Vitamin K is the up and coming vitamin of choice, but it should really be thought of as two vitamins. Poor advice is leaving people potentially well below their optimum peak health intake, so read on to find out what to eat and buy.
Vitamin K’s primary purpose in the body is enabling blood clotting, but there is growing evidence that it has functions far beyond this, including proper bone formation, vascular health and dental health.
The 2 main types of vitamin K are:
- K-1 (also known as phylloquinone or phytonadione), which is derived from plants and is the primary form in which we ingest vitamin K. It is mostly used for blood clotting. This is the most talked about form of vitamin K.
- K-2 (menaquinone), can be produced by the intestines from K-1 and is the main storage form in humans. K-2 is used in the calcification of bones, as well as cardiovascular, skin, brain, and prostate health. The main form of K-2 that you will find in supplements is ‘MK-7′, but you may also see ‘MK-4′.
Although K-1 can be converted to K-2 in the body, there is evidence that the two should be treated as separate vitamins. From here:
However, although animals can convert vitamin K1 to vitamin K2, a significant amount of evidence suggests that humans require preformed K2 in the diet to obtain and maintain optimal health. The strongest indication that humans require preformed vitamin K2 in the diet is that epidemiological and intervention studies both show its superiority over K1. Intake of K2 is inversely associated with heart disease in humans while intake of K1 is not (Geleijnse et al., 2004, pp. 3100-3105), and vitamin K2 is at least three times more effective than vitamin K1 at activating proteins related to skeletal metabolism. (Schurgers et al., 2007) And remember that in the study on vitamin K2′s role in treating prostate cancer, which I mentioned at the beginning of this article, vitamin K1 had no effect.
Vitamins D and K: the wonder duo
Vitamins D and K work in unison in the body, with the vit D ‘using up’ the supply of vit K in the body. There is some evidence that the more vitamin D you intake, the more vitamin K-2 you need. In fact, the toxicity asssociated with very high doses of vitamin D could actually be a vitamin K deficiency caused by the vitamin D, although this hasn’t been confirmed yet. If your K-2 levels are too low in comparison to your D levels, you run the risk of calcification of your arteries instead of your bones, increasing the risk of a heart attack. This is especially true for athletes and body-builders who take calcium and vitamin D supplements.
Given the potential benefits of high D dosage, you should seriously consider keeping your K-2 intake up as well. I have seen anecdotal reports of high doses of these two vitamins even repairing tooth decay.
Vitamin A reduces K antagonism
There is evidence that vitamin A also works in conjunction with D and K, and that vitamin A will reduce the vitamin K deficiency caused by high doses of vitamin D. You can find a much more in depth discussion here:
Overall, then, we see that both vitamins are needed for optimal health. Vitamin A alone did nothing to benefit the kidneys or the lungs. Vitamin D alone caused a remarkable reduction in the ability of carcinogens associated with cigarette smoke to induce lung cancer but itself caused kidney stones. When vitamin A was combined with vitamin D, lung cancer was improved just as much, and the kidney calcification was completely eliminated. Moreover, the activation of vitamin K-dependent proteins in the kidney was much stronger with both vitamins than with neither treatment, suggesting that the vitamin A not only “antagonizes” vitamin D toxicity in the kidney, but that the two vitamins synergistically improve kidney health.
Vitamin E may antagonise vitamin K
Consumption of high doses of vitamin E may cause a reduction in vitamin K availability, so bear this in mind if taking E supplements and consider increasing your K intake.
High-dose vitamin E supplementation increased PIVKA-II in adults not receiving oral anticoagulant therapy. The clinical significance of these changes warrants further investigation, but high doses of vitamin E may antagonize vitamin K.
Vitamin K Peak Health Dose
Most people eat just enough vitamin K per day to meet the recommendations from health bodies (between 75 µg and 120 µg) and ‘deficiency’ is rare.
These minimums are really just what you need so that you don’t bleed to death from a cut though. Optimal levels, especially if you have a high level of vitamin D, should be much higher. Also, these recommendations don’t differentiate between K-1 and K-2, both of which are needed for optimal health benefits. However, it’s difficult to find comprehensive research on the optimum doses.
