Unravelling Vitamin K.... the Mysterious One!

It was revealed last week that low Vitamin K status is linked to poor Covid-19 outcomes according to leading researchers.  Let's find out more about this mysterious vitamin and just how valid could that claim be? 
Written by Irene Ní Fhlannúra for West & Mid Kerry Live, June 21st 2020
There was a time when scientists believed that only four nutrients (macro nutrients) were vital for humans to survive – namely carbohydrates, fats, proteins and water.  They were on the right track for quite some time but soon were back to the drawing board after newly discovered diseases came to the fore. They noticed that even when humans had access to adequate amounts of macro nutrients, illness and even death occurred in the absence of any obvious infection, toxin or injury.  It is hard to imagine a time when we did not understand the role of vitamins in human health, but for long periods of our history, humans died of diseases of deficiencies before they copped that there was more to health than first thought. 

From around the late 19th century, the scientific community began to discover another branch of nutrients, now called, micronutrients, that were needed in smaller quantities yet essential, not only for our survival, but for our survival in good health.  The term vitamin was coined by a Polish biochemist, Casimir Funk in 1912, when he formulated the concept of vitamins or “vital amines” and paved the way for others to isolate, identify and name the vitamins now recognized to be essential to all human life.

Vitamins were named alphabetically in the order in which they were discovered, beginning with vitamin A.  They were identified in quick succession soon after first one with B, C, D and E getting their recognition. Vitamin F (linoleic acid) was put on the transfer list when it was re-classified as an essential fatty acid.  Vitamin G is now B2 and vitamin H is now Biotin, also part of the vitamin B complex.  Similarly, vitamins H and I were like the Bs, so they were put on that team too.  This explains the big gap in letters before we get to vitamin K, now you know!

What we now know about vitamins is more than what was understood a few decades ago, and less than what is yet to be discovered. Science is constantly evolving, and the human body is an intriguing yet complex subject.  Saying all that, our knowledge of vitamin K is just as fascinating as all the other vitamins, yet public awareness seems lacking.  COVID-19 has catapulted it into the limelight as scientists grapple for answers as to why some people get extremely sick and die while others go unscathed with little or no symptoms. 

Vitamin K is best known for its role in the blood clotting process.  This was discovered 1929 when Danish scientist, Henrik Dam was investigating the role of dietary cholesterol by feeding chickens a fat-free diet.  After several weeks, the chickens began to suffer from frequent bleedings which did not stop when fat was re-introduced.  Dam figured there had to be something else in the diet that prevented the bleedings.  Years (and many chickens) later, he isolated a component in hemp seed that stopped the haemorrhaging and called it the coagulation factor, soon to be known as Vitamin K.  Decades later vitamin K was further classified into K1 and K2.  Vitamin K1 (phylloquinone) is solely found in plants – green leafy vegetables, lettuce, cabbage, broccoli and brussels sprouts while K2 (menaquinone) is found in liver, eggs and fermented foods such as cheese and natto (fermented soybean).  Vitamin K2 is also produced by our own gut bacteria. These bacteria are particularly fond of the fibre found in the K1 foods (leafy greens and cruciferous plants) - eat more K1 to get more K2 seems to be the lesson here!

Babies are born without the necessary bacteria to make K2 and breast milk is a poor source of it, therefore a vitamin K injection has been recommended for newborns to prevent the risk of internal or external bleeding during their first few weeks of life, until their own bacteria kicks in. Recently K2 has been further classified into MKs - MK4 and MK7 now known to be co-factors in preventing osteoporosis and calcification of arteries.  There is a risk now that they will run out of letters!

Vitamin K in all its forms is absorbed in the small intestine, metabolized rapidly with only a small amount of it stored in our fat cells. Deficiencies can occur when there is a fat malabsorption issue (as in gall bladder disease, Crohn’s disease, Cystic fibrosis).  Defective coagulation leading to excessive bleeding and bruising is the most common symptom.  However, optimum vitamin K intake (which is always more than the RDA) is associated with improved bone density and reduced arterial stiffness.  There is no upper limit for dietary intake of vitamin K1 or K2 because it is metabolized so quickly and much of it ends up in our pee and poo.  However, those taking Warfarin or other anti-coagulants should not supplement with Vitamin K.

Preliminary research into COVID-19 suggests that patients with extreme symptoms have low Vitamin K levels.  As the researchers explain, COVID-19 causes blood clotting and leads to the degradation of elastic fibres in the lungs, which is where vitamin K may play a regulatory role.  Just as in the past, we await further advancements but, for now, we can be confident that to eat more greens, more fermented foods and take care of our gut bacteria is always a good move!