Vitamin D3 and K2: Why This Nutrient Pair Works Better Together
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Why does vitamin D3 come with K2?
Vitamin D and K have become a bit of a Batman and Robin vitamin pairing. Much like the crime-stopping duo, vitamin D gets most of the attention, but without vitamin K as its sidekick, your body can’t manage calcium quite as effectively.
Vitamin D helps your body absorb calcium from the food you eat. Vitamin K2 activates proteins that help guide calcium to the places it’s needed most, like your bones and teeth, while helping to stop it building up where it isn't, such as the walls of your blood vessels. Doesn't sound like an emergency? Hold that thought.
Most of us in the UK are well versed in upping our vitamin D intake. Our endless winters and sunless summers mean a huge number of us struggle to maintain healthy levels through sunlight alone.
What’s less gen-pop-intel is why there’s a balancing act required to keep calcium levels in your body healthy and safe. Read on, reader.
What do vitamins D and K do?
Before the science gets sciencey, let’s go right back to basics. Vitamin D and K are fat-soluble vitamins, which means your body absorbs them best with fat.
You likely know that vitamin D, aka the sunshine vitamin, is so-called because our skin makes it when it’s exposed to sunlight. You can also get smaller amounts from foods like oily fish, eggs and fortified dairy. Less well known is that vitamin D acts more like a hormone than your bog-standard vitamin. Once it's been processed by the liver and kidneys, it becomes calcitriol, its active form.
Its best-known job is helping your body absorb calcium, the main mineral needed for normal bones and teeth. Without enough vitamin D, your body can’t use calcium properly, which is why severe deficiency leads to rickets (not an old wives' tale, no) in children and soft bones in adults.
Vitamin D also supports normal muscle function and immune function, and vitamin D receptors have been found in tissues throughout the body, including the heart. In supplemental form, vitamin D is produced as either D2 or D3. Vitamin D2 typically comes from yeast, and vitamin D3 from sheep wool or lichen (like our Beam & Balance). D3 is generally considered more effective at raising and maintaining vitamin D levels than D2.
Vitamin K is another fat-soluble vitamin. There are two main types of K: K1, or phylloquinone, and K2, or menaquinone. Both have catchy names.
Vitamin K1 is found mainly in green leafy vegetables and is primarily used by the liver to support normal blood clotting. Vitamin K2, found in fermented foods and some animal foods, has a different job. It travels beyond the liver, activating proteins involved in bone health and healthy blood vessels. The two most important proteins osteocalcin and matrix Gla protein. This is where we get a bit more science. Osteocalcin helps bind calcium into bone. Matrix Gla protein helps inhibit calcium from being deposited in blood vessel walls. You can read much more about it in our guide to K2.
The moral of the story is simple: vitamin D helps the body absorb calcium. Vitamin K2 helps your body use that calcium properly. That’s why these two supplements are often found together, and why researchers love to think about the relationship between the two so much so that it even has a name: the calcium paradox.
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The calcium paradox explained: yes, this is a real thing
The calcium paradox is a lot less mysterious than its title suggests. It describes something researchers have observed as we age: calcium in bones can decrease, while calcium deposits in other parts of the body, including blood vessels, can increase.
The paradox is that we gradually get less calcium where we want it, and more where we don’t (agreed: not quite the definition of a paradox, but still).
Over time, lower bone mineral density can increase the risk of osteoporosis and fractures. Calcium buildup in blood vessel walls can also contribute to vascular calcification, making arteries stiffer and less flexible.
This is where the vitamin D3 and K2 come in. Vitamin D3 helps your body absorb calcium, supporting bones and teeth. Vitamin K2 activates proteins involved in calcium regulation. Osteocalcin helps bind calcium into bone, while matrix Gla protein helps inhibit calcium being deposited in blood vessel walls. Now you know as much as we do about the great calcium paradox.
Why should I take vitamin D2 and K2 together?
Because the science indicates that your body uses them as a team. Research suggests that vitamin D3 and K2 work together to support healthy calcium metabolism in the body (if you're wondering what that actually means, jump to our explanation of the calcium paradox). In short: vitamin D3 helps your body absorb calcium from food, while vitamin K2 activates those silly-sounding proteins that put calcium to work in your bones and teeth, while helping to regulate where calcium is being deposited in the body.
We recommend it. It’s why our high-strength vitamin D spray includes vitamin K2. As nutrients go, they sound pretty low on the ‘critical’ list. But healthy levels of both are important for bone, cardiovascular and immune health. Here's where these two start to sound rather interesting.
Vitamin D helps your body absorb calcium. It needs to. Calcium is everywhere. In fact, your body needs it so much so that when there isn't enough circulating, it starts to raid your bones (eek). Over time, this can lead to lower levels of bone density, increasing the risk of osteoporosis.
