Author: Nicole Recine RN, MSN, CDE
Most health-conscious individuals know that green leafy vegetables are rich in Vitamin K. However, Vitamin K comes in several forms with each having a unique role in human health.
The form of Vitamin K found in vegetables is called phylloquinone. This form is also known as Vitamin K1, and it is well known that the liver uses Vitamin K1 to make proteins involved in blood clotting. While this is very important, it is not the only function of Vitamin K, and official recommendations for Vitamin K intake have been made based on this one function. It turns out that there are other forms of Vitamin K that have crucial functions throughout the human body. These other forms are known as menaquinones or Vitamin K2.
Menaquinones are primarily found in animal products and fermented foods. There are several different menaquinones, but two important forms that I will discuss here are MK-4 and MK-7. Although there is still much research going on in this area, it is thought that MK-7 AND MK-4 act as cofactors in enzyme-driven reactions involved in the formation of proteins required for bone and cardiovascular health. MK-7 is thought to be more effective in reaching the bone, and thus plays an important role in bone health. By inhibiting the deposition of calcium deposits in soft tissue, MK-4 seems to prevent coronary artery calcification, which makes it an important component of cardiovascular health.
For the most part, Vitamin K1 (phylloquinone) stays in the liver where it is used to make proteins for normal blood clotting. It is degraded before it can make it out to bones and blood vessels, which is why it is very important that a healthy diet includes sources of both Vitamin K2 and Vitamin K1.
How can you be sure your diet is rich in Vitamin K2?
I always advocate for a nutrient-dense diet rather than supplementation. Unfortunately, current nutrition labels do not differentiate between the types of Vitamin K contained in foods. Additionally, dietary recommendations for Vitamin K are based on phylloquinone (Vitamin K1) needs only. So, there is no official daily recommendation for Vitamin K2. However, the current recommendation for total Vitamin K is 90 mg per day.
Which foods are rich in Vitamin K2?
MK-7 is abundant in fermented foods. Examples include hard cheeses and natto (fermented soybeans). There are also trace amounts found in soft cheeses and liver.
MK-4 is found primarily in animal foods. Eggs and liver are both rich sources of MK-4. Other good sources include:
There are also smaller amounts of MK-4 found in other parts of the animal including various cuts of steak, bacon, organ meats, or roasts.
My point here is not to attempt to measure or quantify Vitamin K2 in the diet but to highlight the importance of eating a variety of whole foods from healthy animals to ensure that you are getting all of the forms of Vitamin K necessary for health.
Many supplement companies will isolate one form of a vitamin, such as Vitamin K1, and consumers take these supplements assuming it is equivalent to getting vitamins and minerals from food. As we have seen with Vitamin K, this is not the case. Whenever supplement or pharmaceutical companies isolate specific compounds, they often neglect the complexity of the relationship of that compound with other nutrients found in the actual food. Nutrients often work synergistically, making an isolated compound suboptimal when compared to real food.
Luckily, USWM offers endless options rich in Vitamin K2 from cheeses, sausages, and ghee to meat and offal. I encourage you to incorporate a variety of whole animal foods plus green leafy vegetables in your diet to ensure that you are consuming all forms of Vitamin K.
About The Author:
Nicole Recine is a nurse practitioner that specializes in diabetes. Nicole was a featured speaker at the 2017 KetoCon. Watch her KetoCon presentation.
Beulens, J. W. J., Booth, S. L., van den Heuvel, E. G. H. M., Stoecklin, E., Baka, A., & Vermeer, C. (2013). The role of menaquinones (vitamin K2) in human health. The British Journal of Nutrition, 110(8), 1357–68. https://doi.org/10.1017/S0007114513001013
Campbell, A. W. (2017). Vitamin K2 in the Prevention of Cardiovascular Diseases and Diabetes. Alternative Therapies In Health And Medicine, 23(2), 8–10.
Masterjon, C. (2016, December 9). Chris Masterjon Phd [Blog]. Retrieved December 19, 2017, from https://chrismasterjohnphd.com/2016/12/09/the-ultimate-vitamin-k2-resource/#infographic1
Sakamoto, N., NIiskike, T., Iguchi, H., & Sakamoto, K. (2000). Possible effects of one week vitamin K (menaquinone-4) tablets intake on glucose tolerance in healthy young male volunteers with different descarboxy prothrombin levels. Clinical Nutrition, 19(4), 259–263. https://doi.org/10.1054/clnu.2000.0102
Shanahan, C. (2017). Deep Nutrition: Why Your Genes Need Traditional Food (1st ed.). Flatiron Books.