Vitamin K2: Benefits, Food Sources & Side Effects

Vitamin K2: Benefits, Food Sources & Side Effects

Many of us have heard about the importance of vitamin D3 and its role for strong bones and yet few have heard about vitamin K2 and its benefits for bones and the heart.  Vitamin K2 contributes to normal blood clotting & the maintenance of normal bones.

I now believe that vitamin K, especially vitamin K2, is another vitamin that is being recognised as very important as more research uncovers its amazing health benefits. Often labelled as the ‘forgotten vitamin’, this vitamin is regulated by some governments because of its health benefits and yet, it is estimated that many of us are deficient in vitamin K.

Why is vitamin K important?

Vitamin K has many benefits, including:

  • It builds strong and healthy bones.
  • Protects the cardiovascular system.
  • Prevents haemorrhage in newborn babies.
  • Fights premature ageing.
  • Enhances memory function.

What causes a vitamin K deficiency?

As mentioned above, it is estimated that large numbers of the adult population are likely to be deficient in vitamin K, so how is this possible? Firstly, vitamin K is fat soluble, so if your diet incorporates very little fat then deficiencies are very likely. Drinking even moderate amounts of alcohol can have an effect on the liver, which works in an oil environment and hence reduces the storage of vitamin K. Taking antibiotics, which affect the natural friendly bacteria in the gut that help with the absorption of vitamin K can also cause a vitamin K deficiency.

Other possible causes include cholesterol-reducing medications and even aspirin, which can have an impact on the absorption of this vitamin. Certain inflammatory gastrointestinal concerns such as Crohn’s disease, ulcerative colitis and even coeliac disease can interfere with the absorption of vitamin K.

What are the best vitamin K supplements?

In 1929, Danish scientist Dr Henrik Dam discovered vitamin K. The ‘K’ stands for koagulation, meaning essential for blood clotting. There are three main forms of vitamin K and include:

  • K1 – phylloquinone
  • K2 – menaquinone
  • K3 – menadione synthetic variant.

Vitamin K3 is the synthetic variant that I recommend avoiding. Vitamin K1 makes up over 90 percent of the diet and is found in green leafy vegetables including broccoli, spinach and lettuce. In recent years, there has been a lot of research on vitamin K2, which has been shown to decrease fractures and it has been approved in Japan for the prevention and treatment of osteoporosis since 1995. It is interesting to note that Japan has a much lower incidence of osteoporosis than both the US and UK. Vitamin K2 helps to carry calcium into the bones and a deficiency in this vitamin allows the calcium to be deposited onto the arteries and soft tissues of the body causing the hardening of the arteries and other cardiovascular concerns. This is also termed as calcification of the tissues.

What are the best sources of vitamin K2?

Foods with vitamin K2 include fermented foods such as natto. This is a fermented soya bean food and also provides healthy bacteria to the gut. Several studies have shown that levels of vitamin K2 after consumption of natto are far greater than the concentrations of vitamin K1 after consumption of green leafy vegetables and in fact some ten times higher. Even worse is the fact that the absorption of vitamin K1 through green leafy vegetables is highly inefficient and roughly between 10-15% gets absorbed into the bloodstream. It follows from this that natto would be an ideal source of this vital nutrient but unfortunately most people never acquire a taste for natto since it has a slippery texture and a pungent aroma. Is it a wonder given these facts that we are deficient in vitamin K?

Since natto is derived from soya, many of you will ask the question on whether it really is healthy. Soya products have had controversy as to whether they are truly healthy and many do not recommend unprocessed soya foods such as soya milks, soya cheese and burgers. This is because processing can leave toxic residues behind, possibly affecting thyroid hormones amongst others in the body. Natto is not derived from unfermented soya and in fact it is a healthy fermented soya food with a rich source of vitamin K2.

Other vitamin K sources include fermented dairy products such as curd cheese, which is often used to spread on crackers or used in cheesecakes. Even though these products contain roughly 30 times less vitamin K2 than natto, they are very palatable in comparison and can be eaten on a daily basis. I recommend curd cheese because it has a lower fat content than regular cheeses.

Vitamin K2 and its benefits

Nutrients such as calcium, magnesium and vitamin D3 play a vital role in maintaining and promoting bone health but increasingly evidence points to vitamin K's benefits in bone metabolism and healthy bone growth.

Vitamin K2 has been linked to osteoblasts, the cells that generate bone and produce a specific protein called osteocalcin. Osteocalcin acts as a framework holding the calcium in place and osteocalcin cannot perform this role without vitamin K2 since this vitamin converts it into an active bone-building form. Whilst osteoblasts are busy building bone, there are other cells called osteoclasts which break down bone and remove bone tissue. This vitamin is important because it not only enhances osteocalcin production, but it has also been shown to inhibit osteoclasts and helps maintain healthy bones. The evidence is compelling when it comes to vitamin K2 and its positive effects on maintaining healthy bones.

Other benefits of vitamin K2 include:

  • Protecting and supporting skin.
  • Promoting a healthy heart.
  • Boosting the immune system.
  • Providing powerful antioxidant protection.
  • Helping to support normal blood sugar levels.

What is the best way of getting vitamin K2?

As mentioned above, the best sources of obtaining natural source vitamin K2 is by using natto. However, for the vast majority, even after acquiring a taste for this, it simply is not the food that very few could enjoy on a daily basis. In my opinion, in order to get this vitamin, one does need to supplement, but even here there are many vitamin K2 supplements on the market.

The vitamin K2 supplement to choose must:

Use Vitamin K2 in the formula – There are several different subtypes of vitamin K2. The most important ones are MK-4 and MK-7 with several studies confirming their benefits to bones, teeth and the heart.
Be Allergen-free – The formula must be free from milk, egg, fish, peanuts, wheat, shellfish and numerous other known allergens.
Pure – That is that it should be from a reputable manufacturer with GMP (Good Manufacturing Practice) in place

The supplement that I would recommend for correcting deficiencies in the adult population would be Super K by Life Extension. This contains vitamin K2 MK-7 as well as vitamin K2 MK-4 subtypes. 

Contraindications: If you are taking anticoagulant or antiplatelet medications, or have a bleeding disorder, consult with your healthcare provider before taking this product. If you are taking a vitamin K antagonist (e.g. warfarin) consult your healthcare practitioner before taking this product. People with a rare metabolic condition called Glucose-6-phosphate dehydrogenase (G6PD) deficiency should avoid vitamin K. People who are receiving dialysis for kidney diseases can have harmful effects from too much vitamin K.

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