This is an abstract of an article by Chris Masterjohn titled "On the Trail of the Elusive X-Factor" which was published in Wise Traditions, Volume 8 Number One, Spring 2007, pages 14–32.
Dr. Weston A. Price's research into health and dental defects led to his discovery of a vitamin-like substance found in the traditional diets of the healthy peoples he studied, a substance he called "Activator X." He found that Activator X "played an influential role in the utilization of minerals, protection from tooth decay, growth and development, reproduction, protection against heart disease, and the functioning of the brain."
The author lays out a clear case for the equivalence of Activator X and vitamin K2, that they are one and the same.
The K vitamins belong to the class of chemicals called quinones. "There are two natural forms of vitamin K: vitamin K1 and vitamin K2. Vitamin K1 ... is found in the green tissues of plants .... When animals consume vitamin K1, their tissues convert part of it into vitamin K2 .... The ability to convert K1 to K2 varies widely between species and breeds of animals; it has not been determined in humans."
Recent "research is demonstrating that these two substances are not simply different forms of the same vitamin, but are better seen as two different vitamins."
Vitamin K was first identified in the 1930s, the same period when Dr. Price conducted his research. It was originally thought to only play a role in blood clotting. In 1997 it was first understood that vitamin K was active in much more than clotting. The first efforts to measure K2 in foods were done in 2006. Details of an optimal quantity of dietary K2 lie in the future.
Considering whether vitamin K2 is an essential nutrient, the author wrote "there are a number of lines of evidence strongly suggesting that humans require preformed K2 in the diet to obtain optimal health." Apparently humans "have a finite ability to absorb vitamin K1 from plant foods," no more than 200 micrograms per day. Additionally, epidemiological and intervention studies show that dietary K2 is better than K1 at establishing optimal health.
Natural food sources of vitamin K2 include raw butter from animals grazing on rapidly growing green grass, organs and fats of grass-fed animals, fish eggs, bones, and fermented foods such as sauerkraut, cheese, and natto. Natto, made from soy beans, contains the highest amount of K2 ever measured.
The vitamin K2 content of these selected foods is in micrograms per 100 grams:
|goose liver paste||369|
|egg yolk (USA)||15|
The best way to add K2 to your diet is by eating foods naturally rich in it, including high X factor butter oil. You can also supplement with K2. There are two forms of vitamin K2 supplements available: MK-4 and MK-7. "MK-4 is a synthetic product that is believed to be chemically and physiologically identical to the vitamin K2 found in animal fats .... Although synthetic, it is effective, and there is no known toxicity." MK-7 is a natural extract of natto. No studies have compared the efficacy of these two forms. MK-7 is more expensive than MK-4.
MK-4 supplements are available from Thorne Research and Carlson Laboratories. Thorne's product is liquid, dissolved in medium-chain tryglycerides with mixed tocopherols. Carlson's product is in dry capsules with cellulose and fillers.
MK-7 supplements are available from Jarrow Formulas and Source Naturals. Jarrow's product is in gel caps, and made from genetically unmodified soy beans; other ingredients are evening primrose oil, medium chain triglycerides, beeswax, and lecithin. Source Naturals' product is in gel caps, they do not say whether their soybeans are GMO; other ingredients include dibasic calcium phosphate, stearic acid, colloidal silicon dioxide, modified cellulose gum, and magnesium stearate.