Vitamin K & Health
This week, we will be wrapping up our exploration of the fat soluble vitamins: Vitamins A, D, E, and K. After this week, I will be taking a much-needed break in these weekly articles which I have continuously published for the past year and a half: 80 weeks in a row folks! This will allow me some time to catch up on my research and writing, get through some upcoming travels, and quite honestly enjoy a bit more of my personal life.
I will return to weekly offerings in October when we will dive into Vitamin C.
In the meantime, be sure to play catch up while I’m gone. There are all of this year’s nutrition articles as well as last year’s herbal medicine articles. I’m sure there will be plenty for you to ponder and play with until my return!
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On to vitamin K!
What is Vitamin K?
Vitamin K is the name given to a family of molecules known as phylloquinone (K1) and menaquinones (K2). These are fat soluble vitamins, which means they are found in fat and absorbed with fat.
What does Vitamin K do?
Vitamin K was first discovered in its role in blood clotting and got its name from the German word “koagulation” (1). Since this discovery, we have found vitamin K to have roles in bone health and the prevention of tissue calcification. All three roles are quite important!
Blood clotting:
Vitamin K is needed in order for us to form blood clots, and blood clots are needed to prevent us from bleeding to death from every minor injury. Without the ability to clot, blood -- once released -- would continue to flow due to our blood pressure. Those on blood thinning medications such as warfarin are on high alert for signs of excessive bleeding and regularly have their bleeding times measured to ensure their treatment is effective - but not too effective.
Vitamin K is needed at several different steps in what is known as the blood clotting cascade. This is a series of biochemical reactions needed in order to form a blood clot. Warfarin, our most common anticoagulant treatment, interferes with the function and recycling of vitamin K within our bodies.
Bone health:
Vitamin K works hand-in-hand with vitamin D to move calcium into our bones, increasing our bone mass density - a measure of bone strength. Vitamin K also plays a role in creating mature calcium hydroxyapatite crystals - the stable form of calcium found within the lacey matrix of our bones.
Without vitamin K, no amount of calcium, phosphorous, boron, or other bone mineral supplementation will result in strong, healthy bones. We need vitamin K (along with vitamin D) to create the proper bone structure that combines the flexibility and tensile strength of our bone proteins (collagen) with the hardness and resistance to compression (our hydroxyapatite mineral structure).
Prevention of tissue calcification:
While calcification of our bones is a good thing, calcification of our skin, cartilage, eyes, and blood vessels is not. Vitamin K plays an important role in preventing calcium from moving into these tissues and creating long-term problems that can include cardiovascular disease, bone spur formation, and visual disturbances.
Where do I Find Vitamin K?
The simple answer is green leafy vegetables! In fact, one cup of kale will give you about four days worth of vitamin K1. (1)
But, to answer more completely, we need to differentiate between vitamin K1 and K2. K1 is found in plants and most abundantly in leafy greens. K2 is found in animal liver as well as fermented foods. The Japanese staple of fermented soy beans known as natto is a particularly rich source of K2. Our intestinal flora also create vitamin K2 for us, but we aren’t yet sure how well this is absorbed or if it plays more of a local role in our digestive tract.
Before you get excited and decide to eat a cup of kale twice a week and call it good, we do need to touch on storage. Our bodies do not store vitamin K well. They do recycle this important nutrient, but we still need to consume it daily. Twice a week salads won’t work.
Applications:
We see vitamin K playing multiple roles:
Allowing our blood to clot and preventing us from bleeding out from a paper cut
Moving calcium into our bones and helping us form strong and resilient bones
Keeping calcium out of tissues where it doesn’t belong and would cause trouble
We see green leafy vegetables as our best source of vitamin K, and we also have come to understand that we need to eat these daily for optimal vitamin K intake.
Our next topic to investigate is supplementation. Unfortunately for those who would rather get their vitamin K in through supplements, the research is not in your favor. What we do see is dietary vitamin K increasing bone mineral density, reducing fracture risk and reducing cardiovascular disease.
We do see intramuscular injections of vitamin K1 at birth reducing deaths related to intracranial bleeding in newborns. There was worry that this practice may increase risk of cancer in children; fortunately, large studies in the US and Sweden found no relationship between vitamin K injections and cancer in children.
Taking all of this into consideration, what would a person interested in maintaining adequate levels of vitamin K be advised to do? It is as simple as eating a single cup of green leafy vegetables daily. These can be cooked or raw. Not only will those greens provide ample vitamin K, you will also be ingesting ample amounts of folate, beta carotene (vitamin A), vitamin C, magnesium, potassium, calcium, manganese, fiber, protein, and iron. That’s just from the leaves themselves, imagine what else you are benefiting from when you eat those greens as part of a meal!
I will end this article with a quote from the Linus Pauling article on vitamin K that helps put the role of food into perspective:
“[B]ecause green leafy vegetables are the primary dietary source of phylloquinone [K1] and because they are usually part of a balanced diet, high phylloquinone consumption may be just and indicator of healthy eating habits which may, rather than phylloquinone itself, account for all or part of the association reported in observational studies.”
These observations were an association between high vitamin K intake and lower rates of hip fractures. We study vitamins and minerals along with macronutrients to better understand the biochemistry of nutrition and disease, but we don’t eat these individual nutrients, we eat food. Let’s not miss the forest for the trees by over-emphasizing individual nutrients and ignoring our relationships with food.
To our health!
References:
Higdon, J, Vitamin K, Linus Pauling Micronutrient Center, 2000, updated 2014, Vitamin K | Linus Pauling Institute | Oregon State University accessed 7/12/2021
