Vitamin K2: An update
FROM TRACK YOUR PLAQUE
Another study has been released that confirms a connection between intake of vitamin K2 and coronary disease. This study takes the discussion one step further by using coronary calcium scoring obtained with heart scans, an experience that we had lacked previously.
You may recall from our initial Vitamin K2 discussion, Vitamin K2: An emerging story, that basic observations in both animal models and humans have provided a plausible basis for a role for vitamin K2 in vascular calcification.
Deficiency of K2 in both mice and humans is associated with coronary calcification; low vitamin K2 levels are associated with increased activity of Gla matrix protein, an enzyme that causes calcium deposition in artery walls. People who take warfarin (Coumadin®), a potent blocker of vitamin K2, experience more arterial and heart valve calcification.
The 2004 Rotterdam Heart Study was the experience that really brought this concept closer to our interests. This well-conducted study of 4800 Dutch demonstrated an association of vitamin K2 intake with 57% reduction in cardiovascular events and lesser degrees of aortic calcification (another surrogate for atherosclerosis). Benefit appeared to be associated with a daily K2 intake of 32.7 micrograms per day (Geleijnse JM et al 2004). An important corollary of this study is that it suggests that a vitamin K2-mediated reduction in coronary calcification is accompanied by reduced likelihood of heart attack and other events.
Another study has been conducted by the same group of researchers in the Netherlands who engineered the Rotterdam Study. In this most recent experience, 564 women (average age 67, average BMI 26.7) completed a 77-item food frequency questionnaire that quantified intake of vitamins K1 and K2.
Among the participants, average intake of vitamin K1 was 217 micrograms per day, while vitamin K2 intakes averaged 31.6 micrograms per day for the entire study population. (This is consistent with prior studies showing that K1 intake is about 10-fold greater than K2.) The majority (82%) of K1 came from vegetables. Vitamin K2 came from cheese (54%), milk products (22%), and meat (15%), all of which are dietary sources of the MK-4 form of K2 along with lesser quantities of MK-8 and MK-9.
All participants underwent a heart scan (16-slice MDCT). 62% of women had positive heart scan scores (>zero). Daily intake of K1 and K2 were divided into four groups from lowest daily intake to highest daily intake. Study results and dosing considerations for your personal program
While no association was found between K1 intake and heart scan scores, the group with the highest daily vitamin K2 intake of 45 micrograms per day was associated with 20% decreased likelihood of having a positive score compared with the group with the lowest daily intake of K2 (18 micrograms per day).
Unfortunately, data regarding the distribution of heart scan scores was not published. Women were simply divided into +calcium or –calcium. (We communicated with the principal author of the study, Dr. Joline Beulens, whether such an analysis was being planned. She said that such analyses were done but did not change the results in any way beyond just zero score vs. positive score.)
As we’ve previously discussed, though the prospects for vitamin K2 are growing as an important component of the Track Your Plaque program, we still remain on uncertain ground on a number of important issues. If we include K2, what dose should we consider? Rotterdam suggested a threshold of 32.7 micrograms. This more Dutch recent experience suggests 45 micrograms. Both experiences are also based on dietary sources of MK-4 only with little or none of the other forms. MK-4 lingers for only a few hours in the body, making it potentially necessary to ingest K2 as MK-4 at every meal.
On the other hand, the Japanese experience is based mostly on the MK-7 form of K2 sourced from natto. MK-7 is far more long-lasting in the body, persisting several days. MK-7 is also the form with greatest validation as a prescription treatment (in Japan) for osteoporosis or osteopenia when used at doses of 15-40 mg (15,000-40,000 micrograms), far higher doses than the MK-4 intake of the Dutch studies.
Is one form, MK-4 vs. MK-7 vs. mixture that includes MK-8, MK-9, better than the other? If 45 micrograms is good, is 100 micrograms better? How about 1000, 5000, 40000 micrograms?
We clearly need more data. The Track Your Plaque experience with vitamin K2 also remains preliminary and has not yielded confident feedback on whether or not K2 is an important contributor to reduction of heart scan scores. We are confident, however, given the data and experience thus far that K2 supplementation appears to exert no side-effects.
Given the lack of side-effects and the reasonable potential for benefit, we advocate considering a dose of vitamin K2, in either the MK-4 and/or MK-7 form, as a supplement at a total dose of 1000 micrograms per day. We also advocate inclusion of cultured cheese, 1-2 oz per day, such as Camembert, Bleu, Swiss, feta, etc. for MK-4. While the data are too preliminary to regard any form of vitamin K2 as a requirement for the starting Track Your Plaque regimen, little is lost (beyond expense) by including this fascinating nutrient.
Note: If you take Coumadin (warfarin), use of vitamin K should be discussed with your doctor before you begin supplementation, since substantial changes in blood thinning (protime or INR) will occur. Note that, however, there are data to suggest that modest supplementation of vitamin K1 adds to long term stability of blood coagulation.
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References:
Geleijnse JM, Vermeer C, Grobbee DE et al. Dietary intake of menaquinone is associated with a reduced risk of coronary heart disease: The Rotterdam Study. J Nutr 2004;134:3100–3105.?
Beulens JWJ, Bots ML, Atsma F et al. High dietary menaquinone intake is associated with reduced coronary calcification. Atherosclerosis 2008, doi:10.1016/j.atherosclerosis.2008.07.010 |
