The fact that vitamin D helps our bodies use calcium has been extensively spoken about for some time now. An emerging topic of discussion is the fat-soluble pair – vitamin D and vitamin K. Rumor has it that vitamin D can be harmful if your vitamin K intake is low.
First, we need to understand how this correlation was made.
Vitamin D And Vitamin K Work Hand In Glove
Vitamin D promotes calcium absorption from food into the blood and, thus, regulates blood calcium levels.1 If our dietary intake of calcium is low, it extracts calcium out of the bones and into the blood to stabilize blood calcium levels. It is easy to foresee how this may adversely affect your bone health. It is also important to note that vitamin D’s priority seems to be blood calcium levels and not bone calcium levels.
Vitamin K directs the calcium in the blood to the bones and teeth for accumulation and away from soft tissues like blood vessels and kidneys.2 3 This strengthens the skeletal system and prevents the detrimental hardening of soft tissues.
Is Vitamin D Harmful Without Enough Vitamin K?
Coming back to the concern. If vitamin D levels are extremely high, it would mean higher blood calcium levels that would overshadow the effects of vitamin K. Unhealthy calcium levels pose a variety of threats like arterial plaque formation.
Here’s how one thing leads to another:
1. High Doses Of Vitamin D Cause Blood Vessel Calcification
Too much vitamin D can be toxic for you, a phenomenon called vitamin D toxicity.4 The excess vitamin D increases calcium levels to the extent that the excess gets deposited in soft tissues, including blood vessels. In addition to the life-threatening hardening of blood vessels, this irreversible calcification can cause organ malfunction.
2. Blood Vessel Calcification May Cause Heart Disease
When calcium gets deposited along the lining of blood vessels, it narrows the lumen of the vessels, restricts blood flow, and causes arterial stiffening. Studies show that blood vessel calcification is a well-recognized risk factor for heart disease.5 Thus, indirectly, high vitamin D levels can cause heart disease.
3. Vitamin K Supplements May Reduce Blood Vessel Calcification
Both animal and human studies have shown that supplementation with vitamin K can help counteract blood vessel calcification.6 Considering it’s calcium-directing role, it only makes sense. In this way, vitamin K may help reduce risks of heart disease caused due to calcification.
Long story short, there seems to be a logical connection: high doses of vitamin D encourages calcification in blood vessels, while vitamin K works to discourage this from occurring.
High Levels Of Vitamin D May Deplete Vitamin K
While you may feel thoroughly convinced that vitamin D without vitamin K can be harmful, the truth of the matter, however, is that the human body is not all that simple.
One hypothesis doing its rounds says that vitamin D itself may deplete vitamin K when present in high concentrations.7 This subtly implies that whether or not your body has enough vitamin K, high levels of vitamin D will be the overpowering factor and blood vessel calcification will take place anyhow. This may not necessarily be through elevated calcium levels.
That just interferes with our simple flow chart, doesn’t it?
Most People Are Deficient In Vitamin D
There is no scientific proof yet blatantly saying that moderate levels of vitamin D are harmful when we don’t consume enough vitamin K. As average vitamin D levels stand, this does not seem to be an immediate or even near future concern at all, particularly because every 1 out of 2 individuals in the world are deficient in vitamin D.8 Developing dangerously high levels of it may seem a little farfetched.
More Research Is Needed
The takeaway is this: According to current research, we can only say that high vitamin D levels in our body may be a concern if our vitamin K doesn’t match up. More detailed research is needed to fill in the missing links.
In the meantime, try getting plenty of vitamin D and vitamin K as they are both essential vitamins. For vitamin D, increase your sun exposure, after applying sunscreen, and consume fatty fish and fish oil. For vitamin K, consciously add leafy greens, legumes, egg yolk, liver, and cheese to your diet.
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