfarin would benefit from consuming foods that provide a minimum of 90 micrograms of vitamin K per day for women and 120 micrograms per day for men, Ferland said.

Guylaine Ferland will present this research on Tuesday, June 11, from 11:15 - 11:30 a.m. in the Baltimore Convention Center, Room 319/320 (abstract). Contact the media team for more information or to obtain a free press pass to attend the meeting.

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This release may include updated numbers or data that differ from those in the abstract submitted to Nutrition 2019.

Please note that abstracts presented at Nutrition 2019 were evaluated and selected by a committee of experts but have not generally undergone the same peer review process required for publication in a scientific journal. As such, the findings presented should be considered preliminary until a peer-reviewed publication is available.

About Nutrition 2019

Nutrition 2019 is the annual meeting of the American Society for Nutrition held June 8-11, 2019 at the Baltimore Convention Center. It is the national venue for more than 3,600 top researchers, practitioners and other professionals to announce exciting research findings and explore their implications for practice and policy. Scientific symposia address the latest advances in cellular and physiological nutrition and metabolism, clinical and translational nutrition, global and public health, population science, and food science and systems. http://www.nutrition.org/N19 #Nutrition2019

About the American Society for Nutrition (ASN)

ASN is the preeminent professional organization for nutrition research scientists and clinicians around the world. Founded in 1928, the society brings together the top nutrition researchers, medical practitioners, policy makers and industry leaders to advance our knowledge and application of nutrition. ASN publishes four peer-reviewed journals and provides education and professional development opportunities to advance nutrition research, practice and education. http://www.nutrition.org

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