The Center for Better Bones advises that ‘for optimization of the bone protein osteocalcin adults would do well with a daily K1 intake of 1000 µg‘.
In her book Vitamin K2 and the Calcium Paradox: How a Little-Known Vitamin Could Save Your Life, Dr. Kate Rheaume-Bleue suggests taking 100-200 µg of vitamin K2 for every 1,000 IUs of vitamin D you take. If you are aiming for peak health, chances are you are getting anything from 4000-10,000 IUs of vitamin D per day, so aiming for 1000µg of K-2 would cover this.
The body stores a limited amount of excess Vitamin K, so daily intake isn’t an absolute necessity but is preferable.
There is no evidence of any issues caused by high doses of vitamin K.
Getting vitamin K from food
It’s possible (but not easy) to get high doses of K-1 just from your diet, even if you are aiming to achieve over 500 µg per day. K1 is found in many dark green leafy vegetables.
K2 (as MK-4) is produced by bacteria in fermented foods such as cheese, but you can also get it from eating lots of free range chicken. You can get MK-7 from Natto, which apparently tastes too nasty for most people. Getting a high dose of K-2 just from food is going to be very difficult.
Research has shown that the body more easily absorbs vitamin K from supplements than from food, but this might be to do with its fat soluble nature – don’t forget to eat some fat while eating your kale; a bit of grass fed butter melted over the top, for example.
Foods high in vitamin K-1
- One cup of cooked kale (135g) has more than 1,000 µg.
- A cup of cooked spinach (185g) has more than 800 µg.
Foods high in vitamin K-2
- Natto. most K-2 supplements are derived from this, but no one really eats it! Around 750-1,000μg per 100g
- Gouda and Edam cheese = about 75µg per ounce (28g)
There may also be reasonable amounts of K-2 in chicken (15-35µg per 100g) and beef but it will depend on the diet of the animals. Battery farmed and grain fed animals will have much lower K-2 concentrations.
There are small amounts in egg yolks (2.8µg per egg), butter and soft cheese too, and these all add up during the day which is why most people meet the RDA.
There is a full table of K-2 in food concentrations here.
Supplement Buyer’s Guide (contains affiliate links)
The quantity of vitamin K included in supplements seems to vary considerably, starting at around 100 µg (micrograms, sometimes written as mcg) . 100µg is less than you should be getting daily from a decent diet, and a good multi-vit such as OPTI-MEN has 75µg in it anyway. Therefore, if you are going to splash the cash on a separate supplement, I would be looking for something with 500 µg of both K-1 and K-2 as a minimum; and there don’t seem to be many offering this.
Many supplements only offer one version of vitamin K (usually K-2), so check the label to make sure that K-1 and K-2 are both included. Alternatively, if you can find them cheaply enough, you can buy separate K-1 and K-2 supplements. These are the only supplements I can find out there offering high levels of K:
This contains 100omcg of K-1, 1000mcg of K-2 (MK-4) and 200mcg of K-2 (MK-7), costing $19.81 for 90 days’ supply. In the UK it costs £15.13.
This is K-1 only, but very cheap at $5.22 for 100 tablets. You pay £8 for 200 in the UK.
$15.83 for 60 K-2 pills.
- The Daily Value (DV) set by the FDA for vitamin K is 80 µg (micrograms).
- The Institute of Medicine recommends an RDA (Recommended Dietary Allowance) of 120 µg for men and 90 µg for women.
- In the UK, the RDA (Recommended Daily Allowance) is 75 µg for adults.
Things that may lead to vitamin K deficiency include:
- Health problems that can prevent your body from absorbing vitamin K, such as gallbladder or biliary disease, cystic fibrosis, celiac disease, and Crohn’s disease
- Liver disease
- Taking blood-thinners, such as warfarin (Coumadin)
- Long-term hemodialysis
- Serious burns
- http://articles.mercola.com/sites/articles/archive/2011/03/26/the-delicate-dance-between-vitamins-d-and-k.aspx (take with a pinch of salt!)