This becomes particularly relevant during perimenopause and after menopause. As oestrogen levels fall, bone loss accelerates, making healthy calcium regulation more important than ever. Researchers are increasingly interested in the role vitamin K2 plays in supporting this process.
Our arteries carry oxygen-rich blood from the heart to the rest of the body. As we age, calcium can build up in blood vessel walls, contributing to vascular calcification and making arteries stiffer over time.
One of vitamin K2’s biggest jobs is to activate matrix Gla proteins (there it is again), which helps inhibit calcium from being deposited in blood vessel walls. Researchers are also exploring how healthy vitamin D3 and K2 levels may support metabolic health, including insulin sensitivity, which plays an important role in long-term cardiovascular health and potentially reducing the risk of heart disease.
Vitamin D3 and K2 are both team players supporting the immune response. Short-term inflammation is essential and a normal part of healing, but when the body becomes stuck in chronic inflammatory cycles, it can contribute to a range of health conditions.
Vitamin D plays a role in developing immune cells that support the body's natural defence against invading pathogens. Many of our immune cells contain vitamin D receptors. Once vitamin D binds to these receptors, it stimulates the production of two antimicrobial peptides called cathelicidin and β-defensin-2 (keep up, there will be a test at the end), which help to keep harmful bacteria at bay. They also play a role in autophagy, a natural process that removes or recycles damaged cells or bits of cells we no longer need.
Lower levels of vitamin D have been associated with autoimmune conditions, although these are complex diseases with many contributing factors.
The story of K2 and the immune response is still unfolding. Early studies indicate that K2 might also help regulate inflammation, but we’re not to get too excited about this until much more research has been done.
If you want to learn more about the best supplements for your immune system, our guide has all the answers.
We shan’t get ahead of ourselves here, either, but vitamin D is being investigated for its anti-inflammatory properties and K2 for its role in supporting healthy tissue, both of which may have knock-on effects for the elasticity and health of our skin. Watch this space.
In summary, the research into these two sounds pretty serious. Yes. However, it’s an easy fix, which is why we based an entire range of vitamin D products on this science and ensured they contain vitamin K2.
How much vitamin D3 and K2 should I take daily?
Getting enough vitamin D3 depends on your diet, lifestyle and how many sunlight hours you get day to day. Beach lifeguards and underground car park attendants, take note. These factors can all affect how much vitamin D3 you need, which is why regularly testing your vitamin D levels is the best way to understand what’s right for you.
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Vitamin D
The official recommendations for vitamin D are fairly broad-brush. In the UK, the NHS recommends 400 IU per day, particularly during autumn and winter, because “around 1 in 6 adults and almost 20% of children” have lower than recommended levels of vitamin D.
Some health experts recommend much higher doses. Dr Rhonda Patrick, for example, has discussed intakes around 4,000IU. The Institute of Medicine set 4,000IU limit as the tolerable upper intake level for adults, meaning it’s considered a safe upper limit for most people, rather than the standard recommended dose.
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Vitamin K
Vitamin K2, on the other hand, does not currently have the same established upper intake limit. Most adults need around 90-120 mcg of vitamin K per day, although up to 300mcg may be optimal. The NHS recommends calculating your daily intake based on your weight: 1microgram per kilogram of your body weight. So if you’re 65kg, you will need 65 micrograms a day of vitamin K.
Yes. We’re not into calculating it either. So we’ve made our Beam & Balance to help people who want to get the right amount of vitamin D3, and vitamin K2 ratio. So you don’t have to do another daily maths operation.
Are vitamins D3 and K2 Safe To Take Together?
Yes, generally speaking, vitamin D3 and K2 are safe for most people when taken at recommended doses. However, some people may experience a mild upset stomach after taking K2, but the main thing is to be aware of its medical interactions.
Good to know
Both vitamin D3 and K2 are fat-soluble, so medicines that affect fat absorption, like orlistat, might impact how they are absorbed in the body.
Vitamin D3 can interact with some medicines, such as steroids, thiazide diuretics, and some cholesterol-lowering medicines, because these can affect vitamin D absorption, metabolism, or calcium levels.
Vitamin K2 needs a little extra care if you take blood-thinning medication such as warfarin. Vitamin K plays an important role in normal blood clotting, so sudden changes in vitamin K intake can affect how these medicines work. If you take warfarin or similar anticoagulants, speak to your doctor before taking vitamin K2. Long courses of certain antibiotics and some cholesterol-lowering medicines may affect vitamin K levels too.
