Vitamin K refers to a group of structurally similar, fat-soluble vitamins that the body needs to produce a protein (prothrombin), which promotes blood clotting and regulates bone metabolism. In other words, it produces the necessary components without which the blood coagulation process would not work. Vitamin K naturally occurs in two forms:
- K1 or phylloquinone is mostly found in plant foods and occurs naturally in dark leafy green vegetables. However, the body has difficulty absorbing K1 from plant foods, because it is fat-soluble substance. That is why eating dietary fats, such as plant oils butter, may enhance the body’s absorption of K1 from plants.
- K2 or menaquinone is present in meat, dairy products and fermented foods. About 1/5 of necessary K vitamin levels we get from menaquinone. Our gut bacteria also produce K2, it can synthesize K1 into K2.
The body needs vitamin K for the carboxylation of glutamic acid (Gla), in other words for carbon binding. The presence of Gla in certain proteins also allows binding of calcium. Bone tissue consists several Gla-containing proteins, some of which play an important role in the regulation of bone growth and mineral deposition, but also in the elasticity of soft tissues.
Recent clinical studies have shown that taking vitamin K2 supplement could help reduce the bone loss that women suffer with age and could also improve cardiovascular health through the reduction of arterial stiffness.
Even more, taking vitamin K2 supplements could also help prevent the loss of elasticity in the skin and reduce varicose veins. That`s why it is nature’s unacknowledged anti-ageing supplement.
How do We Get this Vitamin – The Best Natural Sources
Our body absorbs vitamin K from the small intestine, after that it is transported to the lymph. The lymphatic system stores it in the liver, but also in bone tissue, adipose tissue, the pancreas and the heart. When looking at the supply of various fat soluble vitamins in the body, the total supply of vitamin K is quite modest. This is primarily due to the rapid effect of phylloquinone synthesis.
Therefore, it is very important to ensure a steady supply of this vitamin. As even a short period without the necessary sources will cause a rapid drain in your body vitamin stocks. Health problems such as poor absorption of fats directly affects the absorption of vitamin K, because without dietary fats, it cannot absorb properly.
The bioavailability of phylloquinone as the main synthesizer of vitamin K in food is approximately 1/10. Meaning, it is very low compared to the phylloquinone bioavailability in dietary supplements.
- The main sources of phylloquinones (K1) are dark green leafy vegetables, vegetable oils and fats. Also foods such as parsley and other herbs, nettle, Brussels sprouts, spinach, wheat germ, cauliflower, broccoli, rapeseed oil, cabbage, wheat bran, potatoes, oats and corn.
- Your body obtains menaquinones (K2) mainly from animal products such as meat and liver, soybean meals, egg yolk, fermented foods such as sauerkraut and dairy products.
Vitamin K Benefits
- Bones. Vitamin K is associated with bone mineralization, meaning that bone density maintains its normal state better when consuming adequate amounts of this vitamin. So it promotes healthy bone mineral density by carboxylation of osteocalcin, a protein that binds calcium to bones. It has also been found beneficial to combine this vitamin with calcium and vitamin D, which results in improved bone density.
- Heart. Vitamin K affects also your heart health, especially in terms of preventing heart conditions, lowering the risk of cardiovascular damage and improve overall health of the heart. It is inevitable that in old age calcification of the blood vessels can happen, which makes blood vessels less elastic and narrow. This can eventually lead to ischemic heart disease. Vitamin K has an indirect positive effect on the coronary arteries of the heart. Coronary arteries directly supply the heart with nutrients.
- Cancer. Several experiments have shown that due to its antioxidant properties, vitamin K2 also has some anti-cancer effects. In addition, findings suggest that K2 may suppress genetic processes that lead to tumor growth.
- Diabetes. Maintaining a normal level of vitamin K can also alleviate inflammation and positively influence insulin regulation, thus helping prevent diabetes.
- Anxiety & depression. High blood glucose levels may increase a person’s risk of developing anxiety, depression, and cognitive impairment. According to a 2016 study which investigated the effects of vitamin K2 in rats, after 10 weeks treatment with vitamin K had normalized blood glucose and reduced symptoms of anxiety and depression.
- Elasticity. Helps to prevent the loss of elasticity in the skin and helps to reduce varicose veins.
According to a study done in 2019, vitamin K2 (in the form of MK-7) is 10 times more absorbable than vitamin K1. It has been found, that vitamin K from menaquinones, in particular all-trans MK-7, will give the best results. The MK-7 is preferred over both – phylloquinones and other menaquinones (such as MK-4), mainly because of its longer duration of action.
Therefore, the same amount will at substantially the same time, do more work, thus having a much greater efficacy at the usual dose. It is important that, for example, before taking MK-7 supplements, you determine that it is an all trans variant.
Vitamin K2 Deficiency Symptoms
The first symptom of vitamin K deficiency is bleeding. It is especially dangerous for newborns, as they may have intracranial bleeding due to a deficiency of this vitamin.
The main risk of suffering from deficiency is due to inadequate absorption of this vitamin because of the use of antibiotics, blood thinners and parenteral nutrition.
Your daily diet can also be the cause of insufficient absorption. Because the absorption directly depends on the amount of consumed fats, so if your diet does not consist enough fats, vitamin K cannot absorb. At the same time, the fact that some persons cannot break down fats, can influence the absorption. For example, this can occur in case of removed bile.
Vitamin K2 deficiency can cause following health conditions:
- blood clotting problems;
- more prone to bruising and bleeding;
- increased risk of hemorrhage;
- inadequate bone mineralization, which can lead to osteoporosis.
Vitamin K Deficiency Risk Groups
- People with certain gastrointestinal disorders, such as ulcerative colitis, celiac disease or removed bile.
- People who take long courses of antibiotics, as antibiotics can kill the gut bacteria that produce vitamin K.
- Persons who take cholesterol-lowering medications, as some of these medications can also interfere with the body’s ability to absorb this vitamin.
- People who take blood thinners, such as warfarin, because it can interact dangerously with the vitamin.
It is extremely important for people taking these medications to consume the same amount of dietary vitamin K supplements each day. Also, it is vital to speak to a doctor before taking supplements or making any dietary changes.
Vitamin K – Required Amounts and Availability
There is no consensus on how much vitamin K should be consumed, because it is almost impossible to achieve clinical deficiency symptoms with poor nutrition. However, the estimated daily requirement is about 75µg. Our own microbiome also produces vitamin K2, but it is certainly not enough to maintain normal levels.
The recommended daily intake, regardless of age, is 1 µg / kg body weight.
The average amount of vitamin K in breast milk is 2.5 µg / l. However, this is too low, so newborns will get prophylactic injections of this vitamin to prevent both – brain and other bleeding.
In case of taking naturally sourced vitamin K, there has not yet been found upper limit or toxic amount, but that does not mean that it may not be. Therefore, you should not over-consume the recommended amount on your own initiative. However, the synthetic version of this vitamin can have a negative effect on the liver and hematopoiesis.
For conclusion, if you do not have a varied diet, it is worth to take vitamin K2 dietary supplements.
Edited by Ecosh: Maria-Helena Loik
Compiled by Maria-Helena Loik
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