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Vitamin D3 and K2: Better Together
Vitamin D gets a lot of attention, and for good reason. Your body needs it to absorb calcium, and many of us don't get as much as we think. Your skin makes it from sunlight, but long days indoors, sunscreen and shorter days all get in the way.
But vitamin D rarely works alone. It helps you absorb calcium, and vitamin K2 helps your body put that calcium to use. One without the other is only half the story.
Here's why vitamin D3 and K2 work best as a pair, who tends to run low, and where to find them.
What Vitamin D3 Does
Vitamin D helps regulate the amount of calcium and phosphate in your body. Those are the minerals that keep bones, teeth and muscles healthy.
The main vitamin D3 benefits:
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Calcium absorption: it helps your gut absorb calcium from food
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Bones and teeth: it supports their normal structure
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Muscles: it supports normal muscle function
Vitamin D comes in two main forms. D2 comes from plants and fungi. D3, also called cholecalciferol, is the form your skin makes from sunlight. Research comparing D3 vs D2 suggests D3 is generally better at raising vitamin D levels in the blood, which is why most supplements, Tmrw included, use it.
What Vitamin K2 Does
Vitamin K isn't one nutrient. It's a family. K1 comes mostly from leafy greens. K2 is a group of compounds called menaquinones, found in fermented foods and some animal foods.
Most vitamin K2 benefits come down to one job: activating certain proteins in your body. Two matter most here:
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Osteocalcin: a protein found in bone
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Matrix Gla protein (MGP): a protein found in blood vessel walls, bone and cartilage
These proteins need vitamin K to switch on. Without enough of it, more of them stay inactive.
K2 comes in several forms. MK-7 is one of the most studied, and it stays in the body much longer than K1, which keeps levels steadier over time. It's the form Tmrw uses.
Why D3 and K2 Work Better Together
So why take vitamin D3 with K2? Vitamin D tells your body to make more of those calcium-handling proteins, osteocalcin and MGP. But those proteins only work once vitamin K activates them.
So D3 brings calcium in and builds the tools to manage it. K2 switches those tools on.
|
Vitamin D3 |
Vitamin K2 |
|
|
Main role |
Helps you absorb calcium |
Activates proteins that use calcium |
|
Works on |
Your gut and calcium levels |
Osteocalcin (bone) and MGP (blood vessels) |
|
Where you get it |
Sunlight, fatty fish, egg yolks |
Fermented foods, cheese, eggs, chicken |
|
Why it needs the other |
Makes proteins that need K to work |
Works on proteins that D helps produce |
Researchers who have looked at how the two interact say getting enough of both appears to support bone and heart health, and that taking them together may work better than either one alone.
Who Tends to Run Low on Vitamin D
Vitamin D deficiency is common, partly because vitamin D is found in very few foods, so most of us rely on the sun. That makes it easy to fall short, especially if you:
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Spend most of the day indoors: office jobs, commutes and screen time all cut sun exposure
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Go through darker months: when days are short and the sun sits low, your skin makes much less vitamin D
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Cover up outside: clothing and sunscreen block the UV light your skin needs
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Have darker skin: more melanin means your skin makes less vitamin D from the same amount of sun
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Are getting older: aging skin makes far less vitamin D from sunlight than younger skin
K2 is harder to track, since it isn't part of routine blood tests. Your gut bacteria make some, but it's unclear how much your body actually absorbs. And the richest food source, natto, isn't on most people's plates.
Where to Find D3 and K2 in Food
Vitamin D3 is in short supply in most diets. Foods high in vitamin D include:
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Fatty fish like salmon and mackerel
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Egg yolks
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Red meat and liver
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Fortified foods, like some cereals and spreads
Vitamin K2 foods are mostly fermented or animal-based. The main sources are:
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Natto (fermented soybeans), the richest source of MK-7
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Hard cheeses like cheddar
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Eggs
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Chicken and chicken liver
Natto is in a league of its own. Outside of that, most everyday foods offer only small amounts of K2, and very little MK-7.
Why It's Hard to Get Enough From Food and Sun Alone
In theory, you could cover both with sunshine and the right foods. In practice, it's harder than it sounds:
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Sunlight is unreliable: time of day, season, cloud cover, sunscreen and skin tone all change how much vitamin D your skin makes.
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Few foods contain vitamin D: fatty fish like salmon and mackerel are among the only good sources, and most people don't eat them often.
-
The best K2 food is an acquired taste: natto is the richest source, and most people never eat it.
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Everyday K2 sources are small: cheese, eggs and chicken contain only modest amounts, and mostly not as MK-7.
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They need fat to absorb: D3 and K2 are both fat-soluble, so they're absorbed best alongside some fat.
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Your levels are invisible: without a blood test, most people have no idea where their vitamin D sits.
The answer isn't a perfect diet. It's a simple routine you can stick to every day, sunny or not.
How Tmrw Includes Both
Every scoop of Tmrw includes vitamin D3 and K2 together, so you're not relying on sunshine or natto to cover them.
|
Ingredient |
Form |
Per scoop |
|
Vitamin D3 |
Cholecalciferol |
1,000 IU (25 mcg) |
|
Vitamin K2 |
MK-7 |
100 mcg |
They sit alongside 86 other science-backed ingredients, from probiotics and minerals to antioxidants and amino acids. That means the partners D3 and K2 work with, like magnesium, are already in the same drink.
Want to take it a step further? Pair your scoop with Tmrw Omega. Its healthy fats help your body absorb the fat-soluble nutrients in Tmrw, including D3 and K2.
One scoop in water each morning, and that's your daily vitamin D and K2 covered, all year round.
Try Tmrw today and see what a better daily ritual feels like.
Sources
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NHS. Vitamin D.
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National Institutes of Health, Office of Dietary Supplements. Vitamin K: Fact Sheet for Health Professionals.
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Tripkovic L, et al. Comparison of vitamin D2 and vitamin D3 supplementation in raising serum 25-hydroxyvitamin D status: a systematic review and meta-analysis. American Journal of Clinical Nutrition, 2012.
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Schurgers LJ, et al. Vitamin K-containing dietary supplements: comparison of synthetic vitamin K1 and natto-derived menaquinone-7. Blood, 2007.
-
van Ballegooijen AJ, et al. The Synergistic Interplay between Vitamins D and K for Bone and Cardiovascular Health: A Narrative Review. International Journal of Endocrinology, 2017.
-
MacLaughlin J, Holick MF. Aging decreases the capacity of human skin to produce vitamin D3. The Journal of Clinical Investigation, 1985.
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