Vitamin K for Health
Vitamin K is an important fat-soluble vitamin for health. It consists of two main subfamilies: vitamin K1 (phylloquinone) and vitamin K2 (menaquinone). Naturally occurring forms of phylloquinone (K1) are found in green plants and vitamin K2 is synthesized from bacteria with the intestine. Vitamin K1 has an important function in blood clotting and vitamin K2 moves calcium from soft tissue into bone.
Vitamin K is:
- Essential calcium metabolism and maintenance of bone health
- Assists normal healthy blood coagulation
- Reduces bone mineral density loss in health post-menopausal women
Calcium, vitamin D & A, and estrogen are necessary to maintain bone health and even people with adequate calcium, sunlight and vitamins A & D can struggle to maintain bone health particularly in the latter years when estrogen is also lost. Vitamin D increases the need for vitamin K2 as well as increasing its benefits. Mega-dosing of vitamin D is not recommended as this can increase the risk of calcium deposits in soft tissues, another reason for more is not better! Quality of calcium and the correct nutrients is however important.
Evidence has emerged of the crucial role of vitamin K2 in maintaining health tissues. Vitamin K2 has been shown to assist calcium from blood vessels into bones and in doing so protects against cardiovascular disease whilst depositing calcium in bone and teeth. Vitamin K2 deficiency can occur within 7 days of a vitamin K2 deficient diet. Those that are considered at greater risk are those with:
- Impaired gastrointestinal absorption
- Chronically treated with antibiotics (minimising the ability of favourable gut bacteria to produce K2)
- Newborns with immature gastrointestinal systems
- Diets low in vitamin K
- Fat malabsorption disorders
- Intestinal bypass surgery
- Liver disease and pancreatitis
Vitamin K2 and Bone Health
Vitamin K2 activates certain proteins (i.e. osteocalcin) which then allows them to bind to calcium. Vitamin D is dependent on vitamin K2, and together with vitamin A stimulate the production of osteocalcin (bone forming protein) and inhibits the production of osteoclast cells which break down bone tissue. Estrogen assists vitamin D to form bone and when estrogen levels drop in menopause this activity potentially increases bone loss. It is important to supplement with K2 along with vitamin D in menopause, in the prevention of osteoporosis, although it is equally important to check vitamin D levels (vitamin D 1,25-OH2-D3) before supplementing. Although unclear osteocalcin appears to be involved in bone remodelling or calcium mobilization. Even though vitamin A assists the production of osteocalcin, more is not better. Vitamin A and E excess has been shown to antagonise vitamin K uptake (i.e. prevent absorption and metabolism). It is always about a balance with nutrients!
As vitamin K is a fat-soluble vitamin it is best absorbed with dietary fat. People who have difficulty absorbing fat generally have difficulty absorbing fat-soluble vitamins.
Menaquinones are classified according to their side chains. The longer the side chain the longer it potentially resides in the body (i.e. MK-7), which determines the uptake within the intestine and its distribution throughout the body.
The menaquinones produced by bacteria are predominantly found in animal products such as meat, egg yolk, butter, cheeses and legumes. The most well-known MK-4 is a short chain structure predominantly found in eggs, meat and liver whilst MK-7 is found in higher concentrations within fermented cheeses and in the traditional Japanese food natto (produced by Bacillus subtilis from fermented soy beans.
Cardiovascular Disease and vitamin K2
As calcium is one of the causes of hardening of the arteries, a high arterial calcium score can be measured as a potential risk of heart disease. Studies have shown that adding vitamin K2 to the diet can reduce the arterial content and increase flexibility of the arterial wall.
Interestingly in the northern hemisphere calcification is highest in the Winter months and lowest in August (Summer), due to the animal sources of vitamin K. Grass fed however not grain fed animals have higher K2 in the fat of the animal. Chickens must be fed inopen pasture to have K2 present int he yolk, conventional grain feed reduces vitamin K2 content. Processed (hydrogenated) margarine and other oils that contain cheaper versions of fats have synthetic forms of vitamin K (DHP) which studies have found contain lower amounts of K2.
Content of Vitamin K in selected Foods
Phylloquinone content ug/100g of food
|Eggs||Green beans||Brussel sprouts||Swiss chard|
|Red Meat||Kiwi fruit||Watercress|
|Tea (brewed)||Coffee (brewed)|
Cautions and Warnings
Pregnancy and lactation – all forms of vitamin K supplementation needs to be used with caution and under supervision only.
Using vitamin K in conjunction with anticoagulant medication ie. warfarin is not recommended and needs to be under supervision only.
See Karen Green your professional naturopath, nutritionist and herbalist for further support and guidance at gaininghealthnaturally.com and information here: Karen Green or information calcium read here
Gropper, S., Smith, J., and Groff, J. (2009). Advanced Nutrition and Human Metabolism, 5th ed. . CA, USA. : Cengage Learning.
K2 for Bone Health. (2016). Australia: www.bioceuticals.com.au