INTRODUCTION:
Vitamin K deficiency symptoms include excessive bleeding, easy bruising, and heavy menstrual bleeding. It also contributes to poor bone development, osteoporosis, and cardiovascular disease.[3] It’s one of the significant health risks for older adults for the potential development of osteoporosis. It’s a growing problem expected to take a big toll on the aging population around the globe in the next several decades. Therefore, the need for interventions to reduce this risk is imperative.
Nutritional factors affecting bone structure and turnover generally include organic minerals (calcium, magnesium, phosphorus, sodium, and trace minerals), vitamins (vitamins A, D, E, K, and B vitamins), and macronutrients (proteins and fatty acids). Among these factors, calcium and vitamin D have been getting the most attention in conversations on promoting bone health, but vitamin K is much less talked about, even though its role in bone function has been known for several decades. Growing evidence suggests that vitamin K is another modifiable risk factor in the prevention and treatment of osteoporosis.[1]
Vitamin K refers to a group of fat-soluble compounds and was discovered in 1929 as an essential nutrient for blood coagulation. There are mainly two forms of vitamin K1 (phylloquinone) and vitamin K2 (menaquinone). Vitamin K1, the main dietary source of vitamin K and mostly found in leafy green vegetables, is primarily involved in blood coagulation, whereas vitamin K2 may have a more diverse range of functions in the body.[2]
WHAT’S THE BEST FORM OF VITAMIN K FOR BONE DENSITY SUPPORT?
One of vitamin K’s most important functions is to regulate calcium deposition. In other words, it promotes the calcification of bones and prevents the calcification of blood vessels and kidneys. Some scientists have suggested that the roles of vitamins K1 and K2 are quite different and should be classified as different nutrients. This idea is supported by an animal study showing that vitamin K2 reduced blood vessel calcification, whereas vitamin K1 did not. Controlled human studies also observed that vitamin K2 supplements generally improve bone and heart health, while vitamin K1 has no significant benefits.[2]
A crucial factor to consider here is that not all vitamin K2s are made equal. There are two forms of vitamin K2: menaquinone-4 (MK-4) and menaquinone-7 (MK-7). Both have been used as nutrients by the food industry and as nutritional supplements to support bone and cardiovascular health. Based on the result of current studies, MK-4 has poor bioavailability, whereas MK-7 is well absorbed.[4] So, the conclusion is that the most absorbable form of vitamin K for supporting bone health is vitamin K2 MK-7.
DIETARY RECOMMENDATIONS:
According to the National Academy of Science Food and Nutrition Board, the dietary requirements are based on the intake of healthy adults, and the adequate intake of vitamin K is 120 and 90 ug/day for men and women, respectively. However, it doesn’t specify what form of vitamin K people should take.
Vitamin K1 is widely available in dietary sources such as dark leafy green vegetables, but foods rich in vitamin K2 are not commonly found. Vitamin K2 deficiency is especially prevalent in older people. As people get older and older, their ability to absorb nutrients gradually declines due to aging and digestive dysfunctions. Moreover, their overall energy production naturally reduces, making it more challenging to make homemade meals, potentially resulting in nutrient deficiencies.
The sources for vitamin K2 include the following[2]:
Plant sources: sauerkraut, natto (a traditional Japanese dish of fermented soybeans)
Animal sources: liver and other organ meats, beef, pork, chicken, fatty fish, such as salmon, dairy products, especially hard cheeses, egg yolk
FINAL NOTE:
These vitamin K2-containing foods listed above are either not as commonly available or don’t contain enough of our body's needs in average consumption. Therefore, I highly recommend a dietary supplement from Vitamin K2 menaquinone-7 (MK-7). Based on various research studies, the indicated nutritional dosage of MK-7 for proper bone function is 45–90 μg daily.5 A higher dosage may be necessary if you have already developed osteopenia or osteoporosis.
Jenny Noland, MS, CNS, CNGS, CKNS, LDN, MBA
Functional Nutritionist in Eugene, Oregon
Board-Certified Nutrition Specialist
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Personalized Nutrition Therapy for Metabolic Dysfunction and Cancer Care
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Reference:
Kaczor, T., & Kaczor, A. (n.d.). Vitamin K and Osteoporosis. Retrieved June 13, 2020, from https://www.naturalmedicinejournal.com/journal/2009-09/vitamin-k-and-osteoporosis
Vitamin K-2: Functions, sources, benefits, and deficiency symptoms. (n.d.). Retrieved June 13, 2020, from https://www.medicalnewstoday.com/articles/325059
Learn signs of vitamin K deficiency. (n.d.). Retrieved June 13, 2020, from https://ada.com/conditions/vitamin-k-deficiency/
Sato, T., Schurgers, L., & Uenishi, K. (2012, November 12). Comparison of menaquinone-4 and menaquinone-7 bioavailability in healthy women. Retrieved June 13, 2020, from https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3502319/
Sato, T., Schurgers, L., & Uenishi, K. (2012, November 12). Comparison of menaquinone-4 and menaquinone-7 bioavailability in healthy women. Retrieved June 13, 2020, from https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3502319/