This is page 3 of an 8-page Article. Please begin at Page 1 here, to fully understand how vitamin K2 gives you strong bones & teeth.
How Much K1 & K2 Do You Need?
The RDI for vitamin K1 is set at 90 mcg for women and 120 mcg for men (RDI = Recommended Daily Intake).
No study to date has calculated the RDI for vitamin K2.
You need only a small amount of K1 for blood to clot — but far more K2 to activate all those K2-dependent proteins that keep at bay osteoporosis, arterial calcification, senility … see Dr. Kate’s chart for the wide variety of work these proteins do!
Dr. Kate suggests 100 mcg of K2 a day in her book. Later in her youtube interview with Dr. Mercola she advises 200 mcg/day. When she was pregnant, she took 300 mcg a day.
Dr. Mercola’s K2 supplement (#ad) is 150 mcg. Uniquely it’s made from fermented organic chickpeas and not from soya.
In this article, I guesstimate that 200 mcg/day of K2 is the amount we need. That’s double the RDI for K1.
No known toxicity is linked to high doses of K1 or K2, so no tolerable upper intake level (UL) has been set. Unlike the other fat-soluble vitamins, vitamin K is not stored in any significant quantity in the liver.
However, you must remember that taking any supplement will upset the balance in your metabolic pathways.
The Different Forms of Vitamin K2
The two food sources of K2 — animal and bacterial — each supply a different form of menaquinone.
Animals, birds, and algal-eating fish synthesize K2 from K1. The K2 they produce — in grass-fed organ meat, butter, egg yolk, and in fish eggs — is MK-4 (menaquinone-4). It has a hydrocarbon tail with four double bonds.
Bacteria produce, via fermentation, a range of other menaquinones, MK-5 to MK-10, depending on which bacterium is fermenting the K2.
MK-7 (menaquinone-7) is the one you get in natto. It has a longer tail of seven double bonds.
To date no one knows if MK-4 or MK-7 is better for your health. Or if both are needed. Both forms are equally effective at activating K2-dependent proteins.
It’s claimed only 5-10% of the K1 you eat is absorbed and reaches your blood. With K2 the absorption rate of both forms — MK-7 in fermented food and MK-4 in animal tissue — is nearly 100%.
Fermented Plants: Vegan Source of Vitamin K2
You can’t jump to the conclusion that all fermented foods have vitamin K2. Sadly, they don’t.
Really you need a home K2-test kit to check how much K2 is in a fermented food. We don’t have that yet.
Four variables affect the fermenting process:
- the Starter Culture — the bacteria or yeast you use to do the actual fermenting;
- the Substrate — the food you’re fermenting, such as milk or cabbage;
- the Container — and the factory if it’s not home-made;
- the Environment — such as temperature and air-borne bacteria.
Let’s take a look at each variable as it affects K2.
1. The Starter Culture
You must begin with a starter culture of K2-producing bacteria. The most commonly available one is Bacillus subtilis (natto). It will ferment soya beans into a stinky slimy dish called natto.
We know that many Gram-positive bacteria — such as lactic acid bacteria and other anaerobic ones — can be K2-producing (MK-7 to MK-10).
But here’s the problem. Even when bacteria belong to the same species, one strain will produce K2 and another will not. Nagai reports that B. subtilis (natto) and B. subtilis are the same species. Yet only B. subtilis (natto) can make natto (and hence K2).
Similarly, a 1999 study found that of the 21 strains of lactic acid bacteria they tested, only five could produce vitamin K2.
Even those five aren’t so hot. They gave 29 to 123 mcg of K2 (as MK-7) per liter. Who drinks a liter of fermented soya milk a day? It’d be unhealthy. It’s a machine-made food. The goal is to eat food from Nature.
Bottom line, you can’t assume the bacteria you use to ferment soya milk into yogurt, are happily making K2. You simply don’t know if it’s a K2-producing strain or not.
By the way, when I lived in New York, I found that EdenSoy Organic Original Soymilk (#ad) and Solgar’s Advanced Multi-Billion Dophilus with FOS (#ad) made the best vegan soya yogurt. In South Africa where I live now, there’s no EdenSoy.
As for vegetables, you can NOT rely on the bacteria on the vegetables themselves, and in the air, to produce K2. This is clear from the low K2 content of sauerkraut — 4.8 mcg of K2 per 100g. That’s virtually none.
The good news is that Dr. Mercola offers a K2-producing starter culture, called Kinetic Culture (#ad).
You use one packet of his Kinetic Culture (#ad) for each quart-sized jar of fermented veggies.
Dr. Mercola’s staff emailed me that, when his recipe is followed, there will be 4.85mcg of K2 per gram of fermented vegetables (mostly MK-7 form).
28 ounces or 800 grams of veggies fit a quart jar. So that gives you a whopping 3,880 mcg of K2 per jar! Since you need only about 200mcg/day, you could eat the quart jar of fermented veg over two weeks.
However, Dr. Mercola writes on his site:
“We found the levels of vitamin K2 slowly degraded over time. So it is best to consume your fermented vegetables sooner than later.”
I’d say one week is a good bet — say, 3.5 ounces or 100 grams a day. Do you recall that with natto (fermented soya beans) you need only 18g or 3/4 ounce a day? But natto is tough to swallow for most of us!
Dr. Mercola’s staff also emailed me:
“The Kinetic Culture Starter Packets are stable for up to 12 months when stored in a cool dry place. Refrigeration recommended, but not required.”
