I know what you're thinking: Okay, I can avoid trans fat, but what if I can't find pastured eggs and dairy products? Am I doomed to a life of wrinkles and varicose veins? No, you are not. While we are waiting for the supply of foods from grass-fed sources to catch up to the demand, there are other food sources of menaquinone that will help satisfy our need for K2. Before we delve into what those sources are, it is useful to know about two main forms of menaquinone found in food. They both provide the benefits we seek from K2, but they are found in different types of food.
In Chapter 2 I mentioned that we get vitamin K2 from two sources, diet and intestinal bacteria, but that the latter contributes only a negligible amount to our K2 status. In other words, the amount of K2 synthesized by bacteria in the human intestines won't save humans from K2 deficiency. However, there are other microorganisms in nature that produce K2 very efficiently, providing us with menaquinone-rich foods, namely certain types of cheeses and a Japanese
soy food called natto. The two main food sources of K2—animal and bacterial
—each supply a different type of menaquinone.
The kind of K2 synthesized by mammals and found in grass-fed meat, egg yolks and butter is called menaquinone-4, or MK-4 for short. It is so named because the molecular structure of this form of K2 has a hydrocarbon “tail”
that contains four double bonds. Bacterial fermentation, on the other hand, produces a range of other menaquinones, designated MK-5 to MK-10, depending on the specific microorganism in the food. Of these, menaquinone-7, or MK-depending on the specific microorganism in the food. Of these, menaquinone-7, is especially important. Its structural tail contains seven double bonds, and it is the primary menaquinone found in the superfood natto. Don't bother stretching your brain back to high school chemistry to remember the significance of double bonds. Just know that the structures of MK-4 (animal origin) and MK-7 (bacterial origin) vary slightly and this structural variance confers different properties to each form of menaquinone. These properties will become more important when we discuss choosing a supplement later in this chapter. The health benefits are the same for each type when taken in appropriate doses.
Molecular structure of menaquinone-4 (MK-4)
Molecular structure of menaquinone-7 (MK-7)
Vitamin K2 content of selected foods
Food (3 1/2 ounce portion) Micrograms Proportion of vitamin Ks
Natto 1,103.4 (90% MK-7, 10% other
MK)
Goose liver pâté 369.0 (100% MK-4)
Hard cheeses (Dutch Gouda style) 76.3 (6% MK-4, 94% other MK)
Soft cheeses (French Brie style) 56.5 (6.5% MK-4, 93.5% other
MK)
Egg yolk (Netherlands) 32.1 (98% MK-4, 2% other MK)
Egg yolk (Netherlands) 32.1 (98% MK-4, 2% other MK)
Goose leg 31.0 (100% MK-4)
Egg yolk (U.S.) 15.5 (100% MK-4)
Butter 15.0 (100% MK-4)
Chicken liver (raw) 14.1 (100% MK-4)
Chicken liver (pan-fried) 12.6 (100% MK-4)
Cheddar cheese (U.S.) 10.2 (6% MK-4, 94% other MK)
Meat franks 9.8 (100% MK-4)
Chicken breast 8.9 (100% MK-4)
Chicken leg 8.5 (100% MK-4)
Ground beef (medium fat) 8.1 (100% MK-4)
Chicken liver (braised) 6.7 (100% MK-4)
Hot dog 5.7 (100% MK-4)
Bacon 5.6 (100% MK-4)
Calf's liver (pan-fried) 6.0 (100% MK-4)
Sauerkraut 4.8 (100% mixed MK)
Whole milk 1.0 (100% MK-4)
Salmon (Alasksa, Coho, Sockeye, Chum and King wild
(raw)) 0.5 (100% MK-4)
Cow's liver (pan-fried) 0.4 (100% MK-4)
Egg white 0.4 (100% MK-4)
Skim milk 0.0
Sources: Schurgers LJ, Vermeer C. Determination of phylloquinone and menaquinones in food. Effect of food matrix on circulating vitamin K concentrations. Haemostasis. 2000 Nov-Dec, 30(6):298-307;
Elder SJ, Haytowitz DB, Howe J, et al. Vitamin K content of meat, dairy and fast food in the U.S. diet.
J Agric Food Chem 2006, 54:463–67.
Now that you know about the different types of K2, you can understand why some foods, like cheese, are happily higher in menaquinone than you might expect. Whole milk from your average grain-fed cow contains a paltry 1.0 micrograms of K2 per 100 milliliters. Cheese made from that milk can be as high as 76.3 micrograms per 100 grams. That's because bacterial fermentation augments the K2 content. In this example only, about 6 percent of the menaquinone content is from the milk that went into the cheese;
bacteria generously provided the rest. The “other MKs” (other menaquinones) in the list refer to MK-5 through MK-9, the range of long-chain forms of vitamin K2 produced by bacteria. According to our current understanding, they all have the same health benefits.
Notice that egg yolks in the Netherlands contain more than double the K2 of American (and presumably Canadian) egg yolks. That reflects feed quality and the fact that the average Dutch chicken is more likely than her North American counterpart to spend some time in the great outdoors. Another unmistakable trend is the very high K2 content of rich, indulgent “sin” food like goose liver and fatty cheeses. This explodes the alleged contradiction between the indulgent consumption of rich food in European diets and the relatively low rate of heart disease in Europe. The French Paradox isn't a paradox at all. The very same pâté de foie gras, Camembert, egg yolks and creamy, buttery sauces that we inaccurately labeled “heart attack on a plate”
liberally supply the single most important nutrient to protect heart health.
Good news for the bon vivants among us.
On a less gourmet note is the K2 content of frankfurters and hot dogs. I debated long and hard as to whether these entries should be included in the list. I'm not trying to encourage people to rely on or justify eating these highly processed, nitrate-laden items for their slight K2 content. I ended up including them to make the point that the unexpected menaquinone content might very well reflect the higher amounts of K2-rich organs that go into these “mystery meats.”