This post relies heavily on the excellent book by Kate Rheaume- Bleue entitled “Vitamin K2 and the Calcium Paradox: How a Little-Known Vitamin Could Save Your Life”(1)
As indicated in Blog 21, the fermented product prepared from soya is a particularly good source of Vitamin K2 (VK2) which is readily available in certain parts of Japan. However this is not easily obtained in Europe or the USA and in any case it has an acquired taste and would probably not be acceptable to those who have not been brought up on it. In practice therefore the non-Japanese will be dependent on two main sources, namely:
- Products from grass-fed animals
Animals have the ability to convert Vitamin K1 (VK1) which is present in green chlorophyll containing plants into VK2. For many farm animals this is provided by grass in their habitual diet. However most of the modern-day animal production systems do not include access to grass with the result that the amount of VK2 produced can be severely limited. In addition even when there is a high content of VK2 present as in meat or milk produced from grass-fed animals, many people still miss out. This is because they are attempting to comply with the dietary recommendations which advise that saturated/animal fats should be avoided or reduced. As a consequence they trim the fat from meat and choose semi-skimmed milk. Unfortunately this means that they also reduce the intake of VK2 which is present in the fat.
The other main source is cheese because the VK2 is produced by the bacteria during the cheese fermentation. In the EPIC study on cancer described in Blog 21 it was found that almost half of the VK2 intake was from cheese and that the difference in cheese consumption was responsible for much of the difference in intake between individuals. It was also noteworthy that there was an inverse relationship between cheese intake and cancer incidence. The researchers concluded that:
“the findings of our study imply that the consumption of cheese may have a beneficial effect with respect to cancer, particularly prostate and lung cancer in men”(2)
The possibility that there are other factors present in cheese which help to control cancers cannot be ruled out. Certainly there is no evidence to support the recommendation that cheese, especially full fat versions should be avoided. In fact it is probably the reverse.
Other good sources include goose liver pate, egg yolk, fresh meats especially from animals with access to grass. Cheese, especially Gouda and Brie, is a very good source. The presence of VK2 in these products may help to explain why the incidence of heart disease in countries such as France is relatively low.
It is important to appreciate that there are minor differences in the chemical structures of the VK2 produced by animals (referred to as MK 4) and that produced during cheese fermentation (referred to as MK 7). The MK 7 has a longer half-life than the MK4 which means that they provide higher and more stable VK2 levels in blood than foods which contain MK 4. It also has the advantage that a relatively low dose is effective.
For those who wish to take supplements therefore it is preferable to select products which contain the MK 7 rather than MK 4. Unfortunately the authorities are not up-to-date with devising “Recommended Daily Intakes” so complying with them will not necessarily ensure an adequate intake. Kate Rheaume-Bleue advises that a daily intake of 120 micrograms for the majority of people but for menopausal and post-menopausal women it may be advisable to take 240 micrograms or more. She also points out that the MK 7 is prepared from natto and may not be suitable for those who are allergic to soya. Supplements in the form of a soft gel or oil-based liquid suspension will be more efficiently utilised than those which are hard gels or tablets.
One final point is that an adequate supply of VK2 is particularly critical for anyone already taking supplements or calcium or vitamin D. For these nutrients to be utilised effectively by the body it is essential to have ample VK2. Otherwise there is a real danger that the calcium and the Vitamin D will do more harm than good.
- K Rheaume-Bleue (2012) Vitamin K2 and the Calcium Paradox: How a Little-Known Vitamin Could Save Your Life. John Wiley & Sons Canada
- K Nimptsch et al (2010) American Journal of Clinical Nutrition 91(5) pp1348-1358