Daily D3/K2

Daily D3/K2 is a foundational fat-soluble vitamin formula built around 5,000 IU of vitamin D3, dual-form vitamin K2 (MK-4 and MK-7), magnesium taurate, and boron glycinate. It supports vitamin D status, calcium absorption and utilization, bone health, and cardiovascular health.‡

The formula doesn't contain calcium itself — most adults get enough calcium from diet. What Daily D3/K2 supports is the body's ability to absorb dietary calcium efficiently (the D3 side) and direct it to the right tissues (the K2 side), with magnesium and boron as cofactors that the D and K pathways depend on.‡

One capsule daily with breakfast or another meal containing fat.

Because vitamin D doesn't do its job alone — and supplementing D3 without K2 can leave a meaningful gap in the system.‡

Vitamin D3's primary role is supporting calcium absorption from the gut. Once calcium is in the bloodstream, where it goes next matters: calcium belongs in bones and teeth, not in arterial walls or soft tissue. The proteins that direct that traffic — osteocalcin (which binds calcium in bone) and matrix Gla protein (which keeps calcium out of arterial walls) — are vitamin K-dependent. They require vitamin K2 to become "carboxylated," the activated form that lets them do their work.‡

Vitamin D3 helps you get calcium in. Vitamin K2 helps it go where it's supposed to. Taking D3 without adequate K2 is supporting one half of the system while leaving the other under-resourced.‡

Reference: Vitamins D and K synergy review — https://pmc.ncbi.nlm.nih.gov/articles/PMC5613455/

Vitamin K2 isn't a single molecule — it's a family of menaquinones, and the two best-studied forms behave very differently in the body. Daily D3/K2 includes both because each covers a gap the other leaves.‡

MK-7 has a long circulating half-life (roughly three days), so a modest daily dose builds and sustains steady serum levels. It's the form most associated with systemic activation of vitamin K-dependent proteins like matrix Gla protein, which supports cardiovascular pathways. Daily D3/K2 provides 180 mcg of MK-7 per capsule — the dose used in most of the relevant cardiovascular and bone trials.‡

MK-4 has a much shorter half-life (about one hour) and is the form tissues preferentially use locally. Bone-related research on vitamin K2 has historically centered on MK-4 at higher doses, where it appears to play tissue-level roles that MK-7 doesn't fully replicate. Daily D3/K2 provides 2,000 mcg of MK-4 per capsule — meaningful, but well below the pharmacological 45 mg doses sometimes used in clinical research.‡

Pairing a long-acting systemic form with a higher-dose tissue-active form gives broader coverage of vitamin K-dependent pathways than either form alone. As for the question of the "best D3-to-K2 ratio" — there isn't a single universally accepted answer. Optimal status depends on diet, sun exposure, labs, medications, and health history. Daily D3/K2's combination is designed as a practical foundation for adults seeking daily support across the relevant pathways.‡

References:

• MK-7 and bone quality review — https://pmc.ncbi.nlm.nih.gov/articles/PMC7230802/
• Vitamin K2 and cardiovascular health — https://pmc.ncbi.nlm.nih.gov/articles/PMC8596038/

Both are cofactor doses, not primary mineral sources — small amounts of specific chelated forms chosen for absorption and to round out the vitamin D and K pathways.

Magnesium is required for vitamin D3 to be activated and used. Vitamin D enters the body as cholecalciferol (the D3 form) and has to be converted twice — first in the liver to 25-hydroxyvitamin D (the form measured on most lab tests), then in the kidneys to 1,25-dihydroxyvitamin D (the bioactive form). Both conversion steps are magnesium-dependent. Inadequate magnesium can blunt the response to vitamin D supplementation regardless of how much D3 you take.‡ Daily D3/K2 provides 15 mg of elemental magnesium as magnesium taurate — taurate is selected for its cardiovascular-supportive profile.‡

Boron has a less well-defined role but is involved in mineral metabolism and appears to support vitamin D status, bone-related pathways, and healthy hormone metabolism.‡ Daily D3/K2 provides 1 mg of boron as boron glycinate, a chelated form selected for absorption.

