Holy samoly, this was clotting disorders week in my office! Undoubtedly this is a "sign" that it's time for me to introduce you to the "forgotten vitamin" – Vitamin K. Check your mental Rolodex card for this one – if you're like most people, um, you're pretty much tabula rasa. So let's fill in for you – Vitamin K is as essential to a happy healthy life as Kisses!
Vitamin K is elegant. It helps you build a sturdy skeleton AND will keep you from bleeding to death – which you might be more likely to do in the upcoming leafy, active, climb-on-the-roof seasons. Mother Nature put this simple fat-soluble vitamin right into leafy green vegetables – which you are designed to yearn for especially in the spring – and bacterially-fermented foods which, if your fridge looks like mine in gardening season, does not pose a problem. Anyway, this is
an ancient system, and robust.
In blood and bone, Vitamin K is essential for getting calcium connected to protein molecules. It's like a chemical claw – molecular Velcro, maybe. For instance, you need K to form a special bone-building protein called osteocalcin, which glues calcium into the bone matrix. In the Nurses' Health Study (which looked at 72,000 women for 10 years and is probably the best nutritional epidemiologic study we have), women whose vitamin K intakes were in the lowest fifth had a much
higher risk of hip fracture than women with higher intakes.
Vitamin K is also an essential ingredient in the "coagulation cascade." It draws calcium into this system to serve as an "on" switch for a bunch of clotting chain reactions, while the K itself participates in a different but related wing of your almost unbelievably intricate blood clotting system.
Folks on blood-thinning medications (like Coumadin or warfarin) are told to be very consistent about the amount of green vegetables they eat each day, because too much green stuff will counteract the anti-clotting power of the drug. (Back when I was in school, they were told not to eat any green vegetables at all! I'm SO this has evolved. I mean, come ON!)
But don't be afraid that eating lots of greens will turn your blood to sludge – Vitamin K also has an anti-clotting capacity that normally holds that whole system in balance and able to respond appropriately to the situation on the ground. (We also look to aspirin and Omega-3 fats for some of this effect, right?) So if you got scared, there you can let that go.
The other good sources of Vitamin K are soybeans and fermented foods like sauerkraut and kimchee and natto – not particularly heavy hitters at the Piggly Wiggly. (I mean, do you even know what natto IS?)* And even if you do love sauerkraut, unless you make it yourself or specifically look for unpasteurized brands, it's been heated, and all the K-providing bacteria are dead. (SOB!)
People who have used antibiotic therapy a lot or for a long time, or who have digestive problems that interfere with nutrient absorption may also be at risk for Vitamin K deficiency. Vitamin K metabolism is altered after menopause, too, so women need to increase their intake as they get older.
In nature's plan, you get your first dose of Vitamin K from the bacteria you ingest while you are being born. These friendlies colonize your gastrointestinal tract and evolve into that critical inner ecosystem you need to digest your food and support your immune system. (Often we disrupt this process with the increasing use of antibiotics in labor and delivery methods which do not involve the vagina, then compound the problem with overuse of antibiotics in general. But I
Indeed, unless the parents refuse it, hospital-born babes in the US are pretty routinely given a shot of Vitamin K to prevent brain bleeding since they have an "immature" clotting system and human breast milk is "deficient" in Vitamin K as compared to infant formula. (Does it make sense to you that Mother Nature might have gotten this essential safety mechanism so wildly wrong, when everything else about the reproduction of the species is so blindingly, perfectly elegant?
But I digress.)
Look at this gorgeous list of springy greens which are loaded with Vitamin K: kale, collards, spinach, turnip greens, beet greens, mustard greens, dandelion greens, leaf lettuce, Brussels sprouts, broccoli, green onions, parsley, asparagus, and sauerkraut – one cup of any of these contain more than the RDA of vitamin K for men (120 mcg) or women (90 mcg). Notice that iceberg lettuce, the number one green vegetable consumed in the US, is not on the list – it has a quarter
of the Vitamin K found in other lettuces. Considering that you get 220 mcg in a cup of broccoli and 460 mcg in a half cup of Brussels sprouts, you can see that there may be a Natural Design that wants you to get quite a bit more than the RDA of this stuff.
This vitamin is also helpful for decreasing your risk of cardiovascular diseases, though the actual mechanism might be new to you. Typically, when we think veggies and heart disease, we think inflammation and antioxidants. (And indeed, K is a strong antioxidant.) But wait, there's more! Vitamin K regulates calcium metabolism (that "claw" thing again) and keeps you from stashing excess calcium in the walls of your blood vessels. Thus, they remain flexible and resilient. You
do not want your vascular system to be built with rocks.
Even though it's fat soluble, excessive intake of vitamin K rarely occurs. I've read that you have to eat something like 1000 times the RDA to trigger a coagulation problem. Population surveys indicate we're more likely not to be having enough (which, considering how little green stuff you need to eat to get more than plenty, is astonishing!) Probably figuring that you'll be eating it on a regular basis, the body stores very little Vitamin K.
I wouldn't be surprised if relatively soon we learn that "everything we know is wrong" about Vitamin K – sort of like what we did with Vitamin D. Well, not "wrong" so much as – "indescribably, mortifyingly incomplete."
I'm not aware of a clinically useful test for Vitamin K; I'd rather you just work on eating enough of the K-rich foods and forget about testing. Go spend that money on a farm share. In fact, I think I'll suggest that you maybe take a break from reading now, and go have a big gorgeous fresh salad! Be sure to use real salad dressing – since it's a fat-soluble vitamin, you'll absorb more K if you eat it with a fat source, like olive oil. Yum!
*Natto is also known as vegetable cheese; it's made from fermented soybeans and is a traditional medicinal superfood in Japan.