As always, if you take regular medication, are pregnant, breastfeeding or managing a health condition, check with your GP, pharmacist or practitioner before starting a new supplement.
BEST SOURCES OF VITAMIN D AND K2
1. BEST FOOD SOURCES OF VITAMIN D
We can get a small amount of vitamin D3 from our diet, but usually not enough to maintain optimal levels on its own. Aside from fortified foods, good sources include:
- Fatty fish, e.g. sardines, salmon, mackerel
- Egg yolks
- Beef liver
Otherwise, a good, healthy dose of sun exposure or supplementation is the only way to make up that balance.
2. BEST FOOD SOURCES OF VITAMIN K2
As for vitamin K2, the most bioavailable form (Mk-7, for more on this, jump here) is found in the following foods:
- Natto, a Japanese fermented soybean dish (an acquired taste!)
- Cheeses made using specific bacterial fermentation, such as Jarlsberg
- Sauerkraut and other fermented foods
Smaller amounts are also found in butter, free-range egg yolks and meat from grass-fed or outdoor-raised animals.
How to choose the best Vitamin D and K Supplement
Supplemental forms of vitamin D and K have their own subtypes. Quickly, to save the scroll:
Vitamin D comes in two supplemental forms. D2 typically comes from yeast, while D3 comes from sheep wool or lichen. Both can raise vitamin D levels, but D3 is generally preferred because it tends to raise and maintain vitamin D levels more effectively.
Vitamin K2, also known as menaquinone, is available in many subtypes, named after the length of their molecular chain. MK-7 is most commonly used in combined supplements because our bodies absorb it well and it lasts much longer.
Liquids and sprays offer ease of use and flexibility in dosing. Some sprays can be taken sublingually, fancy way of saying under the tongue, which may help with absorption and makes them very easy to take daily.
What about Vitamin D and Fish Oil?
Yes. If you look at the nutritional stats, oily fish should be a rich source of vitamin D. However, during the careful purification of fish oil for omega-3 supplements, the vitamin D is left behind.
Found together in nature, omega-3 and vitamin D are excellent nutritional partners. They have complementary roles in supporting immune function, cardiovascular health, and the maintenance of healthy bones. There’s also growing research into how both nutrients contribute to brain health, with emerging research exploring their role in mood regulation and cognitive performance.
Taking a vitamin D supplement like Beam & Balance alongside an omega-3 supplement is a great way to reunite these nutrients back together.
If you’d rather not rattle, we have a handy two-nutrients-in-one option. Rise & Shine provides 1,600mg of total omega-3, including 1,035mg EPA and 470mg DHA, together with 1,000 IU of vitamin D3 per daily serving (2 capsules)
Rise & Shine doesn’t contain vitamin K2 because it’s designed as an everyday omega-3 supplement with vitamin D. If your vitamin D levels are low or deficient, and you’re looking to increase them more quickly, Beam & Balance provides a higher dose of vitamin D3 alongside vitamin K2.
So what does it mean for your body?
There’s a lot of science behind the pairing of vitamin D3 and K2, but don’t let it spellbind you. The simple version goes like this: vitamin D3 helps your body absorb calcium, while vitamin K2 helps your body put it to use in the right places.
That’s why the two are so often found hanging out in supplements together. They support the bigger picture: healthy bones, blood vessels, and balanced calcium metabolism.
Taking vitamin D without K2 doesn’t spell disaster. It won’t automatically mess with your body. But the evidence does suggest that adding K2 is a smart idea if you’re supplementing with higher doses of vitamin D3.
We’ve taken the decision out of it, so you don’t have to overthink it.
FAQ
What is the benefit of taking vitamin D3 and K2 together?
This pair are a bit like Batman and Robin. They work better together. Vitamin D3 helps the body absorb calcium from food. Vitamin K2 activates proteins that help the body use calcium properly, including supporting bone mineralisation and healthy blood vessels. Taken together, they support calcium metabolism, which is why they are often paired in supplements.
Frequently asked question
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Can I take vitamin D3 without K2?
Yes. It’s not dangerous. Taking vitamin D3 without K2 doesn’t immediately spell disaster. There is no evidence that vitamin D3 alone is automatically harmful. However, K2 supports calcium regulation by activating vitamin K-dependent proteins, so it may be useful alongside regular or higher-dose vitamin D3 supplementation.
Who should not take Vitamin D3 and K2?
Vitamin D3 and K2 are safe for most people, taken at recommended doses. The only exception would be for people taking blood-thinning medication, such as warfarin, who should speak to a doctor before taking vitamin K2, as vitamin K can affect how these medicines work. Anyone who is pregnant, breastfeeding, taking regular medication or managing a medical condition should seek professional advice before starting a new supplement.