VITAMIN K
Exciting possibilities for a common nutrient.
Like vitamin D, research related to vitamin K has rapidly grown in recent years, emphasizing the importance of supplementation for certain populations. These studies have explored bone benefits and vascular health, with a focus on vitamin K-2, found in certain fermented foods and produced in healthy digestive systems. Most multivitamins contain the older form, vitamin K-1, which is easily obtained in broccoli and green leafy vegetables. This discussion will focus on the studies supporting vitamin K-2.
Vitamin K comes in many forms and from various sources. Plants, such as vegetables, provide K-1, or phylloquinone. In recent years, vitamin K-2 has been divided into two groups: menaquinone-4 (MK-4) and menaquinone-7 (MK-7). Vitamin K-3 is the synthetic form.
MK-4 and MK-7 are found in fermented cheeses and a fermented soy product called Nattō. It is also made by bacteria in the intestinal tract [1]. Because of this, those with chronic bowel problems, like diarrhea or inflammatory bowel conditions, are commonly at risk of vitamin K deficiency.
Vitamin K signals the protein osteocalcin, which aids in the ongoing bone remodeling process [2. 3]. Treatment with vitamin K-2 has shown effectiveness in fighting bone loss, especially when used with conventional treatments [4, 5, 6].
Vitamin K is also being recognized for its role in vascular health. Inflammation is thought to be the trigger that initiates injury in the blood vessels. Atherosclerosis, commonly referred to as a hardening of the arteries, or plaque, is thought to succeed inflammation. This hardening includes calcium deposits in the artery walls. Vitamin K-2 intake can actually help prevent calcium build up in the blood vessel walls [7]. Further research has documented a lowered risk of heart disease with higher vitamin K-2 intake [8].
Although generally safe, there are a few cautions tied to this nutrient. Vitamin K was originally studied for its role in blood clotting. The drug warfarin, used for the prevention of blood clot formation, inhibits vitamin K’s role in the blood clotting system. Patients on warfarin have to be careful with their vitamin K intake, as it will lessen the effect of the medication. Consider consulting a doctor prior to supplementation.
Vitamin K-2 presents exciting new possibilities for bone and blood vessel health. The decision to supplement with vitamin K should be based on a person’s own risk and family history. Adding this nutrient to your daily regimen is a smart option for those at risk for osteoporosis and heart disease.
Vitamin K-1 is commonly found in multivitamins, but the K-2 form is recommended for those with cardiac issues. The dosage of MK-4 compared to MK-7 is substantially varied. This is because the body absorbs MK-7 better. MK-4 isn’t ineffective; it just requires a significantly higher dosage to provide equal benefit. Caution is advised in regards to the form you choose, so proper dosages are observed.
Dosage for common forms:
• K-2. Take both forms with food.
• MK-4. 45 mg or 45,000 mcg daily.
• MK-7. 150 mcg daily.
References:
1. Plaza, S.M., Lamson, D.W. (2005). Vitamin K-2 in bone metabolism and osteoporosis. Alternative Medicine Rev, 10(1):24-35.
2. Askim, M. (2001). Vitamin K in the Norwegian diet and osteoporosis. Tidsskr Nor. Laedegoren, 121 (22):2614-6.
3. Okano, T. (2005). Vitamin D, K and bone mineral density. Clin Calcium, 15(9):1489-94.
4. Kaneki, M. (2005). Vitamin K-2 as a protector of bone health and beyond. Clin Calcium, 15(4):605-10.
5. Kishimoto, H. (2004). Vitamin K and bone quality. Clin Calcium, 14(4):621-6.
6. Iwamoto, J., Takeda, T., Ichimura, S. (2003). Combined treatment with vitamin K-2 and bisphosphonate in postmenopausal women with osteoporosis. Yonsei Med J, 30;44(5):751-6.
7. Schurgers, L.J., Teunissen, K.J., Knapen, M.H., et al. (2005). Novel conformation-specific antibodies against matrix gamma-carboxyglutamic acid (Gla) protein: Undercarboxylated matrix Gla protein as a marker for vascular calcification. Arterioscler Thronb Vasc Biol, 25(8):1629-33.
8. Geleijnse, J.M., Vermeer, C., Grobbee, D.E., et al. (2004). Dietary intake of menaquinone is associated with a reduced risk of coronary heart disease: the Rotterdam Study. J Nutr, 134(11):3100-5.
Other Trusted Sources:
Oregon State University
Medline Plus
