Investing in Nutrient Dense Food: Vitamin K
In Nutrition and Physical Degeneration, Dr. Weston A. Price repeatedly refers to an 'Activator X', a nutrient he knew existed in certain foods eaten by the traditional societies he studied and that served a very important purpose in the development and maintenance of healthy, straight teeth, but that hadn't been identified at the time his book went to print. Price's Activator X turned out to be vitamin K2, a group of fat soluble vitamins that, along with vitamin K1, make up the naturally occurring forms of vitamin K. As I've done for previous posts focusing on vitamin A and vitamin D, this post will offer some background information on vitamin K and attempt to offer cost-effective strategies for acquiring this vital nutrient.
Vitamin K1 is the plant-derived form of vitamin K, and is known by the chemical name phylloquinone [1, 2]. Vitamin K2 comes in many forms, all collectively called menaquinones, which can be manufactured from vitamin K1 in the body to limited degrees and can be acquired directly from animal foods. Vitamin K1 is used to modify proteins to help blood coagulate, while K2 aids in bone mineralization, cell growth and also protects against heart disease, cancer and other degenerative diseases [3, 4, 5].
The graph below shows the cost of meeting a daily allowance of 100 μg of vitamin K via a variety of foods. All nutritional information is from the USDA's National Nutrient Database except butter and goose liver, which are taken from Schurgers & Vermeer (2000) [6, 7]. Prices for different foods were recorded at recent visits to my local farmers' market or grocery cooperative and represent pasture raised animals and certified organic fruits and vegetables.
My analysis of vitamin K requires more caveats than those for previous analyses of vitamins A and D. Vitamin K1 is most cost-effectively acquired from plant foods, particularly deep green leafy vegetables like kale, spinach, swiss chard and even romaine lettuce, all of which offer a daily allowance of the vitamin for under $1 per day even when paying the price premium associated with buying certified organic. Vitamin K1 does serve blood clotting functions in the human body, but it can't support bone mineralization and disease resistance like vitamin K2 does. The USDA's National Nutrient Database generally doesn't differentiate between vitamin K1 and K2, which is bothersome since the two vitamins carry out very different functions in the body and our bodies don't readily convert K1 into K2. Data on the vitamin K2 contents of food is sparse, although organs such as brain, liver, kidney and pancreas can serve as good sources, along with grass fed dairy products and some fermented foods [7, 8].
USDA data on the vitamin K2 content of animal foods suggests few good sources, but realize that most animal food samples analyzed were likely from confined feedlot animals whose diets are dominated by grain and are likely low in vitamin K1, which many other animals can readily transform into K2. Thus, data in the USDA's National Nutrient Database isn't representative of the vitamin K2 that animals foods could have if raised well, obviously undermining my analysis of cost-effectiveness. This issue rings true for vitamins A and D as well, although I suspect for these prior vitamins it makes less of a difference.
My guess is that those who are willing to invest in grass fed meats, eggs and dairy products have better access to vitamin K2 than those who choose conventional grain fed products, particularly those who eat organs like brain, pancreas, kidney and liver, all of which seem to concentrate the nutrient. Pastured poultry organs - especially liver - seem to be particularly good sources . Vitamin K2 deficiency is likely a huge issue throughout modern society by virtue of the low quality foods that pervade our food system, and I hope that research on this important vitamin is made available in the near future to better guide us towards more cost-effective sources of this nutrient.
- Vitamin K Overview. University of Maryland Medical Center.
- Vitamin K. Micronutrient Information Center, Linus Pauling Institute, Oregon State University.
- S. Plaza & D. Lamson (2005) Vitamin K2 in bone metabolism and osteoporosis. Alternative Medicine Review, Vol. 10, Pgs. 24-35.
- J. Geleijnse, et al. (2004) Dietary intake of menaquinone is associated with a reduced risk of coronary heart disease: The Rotterdam Study. The Journal of Nutrition, Vol. 134, Pgs. 3100-3105.
- H. Tokita, et al. (2006) Vitamin K2-induced antitumor effects via cell-cycle arrest and apoptosis in gastric cancer cell lines. International Journal of Molecular Medicine, Vol. 17, Pgs. 235-243.
- National Nutrient Database for Standard Reference. United States Department of Agriculture, Agricultural Research Service.
- L. Schurgers & C. Vermeer (2000) Determination of phylloquinone and menaquinones in food. Haemostasis, Vol. 30, Pgs. 298-307.
- H. Thijjsen and M. Drittij-Reijnders (1996) Vitamin K status in human tissues: tissue-specific accumulation of phylloquinone and menaquinone-4. British Journal of Nutrition, Vol. 75, Pgs. 121-127.
Teaser image: Wikipedia/Borenkool/CC BY-SA 3.0
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