We're learning more and more every day about the human body and the vitamins and minerals we need to lead a long and healthy life. Most of us know about the different vitamins that are essential in our diets, and some of us even take dietary supplements to boost our intake of nutrients.
Vitamin K is a natural vitamin readily created in the body that may help us to avoid a number of chronic illnesses.
What is Vitamin K
Vitamin K is by no means a new scientific discovery. However, this vitamin isn't common in the western diet, and doesn't get much mainstream attention.
Vitamin K first came to people's attention back in 1929 when it was mentioned in a scientific journal as an essential nutrient for blood coagulation, or blood clotting. As the journal was German, the author coined the term 'Koagulationsvitamin' - hence Vitamin K.
Scientists thought that some unknown nutrients seemed to be protecting against chronic illness and tooth decay. Experts now think that it was vitamin K all along.
Vitamin K refers to a family of fat-soluble vitamins that the body needs to produce a protein called prothrombin. There are two forms of Vitamin K: Vitamin K1 (phylloquinone) and Vitamin K2 (menaquinone).
Vitamin K1 (phylloquinone)
Vitamin K1 can be found in plant foods like dark, green leafy vegetables, and is common in our diets overall.
Vitamin K2 (menaquinone)
On the other hand, Vitamin K2 is found in animal foods and foods that are fermented. This vitamin is therefore quite uncommon in our diets. Gut bacteria also produce Vitamin K2.
Vitamins K1 and K2: How do they work?
Research suggests that calcium metabolism, heart health and blood clotting are all affected by proteins activated by vitamin K. Vitamin K also aids energy production in cell mitochondria.
A key function of vitamin K is to regulate calcium deposition. It makes sure that bones become calcified, but blood vessels and organs do not.
Animals studies have shown that vitamins K1 and K2 may be quite different, and calls have been made by scientists to classify them as separate vitamins. These studies showed that vitamin K2 reduced blood vessel calcification, but this didn't happen with vitamin K1.
Studies in humans have also shown that vitamin K1 supplements have no significant benefits towards improving heart and bone health, while vitamin K2 supplements do.
More scientific studies on humans are needed to further investigate vitamin K and its effects on humans.
Vitamin K For Possible Heart Disease Prevention
One of the biggest risk factors for heart disease is caused by a buildup of calcium in the arteries around the heart. If we can in any way reduce the risk of this buildup, we're going in the right direction.
Vitamin K is believed to reduce this calcium buildup by preventing it from being deposited in the wrong areas of the body, like the arteries.
In two separate observational studies, a higher intake of vitamin K2 was linked to reductions in the risk of heart disease.
One study over a period of 7-10 years showed that the people with the highest intake of vitamin K2 were 52% less likely to develop artery calcification, and had a 57% lower risk of death caused by heart disease, compared to people who consumed minimal vitamin K.
Another study in women showed a 9% reduction in the risk of heart disease for every 10mg of vitamin K2 consumed per day.
The same could not be said for vitamin K1, however, which showed no influence in either of the studies.
More controlled trials are needed to study the long-term effects of vitamin K2 consumption and the positive effects it may have on the human body when it comes to preventing heart disease.
Vitamin K: Bone Health and Osteoporosis
We learn in our childhoods the importance of bone health and keeping our bones strong. As mentioned earlier, intake of vitamin K2 is essential for the metabolism of calcium, which is the principal mineral found in our teeth and bones.
Osteoporosis - meaning 'porous bones' - is quite a common illness in Western countries, especially among older women. As a result of weakened bones, osteoporosis greatly increases the risk of bone fracture.
Vitamin K2 has been shown to activate the calcium-binding action of two proteins - matrix GLA protein and osteocalcin. Each of these help to build and maintain bones, making them stronger.
One study of over 200 postmenopausal women over a 3-year period found that those who took vitamin K2 supplements had a far slower decrease in age-related bone mineral density.
In Japan, more long-term studies have been carried out among Japanese women, although much higher doses of vitamin K2 were used. Over 92% of the women studied showed significant improvements.
Vitamin K2 supplementation is now recommended officially in the treatment and prevention of osteoporosis in Japan.
Dental Health and Vitamin K
Vitamin K2 may affect dental health, according to speculation by researchers based on studies of animals. No such studies have been carried out on humans to date.
However, we know that osteocalcin is one of the main regulating proteins in dental health, and is essential for bone metabolism. Osteocalcin signals to a mechanism that stimulates the growth of new dentin, the layer of calcified tissue underneath the enamel on our teeth.
This same protein is activated by vitamin K2, so it would make sense to assume that vitamin K2 may have dental health benefits.
Vitamin K May Help Fight Cancer
As advanced as western medicine has become, there has still been no cure found for cancer. There are many ways to treat cancer, like chemotherapy, but the majority of these treatments have detrimental side effects often making patients sick and causing damage to other parts of the body.
