Vitamin D3 has been in the spotlight because of its critical role in immunity, bone health, and mood stability, but there is a lesser known partner that is equally vital in making sure D3 works as it should: vitamin K2.
Most people with D3 supplements do believe that they're more optimally maintaining bone health and reducing long-term disease risk. But without vitamin K2, the strategy will not be nearly as effective as it seems to be. So much so, in fact, that consuming very high levels of vitamin D3 in the absence of vitamin K2 may even cause the body to misdirect calcium. Instead of being deposited into bones and teeth, it could accumulate in arteries and soft tissues and cause calcification over the long term.
What Does Vitamin D3 Do?
Vitamin D3, or cholecalciferol, is the active vitamin D form produced in your body when your skin is exposed to sunshine. It works more like a hormone than a typical vitamin, controlling more than 200 genes and affecting everything from mood to immune function.
The main advantages of vitamin D3 are:
• Increased gut absorption
• Modulation of the immune system
• Regulation of mood and mental health
• Muscular and skeletal maintenance
• Hormonal regulation
Low D3 levels are associated with higher risks of infection, osteoporosis, mood disorders, and even cardiovascular disease. Given that sunlight is scarce in the UK and Northern Europe, supplementation is not only useful but actually essential.
The Overlooked Role of Vitamin K2
Vitamin K2 is part of the vitamin K family, which is most famously used for blood clotting, but K2 is more than that. It guides proteins that allow calcium to reach the bones and exclude it from arteries and organs where it is not required.
Two are the main types of K2:
- MK-4: Part of animal sources and has a shorter half-life.
- MK-7: This is obtained from fermented food sources like natto, and has a longer half-life that makes it more potent in supplement form.
The two most important proteins that vitamin K2 activates are:
- Osteocalcin: It directs calcium to the bone matrix.
- Matrix Gla Protein (MGP): Inhibits calcium from being deposited in the arteries.
Without enough K2, even if your vitamin D3 is doing its job of increasing calcium absorption, that calcium can be in the wrong places.
Why You Should Take D3 and K2 Together
The magic starts when D3 and K2 are taken in combination. D3 increases the uptake of calcium into the bloodstream, and K2 ensures that it gets deposited where it's supposed to be: in your bones and teeth, not in your arteries.
Here's what the research says:
A 2017 journal article from the Integrative Medicine reemphasized that the interaction between D3 and K2 is necessary to prevent arterial calcification and improve bone mineral density.
A 2012 journal article published in Thrombosis and Haemostasis noted that patients who received both D3 and K2 had a much better outcome in calcium metabolism than those who received D3 supplementation alone.
Epidemiologic studies have found that populations with high K2 consumption (mainly in Japan) have decreased cardiovascular and osteoporosis prevalence.
Such synergy is particularly vital in those individuals who are getting older, menopausal, or using more substantial doses of D3 when winter or the period of less sunlight sets in.
The Problem With Taking D3 Alone
Most traditional supplements provide vitamin D3 alone, and that can become an issue in the long run, particularly with extended use. When D3 raises calcium absorption without having any mechanism for how that calcium will be directed, the threat of stiffening of arteries and calcification of vessels rises.
You may not feel the effects immediately, but the overall effects can reach you after several years. Because of this, high-dose D3 monotherapy is contraindicated in functional and integrative medicine without the concomitant administration of K2.
Who is D3 with K2 Good For?
This combination is typically suitable for most adults, especially those who:
- Live in low-sunlight regions
- Work indoors during the day
- Are above 40 years old
- Are pregnant or lactating
- Are at risk of osteoporosis or heart disease
- Are taking calcium or vitamin D supplements
- Follow a dairy-free or vegan diet
In all of these situations, using D3 supplementation by itself may not give you the full benefit and may cause misdirection of calcium if K2 levels are low.
Successful Supplementation with D3 and K2
If you're already supplementing vitamin D3, read what you have. If it isn't with a K2 in the formulation and specifically MK-7, take each individually in supplement form with a K2 or switch to a blended supplement.
Individual optima differ by health status, but following is a clinical combination that can be generally used:
- 1000 to 4000 IU D3
- 90 to 200 mcg of K2 in MK-7 form
The amounts are both effective and safe for long-term bone and cardiovascular health.
Conclusion
Vitamin D3 and vitamin K2 complement each other, but they are also interdependent. Taking one without the other is like building a house and failing to put in the foundation. D3 helps the body absorb calcium, but K2 makes sure it is put to use in the right places.
If you value bone density, cardiovascular health, and aging well, make sure your vitamin D supplement contains K2.
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