These doses are intentionally functional rather than therapeutic. If you want a clinically meaningful magnesium dose, Mag² + Boron is the dedicated magnesium product.

References:

• Magnesium and vitamin D activation — https://pubmed.ncbi.nlm.nih.gov/29480918/
• Boron and vitamin D — https://pmc.ncbi.nlm.nih.gov/articles/PMC4712861/

5,000 IU is higher than the basic RDA (600–800 IU), but the RDA was designed to prevent overt deficiency (rickets, osteomalacia), not to optimize 25-hydroxyvitamin D status. A 2014 reanalysis of the original Institute of Medicine data identified a statistical error in the RDA calculation; with the correction applied, approximately 8,900 IU/day would be needed for 97.5% of adults to reach the 50 nmol/L (20 ng/mL) threshold the IOM itself was targeting. Many adults, particularly those with limited sun exposure, darker skin tones, higher body weight, or low baseline status need substantially more than the RDA to reach the range many clinicians target. The Endocrine Society characterizes up to 10,000 IU/day as appearing safe for most healthy adults in long-term use.‡

The honest answer: whether 5,000 IU is the right daily dose for you depends on your baseline 25(OH)D level, body weight, sun exposure, season, and other supplements you take. The cleanest way to know is to test.

Reference: Veugelers & Ekwaru, Nutrients, 2014 — https://pmc.ncbi.nlm.nih.gov/articles/PMC4210929/

One capsule daily, with breakfast or another meal containing some dietary fat.‡

Both vitamin D3 and vitamin K2 are fat-soluble, which means absorption depends on the presence of dietary fat in the gut at the same time as the capsule. Taking D3/K2 with a low-fat meal or on an empty stomach can meaningfully reduce how much of the dose actually gets absorbed. The meal doesn't need to be high-fat — eggs, avocado, full-fat yogurt, olive oil on something, butter on toast, any meal with moderate fat works.

A few practical notes:

• Morning works well because it pairs with breakfast for most people.
• If you sometimes skip breakfast, take it with the next meal that has fat in it. Daily consistency matters more than the specific time.
• If you eat a strictly low-fat diet, take D3/K2 with whichever meal has the most fat — even small amounts (5–10 g) substantially improve absorption.

Yes. Daily D3/K2 is a foundational daily morning capsule that stacks cleanly with the rest of the modular formulary.

In the Marek daily schedule, Daily D3/K2 sits with the other "with breakfast, with food" capsules: Methylate, Thyroid Support, P5P+, and Berberine⁵ (first dose). Take them together; the meal-with-fat requirement covers all the fat-soluble nutrients in this group.

Consult your healthcare provider before starting Daily D3/K2 if you:

• Take blood-thinning medication (warfarin, Coumadin, or other vitamin K-sensitive anticoagulants). Vitamin K can interfere with the action of these medications, and dose adjustments are required if you start, stop, or change a K-containing supplement.
• Have hypercalcemia, hyperparathyroidism, or another disorder of calcium metabolism.
• Have kidney disease or impaired renal function. Vitamin D activation occurs in the kidneys, and high-dose D supplementation can affect calcium handling in ways that matter for people with kidney disease.
• Have granulomatous disease (sarcoidosis, tuberculosis, lymphoma), which can cause abnormal vitamin D metabolism.
• Are taking other vitamin D supplements or high-dose multivitamins — verify total intake.
• Are pregnant or nursing.
• Already have 25(OH)D levels at the high end of the reference range.

Daily D3/K2 is a dietary supplement and is not intended to diagnose, treat, cure, or prevent any disease. If you're managing a condition or under medical supervision, work with your provider to determine whether high-dose vitamin D fits your protocol.