It continues to be a race against time to find a cure, or, even better, a way to prevent cancer cells from mutating in the body.
There have been a number of clinical studies carried out using vitamin K2 on certain types of cancer.
Two of these studies have suggested that vitamin K2 can reduce the recurrence of liver cancer and increase survival time.
On top of that, a 63% lower risk of prostate cancer was found during an observational study of 11,000 men who were on a high intake of vitamin K2.
It's important to note that Vitamin K1 had no effect in this same study and that, in general, a larger number of studies will need to be carried out before any definitive statements can be made on the matter.
Vitamin K to Reduce Anxiety and Depression
Depression, anxiety, and cognitive impairment may be increased due to high blood glucose levels.
In 2016, a study was carried out to investigate the effects of vitamin K2 in rats that had metabolic syndrome, high blood glucose levels and showed symptoms of anxiety, depression, and memory deficit.
Within ten weeks, the vitamin K treatment had normalized blood glucose and had reduced symptoms of anxiety and depression. It did not, however, improve memory deficit in the rats.
How to Get Vitamin K for the Body
We've seen that vitamin K1 is widely available in green vegetables and leafy vegetables, so it's not difficult for us to include it in our diet. However, it appears from these studies that vitamin K1 isn't the vitamin that gives us all of the benefits like heart disease prevention, and bone and dental health support.
Vitamin K1 foods:
Foods that are great sources of vitamin k1 include:
- Vegetable oils
Vitamin K2 foods:
On the other hand, vitamin K2 (menaquinone) appears to have greater benefits for the human body, but it's more difficult to include in our diet.
Vitamin K2 isn't readily available in our commonly consumed food sources. Instead, it's found in some animal foods and fermented foods. Gut bacteria in the large intestine also create vitamin K2.
Our bodies are capable of converting vitamin K1 to vitamin K2, but the process isn't efficient. It is useful in that we generally consume ten times more vitamin K1 than vitamin K2 but the inefficient nature of the conversion means that we're not receiving the adequate intake.
The animal foods that vitamin K2 is found in include high-fat meat and dairy products, like grass-fed cows and egg yolks. You can also find this vitamin in liver and other organ meats, beef, pork, chicken, and fatty fish, such as salmon.
Another way of introducing more vitamin K2 into your diet is through fermented foods like sauerkraut (a fermented raw cabbage), natto (a fermented soybean) and miso (a fermented Japanese paste).
Vitamin K Supplements
As always, it's much better to consume vitamins from a natural source through a healthy diet. However, if you're unable to get your hands on vitamin K2-rich fermented or animal foods, you can opt for vitamin K2 supplements, which you can find in most health-food stores and online.
The types of vitamin K commonly available in dietary supplements include:
- Vitamin K1, in the form of phylloquinone or a synthetic form called phytonadione
- Vitamin K2, in the form MK-4 or MK-7 (subtypes of vitamin K)
If you're already taking a vitamin D supplement, you may notice even greater benefits combined with vitamin K2 intake as the two vitamins have synergistic effects.
How much Vitamin K do I need?
According to the Office of Dietary Supplements (ODS), the recommended daily intake of vitamin K for adults is 120 micrograms (mcg) for males and 90 mcg for females. There's no recommendation for vitamin K2, only mentioning vitamin K in general.
Am I Vitamin K deficient?
In the United States, very few adults are affected by vitamin K deficiency. A deficiency in this vitamin tends to only affect newborns and people who suffer from gastrointestinal disorders, like celiac disease or ulcerative colitis.
A severe vitamin K deficiency leads to longer blood clotting times. This makes a person much more prone to bruising and bleeding, and increases the risk of a haemorrhage.
Bone mineralization is more common in people deficient to vitamin K, which can lead to osteoporosis as the bones are weaker.
People can also suffer from a vitamin K deficiency if they take certain medications, like antibiotics, over an extended period of time. This kills off the gut bacteria that produce vitamin K.
Certain blood thinners such as Warfarin present a risk factor as they interact dangerously with vitamin K. Anyone who takes this medication should consult their doctor or medical practitioner before starting to take vitamin K supplements.
There are two main forms of vitamin K: vitamin K1 and vitamin K2.
To boost vitamin K intake, add more foods that are good sources of Vitamin K. Bacteria that are found living in the human gut also produce small amounts of K2.
Both forms of vitamin K are vital for blood clotting and healthy bones. With that said, vitamin K2 may also protect against certain types of cancer and heart disease.
If you're concerned about your vitamin K intake, you probably don't need to be. Vitamin K deficiency is not common, and most people get enough of this vitamin from their diet. Some gastrointestinal conditions may increase the risk of a vitamin K deficiency. It's best to speak to your doctor before considering taking vitamin K supplements.