Vitamin K, found in green vegetables (spinach, cabbage, broccoli), has been known for its coagulant properties since the 1930s: in fact, the letter “K” comes from the German word for coagulate (Koagulieren). In a growing number of studies in the past 25 years, this vitamin has repeatedly surprised researchers as a result of its role in cognitive mechanisms. Is this a vitamin that can make you intelligent? “Let’s say that not eating enough of it could lead to cognitive problems,” explains Guylaine Ferland, Professor in the Department of Nutrition at Université de Montréal, whose research focuses mainly on this mysterious vitamin. “In any event, rats who are partly deprived of vitamin K experienced cognitive impairment at an advanced age.”

In her laboratory, the researcher has been putting rats through the “Morris pool” test. In a tank, the rat is guided by visual markers that help it find a submerged plate on which it can rest. At the age of 6 and 12 months, the rodents have no trouble orienting themselves, even when their diet is poor in vitamin K. But at 21 months, a dietary deficiency begins to take its toll. “The difference in performance on this test, which is designed to measure cognitive learning, is approximately 35% between rats whose diet was lacking vitamin K and rats whose diet was adequate,” notes Dr. Ferland.

Professor Ferland’s team has done unprecedented work on the way vitamin K is distributed in the brain. She found that it concentrates in the mesencephalon and the medulla oblongata, regions rich in white substance (myelin). Since one protein in the nervous system, Gas6, is dependent upon vitamin K, we want to know exactly what the effects of a deficiency are. The next step will be to do experiments on human subjects. Prof. Ferland, who is Head of Clinical Research at the Institut universitaire de gériatrie de Montréal, feels that the in vitro and in vivo studies are sufficiently advanced to enable her to make the leap. The neuroscience research centre at the Insititute will be a valuable resource in the study.

At present, vitamin K is missing from multivitamin complexes available over the counter. It is available in synthetic form, but by prescription only, since it can interfere with anticoagulant drugs such as Coumadin. While green vegetables are the richest sources of vitamin K, they are not the only source: it is found in soy and colza oil, as well as green tea leaves. Another important source is herbs. “We measured the vitamin K content of about thirty herbs, and found that some, such as oregano, estragon, celery flakes, savoury, rosemary and sage, contain large amounts. Whether they are consumed dry or fresh does not generally change the quality.” Daily recommended doses of vitamin K are 120 micrograms for men and 80 micrograms for women. As an example, there are 180 micrograms of the vitamin in a cup of raw cabbage and 76 in a raw cucumber
with peel.

Researcher: Guylaine Ferland
Telephone: (514) 343-7167
Funding: National Science and Engineering Research Council. Fonds de la recherche en santé du Québec.