Do you live outside USA, like me? A friend, Terence, told me that he checked a written list of the strains in EM-1 (effective micro-organisms developed by Professor Teruo Higa in Japan) against a list of those in Dr. Mercola’s Kinetic Culture. He reports they’re the same.
Terence believes that if you use EM-1 to ferment your veggies, you’ll enjoy a good steady supply of vitamin K2. Sadly we can’t test it. I asked Dr. Mercola’s staff what K2 test kit he’s using (hoping to buy it myself) but his team replied:
“We are sorry, but Dr. Mercola’s research methods are proprietary and we are not able to ask him precisely how he is testing the Vitamin K2 levels … We do not have any information on how to test food for Vitamin K2.”
I now use EM-1 to ferment my cabbage and root vegetables. If I lived in the US, I’d use Dr. Mercola’s Kinetic Culture (#ad).
2. The Substrate
You can have the perfect K2-producing starter culture, yet it will produce K2 only with some foods, and not others.
The 1999 study of lactic acid bacteria found that, of the five strains they isolated as K2-producing, only two worked with reconstituted NDM (nonfat dry milk), while all five strains acidified the soymilk.
Even with the powerful K2-producing Bacillus subtilis (natto), it may work only on a specific type of soya bean! And not on any other bean.
All soya beans belong to the same species (Glycine max) but they vary in size and seed coat colors. One user of the starter culture “Mitoku Traditional Natto Spores” at Cultures for Health reports on 2/13/13 that:
“Large beans will not allow the natto spores to penetrate the bean enough … to make good natto … there is a family farm in Iowa that has started growing really honest to goodness natto soybeans… the tiny ones! Well we ordered them up right away and oh my what excellent natto!!”
Wikipedia reports that Bacillus subtilis can be used to ferment other beans, and even sesame seeds.
Cultures for Health reply in the Q&A on their Natto Spores, that you can use other beans like black beans, azuki beans, kidney beans and even sunflower seeds. “However,” they state, “Bacillus natto thrives best on soybeans. It appears that soybean’s protein helps to produce nattokinase more efficiently.”
In an email to me on 11/5/13, their team makes it clear that you don’t know if you’re getting vitamin K2 when you use anything other than soya. They write:
“Yes, our Mitoku Traditional Natto Spores are the Bacillus subtilis. You may be able to use the spores to ferment other beans, but not vegetables, as far as I know. With other beans, you may not get the slimy strands and consistency that you get when fermenting soy beans. I’m sorry, I do not have any information on possible K2 content in that case.”
Bottom line, even when you’re using a K2-producing starter culture, it (that tiny bacterium invisible to your naked eye) makes the decision whether to produce K2 for its energy needs or not, depending on the food it’s working on.
Other fermented soya products, like miso and tempeh, are not good K2 sources.
3. The Container
For natto and cheese — and hence for vitamin K2 — containers must be sterilized. That’s because you want only the specific starter culture to act on your food.
A 2012 study found that natto gets contaminated by bacteriophages if it’s not made in a highly sterilized stainless steel factory. The phages infect the bacillus. You see their teeny heads and tails under an electron microscope.
The old factories in Japan made of clay walls are the worst for contamination. The roughness of the clay makes it impossible to clean off the soya debris. The phages multiply on this debris.
I mention this because it means the nifty porous ceramic bowl you use for fermenting cabbage into sauerkraut will not work for fermenting soya beans into natto. If it’s glazed, then it may be okay.
You’ll see in this How To Make Natto recipe, that the very first step is:
“Be sure the entire process, including all utensils, pots, cheese cloth, etc. are as sterile as possible. Boil utensils for 5 minutes prior to using.”
Cheese making sites advise you to wipe all counters with a food grade sanitizer, and to boil all utensils for ten minutes.
4. The Environment
You know that fermenting is sensitive to temperature. But with K2, you also don’t want air-borne bacteria to get into your ferment.
You want only your K2-producing starter culture bacteria to do all the action.
If your natto has no slime (in scientific terms, no “viscous polymer PGA”) then you know it’s contaminated by bacteriophages, and unlikely to have vitamin K2.
Do Grains Carry a K2-producing Bacterium?
It’s my personal hypothesis that you’ll find K2-producing bacteria on all grains. And that when you ferment grains into grain milk, as the late Dr. Ann Wigmore taught us, you’re drinking vitamin K2 in good amounts.
Please don’t go write on your blog, “Val Archer of GreenSmoothie.com says you get vitamin K2 from fermented grain milks” 🙂
I don’t say that. I’m hypothesizing it! It needs to be tested empirically in a lab with a variety of grains.
What grounds do I have for my hypothesis? Both circumstantial and epidemiological evidence.
To begin, we know very few foods will naturally ferment. If you place lettuce in water, it’ll go rotten. Place cabbage in water and it ferments.
Go to the seed world. Place a seed in water and it will eventually rot. This is true of both sproutable seeds like sunflower, and non-sproutable like cashew.
Yet when you place grain seed in water, it begins to ferment, turning the water into a tangy lemony taste within two days. You can do it with both sprouted grains, like wheat, and ones that don’t sprout, like oats.
Most oat groats are steamed. Yet you can still soak and blend the oats, and leave the blend (with a little water on top) to ferment into a yogurt or sour cream.
This tells me that both cabbage and grains carry bacteria on them that will ferment their sugars into acids such as lactic acid.
In addition, the bacteria on grains are heat-stable, they survive the steaming that factories put oat groats through, to stop them from going rancid.