Pseudoxanthoma Elasticum:
Are Vitamin K, Its Precursors and Metabolites
the New Kids on the Block?

Listen

click to listen ( 1148.7KB)

By Berthold Struk, MD, PhD

Evidence from ABCC6 (-/-)

  • Mice Tissue calcification in PXE results from loss of function of ABCC6 in the liver

  • The phenotype can be rescued by transplantation of normal liver cells (from wild type mice) into the knockout mouse

Metabolic Disease Hypothesis

  • Tissue calcification is due to the absence of a plasma factor secreted from the basolateral hepatocyte membrane due to loss of function of ABCC6 

  • The missing plasma factor could be vitamin K, a vitamin K precursor or a vitamin K metabolite

    • since vitamin K is an important co-factor for the gamma-carboxylation of gla-proteins, that in the carboxylated form prevent tissue calcification. 

GLA-Proteins

  • Prevent tissue calcification

    • if they are carboxylated

  • GLA-proteins are the

    • Vitamin K-dependent clotting factors II, VII, IX and X (liver

    • osteocalcin

    • matrix gla-protein (MGP)

Matrix GLA Proteins

  • excretion by vascular smooth muscle cells (VSMC)

  • it is poorly soluable and remains close to VSMC

  • associated with liver-derived alpha-fetuin

History of K-Vitamins

  • The chemical substance class of "quinones"

    • was known since at least 1910

    • their ability to oxidize iodide to iodine

    • iodometric determination 

  • Iodometric determination

    • was used for the determination of the content of quinones in different

      • animal tissues

      • foods

  • Iodometric determination

  • quinone + hydriodic acid → reduced quinone + iodine
    I2 (Iodine) + Starch Blue Color

  • 1945 Weston Price described a new vitamin-like activator

    • influential on utilizing minerals

    • protecting against tooth decay

    • protecting against heart disease

    • important for growth, development, reproduction and function of the brain

Chemical Structure of Vitamin K Precursors and Metabolites

Vitamin K dependent carboxylation of GLA-proteins

  • the Vitamin K-dependent gamma-glutamyl carboxylase (GGCX)

    • rearranges the chemical bonds within carbon dioxide by creating a carboxyl group

    • adds such carboxyl group as second group to the side chain of the amino acid glutamate and transforms it into c­carboxyglutamate

  • the process is called c—carboxylation

Natural Sources of K Vitamins

  • butterfat

  • organs and fat of animals consuming rapidly growing green grasses

  • sea foods such as fish eggs

  • fermented food (hard cheeses, sauerkraut, natto)

Vitamin K2 Content of Selected Foods
(micrograms per 100 gram serving)

FOOD

VITAMIN K2

(mcg/100g)

Natto

1103.4

(0% MK-4)

Goose Liver Paste

369.0

(100% MK-4)

Hard Cheeses

76.3

(6% MK-4)

Soft Cheeses

56.5

(6.5% MK-4)

Egg Yolk ( Netherlands )

32.1

(98% MK-4)

Goose Leg

31.0

(100% MK-4)

Curd Cheeses

24.8

(1.6% MK-4)

Egg Yolk ( United States )

15.5

(100% MK-4)

Butter

15.0

(100% MK-4)

Chicken Liver

14.1

(100% MK-4)

Salami

9.0

(100% MK-4)

Chicken Breast

8.9

(100% MK-4)

Chicken Leg

8.5

(100% MK-4)

Ground Beef (Med Fat)

8.1

(100% MK-4)

Bacon

5.6

(100% MK-4)

Calf Liver

5.0

(100% MK-4)

Sauerkraut

4.8

(8% MK-4)

Whole Milk

1.0

(100% MK-4)

2% Milk

0.5

(100% MK-4)

Salmon

0.5

(100% MK-4)

Mackerel

0.4

(100% MK-4)

Egg White

0.4

(100% MK-4)

Skim Milk

0.0

 

Fat-Free Meats

0.0

 

What is Natto?

  • Nattō (なっとう or 納豆?) is a traditional Japanese food made from fermented soybeans, popular especially for breakfast

  • As a rich source of protein, nattō and the soybean paste miso formed a vital source of nutrition in feudal Japan

  • For some, nattō can be an acquired taste due to its powerful smell, strong flavor and sticky consistency

  • In Japan nattō is most popular in the eastern regions, including Kantō, Tōhoku, and Hokkaido .

  • Nattō is made from soybeans, typically a special type called nattō soybeans.

    • Smaller beans are preferred, as the fermentation process will be able to reach the center of the bean more easily.

    • The beans are washed and soaked in water for 12 to 20 hours. This increases the size of the beans.

    • Next, the soybeans are steamed for 6 hours, although a pressure cooker can be used to reduce the time.

    • The beans are mixed with the bacterium Bacillus subtilis natto, known as nattō-kin in Japanese.

    • From this point on, care has to be taken to keep the ingredients away from impurities and other bacteria.

    • The mixture is fermented at 40°C for up to 24 hours. Afterwards the nattō is cooled, then aged in a refrigerator for up to one week to add stringiness. During the aging process at a temperature of about 0°C, the Bacilli develop spores, and enzymatic peptidases break down the soybean protein into its constituent amino acids.

Vitamin K2 Supplements
(ASK YOUR PHYSICIAN FIRST!)

Editor’s Note – Dr. Struk urges NAPE readers to tap into and read more about Vitamin K at the following website which provides much useful detail:
http://www.westonaprice.org/basicnutrition/vitamin-k2